turning the tide, tidal power in the...

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Sustainable Developm

ent Comm

ission

The Sustainable Development Commission is the Government’s independent watchdog on sustainable development, reporting to the Prime Minister, the First Ministers of Scotland and Wales and the First Minister and Deputy First Minister of Northern Ireland.

Through advocacy, advice and appraisal, we help put sustainable development at the heart of Government policy.

www.sd-commission.org.uk

Tidal Power in the UK

Turning the Tide

Turning the TideTidal Power in the UK

Contents

Executive Summary 5

1 Introduction 15

1.1 Backgroundtothisproject 16

1.2 Ourapproach 17

1.3 UKtidalresource 19

1.3.1 Twotypesoftidalresource 19

1.3.2 Electricitygeneratingpotential 22

1.3.3 Resourceuncertainties 22

1.3.4 Timingofoutputfromtidalsites 23

1.3.5 Transmissionsystemconstraints 25

1.4 Energypolicycontext 28

1.4.1 CurrentGovernmentpolicy 28

1.4.2 TheSDC’sadvice 28

1.5 Publicandstakeholderengagement 29

1.5.1 Tidalpowerandsustainableenergy 29

1.5.2 Tidalpowertechnologies 30

1.5.3 Conditionsforacceptability 31

1.6 ReportStructure 32

2 Tidal Stream 35

2.1 Technologyoverview 36

2.1.1 Tidalstreamdevices 36

2.1.2 Currentlevelofdevelopment 37

2.1.3 Futureprospects 37

2.2 CurrentGovernmentpolicy 38

2.2.1 Tidalstreamfunding 38

2.2.2 Regulatoryandplanningframework 40

2.2.3 Europeanenvironmentallegislation 40

2.2.4 Seabedlicences/leases 40

2.2.5 Roleofnatureconservationagencies 41

2.3 Environmental,socialandeconomicimpacts 41

2.3.1 Physicalconfigurationofdevices 41

2.3.2 Environmentalconsiderations 42

2.3.3 Summaryofenvironmentalimpacts 45

2.3.4 Socialandeconomicimpacts 46

2.4 Opportunitiesandbarriers 48

2.4.1 Fundingregime 48

2.4.2 Gridconstraints 50

2.4.3 Gettingtheregulatoryframeworkright 52

2.4.4 Dealingwithinformationgaps 53

2.4.5 UtilisingtheEMECresource 54

2.4.6 Creatingadevelopmentpath 55

3 Tidal Range 57

3.1 Tidalrangetechnologies 58

3.1.1 Tidalbarrages 58

3.1.2 Tidallagoons 59

3.2 Fundingregime 62

3.3 Exploringthepolicyoptions 62

3.4 Tidalrangecasestudies 63

MerseyEstuary 63

LoughorEstuary 65

DuddonEstuary 65

WyreEstuary 66

ThamesEstuary 66

4 A Severn Barrage 69

4.1 Background 70

4.1.1 Chapteroutline 70

4.2 StrategicoverviewoftheSevernEstuaryresource 70

4.2.1 TheSevernEstuary 71

4.2.2 Severnbarrageoptions 72

4.2.3 Alternativestoabarrage 74

4.2.4 Compatibilityofoptions 74

4.2.5 Dealingwithdataconstraints 75

4.3 Electricityoutputandcharacteristics 75

4.3.1 Contributiontoelectricitysupply 76

4.3.2 Methodofoperation 76

4.3.3 Loadfactor 76

4.3.4 Outputprofile 77

4.3.5 Implicationsforgridmanagement 79

4.3.6 Implicationforthetransmissionsystem 81

4.4 Carbonemissions 83

4.4.1 Carbonpayback 83

4.4.2 Carbonreductionpotential 83

4.5 Physicalimplicationsofabarrage 84

4.5.1 Soundscienceanduncertainty 85

4.5.2 Waterlevelsandcurrents 85

4.5.3 Morphology 87

4.5.4 Sedimentaryprocesses 87

4.5.5 Decommissioning 88

4.6 Environmentalimpacts 89

4.6.1 Scopeofenvironmentalreview 89

4.6.2 ProtectedstatusoftheSevernEstuary 89

4.6.3 Habitatsandecology 93

4.6.4 Waterquality 97

4.6.5 Birds 98

4.6.6 Fish 100

4.6.7 Landscapeandvisual 101

4.6.8 ClimatechangeandtheSevern 102

4.6.9 Impactofabarrageonprotectedfeatures 103

4.6.10 BiodiversityimpactofaSevernbarrage 105

4.7 Economyandsocietyataregionallevel 105

4.7.1 Portsandnavigation 105

4.7.2 Transportlinks 107

4.7.3 Coastaldefenceandfloodprotection 109

4.7.4 Employment 113

4.7.5 Developmentandhousing 113

4.7.6 Leisureandtourism 115

4.7.7 Fishingactivities 116

4.7.8 Aggregatesindustry 116

4.8 Costandfinancing 117

4.8.1 Costofconstruction 117

4.8.2 Unitcostofoutput 117

4.8.3 LevelofGovernmentinvolvement 120

4.8.4 Financingoptions 122

4.8.5 Considerationofancillarybenefits 125

4.9 Publicandstakeholderopinion 125

4.9.1 Publicattitudesandopinions 125

4.9.2 Stakeholderattitudesandopinions 127

4.10 Policyprocessandgoodgovernance 127

4.10.1 Researchandassessmentstages 128

4.10.2 Theimportanceofengagement 128

4.10.3 RelevanceoftheDirectives 129

4.10.4 Complyingwiththeenvironmentallegislation 131

5 Conclusions and Recommendations 135

5.1 Aconsensusview 136

5.2 TidalpowerintheUK 136

5.2.1 Tidalstream 136

5.2.2 Tidallagoons 138

5.2.3 Tidalbarrages 139

5.3 ConditionsforasustainableSevernbarrage 139

5.3.1 Energypolicycontext 140

5.3.2 Ensuringthepublicinterest 140

5.3.3 Complyingwiththeenvironmentallegislation 142

5.3.4 OuradvicetoGovernment 144

5.3.5 Movingforward 146

6 References 149

SustainableDevelopmentCommission Tidal Power in the UK 5

TheUKhasthepotentialtogeneratelargeamountsofcleanandsecureelectricityfromthetides.Usingbothtypesoftidalresource–tidalstreamandtidalrange–wecouldsupplyat least10%of theUK’selectricity if fullyexploited,around5% fromeachresource. Such a substantial prize deserves verycloseattentionaspartofmuchwideractionaimedat tackling the twin challenges of climate changeandenergysecurity.

Thisreportdiscussesbothtidalstreamandtidalrange technologies, and considers a wide rangeof research, including the results of a public andstakeholder engagement programme. It presentsthe Sustainable Development Commission’sposition and recommendations on proposals for aSevernbarragewhich,ifbuilt,wouldutiliseaverylarge proportion of the UK’s tidal range resource,andcouldgenerate largequantitiesof lowcarbonelectricityforover120years.

Thereisminimalconflictbetweentheexploitationoftidalstreamandtidalrangeresources,orbetweenthetechnologiesthatmightbedeployed.Thebesttidal stream sites are in the north of Scotland,withsignificantpotentialalsoaroundnorthWales,NorthernIreland,andtheChannelIslands.Thetidalrangeresource isconcentrated intheestuariesoffthewestcoastofBritain,includingtheSevern,theMerseyandtheHumber.

Exploitingourtidalenergyresourceswillrequireconcerted action on a number of fronts. The tidalpowertechnologiesthatcouldbedeployedareverydifferentinbothdesignandlevelofdevelopment.Tidal stream devices are currently at thedemonstration stage,andwill requiremanyyearsof targeted support to reach commercialmaturity.Tidalbarrages,ontheotherhand,areaproven,buthighlycapital-intensiveoptionthatwouldrequireastrong leadbyGovernment tobebuilt.With tidallagoons,alackofevidencemeansthatthepriorityshouldbefillinginformationgapsthroughpractical,on-the-groundexperiencesothatlong-termviabilitycanbebetterassessed.

However,all tidal technologieshaveanumberofenvironmental,socialandeconomicimpactsthatneedtobeconsidered.Inparticular,theimpactofaSevernbarrageoninternationallyprotectedhabitatsandspecies,isofgreatconcern.

In this report, the Sustainable DevelopmentCommission (SDC) lays out a series ofrecommendations for Government on how todeveloptheUK’stidalpowerresources.Ontheissueof a Severn barrage, we consider the conditionsunder which such a scheme would be consistentwith the principles of sustainable development,andissueclearadvicetoGovernmentonhowthisshouldbetakenforward.

Executive Summary

Tidal stream technologies

In addition to having an excellent tidal streamresource – one of the best in Europe – the UK iscurrentlyleadingtheworldinthedevelopmentofawiderangeoftidalstreamdevices.Thelong-termpotentialforthisnewindustry–bothintermsofitscontributiontoUKelectricitysupply,anditsexportpotential– isconsiderable.TheUK’ssuccesssofarcanbeattributedtotheingenuityandperseveranceof the device developers combined with thecommitmentshowntodatebytheUKandScottishGovernments.

However,thisnascentindustrystillhasalongwaytogo,withallthedevicesinthedemonstrationandtestingstageofdevelopment.TakingthesuccessfultechnologiesontofullcommercialdeploymentwillrequiresustainedGovernmentsupport–bothfinancial

and practical. Innovation, and the development ofnew low carbon technologies such as tidal streamgenerators,needs tobea fundamentalpartof theUK’s response to the challenge of climate change.TheGovernmentmustincreaseR&Dexpenditureandbecomelessrisk-averseinsupportinginnovation.

AsaresultoftheGovernment’splantointroducetechnologybandingtotheRenewablesObligation,thereisnowanopportunitytobuildonthesuccessof the Scottish Government’s marine energysupportprogrammebychangingthefocusoftheUKGovernment’sMarineRenewablesDeploymentFund(MRDF) from revenue togrant support. This couldbetterservetheneedsofthetidalstreamindustrybyprovidingaccesstofundsaimedatencouragingpre-commercialdemonstration.

6 Tidal Power in the UK SustainableDevelopmentCommission

The successful European Marine Energy Centre(EMEC)inOrkney,whichprovidesatestingsiteforwave and tidal devices, must be used to its fullpotential.Thecentrecouldbenefitfromadditionalfundingtoofferawiderrangeofservices,includingcertificationofdevices,baselineenvironmentaldata,andanexpandedmarineenergyresearchrole.

Furthermore, Government should explore theopportunity to develop a regional tidal streamcluster,or‘hub’,aroundtheOrkneyislandsandpartsoftheCaithness&Sutherlandcoastline.Thiscouldmakegooduseof the less challenging conditionsin these locations to develop a coordinated pre-commercial testing programme. There is potentialforanewinterconnectortotheOrkneyislands,and

a need for better coordination to decide how tomakeuseofavailablecapacitybetweenDounreayand Beauly. The SDC recommends that workdeveloping a regional ‘hub’ is led by the ScottishGovernment,inconjunctionwithEMEC,theNuclearDecommissioningAuthority,andHighlands&IslandsEnterprise.

Finally,theSDCisveryconcernedoverthelong-termabilityfortidalstreamgenerationtoconnecttotheelectricitytransmissionsystemduetoalackofcapacity.Thereisarealabsenceoflong-termthinkingonthepartofOfgemandtheGovernmentonthesolutions necessary to overcome this constraint,which isaparticularthreattothedevelopmentoftidalstreaminthenorthofScotland.

AsyettherehasbeennoattempttoexploittheUK’slargetidalrangeresource,despitenumerousprojectproposals going back many decades. Virtuallyall of these have focused on the construction oftidal barrages, which use similar technologies tohydropower dams and are therefore relativelymature.However,thehighcapitalcostandconcernsover environmental impacts have prevented abarrageeverbeingbuiltintheUK,despiteexamplesinFranceandCanadaoperatingsuccessfully.

Likewise, the concept of a tidal lagoon isnot a recent proposition. Not one has ever beenbuilt anywhere in the world, and although thetechnologies used would themselves be classedas mature, the concept itself is unproven due toa number of remaining uncertainties over design,construction methods and physical impacts. Thismeans there is a lack of evidence with which toassess the long-term potential of tidal lagoons,despiteapotentiallysignificantresourceinshallow

waterareasaroundtheUK.Tohelpfillthisinformationgap,theSDCbelieves

there isastrongpublic interest indevelopingoneormoretidallagoondemonstrationprojectsintheUK.WerecommendthattheGovernmenttakesthisforwardbyprovidingfinancialsupporttoencourageprivate sector or joint initiatives – either throughincreasedsupportundertheRenewablesObligationor by announcing a one-off competition. Thereshouldbea requirement that the research that isconductedisplacedinthepublicdomain.

On tidal barrages, our analysis has focusedon the issue of a Severn barrage, which is dealtwith separately. But we have also looked at theextensive resource outside the Severn Estuary,including the well-developed proposals for theMersey Estuary. We are supportive of selectivefurtherinvestigationofbarragesoutsidetheSevern,andourrecommendationsonaSevernbarragewillalsoberelevanttootherbarrageschemes.

Tidal range technologies

In summary

• TheUKshould‘staythecourse’insupportingnewtidalstreamtechnologies

• InnovationfundingintheUKmustrise,withacommitmenttosupportthedevelopmentoftidalstreamdevicesateverystageoftheinnovationchain

• GovernmentshouldconsiderthepotentialforEMECtobecomeatidalstreamdevelopmentandresearchhubtobuildonthesuccessofthisresource

• OfgemandGovernmentmusturgentlyincreasethecapacityoftheelectricitytransmissionsystemtoaccommodaterenewablesoverthelongterm.

Ourevidence suggests that there isno seriousconflict between the tidal stream and tidal rangetechnologiesthatcouldbedeployedintheSevern.Tidal stream devices are unlikely to be viable intheSevernEstuary,buttherearemoreappropriateconditions further out in the Bristol Channel.Small-scale tidal lagoon development could take

place alongside a tidal barrage. The only optionruled out by a barrage would be large-scale tidallagoon developments, as these would be directlycompeting for resource. We do not consider thatlarge-scaletidallagoondevelopmentintheSevernEstuarywouldofferanyeconomicorenvironmentaladvantageoverabarrage.

In summary

• Thereisminimalconflictbetweenthepotentialdevelopmentoftidalstream,tidalbarragesandtidallagoons

• Thereisstrongjustificationforthedevelopmentofatleastonetidallagoondemonstrationproject

• Governmentshouldofferincentivestoencouragethedevelopmentofademonstrationproject,withtheresultsofanyresearchundertakenplacedinthepublicdomain

• ThereshouldbefurtherstrategicinvestigationofbarragesoutsidetheSevernbasedonrigorousapplicationofthefiveprinciplesofsustainabledevelopment.

A number of different barrage options have beenproposedfortheSevernEstuary.Thisreportconsiderstwo of these in more detail. The Cardiff-Westonscheme isoneof the largeroptionsproposed,andwouldhaveageneratingcapacityofaround8.64GW.TheShootsscheme(whichwouldrunneartothetwoSevernroadcrossings)isasmaller,1.05GWproposal,withanannualoutputofaround2.75TWh.

The SDC’s public and stakeholder engagementprogramme showed that 63% of the public ina national opinion poll had no knowledge ofproposals for a Severn barrage; 18% had onlya little knowledge. After being given summary

information on a barrage proposal, including thepotential advantages and disadvantages, 58% ofpeopleacross theUKwere in favourof abarrageand15%against.Thissupportwasmainlybecauseoftheperceivedclimatechangebenefits.

TheresultsofthepublicworkshopsheldinBristoland Cardiff (where more detailed information wasprovided)werealsoinfavourofabarrage,asdelegatesfelt the benefits outweighed the disadvantages.However, stakeholders were far less positive overthenetbenefitofabarrage,withalargenumberofconcernsraisedovertheperceivednegativeimpacts,particularlythoseaffectingtheenvironment.

A Severn barrage

Power output and cost summary for the two main Severn barrage options

Cardiff-Weston Shoots

Lengthofembankments 16.1km 4.1km

Generatingcapacity 8.64GW 1.05GW

Annualaverageelectricityoutput 17TWh 2.75TWh

ContributiontoUKelectricitysupply(2006data) 4.4% 0.7%

Estimatedcostofconstruction £15bn £1.5bn

Estimatedcostofoutputatvariousdiscountrates(highcasescenario)

2% 2.31p/kWh 2.58p/kWh

3.5% 3.68p/kWh 3.62p/kWh

8% 9.24p/kWh 7.52p/kWh

10% 12.37p/kWh 9.54p/kWh

15% 22.31p/kWh 15.38p/kWh

� Tidal Power in the UK SustainableDevelopmentCommission

The assumption is that both barrages would beoperatedontheebbtide,withtheadditionof‘floodpumping’toincreasethetotalenergyoutput.Thismeansthattheywouldbegeneratingelectricityforaround7-8hours oneach tide, andoutputwouldvary within this period. As a result, the annualoutputofeachbarrageislessthanthatimpliedbytheirsize.Ifbuilt,theCardiff-Westonschemewouldgenerate 17TWh per year, which is equivalent toaround 4.4% of UK electricity supply. This is thesamelevelofoutputaswouldbeproducedbyjustovertwoconventional1GWpowerstations.

Thehighcapitalcostofabarrageprojectleadstoaveryhighsensitivitytothediscountrateused.Atalowdiscountrateof2%,whichcouldbejustifiedforaclimatechangemitigationproject,thecostofelectricity output from both barrage proposals ishighlycompetitivewithotherformsofgeneration.However, at commercial discount rates of >8%,these costs escalate significantly, making privatesector investment unlikely without significantmarketinterventionbyGovernment.

The timing of output from a Severn barrage,regardless of the scheme, is not optimal. Onaverage,bothproposalswouldproducemorepowerat the times of the day when demand is lowest.Nevertheless, electricity from a barrage woulddisplaceoutput from fossil-fuelledpower stations,andwouldmakeagenuineandsizeablecontributiontomeeting theUK’s targetson renewableenergyandonreducingcarbondioxideemissions.TheSDCdoesnotbelievethatthevariabilityinoutputfromabarrage,whichishighlypredictable,wouldraiseanysignificanttechnicalchallengesfortheoperationof theelectricitygrid.Aswe showed inour2005reportonwindpower,variabilityissomethingthatcanbemanagedatverylowcost.

Aswellasbeinganenergy-generatingproject,aSevernbarrageisoftenseenasawaytoprovide

additionalfloodprotectionto low-lying landalongthe estuary, and additional transport links. Onflooding,abarragewouldprovidesomeadditionalupstreambenefitagainsttheriskofcoastalflooding(suchasatidalsurge)andwouldcountertheeffectofrisingsealevels.However,existingflooddefenceswould still need tobemaintained, andabarragewouldprovidenoadditionalprotectionfromfluvialfloodingevents.

The SDC’s conclusion is that there would besubstantial flood riskbenefits fromabarrage, buttheseareonlymarginaltotheeconomiccaseforitsconstruction.Withoutabarrage, it isveryunlikelythattheEnvironmentAgencywouldseektoprovidethis increased level of flood protectionwhen it isviewed against all the other competing prioritiesfor limitedresources.Thefloodprotectionbenefitsofabarrageshouldthereforebeseenasancillaryto a primarily energy-generating project. Optionsfor increased levels of flood protection throughalternativebarragealignmentsordesignsshouldbevaluedinawaythatisconsistentwithexistingpolicyoncoastalfloodriskandthroughastrictanalysisoftheadditionalcostsandbenefitsthatwouldresult.

On the potential for new transport links overthe top of a barrage, the SDC believes that thesebenefitsmayhavebeenoverstated. There is littleevidenceshowinghowaroadorrailcrossingwouldactually be designed, and we conclude that thiswouldpresentanumberofchallengesdueto theexistenceofoneormoreship locks,andcouldbeverycostly.Onthequestionofidentifiedneed,thereis nothing to indicate a strong justification for anadditionalroadlink.Thecaseisstrongerforanewraillink,toreplacetheagingSevernTunnelcrossing,but thiswouldneed tobe consideredagainst thealternativeoptionofbuildingadedicatedrailbridgeoranewtunnel,neitherofwhichrequireabarrageprojecttogoahead.

Potential benefits

In summary

• Electricityfromabarragewoulddisplaceoutputfromfossil-fuelledpowerstations,makingasignificantcontributiontotheUK’srenewableenergytargets

• Thevariabilityinoutputfromabarrageisnotamajorproblemfortheelectricitygridandcanbemanagedatverylowcost

• Therewouldbesubstantialfloodriskbenefitsfromabarrage,buttheseareonlymarginaltotheeconomiccaseforitsconstruction

• Thecasefornewtransportlinksoverabarrageisunproven,andneedstobeassessedlookingatthenetcostsandbenefits.

TheSDChasapproachedtheissueofaSevernbarragefrom a general position that favours renewableenergy. We have then examined the conditionsunder which a barrage might be sustainable,focusingonanumber of controversial, potentially‘deal-breaking’issues.

This approach neither signifies the SDC’sunquestioningsupport forabarrage,norproposesasetofconditionswhichwebelievewouldmakeitimpossibletodevelop.Instead,wehaveconsideredaSevernbarragewithinaframeworkthatplacesa

highvalueonthelong-termpublicinterestandonmaintaining theoverall integrityof internationallyrecognisedhabitatsandspecies.

Wedonottakeapositionontherelativemeritsof the various barrage schemes but have insteadconsideredtheissuesgenerically,withaninevitablefocus on the larger Cardiff-Weston scheme dueto the availability of more detailed evidenceand the greater degree of impact it would have–environmentally,economicallyandsocially.

Conditions for sustainable development

In summary

• TheSDChasapproachedthequestionofaSevernbarragebylookingastheconditionsunderwhichitsdevelopmentmightbesustainable

• Wehavedonethiswithinaframeworkthatplacesahighvalueonthelong-termpublicinterestandonmaintainingtheoverallintegrityofinternationallyrecognisedhabitatsandspecies.

The SDC has a number of concerns over how adecisioninfavourofaSevernbarragemightimpactonwiderenergypolicyaims.ThereisariskthatthedevelopmentofabarragemightdivertGovernment’sattentionawayfromtheothernecessarysolutionstothechallengeofclimatechange.

ASevernbarragehasanumberofdisadvantagesthat are similar to those of nuclear power, anddeveloping such a large amount of electricitygeneratingcapacityinasinglelocationwouldnotofitselfmovetheUKanyclosertoamoredecentralisedenergysystem.Furthermore,theSDC isconcernedthat development of a highly-centralised Severnbarrage project could frustrate efforts to reduceenergydemand,asconsumersperceiveabarragetobeasolutiontoclimatechangemitigation,relievingthemoftheneedtoact.

DespiterecentprogresswiththeClimateChangeBill and the 2007 Energy White Paper, the SDCbelieves that the Government does not yet have

thepolicies inplace todeliver thecarbonsavingsthat will be required to 2050 – and in particular,thedeliveryofemissionsreductionsoverthenext15years.AsshownbytheSternReview,actiontoreducecarbonemissionsneedstobe‘front-loaded’tohavethebestchanceofstabilisingtheaveragetemperaturerisetonomorethan2°C.ThenewEUtargetfor20%ofenergytocomefromrenewablesourcesby2020willalsobeamajorchallenge.

Nevertheless, in the light of increasing publicconcernoverclimatechangeandagreaterpoliticalwillingness to tackle the issue head-on, the SDCbelieves that a Severn barrage could be pursuedas part of a major drive to reduce emissionssubstantiallyoverboththeshortandthelongterm.A robust climate change and sustainable energypolicyisanessentialpre-requisitefordevelopmentofabarrage.Ifthisexists,thereisthepotentialforaSevernbarragetobeusedasasymbolicexampleofthescaleofactionthatisrequired.

Energy policy context

In summary

• DevelopmentofaSevernbarragemustnotdivertGovernment’sattentionawayfrommuchwideractiononclimatechange,includingthedevelopmentofamoredecentralisedenergysystemandthereductionofenergydemand

• Thereisincreasedpublicandpoliticalspaceforactiononclimatechange–itisthereforepossibleforGovernmenttodeliveronaSevernbarrageaspartofacomprehensiveandradicalprogrammeonclimatechange.


If built, a Severn barrage would be designed togenerateelectricityforatleast120years.Itwouldbe a major addition to the landscape, and wouldhave fundamental environmental, social andeconomic impacts on the surrounding area. Thesetimescales emphasis the need for any barrageprojecttobedesignedanddeliveredinawaythatensuresthelong-termpublicinterestratherthanashort-termist,profit-maximisingapproach.

The SDC has a number of concerns over theapportionmentofrisksandbenefitsforanybarragescheme,particularlyonethatisledandownedbytheprivatesector.Itisveryunlikelythataproposalfor a Severn barrage would ever come forwardwithout significant Government intervention, andasubstantialfundingpackagetopayfortheinitialresearchandevaluation.Onceconstructionbegins,theGovernmenteffectivelyunderwritestheprojectduetoitssizeandpoliticalsignificance.Thisincreasestheriskofmoralhazard–i.e.thatunderinsuredriskswillbepickedupbythetaxpayer.

Despite taxpayers and consumers taking on ahighlevelofrisk,abarrageprojectledandownedby the private sector would not result in a fairdistribution of the benefits, and the publicwouldloseout.

Aprojectof thiskindalso raisesconcernsovershort-termism. A private sector developer wouldrequireahighrateofreturnonanybarrageproject,leading to a strong incentive to maximise near-

term revenues through inappropriate ancillarydevelopment. The SDC has identified a numberof risks regarding the possibility of unsustainabledevelopment pressures as a result of a barrage–forexample,housingdevelopmentingreenbeltor environmentally sensitive areas, new transportinfrastructure,negativeimpactsonlocalports–andtheimplicationsoftheseonlocalcommunitiesandonthenetcarbonbalance.

We are concerned that a profit-maximisingapproach would substantially increase thesepressures, putting all the emphasis on the roleof planning controls and regulation, ratherthan integrating sustainability into the barragedevelopment itself. There is also the risk that ashort-termist approach could lead to the use ofsub-optimal construction methods and materials(possibly leading to higher levels of ongoingmaintenance),asmostcommercialprojectsfind itdifficulttovalueadequatelybenefitsthatoccurovertheverylongterm.

Finally,developmentofaSevernbarragewouldrequire a highly coordinated, outcomes-basedapproach to strategic planning and consentingissues. The organisations involved would need toensure that any project was integrated into localpolicy and planning frameworks. This favours anapproach where such considerations are firmlyembedded into the project developer’s aims andobjectives.

Ensuring the public interest

In summary

• ThelonglifetimeofaSevernbarrageplacesaveryhighemphasisonensuringthepublicinterestinthedesignanddeliveryofanydevelopment

• TheSDChasanumberofconcernsovertheapportionmentofrisksandbenefitsforaSevernbarragescheme,particularlyoneledandownedbytheprivatesector–taxpayers

andconsumerscouldendupwithalltherisksbutnoneofthebenefits

• Short-termisminthedesignanddeliveryofabarragecouldleadtounsustainableancillarydevelopmentandpossiblysub-optimalmethodsandmaterialsusedinbarrageconstruction.


The Severn Estuary is a unique and dynamicenvironment. Ithasthesecond largesttidal rangein the world, combined with a high suspendedsedimentload,andhasanumberofspecialfeatures,includingextensiveareasofsaltmarsh,andmobilesandbanks.Itisanimportantsiteformigratorybirds,andforfishmovementsinandoutoftheestuary’stributaries,suchastheWyeandtheUsk.Forthesereasons the Severn Estuary has been designateda protected site under national and internationallegislation.

The most important pieces of conservationlegislationforaprospectiveSevernbarragearetheEUDirectivesonBirdsandHabitats(the‘Directives’),whichprotectsitesdesignatedasSpecialProtectionAreas (SPAs) and Special Areas of Conservation(SACs). The total amount of land protected underthe Directives is a very small percentage of theUK, and the identification of sites is a science-led process that is based on protecting importantecosystem typesand threatenedbird species. TheSevern Estuary is a SPAanda candidate SAC. Theaimofdesignationistoprotectagainstbiodiversitylossby conservinga seriesof importantor at-riskhabitatsandspeciesthatmakeuptheEurope-wideNatura2000network.

The Natura 2000 network is based on theneed to conserve biodiversity across Europe, andinternationally. Biodiversity is a measure of bothquantityandquality,andthereforedistinctiveness.Anincreaseinthetotalquantityofplantoranimallife living inaparticular locationmaynot in itselfrepresentanincreaseinbiodiversity ifthespeciesconcernedarecommonlyfoundelsewhere.

TheSevernEstuary isa relativelyunproductiveenvironmentdue to theharshconditions;yet it ishosttoanumberofhighlydistinctivefeaturesandspecies. Its sheer size ensures that while speciesdensitymayberelativelylow,totalnumbersofsomebirdpopulations,forexample,areverysignificant.Therefore, while a barrage might result in anincreaseinbiologicalproductivity,anyreductioninthequantityofrarerspeciesmightleadtoanoveralllossofbiodiversity.

TheSDCisconvincedthattheSevernEstuarywillremainan important area for biodiversity, despitethe impacts of climate change. Warmer weathermayaccount for someof thecurrentobservationsof bird species shifting to estuaries on the eastcoastofEngland,butthereisnocertaintyastohow

climate change impacts will manifest themselvesoverthelong-term.Asaresult,theSevernEstuarywillremainanimportantfutureoptionformigratorybird species. Furthermore, the estuary may playhost tonew species that are forced to shift awayfrommoresouthern locations – this illustrates theimportance of considering the trans-boundarynatureofbiodiversity.

The Directives are intended to facilitatesustainable development, by ensuring thatenvironmental conservation objectives areadequately considered when proposals are putforwardthatwouldnegativelyimpactonprotectedhabitatsorspecies.

AnydevelopmentthatisproposedwithinaSPAorSACmustgothroughaseriesoftests,asoutlinedby the Directives. If an ‘appropriate assessment’identified the likelihood of adverse impacts, thentheprocessthatmustbefollowedis:

1. Considerationofalternatives:Thefirsttestthenrequiresanassessmentofthealternatives,includingthe‘zero’(no-development)optionandwaystomitigateagainstanyadverseimpacts.

2. Overridingpublicinterest:Iftherearenoviablealternativestothedevelopment,thenapoliticaldecisioncanbetakentoproceedonthebasisof‘imperativereasonsofoverridingpublicinterest’.ThisdecisionwouldnormallybetakenbyaSecretaryofState.

3. Compensationrequirement:Ifthisisthecase,thereisthenacompulsoryrequirementtoprovidecompensatoryhabitattoensuretheoverallcoherenceoftheNatura2000network.Thepracticalityandcostofthisrequirementrepresentsthefinaltestoftheoverallviabilityoftheproposal.

Providinghabitatcompensationcouldincludethecreationofnewhabitat,therestorationofexistinghabitat, or the recreation of habitats within thesite,inotherdesignatedsites,orinnon-designatedsites(andthendesignatingthem). Itmayalsobepossible todesignateotherestuariesnotcurrentlydesignated as SACs. To compensate for impactson fish, compensation could involve the artificialrestockingofcertainfishspeciestomaintainoverallnumbers.

Compliance with environmental legislation


The SDC has looked closely at the relevanceof the European conservation legislation in thefaceof climatechange.SomecommentatorshavearguedforarelaxationoftheDirectiveswhentheyare applied to projects that would reduce carbonemissions. The SDC believes that applying theprinciple of ‘living within environmental limits’,which isoneoftheUK’ssustainabledevelopmentprinciples, must result in the creation of absolutelimitsandboundariesiftheconceptistohaveanymeaning.Biodiversityobjectivesbecomeevenmoreimportant inaworld impactedbyclimatechange,andeconomicdevelopmentmusttakeplacewithinthe environmental constraints imposed by bothbiodiversityandclimatechangeobjectives.

Asaresult,theSDCbelievesthattheUK’slegalobligation to protect habitats and species thatcontributetotheoverallviabilityoftheNatura2000networkshouldbevigorouslyupheld.TheDirectives

provide a clear and robust legal framework forachieving sustainable development and thereforecompliancewiththeDirectivesisacentralconditionforasustainableSevernbarrage.TheSDCwouldbefirmlyagainstmovestoreformorderogatefromtheDirectives,asthiswouldsendadangeroussignaltoother European member states that could end upharming compliance with the Directives, and thebiodiversityobjectivesthattheyuphold.

This means that proponents of a Severnbarrage must be prepared to fully comply withtheprocesslaidoutbytheEUDirectives,includingthe requirement for a full compensatory habitatspackage to be in place before a barrage is built.Providingcompensatoryhabitatonthisscalewouldbe a very significant undertaking matched by anequally high cost, but it needs to be seen as acentralpartofanyproposalwhichmayeventuallydictatewhetherornotitcanproceed.

In summary

• TheSevernEstuaryisadistinctivehabitatthatisprotectedbynationalandinternationaldesignations–inparticular,theEUBirdsandHabitatsDirectives,whichapplyaseriesofteststoprospectivedevelopments

• ASevernbarragecouldleadtoalossofbiodiversity,resultingintheneedforacompensatoryhabitatspackagetomaintaintheoverallintegrityoftheNatura2000network

• TheEUDirectivesprovideaclearandrobustlegalframeworkforachievingsustainabledevelopmentandthereforecompliancewiththeDirectivesisacentralconditionforasustainableSevernbarrage

• ProvidingcompensatoryhabitatwouldbeaverysignificantundertakingonascalehithertounprecedentedintheUK–butthiswouldhavetobeanintegralpartofanybarrageproposal.

TheSDCbelievesthatthere isastrongcasetobemade fora sustainableSevernbarrage, subject totheconditionsweoutlineinthisreport.Thisistheconsensusviewofall19oftheSDC’sCommissioners.OurheadlineadvicetoGovernmentisasfollows:

AdecisioninfavourofaSevernbarrageshouldonlybepartofamajorefforttodeliverat leasta60%cutingreenhousegasemissionsby2050,withactionloadedtowardsthenext20years.

AbarrageshouldonlybeconsideredwithintheconstraintsimposedbytheEuropeanenvironmentallegislation.Asaresult,theprovisionofcompensatoryhabitatshouldbeseenasacorepartofanybarrageproject,andthereshouldbenoattemptsmadeto

weakenorderogatefromtheDirectives.Providingcompensatoryhabitatisnotaburden

ontheproject;rather,itrepresentsan‘environmentalopportunity’ to use a revenue-generating climatechangemitigationprojecttohelpfundalarge-scalecompensationpackagethatisdesignedaroundtheneedforclimatechangeadaptation.Thiscouldbelinkedtocoastalrealignmentstrategies,whichcanhave a number of flood protection benefits. TheGovernmentshouldseekaprogressiveinterpretationof the Directives that takes into account climatechange impacts on the long-term integrity of theNatura2000networkofprotectedsites.

Finally, theSDCbelieves thatabarrage should

Our advice to Government


be publicly-led as a project and publicly-ownedas an asset to ensure long-term sustainabilityin its design anddelivery, and a fair allocation ofrisks and rewards. We believe that a publicly-ledapproachwouldbethebestwaytoensureagainstunsustainableancillarydevelopmentasaresultofa barrage, and the early integration of local andregionaleconomicandsocialpriorities.

A publicly-led approach would enable the useof a low discount rate, justified by the long-termclimate changebenefitsandpotentially facilitatedby the Government’s access to low cost capital.

Atalowdiscountrate,thecostofelectricityoutputbecomeshighly competitivewithother sourcesofgeneration, even if the cost of the compensatoryhabitatpackageishigh.

The SDC is not advocating the nationalisationof the electricity sector, nor are we ruling out astrongrolefortheprivatesector indeliveringandfinancingaSevernbarrage.Instead,werecommendthat Government considers a range of innovativefinancingmechanismsthatwouldmaintainoverallpubliccontrolandownershipoftheproject.

In summary

• TheSDCbelievesthatthereisastrongcasetobemadeforasustainableSevernbarrage

• Muchwiderandstrongeractiononclimatechangeisapre-requisitefortheSDC’ssupport

• Theremaybean‘environmentalopportunity’availablebylinkingacompensatoryhabitatspackagetoclimatechangeadaptation

• ASevernbarragemustbepublicly-ledasaprojectandpublicly-ownedasanassettoensurelong-termsustainability

• Governmentshouldconsiderarangeofinnovativefinancingmechanismsthatwouldmaintainoverallpubliccontrolandownershipoftheproject.

TheSDC’srecommendationsareamajorchallengetocurrentGovernmentenergypolicy.However,theapproachweprescribewould enableGovernmenttodeliverasignificantquantityofnewrenewableenergy without compromising our internationalobligationsonconservationandbiodiversity.

Proposalsof thisscale requireanewapproachto decision-making. Government must avoid a‘decide-and-deliver’approach,andnotsetoffonapre-determined course of action where importantconditions and principles could eventually bediscarded. Instead, it must reflect on the widerimplicationsofsuchadecision,andengagewidelywith stakeholders and public to ensure that theirconcernsandopinionsaretakenintoaccount.

A crucial first step will be to obtain an earlyindicationofthefeasibilityofcompliancewiththeEuropean environmental legislation, and the costof achieving this. This should include an analysisofwhetherthereisan‘environmentalopportunity’available for linking the compensatory habitatpackage to climate change adaptation policies,and this would require early discussions with the

European Commission. As the SDC has clearlystated, if compliance with the Directives is foundtobe scientificallyor legallyunfeasible (which, inthe light of our current investigations, we do notbelieve it would be), then proposals for a Severnbarrageshouldnotbepursued,asthedevelopmentwould fail to satisfy theprincipleof ‘livingwithinenvironmentallimits’.

There isa strongneed fora cross-Governmentapproachtothisissue.Asenergypolicyisareservedmatter, it isappropriatefortheUKGovernmenttotake the lead, with close cooperation requiredbetween BERR, Defra and, critically, the WelshAssembly Government, as well as the relevantstatutory agencies. There is also a distinct andimportantroleonstrategicplanningandeconomicdevelopment issues that should fall to the SouthWestofEnglandRegionalDevelopmentAgencyaswellastheWelshAssemblyGovernment.

The SDC’s advice to Government is based onour assessment of the current evidence, and it isup to the Government to decide how to proceed.However, theSDCwouldbe interested inworking

Moving forward


with Government and other key stakeholders toexplore some of the substantive issues we raise,in particular the prospect of an environmental

opportunity,andinscopingoutinnovativefinancingoptionsthatmaintainoverallpubliccontrol.

In summary

• Governmentmustavoida‘decide-and-deliver’approach

• AnearlypriorityistoascertainthescientificandlegalfeasibilityofcompliancewiththeEUDirectives,andthelikelycostofthis

• Theremustbeacross-Governmentapproachtothisissue.

Introduction

1


ThisreportbytheSustainableDevelopmentCommission(SDC)representsthefirsteverstrategicoverviewoftidalpowerintheUK.ItlooksatthepotentialofawiderangeoftidalpowertechnologiestomakeuseoftheUK’suniquetidalresourcesfortheproductionofreliable,lowcarbonelectricityoverthelong-term.Italsoincludesanin-depthanalysisofthetidalpowerresourceintheSevernEstuaryandthepotentialroleofa‘Severnbarrage’fromasustainabledevelopmentperspective.

Thereportdrawsonawiderangeofexistingandcommissionedevidenceontidalpower,togetherwiththe resultsofasubstantialpublicandstakeholderengagementprogramme.TheSDChasusedthiswork,alongwiththeexpertiseofitsCommissionersandspecialiststaff,todevelopaseriesofrecommendationsforGovernment.1

During development of our work programme for2006-7theSDCidentifiedthepotentialforaprojectontidalpowerfromaUK-wideperspective.Atthesametime,theDepartmentforBusiness,EnterpriseandRegulatoryReform(BERR)2wasbeingaskedtoconduct a fresh assessment of the potential for atidalbarrageintheSevernEstuary.

Thisledtotheannouncementinthe2006EnergyReview3asfollows:

“…Together with the Welsh AssemblyGovernment, we [BERR] will thereforework with the Sustainable DevelopmentCommission, the South West RegionalDevelopmentAgencyandotherkeyinterestedparties to explore the issues arising on thetidalresourceintheUK,includingtheSevernEstuary,includingpotentialcostsandbenefitsof developments using the range of tidaltechnologiesandtheirpublicacceptability.”

Thiscommitmentledtotheformationofawide-ranging SDC research project on tidal power andtheproductionof this report.TheSDCwasalwayskeentoensureaUK-widefocusontidalpower,andtheinclusionofawiderangeoftidaltechnologies.Wewere thereforeverygrateful toobtain fullUK-wide funding of this project from the followingorganisations (placed in order of their level offunding):

• DepartmentforBusiness,EnterpriseandRegulatoryReform

• WelshAssemblyGovernment• SouthWestRegionalDevelopmentAgency• ScottishGovernment• DepartmentofEnterprise,Tradeand

Investment(NorthernIreland)

The fundingobtainedwasused to commissiona series of evidence-based reports, to run ourengagement programme, and for general projectadministration.However,theSDC’sagreementwithour funding partners stipulates that the SDC hasfull editorial control over this document, our finalreport. As a result, the views expressed here arethoseoftheSustainableDevelopmentCommission,anddonotnecessarily represent theviewsofourfunding partners. In addition to securing externalfunding,theSDChascontributeditsownresourcesdirectlytothisprojectthroughthespecialistpolicyandengagementexpertiseofourSecretariat staffandCommissioners.

TheSDChasalsosoughtinputfromawiderangeof stakeholders, both through our engagementprogramme, and through stakeholder meetings,public events, direct contact and our in-houseStakeholderPanel.Wearegratefultoallthosewhohavetakenthetimetoassistusonthisproject.Wewould particularly like to thank our colleagues inthevariousstatutoryagencies4foralltheirtimeandassistanceinhelpingtopeerreviewthereportswecommissioned,andinprovidingadvicetousonanad-hocbasisonawiderangeofissues.

1.1 Background to this project


TheSDCannouncedthestartofthisprojectonourwebsiteinJuly2006.WeinvitedorganisationsandacademicswithknowledgeorexpertiseinthisareatosubmitinformationtotheSDCforconsideration,andreceivedalargevolumeofmaterial.Subsequenttothis,weembarkeduponacompetitivetenderingprocessforfivedesk-basedresearchcontracts,whichwerestructuredasfollows:

Research Report 1–UKtidalresourceassessment:resource mapping of geographical and temporaldistribution of the resource, potential electricitygeneration contribution, grid constraints, strategicpolicyandplanningframework

Research Report 2 – tidal technologies overview:summary of tidal technologies (deployed and indevelopment),includingeconomics,environmentalimpactsandeconomicandsocialfactorsassociatedwiththedifferenttechnologycategories

Research Report 3 – Severn barrage proposals:summaryofvariousbarrageoptionsfortheSevernEstuary, their compatibility with other options,assessment of environmental impacts and theenvironmentalpolicyframework,floodandsealevelrisemanagementoptionsandimpacts,navigation/fishery industry impacts, economics (includingfinancing options), electricity generation/gridimplications(includingconsiderationofpeakoutputand variability), life-cycle carbon emissions, lifeexpectancy,andimplicationsforregionaleconomicand infrastructure development and recreationalopportunities

Research Report 4–Severnnon-barrageproposals:case studies on a number of non-barrage optionsfor the Severn Estuary, their compatibility withotheroptions,andanassessmentofenvironmental,economicandsocialconsiderationsandimpacts

Research Report 5–UKcasestudies:a reviewofa number of case studies and proposals for tidalpowerdevelopmentsacrosstheUKusinganumberofdifferenttechnologies.

Wehavepublishedtheresearchreportsonourwebsiteasstand-alonereportssothattheymaybeused as a public resource. Each research report isreferred to in thisdocumentby its shortened title(e.g.‘ResearchReport1’).

TheSDCbelieves thateffectiveengagement isessential to the development of truly sustainablepolicy-making.Engagementisparticularlyimportantfor understanding new technologies such as tidalpower,asnewtechnologiesrepresentanunknownquantity tomanystakeholdersand to thegeneralpublic. It is also important when consideringpotential large-scale infrastructure developmentsuch as tidal barrages and lagoons, which havesignificant potential effects on the environment,economyandsocietyataregionalandlocallevel.

AlthoughtheSDC’sworkinthiscontextdoesnotaimtoreplaceformalconsultation(byGovernmentor a project developer as part of a strategicenvironmental assessment or an environmentalimpact assessment, for example), engagementwaskeytothisstudy,particularlyinourreviewofspecificproposals for theSevernEstuary.Tobetterunderstand the implications and impacts of theproposedtidaltechnologies,theSDCcommissionedacoordinatedpublicandstakeholderengagementprogramme,theresultsofwhichcanbefoundinastand-alone report alsopublishedonourwebsite.AshortsummaryisprovidedinSection1.5,andinSection4.9inrelationtoaSevernbarrage.

After considering our commissioned evidencebase, the results of our engagement programme,andthewealthofother informationweobtained,theSDCbegantheprocessofassessingthevariousissuesdrawingontheexpertiseofourCommissionersandin-housespecialiststaff.Aswithallourwork,theSDCisguidedbythesustainabledevelopmentprinciples agreed by the UK Government and theDevolvedAdministrationsin2005.5

1.2 Our approach

1� Tidal Power in the UK SustainableDevelopmentCommission

We have used these five principles whenconsidering tidal power development moregenerally,butalsoinrelationtospecificissues,suchastheexploitationofthetidalresourceintheSevernEstuary. Although each principle does not applyequally to the issues surrounding tidalpower, theconceptof sustainabledevelopment isparticularlyrelevantwhenconsideringproposalsthatmayhaveawiderangeofenvironmental,socialandeconomiceffects, both positive and negative. It is for thisreason that we believe the SDC, and sustainabledevelopmentmoregenerally,canaddvalueintheconsiderationofsuchissues.

This reportconsiders the tidalstreamandtidalrange resources separately (see below for anexplanation),beforegoingontoconsidertheissuessurrounding a possible Severn barrage in some

detail. Finally, we present our concluding analysisandourrecommendationstoGovernment.

Finally, the SDC is a non-departmental publicbodywhichwassetuptoadvisetheUKGovernmentand the Devolved Administrations on sustainabledevelopment issues.6 As such, it is not our roleto recommend specific technologies or proposalsfor development where these are subject to anidentifiedcommercialinterest.So,forexample,wedonotseektomakeclaimsastothebenefitsofonetechnologyoveranother,andtheactualperformanceandeconomicviabilityofdifferenttechnologieswillneed to be determined under the framework putin place by Government. However, some of theissuessurroundingtidalpowerrequireGovernmenttomakeanumberofstrategicdecisions,andthesehavebeenthefocusofourwork.

Living within environmental limits

Respecting the limits of the planet’s environment,resources and biodiversity – to improve our environment and ensure that the naturalresources needed for life are unimpaired and remain so for future generations.

Ensuring a strong, healthy and just society

Meeting the diverse needs of all people in existing and future communities, promotingpersonal wellbeing, social cohesion and inclusion, and creating equal opportunity.

Achieving a sustainable economy

Building a strong, stable and sustainable economy which provides prosperity and opportunities for all, and in which environmental and social costs fall on those who impose them (polluter pays),and efficient resource use is incentivised.

Promoting good governance

Actively promoting effective,participative systems ofgovernance in all levels ofsociety – engaging people’s creativity, energy and diversity.

Using sound scienceresponsibility

Ensuring policy is developedand implemented on the basis of strong scientific evidence,whilst taking into accountscientific uncertainty (throughthe precautionary principle) as well as public attitudesand values.

Figure1 UKsustainabledevelopmentprinciples


A detailed description of the UK’s tidal resourceis given in Research Report 1, which presents anoverview of the current knowledge and researchinthisarea.Thissection isbasedprimarilyonthefindingsfromthiswork,unlessotherwisestated.

Box1 Whatcausesthetides?7

1.3 UK tidal resource

Tidesarecausedbythegravitationalattractionofthemoonandthesunactingupontheoceansoftheearthasitrotates.Thetide-raisingforceexertedbythemoonisapproximatelytwicethatofthesun.Therelativemotionsofthesebodiescausethesurfaceoftheoceanstoberaisedandloweredperiodically,accordingtoanumberofinteractingcycles.Theseinclude:

• Adailyorhalf-dailycycle,duetotherotationoftheearthwithinthegravitationalfieldofthemoon.Thisleadstothefamiliaroccurrenceofhighandlowwater,whichwillbeexperiencedatdifferenttimesofthedaydependingonlocation.IntheUK,highandlowwateroccursapproximatelytwicedaily(itis‘semidiurnal’),withthetimeofhighwateradvancingbyapproximately50minutesperday.

• Aworldwide29.5-daycycle,resultingfromthedegreeofalignmentbetweenthemoonandsun.Thisresultsin‘springtides’and,sevendayslater,‘neaptides’.Springtidesarethosehalf-dailytideswiththelargestrange(i.e.highesthighwaterandlowestlowwater),whileneaptideshavethesmallestrange.Springtidesoccurshortlyafterthefullandnewmoon,withneapsoccurringshortlyafterthefirstandlastquarters.Foranygivenlocation,thespringtidehighwaterwillalwaysoccuratthesametimeofday.

• Ahalf-yearcycle,duetothealignmentofthemoon’sorbittothatoftheearth.Thisgivesrisetothelargestspringtides,aroundthetimeoftheMarchandSeptemberequinoxes,andthesmallestspringtides,approximatelycoincidentwiththesummerandwintersolstices.

Thereisalsoa18.6yeartidalcyclethatresultsinlargerthanaveragetides,requiringestimationsoftidalresourcetobebasedonan‘averageyear’.Therangeofaspringtideiscommonlyabouttwicethatofaneaptide,whereasthehalf-yearlycycleimposessmallerperturbations.Intheopenocean,themaximumamplitudeofthetidesisaboutonemetre.Thelawofenergyconservationmeansthattidalamplitudesareincreasedsubstantiallytowardsthecoast,particularlyinestuaries.Thisismainlycausedbyshelvingoftheseabedandfunnellingofthewaterbyestuaries.Insomecasesthetidalrangecanbefurtheramplifiedbyreflectionofthetidalwavebythecoastlineorresonance.

Incombinationwiththe‘Corioliseffect’andfrictioneffects,thesefactorsmeanthatthetidalrangeandtimesofhighandlowwatercanvarysubstantiallybetweendifferentpointsonthecoastline.Theyalsoresultinalargevariationintheenergythatcanbeobtainedfromthetidesonadaily,weekly,andyearlybasis.

1.3.1 Two types of tidal resource

There are two quite distinct categories of tidalresource: tidal stream and tidal range. The tidal stream resource is the kinetic energy containedin fast-flowing tidal currents, which are generallyfound in constrained channels. The tidal range resourcereferstothegravitationalpotentialenergy

thatcanbefoundinestuarineareasthatexhibitalargedifferenceinwaterheight(their‘tidalrange’)betweenhighandlowtides.

The technology used to exploit each of theseresources is quite different. Tidal stream devicesrelyoncapturingsomeoftheenergycontainedinthecurrentspassingbythem,whereastidalrangedevices seek to impound large volumes of water

at high tide, and then release the water throughturbinesatlowtide.Putanotherway,tidalstreamdevices make use of the kinetic energy of tidalcurrents, whereas tidal range devices rely on thegravitationalpotentialenergycreatedwhenwaterathightideiskeptbehindanartificialimpoundment.

There are a large number of prototype anddemonstrationtidalstreamdevicesandtwobroadproposals for harnessing the tidal range resource–tidalbarragesandtidallagoons.ThetechnologieswillbediscussedinmoredetailinChapters2and3,butakeydifferenceisthattidalstreamdevicesaremodular (like wind turbines), whereas both tidalbarragesandlagoonsarelarge,singleinstallations(morelikehydropowerdams).

The two types of tidal resource are generallyfoundinverydifferentlocations.ThemajorityoftheUK’stidalstreamresourceislocatedinthenorthofScotlandinandaroundthePentlandFirth,althoughthere are some significant resources aroundAlderney,AngleseyandtheStrangfordLoughareain Northern Ireland. The UK’s tidal range resourceis primarily focused on the western estuaries ofBritain,withmostof the resource concentrated inthe Severn Estuary. Figure2 and Figure3give anillustrationofwheretheUK’stidalstreamandtidalrangeresourcesarelocatedrespectively–thelightcoloursindicateahighresource.

Figure2 UKtidalstreamresource

High

Medium

Low


Box2 Cubelawfortidalstreamresources

Figure3 UKtidalrangeresource

High

Medium

Low

Theenergyinatidalcurrentorstreamisproportionaltothecubeofthewatervelocity.Thismeansthattheavailablepowerinatidalcurrentiscalculatedusingthecubeofthewatervelocity.Thislawmeansthatevensmallchangesinpredictedtidalcurrentvelocitywillleadtolargechangesinpredictedpowerdensity.Italsomeansthatthereisapproximatelyeighttimesmoretidalstreampowerduringspringtidesthanatneaps.


As this report will illustrate, there arefundamentaldifferencesbetweentidalstreamandtidalrangeresourcesandtechnologies.Asaresult,differentpolicieswouldbeneededtoexploitthesetworesourcesinasustainableway.Forthisreason,

this report will look at each resource separately,beforegoingontolookinmoredetailatproposalsforexploitingtheverylargetidalrangeresourceintheSevernEstuary–a‘Severnbarrage’.

1.3.2 Electricity generating potential

AvailableestimatesoftheUK’stidalresourceallowus to calculate the potential electricity generatingoutputifallthebestresourceswerefullyexploited.Estimating thepotentialelectricityoutput requiresa number of assumptions to be made on thetechnicalconstraintsofthedevice(s)installed,theirefficiency,andtheeffectofresourceextractionontheremainingresource.Thismeansthatthereisalargedegreeofuncertaintyinallresourceestimates,anissuewhichisdiscussedbelow.

The top UK sites for the generation of tidalpowerareshowninTable1.ThisillustratesthelargepercentageofthetotalUKresourcethatliesinthePentlandFirthandtheSevernEstuaryrespectively.

Ofcourse,itmaynotbepossibletoharnessalltheavailableresourceduetowiderangeofpotentialconstraints,butthesefiguresdogiveanideaastothehighlevelresourceandtheprimelocations.

Table1:TopUKsitesfortidalpower

Tidal range sites Tidal stream sites

Sitename Resource(TWh/year)

Sitename Area Resource(TWh/year)

Severn

Mersey

Duddon

Wyre

Conwy

17

1.4

0.212

0.131

0.06

PentlandSkerries

Strøma

DuncansbyHead

Casquets

SouthRonaldsay

Hoy

RaceofAlderney

SouthRonaldsay

RathlinIsland

MullofGalloway

PentlandFirth

PentlandFirth

PentlandFirth

Alderney

PentlandFirth

PentlandFirth

Alderney

PentlandFirth

NorthChannel

NorthChannel

3.9

2.8

2.0

1.7

1.5

1.4

1.4

1.1

0.9

0.8

1.3.3 Resource uncertainties

Estimating tidal resources is a complex task, andthe methodology and data used to make theseestimates is still in development. It is thereforehighly likely that our understanding of the actual

levelofpractical resource(i.e. theresourcethat isavailable after allowing for physical and technicalconstraints)willcontinuetoevolveovertime.


Box3 Quantifyingtherenewableenergyresources

Tidalresourceassessmentscanbeconsideredinthreedistinctstages:

Theoretical resource Atoplevelstatementoftheenergycontainedintheentiretidalresource.

Technical resource Theproportionofthetheoreticalresourcethatcanbeexploitedusingexistingtechnologyoptions.

Practical resource Theproportionofthetechnicalresourcethatcanbeexploitedafterconsiderationofexternalconstraints(e.g.gridaccessibility,competinguse(MOD,shippinglanes,etc.),environmentalsensitivity).

So,foratidalstreamsite,thespringtidalpeakvelocity(m/s)relatestothetheoreticallyavailableresource,theareaofwaterdeepenoughforthechosentechnologyrelatestothetechnicallyavailableresource,andthepotentialimpactonshippinglanesandgeneralnavigationrelatestothepracticallyavailableresource.Anumberofpublicationsprovideguidelinesforsiteselectioncriteria.

One major factor in determining the resourceis the scale of the assessment undertaken. Usinga higher resolution will tend to give a muchbetter prediction of localised current velocities,and therefore totalenergyoutput.However,mostexistingassessmentshavebeendoneatarelativelylowscaleofresolution,leadingtothepotentialforsignificantrefinementovertime.

A recent report commissioned by the npowerJuicefundtoassesstheUK’stidalstreamresourceillustrates some of these uncertainties well.8It predicts a total extractable resource of up to94TWh/year, requiring approximately 200,000devicesdeployedacross11,000km2ofseabed(notmore than 40m deep). Both this work, and theResearchReport 1, highlight a recent theory fromtheacademicliteraturethatsuggeststheUK’stidalstream resource has been under-estimated by afactor of 10 or 20.9,10 These claims have not yetbeensupportedbypeer-reviewedpapers,buttheyhaveunderstandablygeneratedalotofinterestandseemdeservingoffurtherinvestigation.

On tidal range, it is worth noting that theestimation of resource presented in this report isrelatedtothepractical resource,andnot thetotaltheoretical resource.A reportby theWorldEnergyCouncil suggests that the UK might have up to50TWh of electricity generating potential fromtidal rangeresources“ifall reasonablyexploitableestuarieswereutilised”11–thiswouldbeequivalent

to around 13% of UK electricity supply from tidalrangealone. Furthermore,previous calculationsofthepracticalresourcemaynothaveconsideredthepotentialforelectricitygenerationatshallowwatersites, particularly those outside the west coastestuaries, which may have implications for thepotentialoftidallagoons.

1.3.4 Timing of output from tidal sites

Tidalpowerisavariableandyethighlypredictableresource.Thebiggestinfluencesonthetimingoftheelectricityoutputarethetwice-dailytidalcycle,andthe14-dayspring-neapcycle(seeBox1).However,thefluctuation in output of both tidal streamandtidalrangedevicescanbeaccuratelypredictedoverthelifetimeoftheinstallation.

Thesevariationsarediscussedbelow,alongwiththetemporaldistribution(i.e.timingandlocationofoutput)oftidalgenerationifallgoodsitesintheUKweredevelopedtotheirpotential.Thisinformationneedstobeconsideredinthecontextoffluctuationsin UK electricity demand, where demand peaksoccur throughout theworkingdayandparticularlytowardstheearlyevening,withlowestdemandintheearlyhoursofthemorning(thisissueisexploredinmoredetail,inthecontextofaSevernbarrage,inSection4.3.4).


Tidal stream

Themagnitudeofthetidalstreamresource(whichcombines with wind effects to produce currents)varies sinusoidally, with the highest speedsoccurringatmidebbormidflood,andwithspeedsapproaching zero at the turn of the tide. There isalsoaverylargedifferencebetweenaveragepoweroutput during spring versus neap tides, as shownin Figure 4. This difference is accentuated at high

velocity sites, such as those around the Pentlandarea.Whencombinedwiththedailytidalcycle,peaktidal output is around 90-100% of rated capacityonaspringtide,droppingtoa15-30%minimum,whereas peak output on a neap tide is between15-40%, falling to a minimum of less than 10%.In essence the output is continuously changing,albeitinapredictableway.

Figure4 Typicalvariationinoutputfromtidalstreampowerduetospring-neapcycle

10

0

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11 12 13

Day

Dai

ly a

vera

ge p

ower

out

put,

arb

itra

ry u

nits

Figure 4: Typical variation in output from tidal stream power due to spring-neap cycle

Temporally, spring tide peak generation forthe Pentland (North Scotland) sites would occuratmidfloodandmidebbataround9amand3pmrespectively, and then on the subsequent tide ataround9.30omand3.30am. These timingswouldthen shift by approximately an hour each daythroughthespring-neapcycle.

Asaresult,thePentlandresourceisnotideallymatched to UK electricity demand – although nor

isitbadlymatched.ThetimingofoutputfromthePentlandareawouldtosomedegreebeoffsetbydifferenttimingsfromotherUKlocations;however,the dominance of the Pentland resource, alongwiththefactthatspring-neapcyclesarethesameworldwide, means that it has the potential tooutweighanybalancingeffectfrommoredispersedtidalstreamgeneration.


Tidal range

The timingof the tidal range resource ismoredependent than the tidal stream resource on theoperating regimeused.Forexample, it ispossibletooperateatidalbarrageorlagooninebborflood

generation,orboth,andfloodpumping isalsoanoption (to artificially increase the head). On theneap tide the electricity output is 25% that of aspringtide,asshownbyFigure5.

Figure5 Typicalvariationinoutputfromtidalrangepowerduetospring-neapcycle

Maximum electricity output is thought to beachievablebyoperatingatidalbarrageorlagooninebbgenerationmode,possiblywithfloodpumping.Generationtimescouldbeexpectedtooccuraroundthreehoursafterhighwaterandcontinueforaroundfourhours.Asa result, a totalgeneration timeofjustundereighthoursperdaycouldbeexpected.

Again, the dominance of the Severn Estuaryresourcemeansthattheoutputregimefromlarge-scaletidalpowerdevelopmentinthislocationwouldhavethelargesteffectonoveralltidalrangeoutput.Ingeneral,thelikelyoutputcharacteristicsoftidalrangeplantintheSevernarenotparticularlywell-matchedtoUKelectricitydemand,althoughthisisnotamajorbarrier.Amoredetailedanalysisofthis

issueinrelationtoaSevernbarragecanbefoundinSection4.3.

1.3.5 Transmission system constraints

Electricity transmission system

ThetransmissionsysteminGreatBritainismadeupofthe400kVand275kVhighvoltagetransmissionnetwork (plus the 132kV network in Scotland),and has the responsibility for transporting largeamountsofelectricityaroundthecountrytowhereitisneeded(seeFigure6).ItisoperatedbyNationalGrid Electricity Transmission (NGET) plc, who are

10

0

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30

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Dai

ly a

vera

ge p

ower

out

put,

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itra

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1 2 3 4 5 6 7 8 9 10 11 12 13

Day

Figure 5: Typical variation in output from tidal range power due to spring-neap cycle

also the owners of the transmissions systemin England and Wales; in Scotland, the primaryowners are ScottishPower Electricity TransmissionLtdandScottishHydroElectricity Transmission Ltd.

The transmission system feeds into the localdistribution system, which is managed by the14 Distribution Network Operators (DNOs) on aregionalbasis.

Figure6 ElectricitytransmissionnetworkinGreatBritain12,showinggridconstraintsontidalpower.

Major generating sitesincluding pumped storage

Networks ability toexploit tidal power

Connected at 400kVConnected at 275kVHydro Generation

2007/08 Transmission Systemas at 1st December 2006

400kV Substations275kV Substations132kV Substations

400kV Circuits275kV Circuits132kV Circuits

Very HighHighMediumLow

Tidal Range Locations

Tidal Stream Locations

Locations

Start Point

PortlandIsle of Wight

Mersey

Duddon & Wrye

Solway Firth

Kyle Rhea

South Orkney

The Wash

North Orkney

North Channel

Mull of Galloway

Anglesey

Lleyn Peninsula

Pembrokeshire

Severn tidal stream

Severn barrage development

Cornwall


The majority of generation plants in GreatBritain are connected to the transmission system,withsome12GWofgenerationcapacityconnectedto the distribution networks. The capacity of thetransmission system to connect generation andmanage the flows of electricity depends on thecapacityofthenetwork.Theprocessofconnectingto the network is based around the principle ofmatchingtheConnectionEntryCapacity(CEC)(thegeneratingcapacityofthepowerstation)withtheTransmission Entry Capacity (TEC) (the capacity ofthenetworktoacceptanewgenerator).Connectionoffers are made on the basis of an ‘invest andconnect’ approachwhereby CEC canneverexceedTEC, so new lines must be built to connect newgeneration.

System constraints and upgrades

AtpresenttherearesignificantTECconstraintsinthenorthofEnglandandScotlandwhicharepreventingtheconnectionofnewgenerationprojects.Inordertoconnectnewgeneration,areasofthetransmissionnetworkwillneedtobeupgradedtohighervoltagelevels(measuredinkV)toincreasetheTEC.

The132kVtransmissionlinebetweenBeaulyandDennyhasbeenidentifiedasrequiringanupgradetoincreasetheTECofthenetworkinScotland.Ofgemhasapprovedthefundingrequiredtoupgradethelineto400kVlinewhichwouldincreasetheTECbyaround6GW,allowingfortheconnectionof67newrenewableprojectsalreadyinthepipeline.However,as a 400kV linewill have a significant impact onvisual amenity, consent for theupgradehasbeendelayedawaitingtheconclusionofapublicinquiry.Figure 6 shows the areas where TEC constraintswouldhindertheconnectionoftidalprojects.

WiththeintroductionofBritishElectricityTradingand Transmissions Arrangements (BETTA) in 2005,theScottishnetworkbecameanintegralpartoftheGBnetwork.Inanticipationofthis,manygenerators

submittedbids tobe connectedonto thegridbutmost of these did not have planning permission,which can takemanyyears to achieve.A total of9.3GW of capacity is awaiting connection ontothegrid in Scotlandand this is knownas the ‘GBQueue’.

Atthemoment,connectionontothetransmissionsystem is dependent on spare capacity beingavailable, but an alternative approach could betaken.AstheSDCrecommendsinitsreportontherole of Ofgem in delivering a sustainable energysystem,13thereisthepotentialtofreeupcapacityby operating a ‘connect and manage’ approachratherthanastrictqueuingsystem.

Implications for tidal power

These issues pose significant challenges for theconnection of tidal stream projects, and this isdiscussedfurtherinSection2.4.2.Existingcapacityconstraints and delays to network upgrades willfurther delay the date by which tidal streamprojects could connect. If the current approach totransmission connection and management is notmodified, it is unlikely that the UK will see anysignificantleveloftidalstreamconnectionbetweennowand2020.

For tidal range the situation is less significant,fortwokeyreasons.First,tidalrangeresourcesaregenerally located in areas where grid constraintsarelesspronounced,andareclosertohighcapacitytransmission lines and to centres of demand.Second,tidalbarragesand,toalesserextenttidallagoons, are likely to be larger, one-off projectswhen compared to a tidal stream array, makingtheincorporationofgridconnectioncostsasmallerpartoftheoverallprojectcostandthereforemoremanageable. Grid constraint issues related to apossible Severn barrage are discussed in Section4.3.6.


1.4.1 Current Government policy

Energy policy in the UK has risen up the politicalagendainrecentyearsduetothetwinchallengesof climate change and energy security. The UKGovernmenthaspublishedtwoEnergyWhitePapersandtwoEnergyReviewreportsinthespaceofsixyears, and there are no signs that this increasedattention and activity will subside. Indeed, manycommentators now believe that energy policy islikely to remain under a state of constant reviewdue to thegrowing realisationof the scaleof theproblemsweface.

On climate change specifically, the UKGovernment has proposed a new Climate ChangeBill,14 which would bind future Governments tostatutorytargetsforthereductionofgreenhousegasemissions, initiallyfocusedoncarbondioxide.ThisBill, ifsuccessfully implemented,hasthepotentialto fundamentally change thedynamicsof climatechangepolicyintheUK.ClimatechangelegislationisalsobeingconsideredforScotland.15

TheSDCstronglysupportsthefocusonclimatechange and energy security, both of which haveseriousconsequencesforsustainabledevelopmentifnoturgentlyaddressed.ThetwomainaimsoftheUKGovernment’senergypolicyaresummarisedinthe2007EnergyWhitePaper16asfollows:

• TacklingclimatechangebyreducingcarbondioxideemissionsbothwithintheUKandabroad

• Ensuringsecure,cleanandaffordableenergyaswebecomeincreasinglydependentonimportedfuel.

TheUKGovernmentbelievesthattheseenergypolicy goals should be achieved through privatesector companies operating in liberalised energymarkets. This means that Government’s role is tosetthepolicyandmarketframeworkforinvestmentin new electricity generating capacity andassociated infrastructure (including the frameworkforinvestmentinrenewableandlowcarbonenergysources), with energy companies responsiblefor investing in new capacity and for running theelectricity grid. As a result, the Government doesnotdirectlybuildpowerplantsordecidewhereorwhentheyshouldbebuilt.

1.4.2 The SDC’s position on energy policy

TheSDChasdoneawiderangeofworkonclimatechangeandenergypolicyoverthepastfewyears,and we have continually stressed the need foran energy policy hierarchy: starting with energyconservation, moving on to using energy moreefficiently,andfinallythedecarbonisationofenergysupply. The potential for saving energy throughbehaviouralchangeandinvestmentinnewenergyefficienttechnologiesishuge,andmustberealisedifweare tomeetourclimatechangeandenergysecurityobjectives.

In2006,theSDCanalysedarangeofevidencelookingattheUK’spotentialformeetingitsenergyneeds from low carbon sources. This identifieda very large renewable energy resource, and anumberofscenariosthatcoulddelivera60%cutinCO

2emissionsby2050,withouttheneedfornuclear

power.Anumberofmorerecentstudieshavealsoshownthepotentialof lowcarbonenergysourcestodeliverasustainableenergysupply.18,19,20,21

On climate change, we strongly support theconclusionsoftheSternReview,22whichidentifiedthree important policy elements for reducingemissions:

• Carbonpricing,throughsomecombinationoftaxation,tradingandregulation

• Technologypolicy,tosupportthedevelopmentofarangeoflowcarbonandhighefficiencytechnologies

• Removalofbarrierstobehaviouralchange,whichisparticularlyimportantinensuringtake-upofopportunitiesforenergyefficiency.

This report aims to reflect Stern’srecommendations, particularly in relation toinnovation and the use of appropriate discountrateswhen considering climate changemitigationprojects.

IntheUKcontext,theSDChasconsistentlycalledfortheearlyintroductionofeconomy-wideemissionstradingtoprovideaneconomicframeworkforotherclimatechangemitigationpolicies, includingtaxesandregulationwhereappropriate.Thiswouldbuildon the preference of the UK and other Europeancountries for a trading-based approach to carbonpricing, as demonstrated by the establishment oftheEUandUKEmissionsTradingSchemesoverthe

1.4 Energy policy context


last fewyears.However,we remainsceptical thatemissionstradingonitsownwilldeliverthelarge-scaleinvestmentsweneedtomovetoalowcarbonfuture,andthisisastrongthemeinthisreport.

Intheenergyandheatmarkets,webelievethatGovernmentpolicymusturgentlyseektodecoupleenergy use from economic growth, and we willworkwithDefraonproposals to seta capon theenergythatcanbesuppliedtodomesticandsmallbusinessconsumers,23andonfurther investigationinto personal carbon trading. We have long beenadvocates for improved innovation funding, andfor measures that encourage behavioural change.Further details of the SDC’s recommendations onclimatechangeandenergypolicycanbefoundonourwebsiteatwww.sd-commission.org.uk.

However, it is clear to us that no matter howsuccessfultheUKisincuttingenergyconsumptionthrough conservation and efficiency measures,or throughactionon transportor inother sectors,dramatic cuts in the carbon intensity of energysupply will still be needed over the next fewdecades.Thiswillrequireahugeshiftininvestmenttowards renewable energy technologies, and toother low carbon options such as carbon captureandstorage.MeetingnewEU-widetargetsfor20%of all energy to come from renewables by 2020willbechallengingfortheUK,anditisagainstthisbackdropthattheSDCapproachestheissueoftidalpower,anditsroleinalowcarboneconomy.

AsdescribedinSection1.2,aprogrammeofpublicand stakeholder engagement was a major partof this project. This comprised the following keyelements:

• Aseriesofthreeone-daydeliberativeworkshopswith20membersofthepublic(selectedtoformabroadlyrepresentativesample)inBristol,CardiffandInverness

• Aseriesofsixfocusgroupsatthreelocationsthatwouldbedirectlyimpactedbytidalpowerdevelopment:BreanDown,LavernockPoint,andOrkney

• Twoone-dayfacilitatedstakeholderworkshopswithacombinedattendanceof72wereheldinAberdeenandCardiff

• Anationalomnibusopinionpollcomprisingeightquestionswitharepresentativesampleof1010membersofthepublic

• AnonlineforumdebatewiththeSustainableDevelopmentPanel,whichismadeupofmorethan500sustainabledevelopmentstakeholdersfromallwalksoflife24

• Afullandindependentevaluationoftheentireengagementprocess.

Wehavealsoengagedextensivelywithawiderangeofindividualsandorganisationsincludingthestatutoryconservationagencies,non-governmental

organisations (NGOs), local authorities, tradeassociations,andotherinterestedparties.

The results of our commissioned engagementwork can be found in an independent reportavailablefromourwebsite.Asummaryofthetoplevelfindingsisprovidedbelow,andtheworkisalsoreferred to throughout this report. The evaluationreport will also be available from our website assoonasitiscompleted.

1.5.1 Tidal power and sustainable energy

The results from our public engagement showeda reasonably high awareness of climate change,althoughtherearesomedifferencesinopiniononitsimportanceasanissue.Therewaslessawarenessofenergysecurity,butmanypeoplebecameconcernedoncetheyweremadeawareofthisissue.

At a national level, only 55% of people hadheard of tidal power, and the workshop resultsshowed that some of these may be confusing itwithwavepower.Thisismuchlowerthanthelevelofawarenessforwindpower(91%).Thosewiththemostknowledgeoftidalpowerseemedtobemale,thosefromhighersocio-economicgroups,andthoselivingclosesttothesea.

1.5 Public and stakeholder engagement


Figure7 AwarenessofenergysourceswhichcangenerateelectricityintheUK

Bioenergy

Tidal

Wave

Hydro

Gas

Nuclear

Coal

Solar

Wind

20%10%0% 30% 40% 50% 60% 70% 80% 90% 100%

“Which sources of energy have you heard of that can be used to generate electricity in the UK?”

Base: All National – (source 1010)

Awareness of energy sources which can generate electricity in the UK

When asked about the UK’s potential forgenerating energy from the tides, 76% of peoplefeltthattherewasveryconsiderable,orquitealotofpotential.However,manypeople felt that theyneeded more information before they could formaninformedopinionoftidalpower,withparticularconcern for further cost information and real-lifeexamples.

All stakeholders at the workshops and withinthe ‘SDpanel’debatewereawareof tidalpower,although there was varying knowledge of thepossible impacts, and widely differing views onthe desirability of different technology options.Therewasgenerallystrongsupportfortidalpower;however,whenexploredinmoredetailwithintheworkshops, there was a negative opinion overallwhenitcametoaSevernbarrage.

1.5.2 Tidal power technologies

Tidal barrages

Therewasawidedivergenceofviewsbetweenthepublicandstakeholdersontidalbarrages.Thepublictendedtobequitesupportiveofthistechnology,andwereimpressedbythelargequantitiesofelectricityproduced,thelonglifetimeofabarrage,andsomeoftheancillarybenefitssuchasproposedtransport

crossings(despitesomeofthesebeinguncertain).Theyalsobelievedthat thedisadvantagesof tidalbarrages, such as the level of impact they wouldhave on the environment and local communities,andthehighcapitalcost,weremoreprofoundthantidalstreamandtidallagoontechnologies.

Stakeholders were more concerned overthe disadvantages of tidal barrages than thepublic. Although they recognised a number ofsimilar benefits, they emphasised a number ofdisadvantages,includingtheimpactonhabitatsandbiodiversity,theneedforpublicsubsidies,andthepossibleimpactonportsandshipping.

“Tidal barrages have so many impacts onbirdlifeandseashoreecosystem,thattheyshould only be considered in special casesofneed.”

SD Panel Member

Tidal stream

Ontidalstreamtechnologies,thepublicweremorecautiousintheirsupport,andcouldnotseeasmanyadvantages as for tidal barrages. This was due totheperceptionthattidalstreamwouldnotgenerateelectricityatthesamescaleastidalbarrages(dueto its modular nature), its unproven status, the


comparativelyshortlifetimeofthedevices,andthecurrently high cost of electricity output. However,they also identified far fewer disadvantages,although there was some concern over visualimpact.

Again,stakeholderstookaratherdifferentview,generally seeing tidal stream technologies in amuchmorepositivelightthanbarrages.Theywereparticularly attracted by the comparatively lowenvironmentalimpactandbytheirmodularnature,making them more likely to attract investment.Theywere also awareof theUK’s potential to bea leader indevelopingthistechnology,whichwasseenasamajorbenefit.

“Tidal flow technologiesmay be themostappropriate as they may have less impacton theenvironmentonaday today leveland in circumstances where pollution maybe a problem. It would be important toknow how long they would operate for inassessingtheirbenefit.”

SD Panel Member

Tidal lagoons

The public felt that tidal lagoons had the least toofferoutofthethreeoptionsconsidered,withlessenergyproducedthanabarragebutwithahigherenvironmentalandvisualimpact.Itispossiblethatmuchofthisconcerncanbeexplainedbythelackofinformation(particularlyaccuratevisualmaterial)on tidal lagoons,which led thepublic to feel thatthetechnologywasunproven.

Stakeholders perceived tidal lagoons morepositively than the public, although with greaterenvironmental impacts than tidal stream devices.Theyidentifiedthepotentialforlowerenvironmentalimpacts as a benefit when compared to a tidalbarrage,alongwiththepotentialforlocalownershipand UK technological leadership. However, therewereconcernsoverthesourcingoftheconstructionmaterials, the lossof shallowwaterenvironment,andthepotentiallyhighcosts.

“Arecentstudyintotidallagoontechnologyin Swansea Bay suggested it would havea minimal impact on local ecosystemsand ecology, and may in fact create smallrefuges for birds! I think it is vital the DTIsupportsthistechnologyastheUKcouldbe

aworld leader inthissustainablesolution.Weshouldn’tmisstheboataswedidwithwind power in the 70s and 80s. If provenenvironmentally acceptable then it shouldjoinwind,biomassandbuildingintegratedtechnologies in theprovisionof renewableelectricityfortheUK.”

SD Panel Member

1.5.3 Conditions for acceptability

Anyassessmentofpublicandstakeholderopinionof relatively unknown technologies, such as tidalpowerdevices,willsufferfromalackofinformation.Thislimitationmaypartiallyaccountforthelackofenthusiasmshownbysomemembersofthepublictowards tidalstreamdevicesandtidal lagoons,astheresearcherswereconstrainedbytheir inabilitytogivereal-lifeexamplesofwhattheinstallationswouldlooklikeandhowmuchtheywouldcostinthelongerterm.

As a result, the SDC was keen to ensure thatboth the public and stakeholders were askedto identify conditions for acceptability for thedeployment of tidal power technologies at scale.The public were most concerned about dealingwith the environmental impacts related to a tidalpower project, and minimising the visual impact.Meanwhile, stakeholders identified a more wide-ranging set of conditions, which have beensummarisedasfollows:

• Fullecological/environmentalimpactstudyforalloptions

• Accurate,independentandcentrallycoordinatedresearchandevidencebase

• Cleargovernmentpolicyonenergy,theroleofrenewablesandtidalpower

• Improvedplanningandconsentssystems• Fullconsultationwithmarineusers• Reducedrisktodevelopersandinvestorse.g.

throughapilotscheme• Proveneconomicviability.

When it came to the role of Government,the majority of respondents in the national poll(51%) felt that Government should take the leadon researching and supporting new tidal powertechnologies – see Figure 8. The broad view ofstakeholders was that Government should beresponsibleforthe‘top-down’directionandpolicydecisions, with regional organisations and the


Devolved Administrations taking responsibility forimplementation. Stakeholders also felt that whileitwas important forGovernment topromotenewtidaltechnologies,theyshouldalsoensuretheyarefocusedondeliveringgreaterenergyefficiencyanddemandmanagement,aswellasotherrenewableenergysources.

In addition, many SD panel members felt thattidalpowershouldbeevaluatedaspartofabroaderrethinkofenergypolicyaimedatmakingthewholeoftheUK’senergyconsumptionmoresustainable.

“Tidal (and all other types of renewableenergy sources) should not be developedand used unless they are done so as partofamorecomprehensiverenewableenergystrategythatreducestheprofligatedemandson energy that our industries, economies,politicians, and the general consumerexpectsanddemands.”

SD Panel Member

“Topursueatrulysustainableenergypolicywe should prioritise reducing demand andencouragingacultureofenergyconservationandefficiency.Thismustbeaccompaniedbyradicalshiftsinourattitudesandbehaviourstowardstheuseofenergyresources.”

SD Panel Member

Figure8 HowshouldtheUKbestsupporttidalpowertechnologies?

There should be no further research or supportfor new tidal power technologies

Don’t know

Consumers should pay for researching and supporting new tidal power technology through a small increase in their energy bills

Private sector companies should pay for researching and supporting new tidal power technologies

The government should pay for researching and supportingnew tidal power technologies through general taxation

20%10%0% 30% 40% 50% 60% 70% 80% 90% 100%

“How should the UK best support the development of new tidal power technologies?”

Base: All National – (source 1010)

How should the UK best support tidal power technologies

ThischapterhassummarisedtheUK’stidalresourceand electricity generating potential, along withtemporalfactorsandthegridconstraintissuesfacingtidalpowerdevelopments. Ithasalsoprovidedanoverview of Government energy policy, and theSDC’sadviceonhowthiscanbeimproved.Finally,theheadline resultsofourpublicandstakeholderengagementhavebeenpresented.

The rest of the report providesmoredetail oneachtypeoftidalpower,withaparticularfocusonproposalsforaSevernbarrage.

The next chapter considers the potential fortidalstreamdevelopmentintheUK,lookingatthe

technologies,fundingregime,andenvironmentalandsocioeconomicimpacts.Thissectionconcludeswithadiscussionoftheopportunitiesandbarriersfacingtheindustry,andanumberofrecommendationsfordevelopingthisindustry.

Chapter3presentsanoverviewoftidalbarragesand lagoons, including a information on existingbarrage developments in other countries, and anumberofbarrageandlagooncasestudies.Thereisashortdiscussionoverthecostestimatesavailablefortidallagoons,andarecommendationforfurtheraction. Issues related to theenvironmental, socialandeconomic impacts of tidal range technologies

1.6 Report structure


arecoveredinChapter4inrelationtothespecificexampleofaSevernbarrage.

Chapter 4 presents the evidence the SDChas analysed on proposals for a Severn barrage,including an overview of the various barrageschemesthathavebeenputforward,andastrategicanalysisofpotentialconflictsinutilisingtheSevernEstuary tidal resource. It covers a wide range ofissues, and presents a number of conclusions on

the less contentious issueswhere the evidence isconclusive.

The final chapter summarises the SDC’srecommendationsontidalstreamandtidallagoons,before considering the more fundamental, ‘deal-breaking’ issues raised by a Severn barrage. Thisconcludes with the SDC’s advice to Government,and with our recommendations on moving thedebateforward.

Tidal Stream

2


Ashighlighted inChapter1, theUKhasanexcellent tidalstreamresourcethat ispresentlyuntapped.Alargenumberoftidalstreamdevicesareindevelopment,andthereisaconsiderabledegreeofoptimismregardingthelong-termoutlookforthesetechnologies,andtheirabilitytomakeasubstantialcontributiontocombatingclimatechangeandimprovingourenergysecurity.

This chapter begins with an outline of thedifferent typesof tidal technologies, their levelofdevelopment,andtheirlong-termpotential.Itthensummarises the current UK policy context beforeconsidering the issues around the exploitationof the UK’s tidal stream resource, such as theenvironmentalandsocialimpacts.Finally,itpresents

theSDC’sanalysisofthebarriersandopportunitiesfacing tidal streamtechnologies,alongwithsomesuggestionsfortheirresolution.

The material below draws mainly on TidalResearchReports1and2,aswellastheengagementworktheSDChasconductedwithstakeholdersandthepublic.

2.1.1 Tidal stream devices

Tidalstreamtechnologiesworkbyextractingsomeofthekineticenergyfromfast-flowingtidalcurrentsandconvertingthatkineticenergytoelectricity.Todo this they cannot completely block the path ofthetidalcurrents,asotherwisetherewouldbenoenergy to extract. Instead, they are designed toextract the maximum possible amount of energywhilststillallowingtheseatoflowinanormalway–butwithreducedenergy.

Tidal stream devices are in general modular,stand-alonedevicesthatwouldusuallybeinstalledinlargearraystomaximisethepotentialelectricityoutput. They are therefore similar in terms ofdeploymenttotechnologiessuchaswindturbines,which rely on installations of multiple turbines toachieve a significant combined output. However,unlikewindturbines,tidalstreamdevicescanonlybe installedoffshore, and this poses a number ofchallenges. Some of the challenges are similar tothosecurrentlybeingtackledbytheoffshorewindindustrybutthetidalstreamindustrymustdevelopandtestthetechnologyinandunderthewaterinachallengingmarineenvironment;theoffshorewindindustrycouldtaketechnologythatwasdeveloped,testedandprovenonshore.

Duetobeingintheearlystagesofdevelopment,therearecurrentlyaverywiderangeoftidalstreamdeviceswithnoclearsignofwhichwillbethemostsuccessful in the long term. This situation mirrors

theearlydevelopmentofthewindindustry,wherea variety of different designs were developedbeforehorizontalaxisturbinesbecamethestandardfor large-scale installations. The large number ofdevicesunderdevelopmentreflects thesuccessofearlier Government policies towards tidal stream,whereseed funding in the1990shasencouragedthedevelopmentofalargenumberofdesignsandprototypes.

Thereareseveralwaysofcategorisingtidalstreamdevices, with overlap between categorisations.Probably the most obvious design element is therotorconfiguration,ofwhich thereare threemaincategories:

• horizontalaxis• reciprocatinghydrofoil• verticalaxis.

TheseareillustratedinFigure9.

In addition to rotor configuration, tidal streamdevices can be categorised by their placementmethod,whichcanbefixedtotheseafloor,weightedtositontheseafloor,orfloating(usuallythroughtheuseof cables attached to landanchors). Theycanalsobeducted,whichisawayofconcentratingthetidalflowsfroma largeramountofseawaterintoasmallerrotorarea.

For further information on the types of tidalstream devices being developed, please refer toTidalResearchReport2.

2.1 Technology overview


Figure9 Rotorconfigurationoptionsfortidalstreamdevices.

2.1.2 Current level of development

There are a large number of tidal stream devicesindevelopment,witha significantamountof thisactivitytakingplacewithintheUK.Researchreport2 includes references to 24 known tidal streamtechnologies. Although these are inevitably atdifferent stages of development, none of thesedevices has yet progressed beyond the prototypestage, with full-scale demonstration of somedevices ongoing or imminent. After successfuldemonstration, each technology will need toprogress to the installation of small (<5MW) andthen large (<30MW) arrays, before looking to beinstalledas ‘significantprojects’onasimilarscaleto other renewable technologies such as windpower.25

Box5describestheinstallationofademonstrationdeviceinStrangfordLoughinNorthernIreland.

One of the success stories of recent years hasbeen the establishment of the European MarineEnergyCentre(EMEC)inOrkney,northScotland–acasestudyofEMECisprovidedinBox4.EMECisanimpressiveexampleofusingpublicfundstocreateagenericresourcetosupportandstimulateprivatesectorinvestment.

Despite the relatively immature status of tidalstream technologies, there is growingenthusiasmovertheirlong-termpotential.Infact,mostofthetechnologies surveyed have come about primarilyasa resultof concerted innovation fundingduringthe1990s,combinedwithamorerecent injectionof fundingstarting in2001.26Asaresult,progressto date has been comparatively quick and thereisstrongpotential for tidalstreamtechnologiestoreplicatesomeofthegrowthseenintheearlyyears

of the wind industry. This is despite the fact thatmarine renewables in general have received farless R&D fundingworldwide thanother electricitygenerationandlowcarbontechnologies.

TherewouldbeanumberofsignificantbenefitstoUKleadershipinthedevelopmentoftidalstreamtechnologies.Thesecanbesummarisedasfollows:

• Exportpotentialinarelativelyundevelopedmarket

• Thetransferenceofskillsbothintothetidalstreamindustryfromtheoffshoreoilandgassector(whichisfacinglong-termdecline)andtheoffshorewindsector,andfromthetidalstreamindustrytoothermarinerenewables

• Developmentofasignificantcarbon-savingtechnology–bothfortheUKandfortheworld.

2.1.3 Future prospects

Themost recent studyof the long-termeconomicpotentialoftidalstreamtechnologieswascompletedby the Carbon Trust26 in 2006 as part of a widerreviewofmarineenergy,includingwavepower.

TheCarbonTrustconcludesthatinitialtidalstreamfarmscouldgenerateelectricityintheirearlystagesofdevelopmentatbetween9p/kWhand18p/kWh,withcentralestimatesinthesub-rangeof12-15p/kWh.Thesefiguresarewellabovethebasecostofelectricity, but this is unsurprising considering thecurrentleveloftechnologicaldevelopmentandthelowlevelofdeploymentimplied.

Future cost estimates are done on the basisof cumulative installed capacity, as this gives anindicationofpossiblecostreductionsasaresultoflearning.Thisanalysisuses‘costcurves’toestimate


thislearningeffect,andtheresultsshowthatenergycostsfromtidalstreamdevicescouldfallto7p/kWhwith the installation of 1GW of capacity, and 5p/kWh with 1.5GW. These figures would bring tidalstreamoutputcloseto,orwithin,thepossiblebasepriceofelectricity,particularlyiffossilfuelpricesarehighinthefuture.

As a result, the Carbon Trust estimates that1-2.5GWoftidalstreamcapacitycouldbeinstalledacross Europe by 2020, with the majority of thislikelytobeintheUK.

It is worth emphasising that these levels ofcapacity are well within the UK’s identified tidalstream resource, meaning that the UK has thepotentialtodevelopitsindigenoustechnologiesindomesticwaters, resulting in positive benefits forenterprise and employment. Beyond this, carbonpricingand incentives for renewablesare likely todrive international demand for such technologies,presenting an export opportunity for UK-baseddevelopers.

2.2.1 Tidal stream funding

Thereareanumberofsourcesoffundingfortidalstreamdevices,asfollows:

EU Structural Fund (Wales):Fundingisalsoavailablefromthe2000-2006StructuralFundProgrammes,althoughexpenditurecancontinueuntilmid-2008.

Marine Renewables Deployment Fund (MRDF):This£50mfundwassetupbyBERR(previouslytheDTI)in2004andhasfourcomponents;theWaveandTidal-streamEnergyDemonstrationScheme,environmentalresearch,relatedresearch,andinfrastructuresupport.Thedemonstrationschemeaccountsfor£42mofthefundandallowsfortheprovisionofcapitalgrantsandrevenuesupporttotechnologiesthatareenteringearlycommercialdeployment.

Renewables Obligation (RO):TheROisarevenuesupportmechanismdesignedtofacilitatethelarge-scaledeploymentofrenewableelectricitygeneration,thusleadingtolong-termcostreductions.

Research and Demonstration Programme (Northern Ireland):TheSecretaryofStateforNorthernIrelandannounced£15.2moffundinginFebruary2006toencourageandfacilitatethedemonstrationofinnovativerenewableenergytechnologiesoverthefollowingtwoyears.

Technology Programme:Previouslythe‘New&RenewableEnergyR&DProgramme’,fundingfromBERRisavailableundertheTechnologyProgrammeto“furtherdevelop,evaluateandtestwaveandtidalstreamdeviceconceptsandcomponents”.Eligibleprojectsmustbecollaborativeinnatureandgrantsaremadeunderatwice-yearlycompetitivefundinground.

Wave and Tidal Energy Support Scheme (Scotland):A£13mfundsetupbytheScottishGovernmenttoprovidegrantsandsupporttobusinessestosupporttheinstallationandcommissioningofpre-commercialwaveandtidalstreamdevicesattheEuropeanMarineEnergyCentreinOrkney.

The Renewables Obligation works by placingan obligation on electricity suppliers to source anannuallyincreasingpercentageoftheiroverallsalesfrom renewable sources, reaching 15% by 2015.The effect of the RO is to create a premium forrenewableelectricitygeneratorsofaround4p/kWh,thus stimulating investment in thedeploymentoflower cost renewables such as onshore wind andlandfillgas.However,theROprovidesthispremiumtoallrenewablegenerators,andwouldprovideanadditional source of revenue for pre-commercialtidal stream devices. Furthermore, BERR and theScottish Government now intend to introducetechnology banding for the RO, meaning highercostrenewableswillreceiveahigherpremium.ItisproposedthattidalstreamdeviceswouldqualifyfordoublethestandardlevelofsupportundertheRO,leadingtoapremiumofaround8p/kWh.

2.2 Current Government policy


Box4 Casestudy–EuropeanMarineEnergyCentre(EMEC)

Background

TheEuropeanMarineEnergyCentrewascreatedtostimulateandacceleratethedevelopmentofprototypetidaltechnologiesandhelpthemtowardscommercialdeployment.

Thesiteselectionprocessconsidered18differentcriteria,withOrkneybeingselectedastheidealsiteduetoanexcellentwaveandtidalresourcecombinedwithanationalgridconnectionandaccesstotheappropriateskillsbase.

Funding

DevelopmentoftheEMECsitewasledbyHighlandsandIslandsEnterpriseandwasfundedbyalargeconsortiumofpublicsectorpartners,including:

• CarbonTrust

• DepartmentofTradeandIndustry(nowBERR)

• EuropeanUnion,viatheHighlandsandIslandsPartnershipProgramme(HIPP)

• HighlandsandIslandsEnterprise

• OrkneyIslandsCouncil

• ScottishEnterprise

• ScottishExecutive(nowScottishGovernment)

TheEMECprojectwasestablishedasaresultofarecommendationbytheHouseofCommonsScienceandTechnologySelectCommitteein2001.Todate,thefundingconsortiumhasinvestedover£15minbothcapitalstart-upanddevelopmentcosts.ThistotalfundingformspartoftheEMEC’Songoingbudget,althoughthecentreisexpectedtobeginrecoveringsomeofitsoperationalcostsbychargingdevicedevelopersforaccesstothefacilities.

Facilities

ThefacilitiesofthecentrecomprisethreesitesintheOrkneyIslands:

• thewavetestcentreatBilliaCrooonthewesternsideofmainlandOrkney

• thetidaltestcentreinthefallofWarnessofftheoutlyingislandofEday

• theofficeanddatafacilitiesinStromness.

Thewavetestfacilitybecameoperationalin2003,withthetidalfacilitycommissionedin2006.EMECisthefirstcentreofitskindworldwidetooffermonitoring,evaluationandgridconnectiontodeveloperstestingprototypemarineenergydevices.

Thecentre’stidalfacilitiescomprisefivetidalenergyconvertertestberths,whicharesituated2kmoffshoreinwaterupto50mdeep.Therearealsofivesub-seacableslinkingthetestberthstoanonshoresub-station,andanobservationpoint,aweatherstationandadatacentre.Amongtheservicesavailabletopotentialdevicedevelopersareaccesstoagridconnection,spaceformonitoring,centralofficefacilitiesandalimitedenvironmentalmonitoringprogramme.

Projects

Todateonetidaldevice(theOpen-CentreTurbinebyOpenHydroGroupLtd)hasbeentestedatthecentre,witharoundsixdevicesinthepipeline.Despiteaslowstart,developersarenowconcernedthatthecentrewillbeatcapacitywithinthenexttwoyears,meaningtheymayhavetowaitforsparetestberthstobecomeavailable.


2.2.2 Regulatory and planning framework

Planningandconsentingregimesareinplaceacrossthe UK for pre-commercial marine developments.Frameworksforcommercialscaledevelopmentarenotyetinplace.Theplanningandconsentingregimeiscomplex,withprojectsfallingunderanumberofdifferent regimes – furtherdetailsareavailable inResearchReport1.

This section provides an overview of thecurrent regulatory and planning framework. TheSDC’s recommendations on getting the regulatoryframeworkrightarediscussedinSection2.4.3.

England and Wales

Existing planning and permitting arrangementsfor demonstration phase projects in England andWales are described in guidance published byBERR (previously DTI).27 Consent is required undertheElectricityAct1989 forany installationwitharatedcapacityexceeding1MW.Consentsmayalsobe required under the Coast Protection Act 1949,Food and Environmental Protection Act 1985, andtheTownandCountryPlanningAct1990.

TheUKGovernmentposition is thataStrategicEnvironmentalAssessment(SEA)willbeconductedonthetidalstreamresourceoncetheindustryreachesanappropriate stageof commercialdevelopment.This would probably occur in conjunction with aleasing competition fordevelopment rights to theseabedownedbytheCrownEstate.

Scotland

Scottish Ministers have devolved responsibilityfor consenting requirements for tidal streamdevelopment. Consents are required under theElectricity Act, the Coast Protection Act, Food andEnvironmental Protection Act, and the Town andCountryPlanning(Scotland)Regulations1997.

TheScottishGovernment carriedouta StrategicEnvironmental Assessment (SEA) of marinerenewablesinthenorthandwestcoastsofScotlandduring2006-7.Theaimofthisworkwastoconductahigh-levelassessmentofthepotentialenvironmentaleffectsofmeetingtheForumforRenewableEnergyDevelopment in Scotland’s (FREDS) estimate that1,300MWofwaveandtidalenergycapacitycouldbeinstalledaroundScotlandby2020.28

Northern Ireland

TheDepartmentofEnterprise,TradeandInvestment(DETI) has devolved responsibility for consentingmarine energy development under the ElectricityConsents(Planning)(NorthernIreland)Order2006.Again,consentmayalsoberequiredundertheFoodandEnvironmentalProtectionAct,whichwouldbeconsideredbytheDepartmentfortheEnvironmentthroughtheEnvironmentandHeritageService.

Renewable Energy Zone

TheCrownEstatehaspowerstolicencerenewableenergygenerationonthecontinentalshelfbeyondthe12nauticalmile limit, in the areadesignatedasaRenewableEnergyZoneundertheEnergyAct2004. The Scottish Government has responsibilityforthezonebeyondScottishterritorialwaters.

2.2.3 European environmental legislation

The provisions of the European Directives onEnvironmental Impact Assessment, Birds, andHabitats, and the Water Framework Directive, asimplementedinUKlegislation,willalsoberelevantto the assessment and consenting of tidal streamdevelopmentsacrosstheUK.

Inparticular,theHabitatsDirectiverequiresthedesignation of European marine sites as specialareasofconservation(SACs).Wheredevelopmentisbeingconsideredinadesignatedsite(orasitethathas been proposed for classification), additionalregulatory requirementswill apply. Inparticular, ahighlevelofinformationonenvironmentaleffectswillberequiredtodemonstratethatprotectedfeatureswill not be adversely affected. There is extensivediscussionoftheEuropeanenvironmentallegislationinChapter4inrelationtoaSevernbarrage.

2.2.4 Seabed licences/leases

Before deploying tidal devices, developers mustobtainasiteleaseorlicencefromtheCrownEstate,which has a business plan under which it willconsider applications for demonstration-scale tidalprojects. A further legal requirement will be thesatisfactorydecommissioningoftidaldevicesattheendoftheirconsentperiodoroperationallifetime.


2.2.5 Role of nature conservation agencies

TheUKstatutoryconservationagencieshavearolein advising Government on environmental andmarinenatureconservationissuesastheyrelatetotidalstreamdevelopment.Theagenciesarealreadyactively considering the potential implicationsof tidal stream development for the marineenvironment, and are inputting on the evolvingregulatory framework toensure thatanynegativeeffects are identified, and avoided or mitigated.The SDC has received positive feedback on theconstructive and proactive approach the agenciesaretakingonmarinerenewables,whichhasfocusedon the identification of gaps in our knowledgeofthemarineenvironmentandthepossibleimpactofrenewableenergydevices.

TheJointNatureConservationCommittee(JNCC),whichistheGovernment’sstatutoryadvisoronUKand international conservation issues,has takenastrong coordinating role. The Countryside Council

forWales(CCW)hasalsobeenactive,undertakinga high level assessment on the potential natureconservation and landscape effects of marinerenewables development.29 In its submissions tothe2006EnergyReviewand theWelshAssemblyGovernment’sEnergyRouteMap,CCWhasadvocatedaprocessofstrategicplanningtohelpidentifythemostappropriatetechnologiesandlocationsforthedeploymentoftidalstreamandwavedevices.

InNorthernIreland,theconsentingprocessfortheMarineCurrentTurbinesSeaGenprojecthasrequiredtheEnvironmentandHeritageServicetodealwitha specific test device project (see Box 5). EnglishNature had a general policy position statementonrenewableenergy,andNaturalEngland(whichis the new organisation that took over EnglishNature’sresponsibilitiesin2006)hasrespondedtothe Energy Review in similar terms, advocating aprocessofstrategicplanningforrenewableenergydevelopment. ScottishNaturalHeritagealsohasapositionstatementonmarinerenewables.30

Tidalstreamdevelopmentoffersclearandpotentiallyconsiderable benefits for securing a renewableenergysourceandproducinglowcarbonelectricity.Asoutlinedabove,tidalstreamalsoofferstheUKanopportunitytodevelopapotentiallyvaluableexportindustry.

However,asustainabledevelopmentperspectiveconsiders these benefits within a framework thatmustalsoaccountfortheenvironmental,socialandeconomic impacts.These impactswillbeamixofpositiveandnegativeimpactsandthewaytheyplayoutinpracticewillvaryaccordingtothelocationandthe scale of development. This section principallyfocusesonanyimpactsthatmightbenegative,astheseimpactswillrequiretheclosestattentionbyGovernment,developersandcommunitiestoensurethattheyareavoidedormitigated.

Tidalenergyinstallations–whetherdeployedasa single prototype device or an array – will havevarying levels of environmental impact that willrequiredifferentlevelsofenvironmentalassessmentand monitoring for consenting purposes. Theconstruction of tidal energy schemes will requiresome environmental baseline assessment (andsubsequentmonitoring)aspartofanEnvironmentalImpact Assessment (EIA), which will also indicate

mitigation measures to reduce environmentaleffects.

2.3.1 Physical configuration of devices

The physical characteristics and configuration ofdevices will have implications not only for theeconomics and viability of the technology, butalso for the nature and significance of potentialenvironmental, social and economic impacts.Atpresent,alargenumberofdevicesareatdifferentstagesofdevelopmentandthelong-termprospectsof each device cannot be predicted with anyaccuracy. It is difficult to fullydescribe the impactonedevicemighthavewhenit isdeployedinthesea and it is even more difficult to describe thecumulativeeffectsofanumberofdevicesdeployedasanarray.

One differentiator is the location of a devicewithin the water column; a seabed-mountedunderwater device may be more compatible withexisting shipping routes and may have less of avisual impact. Another differentiator is the waterdepth at which a device can be deployed; somedevices with fixed foundations may not be able

2.3 Environmental, social and economic impacts


toutilisehighenergysites located indeepwater.The marine environment itself poses significanttechnical and cost challenges, and developers arelikelytotestdevicesinmoreaccessibleandpossiblyless energy-intensive sites. Later developmentsmayfocusonmorechallengingsites.ThePentlandFirth,forinstance,offersthegreatestconcentrationoftidalstreamresourceintheUKwithsomeofthemostchallengingconditions–thisisunlikelytobeanearlychoicefortidalstreamdevelopers.

The interaction between the design of devicesand their impacts will be iterative, as developerscontinue to test and deploy their devices. Theenvironmental, social and economic impacts ofearlydeviceswillplayapart indetermining theirviability and success, along with other technicalsuccessfactors,suchasenergyoutputandeaseofinstallationandmaintenance.Thismay incentivisedevelopers to search out the low cost and lowimpactoptionsasthetechnologydevelops.

2.3.2 Environmental considerations

Bytheirnature,tidalstreamdevicesaredesignedtoextractenergyfromthewater,andtheirpresencewill affect the physical, chemical and ecologicalfeatures of the marine environment. This sectionprovides an overview of the main environmentalimpactsandsomeofthekeyissuesindealingwiththe potential effects of tidal energy developmentonthemarineenvironment.

Scale and locational factors

Thescaleofeachinstallation(thenumberandsizeof the devices installed) and the total number ofinstallations around the coastline will be the keydeterminants of overall environmental impact.Accordingly, given the relative immaturity of theindustry, and the small number of devices beinginstalled, the risk of any significant impacts is atpresentverylow.

This is an important point for decision-makersto be aware of as consents are sought for newdevices at the testing stage. However, taking along-term view of the industry also requires thatthe potential impacts of large-scale deploymentin the future are considered now and taken intoaccount inevolving the regulatory frameworkandin the ongoing development of device designs.

Todateverylimitedenvironmentalmonitoringhasbeenrequiredforprototypedevices,whichmeansthatopportunitiestodevelopthebaselinedataoneffects of devices could be missed. Nevertheless,theSeaGentestprojectatStrangfordLoughwillbesubject to considerable environmental monitoringovertheperiodofitsfiveyearconsent(seeBox5).

Thelocationoftidalstreamdevelopmentwillbea further determinant of impacts. The desk-basedresearch commissioned by the SDC has primarilyconsidered the potential impacts of tidal streamtechnologies in generic terms. The impacts of aparticulardevelopmentwilldependonsite-specificfactorsrangingfromtheconservationinterestsofthesitetoitslocationinrelationtotownsandmarineindustries. Early tidal installations are most likelyto be developed in the more accessible resourcelocations, with the challenging, high-energyresource locationsdevelopedonce the technologymatures.

These issues are explored in greater depth inResearchReport2.

Available information

Todateveryfewtidalstreamdeviceshavebeendeployed as prototypes, and there is only limitedenvironmental data available. However, thesedevicesarenotfullscale,noraretheydeployedinareas which are likely to be used for commercialgenerationoftidalpowerinthefuture.Inaddition,the environmental impacts of prototype devicescannot necessarily be taken to represent thepotential impacts of generating power from anarrayofdevicesona commercial scale. Thereareadditionalissueswhentheimpactsofoneprototypedevice aremultipliedup to assess the cumulativeeffectsofatidalstreamarray.

Despite the lack of direct observational datarelating to tidal energy, a considerableamountofinformation exists regarding the environmentaleffectsofothermarinedevelopments.Forexample,the offshore wind, and oil and gas industries,provideinformationontheenvironmentalimpactsofdrilling,pilingandsub-seacablinginthemarineenvironment.Thisillustratessomeofthesynergiesbetween both different categories of offshorerenewables, and between offshore renewables(whichareexperiencingsteepgrowth)andtheUK’slargeoffshoreoilandgasindustry(whichisinlong-termdecline).


Thisisalsoariskissue.Atpresent,wheresingletestdevicesarebeingdeployedforarelativelyshorttime (say 1-5 years), the risk that environmentaldamagewill result is low, and the significance ofany adverse consequences is likely to be low aswell.However,astheindustrydevelopsandmoredevices are deployed, the risk and significance ofanyadverseeffectswill increase.Any informationgapswill need to be progressively filled to avoidthisscenarioandallowtheindustrytoexpand.

There is an important exception, whereeven a relatively low level of risk needs to berecognised.ForEuropeanmarinesites,averyhigh

levelof informationwillberequiredaspartofan‘appropriateassessment’, and itwillbenecessarytoshowthatdevelopmentwillnothaveanadverseeffectonaprotectedsiteorfeaturebeforeconsentcanbegiven.31 Thispositionwillmean that thesesites are unlikely to be attractive for early stagetestingandinstallationofdevices.Nevertheless,inthe longer term,developmentwillnotnecessarilybe inconsistent with the objectives of marineconservationprovidedgoodinformationisavailabletomakethecase.

The implicationsof informationgaps forpolicymakersisdiscussedinSection2.4.4below.

Box5 Casestudy–StrangfordLough

Background

Followingthedemonstrationofthecompany’sSeaFlowconceptturbineoffthecoastofLynmouth,northDevon,MarineCurrentTurbines,aUKcompany,hasdevelopedSeaGen,a1.2MWunderwater,twin-turbinetestdevice.Theturbinesaremountedonavertically-moveablecross-armonasinglesupportingpole,whichisdrilledintotheseabedandisvisibleabovethewater.SeaGenisduetobetestedatStrangfordLough,NorthernIreland.Furtherinformationisavailablefromtheprojectwebsite:www.seageneration.co.uk.

Funding and investment

TheDTI’sTechnologyProgrammehasprovidedaround£4.27mingrantsupporttodevelopthetechnology.Thecompanyhasindicatedthatthishascoveredaroundhalfoftheprojectcost.MarineCurrentTurbineshassecuredinvestmentfromEDFEnergy,BankInvestandGuernseyElectricity,andmorerecently,fromTriodosBankandAM2(BermudaLimited).

Site selection

TheStrangfordLoughprojectwasinitiatedinlate2003.Thecompanyselectedthesiteforitswave-shelteredenvironment,strongdirectionaltidalflows,andproximitytotheshoreandlocaltechnicalservices.Onceinstalled,theturbinewillbeconnectedtothelocalgridandgenerateenoughelectricityforapproximately1000homes.Thedeveloperundertookconsultationwithregulators,statutoryconsultees,theCrownEstate,thelocalcommunityandotherstakeholdersoverthecourseofdevelopingtheproject.

Environmental issues

Thesiteisalsoacknowledgedtobeinanenvironmentallysensitiveareaandoneofthekeyissuesfortheprojecthasbeenpredictingandassessingthepotentialenvironmentalimpacts.Thishasinvolvedputtinginplaceacomprehensivemonitoringprogrammeaspartofthefive-yearconsentthathasnowbeengrantedfortheproject.

StrangfordLoughisanimportantinternationalsitefornatureconservationandisdesignatedunderEUHabitatsandBirdsDirectivesasaSpecialAreaofConservation,aSpecialProtection


Areaforbirds(seeSection2.2.3),aswellasbeingaRamsarsiteforinternationallyimportantwetlands.TheSeaGentestsiteisintheStrangfordNarrows,whichconnectstheLoughtotheIrishSea.Theareahasimportantsubtidalandintertidalrock,sand,mud,andhorsemusselhabitatsaswellaswinteringwaders,breedingternsandsealpopulations.AnEnvironmentalStatement(ES)wasinitiallypreparedinJune2005tosupportthecompany’sapplicationforconsentundertheFoodandEnvironmentProtectionAct1985(FEPA)andtoassistthecompetentauthority,NorthernIreland’sEnvironmentandHeritageService(EHS),tofulfilitsobligationsundertheHabitatsDirective.

TheESpreparedin2005recognisedthatthenoveltechnologymeantthattherewassomeuncertaintyaboutthepotentialimpactsonsealsandbaskingsharks.Atmaximumturbinespeedtherotorbladeswouldoperateataround12m/s,aboutathirdoftheaveragewindturbinespeedaccordingtotheES.Aspeedof10m/sismorelikely,whichcorrespondstoaround12revolutionsperminute.

ItwasalsorecognisedthattheinstallationandpresenceofthedevicewillhavesomevisualimpactontheseascapeasthepartofthestructurethatisabovewaterwillbevisiblefromlandandfromtheferrycrossingfromPortaferry.Onceinstalled,theeffectswillbemoresignificantduringmaintenanceasaresultofincreasedactivityandthecross-armbeingraisedabovethewaterlevel.

Outcome and lessons

TheEHSinitiallygrantedaFEPAconsentfortheprojectinDecember2005.However,furtherinvestigationswerenecessarytofullysupportthe‘appropriateassessment’processundertheHabitatsDirective.Thisprocessrequiresaveryhighlevelofconfidencethatinternationally-importantprotectedconservationfeatureswillnotbenegativelyaffectedbydevelopment.TheEHSgrantedafurtherconsentforthefive-yeardemonstrationinFebruary2007.

Theprojectnowhasacomprehensivemonitoringprogrammeinplaceforbirds,habitats,seals,andbaskingsharks.TheconditionsoftheconsentalsogivetheEHSsomeoptionsforstoppingtheoperationifsignificantadverseeffectsoccur,includingtheabilitytorequirefurthermonitoringandassessment,orevenearlydecommissioning.ThemonitoringcanbeexpectedtogenerateusefulinformationontheactualenvironmentalimpactsoftheSeaGendevicewhichwillhaveapplicationinfuturedesignmodifications.Itwillalsohelpinpredictingpotentialenvironmentalimpactsatothersitesorfromtheinstallationofmultipledevices.

Ontheenvironmentalissues,theESindicatedthat,earlyonintheproject,therewasgeneralsupportfromstakeholdersforthedevelopmentofanewrenewabletechnologybutthattherewerepotentialissuesaroundtheinternationaldesignationandimpactsonprotectedspecies.ThedelayintheconsentingprocesstofullyaddressconcernsundertheHabitatsDirectivesuggeststhatitmighthavebeenpossibletoavoidorresolvetheseissuesearliertoensurethatthestrictrequirementsweremetwithoutdelayingtheproject.However,thecasestudyalsoindicatesthatworkinginanenvironmentallysensitiveareaisamajorchallengeforaone-offdemonstrationprojectinvolvinganewtechnology.

Thetestingandmonitoringshouldnonethelessprovidevaluableinformationontheoperationofatidalstreamturbineinthemarineenvironment.TheactualinstallationofSeaGen,whichwasmostrecentlyscheduledforthesummerof2007,hasbeenfurtherdelayedbecauseofaproblemwiththejack-upinstallationvesselbutisduetogoaheadshortly.


2.3.3 Summary of environmental impacts

The key environmental impacts from tidal streamdevelopmentarethoserelatedto:

• ecology(habitatsandspecies)• landscapeandseascape• noise(airborneandunderwater)• seabed,sedimentsandcurrents• waterquality

Impactsonotherusersofthemarineenvironment–suchasfishingandnavigation–willalsoneedtobeconsideredaspartofanenvironmental impactassessment. In practice, these issues need to beconsideredmuchearlieratastrategic levelandinsite selection. The issue of conflicts of use in themarine environment is discussed in Section 2.3,whichconsidersthepotentialsocialandeconomicimpactsoftidalstreamdevelopment.

Environmental impactsatthevariousstagesofdevelopmentwillneedtobeconsidered,including:

• construction• operationandmaintenance• decommissioning.

At theconstructionstage, thekey impactswillberelatedtodrillingandpilingactivities,increasedlevelsofnoise,andincreasedactivityandpollutionriskassociatedwithconstructionboatsandactivity.Direct effects on the seabed are greatest at thisstage.Fortidalstreamdevices,constructionofthedevice itself would usually take place onshore,followedbyinstallationofthedeviceandassociatedcablingatsea.

At the operation and maintenance stage, thedevice may have effects on water movementsand sediment, as energy is extracted from thetidalflows,andunderwaternoiseand the turbineoperationhavethepotentialtoaffectecology,fishandmarinemammals.

Tidalstreamdevices,oncedevelopedtofullscale,canbeexpectedtohavealifetimeofaround20years.At the decommissioning stage, similar effects tothoseidentifiedforcommissioningcanbeexpected.Furthereffectsatthispointmayincludedisturbancetoanynewcommunityofmarineorganismsthathasbecomeestablishedonthedevice.

Theenvironmentaleffectsofassociatedonshoreinfrastructure,inparticularpowercabling,willalsoneed to be taken into account, and can often bea significant practical issue during consenting (asseparateplanningconsentmustbesought).

Ecology (habitats and species)

AnumberofmarinespeciesandhabitatsinUKcoastalwaters have the potential to be affected by tidalenergy schemes. These includebirds, fish,marinemammals, plankton, and benthic communitieson the seabed. Terrestrial habitats may also beaffected by infrastructure works to accommodatethelandwardtransmissionofelectricity.

The main issues affecting habitats arise fromchangestothephysicalenvironment–forexample,changes in water flow and tidal mixing, waveaction, tidal inundation,patternsof sedimentationand erosion, and disturbance of the seabed byconstruction and cabling. These changes can alterthecharacterofmarinecommunities,orleadtothedisplacementof species from feedingor breedingareas.

Fishandmarinemammalsmaybeparticularlyaffectedbythegenerationofunderwaternoise,andthe electromagnetic fields generated by sub-seatransmissioncables.Collision risk isanother factorthat will need to be considered for each device.Although the risk from turbines turning slowlyunderwatermaybelow,thisrisk,andthepotentialbehaviouralchangesofthesespecies,willneedtobeassessedwithcare,andmonitoringofinstalledtestdeviceswillbeneeded.

Therearealsopotentiallypositiveeffects fromtidal streamdevelopment fornatureconservation.A tidal installation may function as a refuge areafor fish populations as a result of reduced fishingpressurefromthecreationof‘no-catch’zones.Thepotentialbenefitsofthiswilldependonthespecificimpactsofadevice,thescaleofitsdeployment,andconsiderationofdecommissioningimplications,butthismayofferanopportunitytointegraterenewableenergygeneration(andacommercialactivity)withnatureconservationobjectives.

Landscape and seascape

Manycoastalareashaveanimportantamenityandnaturalheritagevalueforcommunities,visitors,andrecreationalusers.Theplacementofatidalenergyschemeinwatersclosetotheshoremayhaveanimpactonthelandscapeandseascapeofthearea,particularlywherethedevicesaresurface-piercingstructures.The levelof impactwilldependonthe


landscapecharacterofthecoastalareaandthetypeof tidal energy scheme. Scottish Natural Heritage,for example, has suggested that developmentshould be avoided in isolated or undevelopedcoastalareas.30

Visualeffects–boththeappearanceofadeviceanditsvisibilityfromlandorfromavessel–andtheimpactsonlandscapeandseascapeareoftenakeyissueforlocalcommunities,anddesignandlocationwill need to be considered. While tidal streamdevelopmentislikelytohavealowerimpactthanwinddevelopment,lessonscanbedrawnfromthatindustryabouttheimportanceofearlyengagementontheseissueswithlocalcommunities.Inthecaseofanewtechnology,thismaymeanprovidinggoodinformation todemonstrate thevery lowvisibilityof a device or development. The visual effects ofsupportinginfrastructure–substations,pylons–willalsobeakeyissue.

Noise

Noise and vibrations travel significant distancesunderwater. Increases to background noise duringconstructionandoperationmayhaveseriouseffectsonmarine mammals and fish, depending on thelevel, frequencyanddurationofnoise.Again, thisis an areawhere there is insufficient informationon the potential effects of noise levels from tidalstreamdevices.

Depending on the distance from shore,climatic conditionsandwinddirection,noise fromconstruction, maintenance and decommissioningactivitiesmayalsoaffectlocalcommunities.

Seabed, sediments and current

Theplacementoftidalenergystructuresandtheirassociated cabling on the seabed will result in achange to thephysical characteristics of the area,andmayinvolvealossofhabitat.Fixedtidalstreamdevices will have a relatively small footprint foreach individualdevice,varying inaccordancewithwhether the device is fixed or floating. For anarray of tidal devices, cabling arrangements willbecomplex,effectively increasing the footprintofan installation.Cablingmayhaveasignificantbutshort-term adverse impact on the seabed. At thedecommissioningstage,cablingmaybeleftinplacetoavoidfurtherdisturbance,orre-usedwithanew

installationofdevices.Theplacementofasolidstructureontheseabed

inanareaofstrongtidalflowswilleffectpatternsofsedimenterosion,transportationanddeposition.Byextractingenergyfromtheflow,atidalstreamdevicecanreducethedownstreamvelocityof theturbine considerably, with the effects discerniblesome distance away. This is one of the key areaswherethepotentialcumulativeeffectsofdeployingtidal stream devices in large arrays are unknownandfurtherresearchwillberequired.

Water quality

Themainissuesforwaterqualityfromtidalstreamdevelopmentarethepotentialleakageoflubricantsandhydraulicfluids,andthechancethatincreasedvolumeofvesseltrafficassociatedwiththeschememayresultinincreasedlevelsoffuelandoilleakageintothewater.

Design and mitigation measures

Relativetotidalbarragesandlagoons,tidalstreamdevicesareexpectedtohaverelativelyloweffectsontheenvironment.32Thiswilldependonthetypeand number of devices deployed, as discussedabove. The greatest environmental effects can beexpectedtooccurwherearrays,farmsoraseriesoffarmsaredeployed.

Possible mitigation methods for managingeffectsontheseabed,sedimentsandhydrodynamicsincludesensitivedesignofbasestructuresandchoiceof location to minimise impact on sensitive sites.Thedesignofdeviceswillalsoneedtoconsidertheirinteractionwith fish, birds andmarinemammals.It may also be possible to time construction anddecommissioning activities to minimise adverseimpacts on sensitive ecological receptors (such asmarinemammalsaffectedbynoise).Monitoringoftestdeviceinstallationswillimproveunderstandingof ways in which impacts can be avoided orminimised.

2.3.4 Social and economic impacts

Asthetidalstreamindustrydevelops,thesocialandeconomicimpacts(positiveandnegative)arelikelytorepresentsomeofthemoretangibleeffectsfor


communities at a local and regional level. At thisstage, there is very limited information to drawon, although it is likely that social, economic andenvironmentaleffectswillbecloselyinterrelated.

Economic effect from large-scale tidal streamdeploymentmightincludethoserelatedto:

• commercialfishing• employmentandincomebenefitsfromnew

industries• opportunitiesforlocalindustries• ports,commercialandrecreationalshipping• tourism• widereconomicregenerationandexport

potential.

Many of the impacts from tidal streamdevelopmentcouldbeeconomicallypositiveforlocalcommunitiesandthewidereconomy.Animportantexceptiontothisisnavigationandfishinginterests,whichcouldbenegativelyaffectedbytidalstreamdevelopmentsduetorestrictionsonmovementandaccess.Theissueofconflictbetweenmarineusersisdiscussedfurtherbelow.

Community effects

In addition to the potential for local employmentbenefits, tidal stream developments may alsohave the following impacts or benefits for localcommunities:

• communitybenefitpayments• educationalopportunities• impactonhistoricalorculturalheritagesites• impactontheamenityvalueofthearea• seascapeandvisualimpacts.

TheSDC’sengagementwith local communitiesshows that new and unknown technologies canbe a very emotive subject. There is a particularlystrongneed foraccurate informationon the likelyvisual impact to enable people to take a viewon any proposed development. As with marinestakeholders,earlyandeffectiveengagementwithlocalcommunitiesishighlydesirable.

The use of community benefit payments byrenewable energy developers is common practiceintheonshorewindpower industry,andcouldbeeasilyreplicatedbytidalstreamdevelopers.33Theremayalsobethepotentialtoencouragecommunityinvestment in new tidal stream developments,which is a model that has been applied to some

smallwindfarmsintheUK,andonamuchlargerscaleinDenmark.

Conflicts of use in the marine environment

Tidal stream development, particularly as theindustrydevelopsandbecomesastrongerpresence,isbound to come intoconflictwithotherusersofthemarineenvironment.Otherusersofthemarineenvironmentinclude:

• commercialfishing• commercialshippingandnavigation• dredgingandmineralextraction• MinistryofDefenceactivities• navigationalaidsandlighthouses• oilandgasindustry• otheroffshorerenewableenergy

(wind,wave)• ports• recreationalfishing• recreationalshipping• tourism• underseacablingandpipelines.

TheSDCactively sought toensure thatmarineuserswereinvitedtoparticipateinitsstakeholderworkshops, and a number of representativeorganisationsfromthemarinesectorattendedtheSDC’s stakeholderworkshops. Thestrongmessagefrom those who participated is that this industrymustactivelyengagewithandtakeaccountoftheinterestsofthemarinesector.

Asanewactivityandformofdevelopment,tidalstream developmentwill sometimes conflict withotheractivitiesandinterests,whethercommercialorrecreational.Thisissueofcompatibilityandconflictisoneofthekeychallengesthata‘marinespatialplanning system’, as proposed in the Marine Bill,mayhelp toaddress so thatmultiple, cumulative,and potentially conflicting uses of the sea can bemanagedinasustainableway–seeSection2.4.3forfurtherdiscussion.Itshouldnotbeassumedthatthe impacts of new developments on other userswillbenegative.Whilesafetyzonesaroundoffshorerenewable energy installations may affect fishingoperators, the wider and potentially beneficialeffects on fish stocks should not be ignored if asafetyzoneisabletofunctionasarefuge.

Various marine users have already started torespond to the developing marine renewablesindustry. Most organisations responded initially to


thedevelopmentoftheoffshorewindindustrybuttheirawarenessoftheissuesisbeingextendedtowaveandtidalenergy.Anumberoforganisationshave position statements on offshore renewableenergy. Ingeneral,themarinesectorseemstobesupportiveoftidalenergyinprinciplebuttherearestrong calls for early engagement by renewableenergydeveloperswiththemarinesector.

Onepotential issuewillbearoundovercomingassumptionsof’first-come-first-served’foraccesstothemarineenvironment.Thechallengetoexistingmarineusersmustbethatthemarineenvironmentisacommonresource.Whileimportantcommercialand recreational interests must be maintained,someflexibilitymightberequiredtoaccommodatenew activities. Space must be created to allow

newactivitiestousethatresource,consideringthepressing need to develop alternative, low carbonenergysourcesandtheconsiderableUKpotentialtodosointhemarineenvironment.

TheSDC’sview is that there is sufficient spacefordifferentusersofthemarineenvironmenttoco-exist. A strong strategic overview by Governmentand relevant stakeholders can assist in avoidingandresolvingconflicts.Ataprojectandsite-specificlevel,itisclearthatdeveloperswillneedtoengageearlyandeffectivelywithotherusers.Amodelofstakeholder liaison groups, such as those used inthedevelopmentofoffshorewind,mayalsoassistin ongoing engagement, as well as research andcoordinationissues.

This section presents the SDC’s view on theopportunities and barriers facing the tidal streamindustry,focusingontheroleofGovernment.Drawingon our engagement with industry stakeholders,we lookatanumberofareaswhereGovernmentpolicycouldbe improvedtohavethebestchanceofcreatingaviabletidalstreamindustry.TheSDC’shigh level recommendations on tidal stream arepresentedinChapter5.

2.4.1 Funding regime

The importance of innovation funding

Experience from the wind industry demonstratesthe importance of Government subsidies in theearly stages of development. Generous subsidiesinanumberofEuropeancountrieshelpedtodrivegrowth, which led to convergence on a standardthree-bladed horizontal axis design, followed bysignificantlearningeffectsandcostreductionsovertime.Windpowercostsreducedfromover20Euro

centsperkWhintheearly1980stoaround7c/kWhin the early 1990s with only a few gigawatts ofinstalledcapacity.26

Thelessonsfromthewindindustrypointtotheimportanceofviewingearlysubsidiesashighrisk,state-sponsored venture capital,with evenhigherlevels of risk for each individual ‘investment’ thatismade.AlthoughGovernmentsareoftenwaryoftakingsuchagamblewithtaxpayers’money,thereisastrongconsensusthattheroleforGovernment-fundedinnovationsupport istotaketherisksthattheprivatesectorisunwillingorunabletobear.

For example, the Stern Review highlights theroleofpublicly-fundedresearchanddevelopment,and recommended that global public energy R&Dfunding should double, to around US$20bn. Andthe International Energy Agency (IEA) states that“it is unlikely that the technological challengesfacingtheenergysectorcanbeaddressedwithoutsignificantincreasestoR&DbudgetsinIEAmembercountries”.34Despitethisadvice,theUKhasoneofthe lowest public expenditures on energy R&D ofanydevelopedcountry–seeFigure10.

2.4 Opportunities and barriers


Figure10 Publicly-fundedenergyR&DexpenditureasashareofGDP35

TheSternReviewalsohighlightsthefactthatinnovationisaprocessovertimeandgoesfarbeyondtheinventionstage.Themainstepsintheinnovationchainweresummarisedas:

BasicR&C➔AppliedR&D➔Demonstration➔Commercialisation➔Marketaccumulation➔Diffusion

Despite the obvious simplification of what isactuallyahighlycomplexprocess,itisclearthateachof these stages requires a different mix of policyinterventionsrangingfromdirectresearchgrants,topartnershipfunding,torevenuesupport,andmostlikelyactiontoremovenon-marketbarriers.

Analysis of current policy

Althoughthesumsofmoneyavailabletotidalstreamtechnologies are quite small, the SDC receivedgenerally positive feedback from stakeholders onthesupportbeinggiventotheindustry.However,wedidhearanumberofconcernsovertheassumptionsbehind the establishment of the MRDF, whichappearstobeslightlyaheadofitstimeinaimingforearlycommercialdeployment.Withdevicesstillattheresearchanddemonstrationstages,theScottishGovernment scheme has been roundly welcomedinhelpingtofillagapinthesupportlandscapebyproviding support linked to the highly successful

EMEC(seeBox4).ThisconclusionissupportedbythefactthattheMRDFhasnotyethadanyapplicationsfor funding, against the nine projects (both waveandtidal)thathavebeenawardedfundingfromtheWaveandTidalEnergySupportSchemeinScotland.

The banding of the RO is certainly a positivedevelopment for tidal stream technologies, butis unlikely to stimulate increased activity in itselfas the level of support available is insufficient atcurrentlevelsofdevelopment.TheROisarelativelyblunt tool that was put in place to deliver theUK Government’s target for 10% renewables by2010,andthemorerecenttargetof20%by2020.It was originally justified as a policy measure todeliver long-term reductions in the costs of thesetechnologies,butitwasneverintendedtoprovidestart-upsupporttonewtechnologies.Itsimportancetotidalstreamdevicesoverthenext5-10yearsistherefore limited, though its introduction providestheopportunityforBERRtoreassesshowtouseitsMRDFfundingschemeinamoretargetedmanner.

Source: IEA

0.00%

0.02%

0.04%

0.06%

0.08%

0.10%

0.12%

0.14%

0.16%

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Norway

France

Germany

USA

Canada

Denmark

Japan

UK


A less risk-averse approach

Overall then,although thecurrent funding regimemaybesufficient,theGovernmentmustbepreparedtomakenewfundsavailableover thenext10-20yearsinaflexiblewaythatrespondstotheneedsof devices at different stages in the innovationchain.Thismayrequireanincreaseintotallevelsofsupportovertime.

While the UK Government’s MRDF sought toprovide revenue and grant funding, the proposedintroductionofbandingintheRenewablesObligationprovidesGovernmentwiththeopportunitytoredirecttheMRDFsolelytowardsdirectgrantfundingtohelpsupportfurtherprojectdevelopment.TheROitselfwillprovidethelonger-termsignaltohelpstimulatecommercialisation.

ThesuccessoftheScottishGovernment’smarinefundinghighlightsthefactthatthereiscapabilityinthetidalsectortodeveloptestsitesandearlystagedemonstrationprojects.Withongoingsupportthesecompanieswillbeabletoinstallinitialtidalarraysandpre-commercialschemes.

TheSDC recommends that theUKGovernmentuses the existingMRDF funding in a flexiblewaytofacilitatesimilardevelopments,whilstalsobeingready to provide additional funding in the future.TheScottishandNorthernIrelandgovernmentswillalsoneedtoreviewcurrentfundingschemesattheappropriatetimeandconsidersuccessorfundingtoensure ongoing learning and development in thetidalenergysector.

There is a strong justification this expenditure.The UK urgently needs to increase its R&Dexpenditureonlowcarbonenergytechnologiessothatitcanplayaleadroleinthelowcarboneconomyofthefuture.TidalstreamisagoodexampleofapotentiallynewindustrywheretheUKhasawell-developedcompetitiveadvantage.

CurrentGovernmentpolicytowardstechnologiesis very concerned over being ‘technology blind’,and avoids ‘picking winners’. Although this maynotalwaysbeput intopractice,there isageneralpresumptionagainsttakingriskswithpublicmoneyby putting large amounts of money into singleprojects, in case they fail. However, this aversionto risk may need to be weakened if Governmentisgoingtobepro-active insupportinglowcarboninnovation. As private sector venture capitalactivitiesshow,itissometimesnecessarytobackalargenumberofinnovationsinthehopethatoneortwowillbeabigsuccess.

The UK Government’s Technology Programmehas played an important role to date in fundingresearch, device development and testing. Thisfunding needs to continue, but Government mustgiveconsiderationto(a)thetimelinessofawardingfunding so that development timelines are notdramaticallyincreasedbydelaysinfundingdecisionsand (b) how such funding can be used alongsideothersourcessuchastheMRDF.

AswellascentralGovernmentfunding(fromtheUKGovernment or theDevolvedAdministrations),there are a number of additional ways in whichGovernmentcouldincreasefundingtotidalstreamtechnologies. The Carbon Trust has a number oftechnologysupportprogrammes,andiswellplacedin the industry.And thenewlyestablishedEnergyTechnologiesInstitutecouldbewell-placedtomakeriskierdecisionsasaresultof itsstrong linkswith(andpart-fundingfrom)theenergysector.

2.4.2 Grid constraints

As noted in Section 1.3.5 and in the SDC’s recentreport on the role of Ofgem in delivering asustainable energy system,13 the availability oftransmissioncapacityisamajorissueforrenewablegenerators.Thisisparticularlytruefortidalstreamdevelopers,asthebestresourcesareinmanycasesfound in locationswhere there isasevere lackofgridcapacity.

Grid capacity at tidal stream locations

For tidal generation technologies to connect totheelectricity system thereneeds tobe sufficientcapacityonthegridtomanagetheflowofpowerthattheygenerate–seeSection1.3.5foranoverviewofgeneraltransmissionissues.Thecapacityofthegrid to connect new tidal generation differs bylocation.Atpresent,thereiscapacityfornewtidalgenerationtoconnectinareassuchastheSevern,theMerseyandtheWash,wheretheTransmissionEntryCapacity(TEC) isabovetheConnectionEntryCapacity (CEC). However, the grid in the north ofScotland,wheretherearesignificanttidalresources,isheavilyconstrainedwithlittlesparecapacityfornewgeneration.

In Orkney North, for example, there is onlysufficientcapacitytoallowtheconnectionof15MWof generation. To connect a greater quantity of


generation a new sub-sea cable to themainland,at either 33kV or 132kV, would be required. It ispossiblethatthiswouldnecessitateanupgradeofthelinebetweenDounreayandBeauly,whichcoulditselftriggerfurtherreinforcementofthegrid.

Similarly for Orkney South, any project over10MW would require grid reinforcement. If thetotal resource of over 2GW were to be exploitedthiswouldrequireanew400kVdoublecircuitlinefromDounreayatleastasfarasNorthYorkshire.ThesituationissimilarfortheShetlandIslandsinthatanew600MWwindfarmhasrequiredScottishHydro-Electric Transmission Ltd (SHETL) to plan for theconstruction of a new high-voltage direct current(HVDC)sub-seacabletoconnecttheislandstothemainland.OncethisisbuilttheShetlanddistributionnetwork will become part of the GB transmissionsystemandbesubjecttothesamerules.

Theseexamplessuggestthatthereisstillsomecapacity in the north of Scotland for very smallgeneration projects, but that larger projects willtrigger reinforcements in other parts of the gridfor which the construction timelines are lengthy– ultimately delaying the connection of new tidalstreamgeneration.

InotherareasoftheUKtheseissuesareapparentbut less pronounced. In Anglesey, north Wales,generation of up to 100MW could be connectedwithout triggeringadditional reinforcementof thegrid.However,muchofthiscapacitywilldetakenup by new wind projects, meaning that althoughthe capacity constraints are less onerous it is stilllikely that tidalprojectswould trigger furthergridreinforcement which could delay connection untilafter2012.

Other capacity issues

Thereareanumberoffactorswhichexacerbatetheproblems faced by tidal generators as a result ofashortageofcapacityonthegrid.Thefirstisthatthereareanumberofprojectswhichareawaitingconnectionalready.TheupgradeoftheBeauly-DennylineinScotlandwillallowforanincreaseincapacity;howevertheprojectscurrentlyintheGBqueuewillaccount for the capacity increase, meaning thatany future tidal stream technology thatwishes toconnectwill require a further upgrade to thegridinfrastructureunless it is smallenough toconnecttoalocalnetwork.Thesetriggeredreinforcementscouldmeanthatprojectswouldnotahaveafirm

connectiondateuntilafter2015.TheissueoftheGBQueueiscompoundedbecause

aproposedmajortransmissionlineinScotland,theBeauly-Dennyline,issubjecttoplanningappeals,asitwillaffectalargeswatheoflandacrossScotland,includingdesignated landscapes.Decisions on thepotential for ‘under-grounding’ (i.e. running someof the transmission line underground, rather thanoverconventionalpylons)havenotyetbeentaken.If consent is granted, would mean constructionwould not start until 2012. It is possible that theupgrade of other lines to a 400kV line will meetwithsimilarobjections.

AnadditionalissueisthatsomeoftheprojectsintheBETTAqueuedonothavethenecessaryconsentsor financial backing to proceed, but because thequeue is managed on a first-come-first-servedbasis,theprojectsatthefrontofthequeuewhichdo not have the necessary consents are delayingtheconnectionofprojectsatthebackofthequeuewhichdo. Theenergy regulator,Ofgem,andNGETareworkingonways tobettermanage theBETTAqueuebutatpresentthecurrentregimeisresultinginsignificantdelaystoconnectiontimelines.

The second factor relates to the way in whichthe queue of generators awaiting connection ismanaged.Atpresentplacesinthequeuearegivenonafirstcomefirstservedbasis;thishasresultedinsomemoreviableprojectsbeingdelayedwhilstprojects at the front of the queue seek planningpermissionorfinancialsupport.Newtidalprojectswishingtoconnectwouldhavetojointhebackofthisqueue.Asrecentlyproposedprojectsarebeingofferedconnectiondatesasfaroffas2019,atidalstreamprojectcouldexpecttohavetowaitbeyondthatforaconfirmedconnection.However,therecentchangestothefinalsumsliabilityinadditiontotheNationalGridCompanyproposaltoallowanysparecapacitytobeutilisedbythe“mostsuitableprojects”should help with the management of the queue,andbringforwardsomeprojects.TheSDCbelievesthatoverthelongtermtheregimewillneedtogivegreatercertaintytorenewablegeneratorsandoffershorterconnectiontimes.

TheSDC’sreportintotheroleofOfgem13notedthepotentialforadoptinga‘connectthenmanage’approach as an alternative means of managingtheGBqueue.UnderthisscenariotheTECcouldbeexceeded,butwiththeoutputofgeneratorsbeingmanagedsothatanyincreasedgeneratingcapacityresulting from new renewable projects would


displaceoutputfromconventionalpowerplants.Thethirdexacerbatingfactorisuncertaintyaround

the offshore regulatory regime for transmissioninfrastructure.OfgemandBERRexpect to agree aregimebylate2008;howevertheprocesstodatehasbeencharacterisedbyindecisiononthepartofBERRwhichhasledtosomedelays.Thedecisionstakenoverthenextyearwillhaveanimpactonthecostsfacedbyoffshoregeneratorsforconnectingtothe grid and as such it is unlikely that significantproject proposals will come forward until there iscertaintyaroundtheregime.

These factors together present considerableuncertaintyanddelayaroundtheconnectionofnewrenewableenergygenerationtechnologiesandtidalstreamprojectsinparticular,whichwillneedtobeaddressedbyOfgemandGovernmentiftidalpoweris toplayapart inachievingtheUK’s renewablestargets.

2.4.3 Getting the regulatory framework right

Astheindustrygrowsanddevelops,itisclearthattheframeworkforstrategicplanningandconsentingmustbe robust. Theexistingpositiondescribed inSection2.2.2willonlytaketheindustrysofar,andalongtermviewneedstobetakenfortheregulatoryframework, alongside the innovation support thatwill be required. Certainty around timeframes aswellasregulatoryrequirementswillbeonefactornecessarytoattractinvestmentintothetechnologiesandprojectsastheindustrygrows.

Marine Bill and planning

TheMarineBillisamajorpolicydevelopmentthatwillhaveanimpactontidalstreamtechnologies.36Thebillmakesaseriesofsignificantproposals:

• anewUK-widesystemformarinespatialplanning

• astreamlined,transparentandconsistentsystemforlicensingmarinedevelopments

• aflexiblemechanismtoprotectnaturalresources,includingmarineprotectedzoneswithclearobjectives

• improvementstothemanagementofmarinefisheriesinrelationtoEngland,WalesandNorthernIrelandandtheabilitytosharethecostsofmanagementwithcommercialandrecreationalsectors

• anewMarineManagementOrganisationdeliveringUK,EnglandandNorthernIrelandfunctions.

Of these proposals, marine spatial planningseems likely to be of central importance forcontributing to sustainable development in themarine environment, and to managing conflictsbetweenmarineactivities.Themarineenvironmentis traditionally under-regulated and often under-protected.Asaresult,theSDCis,inprinciple,verysupportiveofthebillbeingtakenforwardasapolicyoption,consistentwiththeprinciplesofsustainabledevelopment and with the aim of providing aworkableregulatoryframework.

ThenewScottishGovernmentrecentlyindicatedthatitintendstointroduceaScottishMarineBill.37

TheAdvisoryGrouponMarineandCoastalStrategyhasrecommendedthatasystemofmarinespatialplanning be introduced, integrated as far aspossiblewithUKandinternationalmarineplanningsystems. The group also recommended a Scottishmarine management organisation and improvedprovisionbemadeformarinenatureconservation.38Thisconsistencyofapproachwillbewelcomedbymarineusers.

The Planning White Paper may also introduceafurtherchangetotheplanningframeworkinthefuturewithproposalsthatwouldaffectconsentingformajorinfrastructureprojectsofnationalsignificanceand would cover large electricity generation inEngland and Wales. The potential implications foronshore cabling and grid requirements will alsobe relevant.However, as these issuesarenot yetresolved and it will be some time before tidalstreamtechnologyreachesthatlevelofcommercialdevelopment, this issue is not explored furtherhere.

Strategic environmental assessment

ThedecisionofScottishGovernmenttotakeforwardan SEA on marine renewables is indicative of thestrong developer base, potential resource andpoliticalsupporttodevelopaworldleadingindustryinScotland.TheenvironmentalreportofthemarineenergySEAwaspublishedin2007anditestimatedbetween1,000MWand2,600MWcouldbedevelopedinScotlandbasedoncurrentenvironmentaldata.39The SEA also outlined key mitigation measureswhichwouldminimisetheenvironmentalimpactof


waveandtidaldevices.TheresultsoftheSEAwillbeusedtoinformtheScottishGovernment’smarineenergystrategyandprovideawiderangeofdatatodevelopersandregulators.

The SEA examined the Northern and WesterncoastlinesandmajorislandareasofScotlandusingtheFREDSestimate28that1,300MWofmarineenergycapacity could be established around Scotland by2020 as a basis for the assessment. It examinedtheeffectthatwaveandtidalenergydevicescouldhaveonarangeonenvironmentalfactors,includingbird,mammalandfishlife,andalsotheeffectthatshipping, fishing lanesandmilitarypractice zonescouldhaveon thedeploymentofmarinedevices.TheresultsoftheSEAindicatethatbetween1000MWand2,600MWcouldbedevelopedaroundtheNorthand West coast with acceptable environmentaleffects.TheSEAconcludedit ispossibletomeetagenerating capacity of 1,300MW with only minorenvironmentaleffects.

TheUKGovernment position is that a SEAwillbe undertaken once the industry reaches theappropriate stage of commercial development,probablyinconjunctionwithaleasingcompetitionfordevelopmentrightstotheseabedownedbytheCrownEstate.However,theybelieveitisimportantthat a SEA is carefully timed to avoid a situationwheretheabsenceofaSEAbeginstoholduptheindustry, or prevents good decision-making onconsentorlocationalissues.

In the absence of good information and data,it is crucial that policy is structured in away thatrecognises and accounts for the limitations of theinformation that is available. A useful approachadvocatedbytheUKstatutoryconservationadvisor,JNCC,totheScottishGovernment,isthatamarinerenewables strategyneeds tobedevelopedusingadaptivemanagementtechniques.40

The suggested approach is intended toaccount for gaps in our knowledge of the marineenvironment by allowing environmental learningfrom demonstration and early commercialprojects, while providing a clear signal to themarket that significant tidal stream resourcemaybe developed over the longer term. The processwould involve several stages, including a gapanalysisonenvironmentalinformation,provisionofcomprehensive environmental impact assessmentguidancetodevelopers,targetedfieldsurveywork,and coordinated and collaborative data collectionand monitoring. These stages would inform bothindividual developers’ environmental impact

assessments as well as a strategic environmentalassessment(SEA).

Role of the Crown Estate

Alongside the strategic planning and consentingframework set by Government, the Crown Estatehasanimportantroleastheowneroftheseabed.The Crown Estate’s marine interests cover morethan half of the UK’s foreshore, the beds of tidalriversandestuaries,andalmosttheentireseabedout to the12nauticalmile limit around theUK.41Apartfromtheusualregulatoryrequirements,tidalstreamdeveloperswillalsoneedtosecureseabedleasesfromtheCrownEstate.

In offshore wind, the Crown Estate has takena role not only in granting leases but also insupporting an environmental data collection andresearchprogramme–CollaborativeOffshoreWindResearchIntoTheEnvironment(COWRIE).Althoughitisanorganisationrunalongcommerciallines,theCrown Estate’s special status enables it to take along-term view of its estate, and it can thereforebe supportiveofpre-commercialprojects that canprovetheirviability.Thenatureofitsinterestsinthemarineenvironmentmeans that theCrownEstateworks closely with government departments andagencies,includingBERRonenergypolicyandDefraonmarinepolicy.

2.4.4 Dealing with information gaps

A real issue facing the tidal stream industry andGovernment is that there is a lack of baselineinformationonthemarineenvironmentandontheimpacts on the marine environment of installingtidalstreamdevicesandextractingenergyfromthetides.

The implication for policy makers is that weneed to take caremakingassumptionsor lookingfordefinitiveanswersaswhatweknowabouttidalstreamdevicesandtheirinteractionwiththemarineenvironmentcontinuestodevelop.Policyneedstobestructuredtotakeaccountoftheimmaturestateoftheevidencebase,sothatitcanrespondaswelearnmoreaboutthemarineenvironmentandtheinteractionoftidalstreamdevelopment.

Some information will be on ‘generic’ issuesrelated to the extraction of tidal energy from themarineenvironmentandmaydrawonexperience


from other marine sectors such as offshore wind,and oil and gas. Basic information on the effectsof drilling, piling and cabling in the marineenvironmenthas someapplication toearly stagesofenvironmentalimpactassessment/startingpointfor assessing effects). In addition, data sets onmarineecosystemsincertainareaswillbeusefulinassessingthepotentialeffectsofatidaldeviceonthoseecosystems.Agapanalysisonenvironmentalinformation will need to focus in particular onseabirds, marine mammals, benthic ecology andcumulativeimpacts.

However,muchinformationwillbespecific:toadeviceandtoasite.Thereisanobviouscostattachedtoobtainingthisinformation,particularlywherefieldworkwillberequiredtoobtaindatafromalocation.The marine environment is a particularly difficultand expensive environment to operate in, and itwill not always be possible to predict in advancewhetherasitemightcontainimportantbiodiversity,habitatsandspecies.Thebestapproachtoobtainingthisinformationinthemostcosteffectivewaywilloftenbetoensurethatenvironmentalbaselinedataisobtainedwhereverpossibleatthesametimeasotherprimarydata.Fortidalsites,modellingofthetidal currents and energy potential at a particularsitewillrequiresuchfieldwork.

The Government, in supporting innovationof these new devices, will also have a role infilling gaps with strategic and generic research.The adaptive management approach outlinedabove can assist. This research will help informthe planning and consenting framework. It willalso support developers to make sound decisionsand by reducing some of the costs. The ScottishGovernment’s Strategic EnvironmentalAssessmenthad a specific objective of putting availableinformation intoa framework thatdevelopers canuse.TheWelshAssemblyGovernmentisconsideringaMarineRenewableEnergyStrategicFramework.

Information gaps cannot be addressed onlyby Government. Developers will need to addressenvironmental considerations upfront. Taking along term view of the potential of a technologyunder development, its environmental impactsandcompatibilitywithothermarineactivitieswillinfluenceitssuccess, ifonlybymakingconsentingforlargescaledeploymentmorestraightforward.

Akeyissueisdevelopingprioritiesforresearch.One example is the COWRIE research programmefor offshore wind, which is starting to considerothermarinerenewables.Baselineecologicaldata

on marine sites is also needed and may comefromdifferentacademicandgovernmentresearchsources, not necessarily related to marine energy.ASEAwouldbeacriticalopportunity todrawthisinformation together. Similarly, any competitivetender round for seabed leases from the CrownEstatecouldconsiderhowdatacanbecentrallyheldand made available in recognition that, whetherfor practical or commercial reasons, datasets maybe difficult to access, and there are considerablebenefits tobegained fromgoodcoordinationandinformation-sharing.

TheSDCbelievesthatGovernmentandtheCrownEstate should ensure thatmarine energy researchneedsaredealtwith throughCOWRIE,as this isawell-developedstructureforsharedlearning.

2.4.5 Utilising the EMEC resource

The decision to set up EMEC, at a cost of £15m,is a good example of public funding being usedto stimulate private sector investment in aneconomically and environmentally efficient way.Theprovisionofasinglesitefortestingsignificantlyreduces the need for each developer to find andconstructtheirowntestingsite,andallowsfortheminimisationofenvironmentalimpactsandfortheimpactofdifferentdevicestobecomparedinsimilarconditions. Furthermore, Orkney is an excellentsiteatwhichtotesttidaldevices,asithasagoodresource without the harsher conditions found inthePentlandFirth.

ButthereisariskthatthefullpotentialofEMECwill not be realised. The centre has a very smallstaff, and is therefore not able to offer the rangeof support services thatmightbemoreefficientlydelivered from a central resource. If the UK is tomaintainastrongleadinthedevelopmentoftidalenergy, then the position of EMEC needs to bestrengthened.

Forexample,thereisminimalbudgetavailablefor environmental baseline studies to assess theimpact of devices on the environment, and thecentre does not offer a certification scheme toenabledevicestohavetheirresultsindependentlymonitoredandrecorded.EMEChasalreadyproducedthe first Assessment Standard for Wave EnergyConvertors,42 a standard that aims to set out auniformmethodology thatwillensure consistencyandaccuracy in themeasurementandanalysisofpowerperformanceofwaveenergydevices.There


isaneedtolookatthedevelopmentofstandardsfortidalenergydevices,aswellasotheraspectsofsite installationandmanagement.ProvidingEMECwithsufficientfundingtosupportworkonstandardsandcertificationwouldstrengthenitsinternationalstanding as a test facility whilst also providingthe industrywith valid, impartial information thatwillbevital inbuilding investor confidence in thetechnologies.

There is also a strong case for funding coreresearch and academic staff at the centre, usingexisting ties with Heriot Watt University, the UHIMillennium Institute as well as other UK highereducationbodies.

2.4.6 Creating a development path

Despite the significant interest from communitiesaround the coastline of the UK in tidal streamdevelopment, initial demonstration projects arelikely to cluster around key locations becausedevicesaresomewayfromcommercialdeployment.InNorthernIreland,testdevelopmentsarelikelytocluster around Strangford Lough and the northerncoastline. In Scotland, developments are likely togrowoutofaninitialclusternowdevelopingfromEMEC.

While our study has identified the excellentresources in the Pentland Firth for tidal streamdevelopments, first and second generationdevicesareunlikelytobelocatedhereduetothechallenging conditions. Therefore, support will beneededfordevelopmentofdevicesinlowerenergyareasthatprovidebettertestinganddevelopmentconditions,before the industry is ready for larger-scaledeploymentinthemostenergyintensivesites.AroundtheHighlandsandIslands,butinparticularinOrkneyandpartsoftheCaithness&SutherlandcoastlineawayfromthePentlandFirth,suitablesitesdoexist.ItthereforeseemssensiblefortheUKandScottishGovernments tosupport thedevelopmentofaregionaltidalenergycluster,or‘hub’,betweenCaithness&Sutherlandand theOrkneys for initialtidaldevelopment.

EMEC would be in a natural position to offersupport and research services, and the ScottishGovernment has already used its Wave and TidalEnergy Support Scheme to good effect to allowschemestodevelopoutofinitialtestingattheEMECsite.Thisapproachcouldbeextended,ifadditionalgridcapacityisprovided.AlongsideEMEC,theNuclearDecommissioning Authority (NDA) has identifiedtheeconomicpotentialof tidal to theCaithness&Sutherlandarea,andHighlands&IslandsEnterprise(HIE)isalong-timesupporteroftidalenergy.

WithintheOrkneysthereisonlylimitedcapacityforfurtherdeployment.However,thereisavailablecapacity inCaithness&SutherlandcurrentlybeingutilisedbyDounreaynuclearfacilityandthecapacityoftheexistingtransmissionlinefromDounreaytoBeaulycouldbeincreasedbyaddinganadditionalstringofwirestotheexistingpylonline.Byadoptingthe SDC’s recommendations on the way that NGCmanages the transmission network, new tidalcapacitycouldbeaccommodated.

ThereisastrongcasefortheScottishGovernmenttocoordinatetheworkofEMEC,theNDAandHIEtodevelopastrongregionaltidalenergyhub,andforone of these bodies to lead on the developmentof additional transmission capacity, including astrengthened link to the Orkneys. However, duetotheOrkneys’statusasaRegisteredPowerZone(which has allowed for additional expenditure bythe Distribution Network Operator on networkmanagement), connection of the first 15MW ofcapacitywouldbepossiblewithoutanyconstraints.

The SDC’s recommendations focus on tidalstream, and care would need to be taken inmanaginganysynergiesorconflictstowardswavepower or other marine renewables. In the longerterm, it may be more helpful to consider thesetechnologies separately (rather than as ‘marinerenewables’), as they are likely to have differentneedsthatGovernmentpolicywillneedtorespondto. Government should seek to minimise anypotentialoverlapbetweencompetingfacilities(forexample, between EMEC and the proposed ‘WaveHub’43 inCornwall) toensurethatpublicmoney isspentinthemostefficientway.

Tidal Range

3


Aswithtidalstream,theUKhasanexcellenttidalrangeresourcethatiscurrentlyunexploited.AlargepercentageofthisresourceislocatedintheSevernEstuary,butthereisalsopotentialforenergyextractioninotherwesternestuaries,andpotentialfromshallowwaterareaswithareasonablyhightidalrange.

This chapter considers some of the generic issuesrelatedtotidalbarragesandlagoons,andcontainsanumberoftidalrangecasestudiesfromaroundtheUK.Amoredetaileddiscussionoftheissuesraisedbytheexploitationofthetidalrangeresource–inparticular, theenvironmental,socialandeconomicimpacts–canbefoundinChapter4inrelationtoaSevernbarrage.Thisreflectsthesite-specificnature

oftidalbarragesandlagoons,thesheerscaleoftheSevernEstuaryresource,andtheSDC’sremitforthisproject.

The material below draws mainly on TidalResearch Reports 3, 4 and 5, as well as theengagement work the SDC has conducted withstakeholdersandthepublic.

Thetidalrangeresourcereferstothe‘gravitationalpotential energy’ that is created as a result ofimpounding a large volume of water on the hightide. This water is then passed through low-headturbinesonceaheightdifferenceiscreatedoneithersideoftheimpoundment,generatingelectricity.

Therearetwoprincipalconceptsforthedesignandplacementofatidalimpoundment,asfollows:

• Tidalbarrage:Ahardbarrierisplacedatastrategicpointinanestuarywithahightidalrange,thuscreatinganimpoundmentupstreamofthebarrageinconjunctionwiththebanksoftheestuary

• Offshoretidalimpoundment,or‘tidallagoon’:Atidallagoonisacompletelyartificialimpoundmentthatwouldbeconstructedinshallowwaterareaswithahightidalrange.

According to the limited evidence available,thereisnotnecessarilyanymajorconflictbetweenthe simultaneous development of tidal barragesand tidal lagoons, due to possible locations forlagoonsoutside themajorestuaries. There is alsovery minimal conflict between the developmentofboththesetechnologies,andthedeploymentoftidalstreamdevices,astheresourcesareingeneralfoundindifferentlocations.ThisissueisdiscussedinmoredetailinSection4.2.4inrelationtotheSevernEstuary.

3.1.1 Tidal barrages

The concept of generating electricity from a tidalbarragehasexistedforover100years. IntheUK,

a series of government-commissioned studiessincethe1920shavelookedatthepotentialforabarrageacross the Severn Estuary, and since thena number of proposals for other estuaries havesurfaced.Despitethisactivity,noproposalhaseverbeen pursued further, mainly due to high capitalcost of constructingabarrageand,more recently,environmentalconcerns.

However, there is some limited overseasexperience with tidal barrages. The largest andoldest energy-generating barrage in the worldwasconstructedatLaRance inFrance,andbeganoperating in 1966. This 240MW barrage, whichgenerates around 540GWh per year, has a verygoodoperatingrecord,whilstalsoprovidingaroadlink across the estuary. It demonstrates well thefeasibilityoftidalbarragesandhasprovidedsomeuseful information on how they can be operated.Unfortunately,duetoalackofbaselinedataandthefeaturesof theestuary, itprovidesvery littledatathatmighthelptoillustratetheeffectofabarrageon theestuarineenvironment,and the impactonspeciesandhabitats.

The Annapolis Royal tidal generating plant,locatedinCanada,isamuchsmaller,20MWbarragethatwascommissionedin1984.ItutilisesthetidalresourceoftheBayofFundy,whichhasoneofthehighesttidalrangesintheworld.TherearealsoanumberofverysmalltidalbarrageprojectslocatedinChinaandRussia,andtherearewell-developedplans for at least twomedium-sized tidal barrageprojectsinSouthKorea.

As Chapter 4 explains in relation to proposalsforaSevernbarrage,tidalbarragesaremajorcivilengineering projects that have very high capital

3.1 Tidal range technologies


costs. This factor, along with the length of timeneeded forprojectdevelopmentand construction,and the subsequent risk of cost overruns, haslimited the private sector’s interest in developingsuch schemes. However, increasing concern overclimatechangeandenergysecurityisleadingsometoreappraisetidalbarrageprojects,whichhavethepotential to provide large amounts of low carbonenergyforover100years.

Environmental concerns remain one of thebiggest obstacles to the development of tidalbarrages.Estuariesareoftenhometoanumberofuniquehabitatsandspecies–particularlythosewithaveryhightidalrange,asthisresultsinparticularlyharshconditionsthatonlysomespeciescanendure.As with hydropower dams,44 tidal barrages couldhave a major impact on local environments, withconcerns raisedoverwiderbiodiversityobjectives.This issue is covered extensively in Chapter 4 inrelationtoaSevernbarrage.

3.1.2 Tidal lagoons

Theconceptofatidallagoonprobablyoriginatesinproposals from the1981BondiCommittee report,which considered a concept called the RussellLagoons(discussedfurtherinBox6).Theproposalwas for a series of three bunded enclosures thatwould be constructed against the banks of theSevern using dredged material to build artificialembankmentsinshallowwaterareas.Thesewouldoperate in a similarway toabarrageexcept thattheywouldnotfullyobstructtheestuary; instead,they would create a narrow channel running in-betweenthethreelagoons.

More recent proposals are for completelyoffshoreimpoundmentstobeconstructed(i.e.notconnectedtotheshore)inshallowwaterareasfromconventional embankments created by dumpingsand and rock on the seabed. This would beprotectedbyarockarmourtodissipatewaveattackandmaintaintheintegrityofthestructure.Thepre-fabricatedgeneratingunitswouldbepositionedontheseawardsideof thestructureandfloated intoplaceascaissons.TheSDCisawareof suggestionsforpossibletidallagoondevelopmentsinSwanseaBay,LiverpoolBay(whichisthesubjectofatheoreticalstudy in ResearchReport 5 and is also studied aspartofarecentreportonthetidalresourceintheMerseyEstuary),andintheThamesEstuary.

Currentlythereisnoexampleofatidal lagoondevelopment anywhere in the world, and thismakes evaluation of the technology difficult. Thevarious technologies and methods that would beusedarenotindividuallyinnovative;anyinnovationthatexistsisintheconceptanditsconstruction.

Tidal lagoons are generally thought to beachievable from an engineering perspective, butthere are some differences of opinion on howtheymightbeconstructed,andtheresultingcosts.Mostofthedifferencesrelatetothedesignofthestructure, such as the gradient and height of theembankments,which in turnmay be site-specific(e.g. the ground conditions for some sites mayallow for a steeper gradient than others). Usingdifferentassumptionsonthegradientandheightoftheembankmentsleadstodifferentestimationsofmaterial requirements, and therefore capital cost.There is also some disagreement over the likelyelectricity output from tidal lagoons, which restsprimarily on whether they are able to achieve ahigherloadfactorasaresultofebb-floodgeneration,ratherthanebb-onlygeneration.ThelatterisoftenassumedastheoptimummethodofoperationduetooutputmodellingdoneonaSevernbarrageandfromexperienceatLaRancetidalbarrage.

Figure11 LaRancetidalbarrage

Box6 TidallagoonproposalsintheSevernEstuary

VarioustidallagoonproposalshavebeenputforwardfordevelopmentintheSevernEstuary,includingtheRussellLagoonsconcept,re-evaluatedaspartofResearchReport4,andtheSwanseaLagoonproposalbeingpromotedbythecompanyTidalElectric.

OurresearchsuggeststhattheRussellLagoonconceptforthreeland-borderedtidallagoonsintheSevernEstuary(seeFigure12)isunlikelybeviablewhencomparedtothealternativeofabarrage.Theenergycapturedwouldbeconsiderableataround6,480GWhperyear,butthisislessthanhalftheestimatedproductionfromtheCardiff-Westonbarragescheme.Meanwhile,thecostsappeartobehigherduetothelongerbarriersthatarerequired.ItisalsopossiblethataRussellLagoon-typedevelopmentwouldhaveasimilarorevenmoredisruptiveimpactontheestuarineenvironmentandpossiblyshipping,duetothechannellingeffectitwouldhaveontidalcurrentspassingbetweenthethreelagoons.SuchimpactswouldputtheRussellLagoonsinasimilarcategorytoaSevernbarrageinrespectoftheenvironmentallegislation–thisisdiscussedinmoredetailinChapter4.

Themuchsmaller50MWproposalforatidallagooninSwanseaBay(seeFigure13)ispossiblymorerealistic,althoughthereareanumberofuncertaintiesovertheeconomicsasdiscussedbelow.Estimatesforannualelectricityoutputforsuchaschemerangefrom124-187GWhperyear,puttingitonasimilarscaletoamedium-sizedonshorewindproject.

Figure12 ProposedpositionofthethreeRussellLagoons

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff


Figure13 ProposedpositionoftheSwanseaBaytidallagoon

Swansea

Dredged to 4.2m

Dredged to 2m

Turbine House

The impact of these assumptions is illustratedwell by comparing estimates of the capital costof a tidal lagoon in SwanseaBay, asproposedbyTidalElectricLtd(seeBox6forfurtherinformation).The developer estimates a total capital cost of£81.5m,comparedtothe£255mestimategivenby

aDTI-fundedstudy.AmorerecentestimatebyRWEnpower45 fora similarly-sized scheme in LiverpoolBayhasacapitalcostrangeof£108m-£135m.

Suchdifferencesincapitalcostestimatesleadtoverylargevariationsinestimatesfortheunitcostofelectricityoutput–seeTable2.46

Table2 UnitcostofoutputestimatesforproposedSwanseaBaytidallagoonproject

Unit cost of output (p/kWh)

Capital cost (£m)

Annual output (GWh/y)

Discount rate

3.5% �% 10% 15%

Tidal Electric Ltd £81.5m 187 2.05 4.15 5.13 7.67

DTI-commissioned review £255m 124 8.7 18.39 22.91 34.63

The SDC does not believe there is enoughinformation to determine which cost estimate forthis first-of-a-kind project ismost accurate due tothe lackofanypracticalexperience.Although the

potentialforcostreductionsovertimeasaresultofinnovationarelimited(thetechnologiesutilisedcanbeclassifiedas‘mature’),therecouldbesubstantialopportunitiesfor‘learningbydoing’.


ThereisnoexplicitGovernmentsupportprogrammefortidalbarragesorlagoons.However,asrenewablesources of electricity, a developer looking toconstruct a tidal barrage or lagoon would qualifyfor supportunder theRenewablesObligation (seeSection 2.2.1 for further details). This providesrevenuesupportoncetheproject iscommissionedand is generating electricity, and therefore tendsto favour technologieswith a low risk profile andcomparativelylowcapitalcosts.

As a result, it is debatable whether the RO(along with the low carbon premium implied bytheEUEmissionsTradingSchemeand theClimateChangeLevy)wouldprovideenoughofanincentiveto stimulate private sector investment in tidalbarragesorlagoonsonitsown.AlthoughthefundingavailableundertheROisduetobebandedaccordingtotechnologytype, it iscurrentlyunclearwhetherbarrages and lagoons will qualify for additionalsupportoncethebandingsareannounced.

Forverylargeschemes,suchasaSevernbarrage,thereisastrongcaseforprovidingsupportoutside

theRO,asthelevelofoutputrepresentedbysuchschemescouldhaveadetrimentaleffectontherestoftherenewablessectorduetofearsofacollapsein the price of Renewables Obligation Certificates(ROCs).Smallerschemesmayfinditpossibletoraisefinanceunder thecurrent funding regime,despitethe constraints imposed by such capital-intensivetechnologies. However, the economics of barrageandlagoonschemesarelikelytoimprovewithscale,making larger (and lesseasy tofinance) schemespotentiallymoreviablethansmallerones.

A lot depends on the perceived risk of atechnology, which relates to concerns overobtaining development consent (and in particular,uncertaintiesoverthecostofcompliancewithanyenvironmentaldesignations),butalsouncertaintiesoverdesignandconstructionmethods,andconcernover possible delays. This is likely to affect tidallagoonproposalsmorethantidalbarrageprojects,asthereisnoexistingevidencetodrawonandtheconceptremainsunproven.

3.2 Funding regime

Fortidalbarrages,thereisgoodjustificationforsomelimited further investigation of options outside theSevernEstuary,particularlywherethereareancillarydevelopments(suchasatransport link,orforfloorprotection)thatcouldbeamajorcomponentofanyproposal. The SDC has not considered non-Severnbarrage options in enough detail to comment ontheneed foranychanges toGovernmentpolicy tostimulatepotentialinterest.However,ourconclusionson a Severn barrage may be relevant to theconsiderationofsomeoftheseschemes,particularlythose on compliance with the environmentallegislationandonownershipmodels.

IfoneormorebarrageoptionsaredevelopedintheUK,thenastrategicoverviewwillbeneededtoensurethatthereisnoconflictbetweenthem.Thisisparticularlyimportantwherehabitatcompensationis required(seeSection4.10.4for furtherdetails),asthecompensationrequiredforoneschememayrelyonotherestuariesremainingundeveloped.

Fortidallagoons,themainissueisalackofhardevidence, particularly on construction methods,costs, and environmental impacts. The SDCbelievesthattheonlywaytofilltheseinformation

gaps is through the construction of one or moredemonstration projects. As there little, if any,researchactivityontidallagoonselsewhereintheworld,thereisaverygoodcasefortheUKtoleadondevelopingamorerobustevidencebasethatcanbeusedbygovernmentsandtheprivatesectortodecidewhether tidal lagoonsareaneconomicallyand environmentally viable way to generate lowcarbonelectricity.

Experience suggests that a tidal lagoondemonstrationproject isunlikely to come forwardwithoutsomeformofadditionalsupport.Thiscouldbeachievedbyplacingtidal lagoonsintoahigherband within the revised Renewables Obligation,possibly combined with grant funding. However,an alternative option would be to announce acompetitiontodeveloponeormoredemonstrationprojects,similar totheprocessbeingproposedforcarbon capture and storage.47 The SDC believesthat thereareanumberofparallelsbetween thetwo technologies thatwould favour a comparableapproach.Finally,anypublicly-fundedresearchthatis conductedon tidal lagoons shouldbeplaced inthepublicdomain.

3.3 Exploring the policy options


Figure14 Artist’simpressionoftheconstructionofatidallagoonwall

Wall visible at high tide Lagoon wall will ‘overtop’ with a very high tide or during a storm without affecting performance

High tide

Low tide

Sea bed

Rock armour

Filter rock

Locally won core materialLagoon bed

Lagoon Open Sea

Asdiscussed inSection1.3,a largepercentageofthe UK’s tidal range resource is concentrated intheSevernEstuary.Due to the scopeof theSDC’sproject,andthecomplexitiesoftheissuesinvolved,theoptionofaSevernbarrage,whichcouldcapturea large percentage of the Severn resource, is

discussedseparatelyinChapter4.Thissectiontakesamoredetailedlookatother

potentialoptionsforcapturingtheUK’stidalrangeresource,withanoverviewoftidallagoons,andasummary of proposals for barrages in the MerseyandThamesestuaries.

3.4 Tidal range case studies

Mersey Estuary

TheMerseyEstuaryhasameanspringtidalrangeof 8m and a potential resource of 1,400GWhper year. It has been the subject of a number ofstudieslookingatthepotentialforatidalbarrage,andculminatinginareportbytheMerseyBarrageCompanyin1992.However,theproposalwasneverprogressedfurther,althoughthereisnowrenewed

interestasaresultofarecentstudycommissionedby Peel Environmental Ltd in associationwith theNorthWestRegionalDevelopmentAgency(NWDA)and the Mersey Basin Campaign.48 The SDC hasconsideredthisnewwork,alongwiththesummaryofexistingproposalsprovidedinResearchReport5,inpreparingthisbriefsummary.

Zone 1

Zone 3

Liverpool

Birkenhead

Zone 4

Zone 2

Source: Peel Environmental Ltd.

Figure15 MapoftheMerseyEstuaryshowingstudyzonesforusedinNWDAstudy


As highlighted by NWDA study, there are anumberofpotentialoptionsforharnessingenergyfrom the Mersey Estuary. In order to assess theoptions,theestuarywasdividedintostudyzones,asshowninFigure15.TheonlyviableoptionforZone1wasconsideredtobeatidallagoon,whichcouldbeoperatedindependentlyfromtheotheroptions.Forthe remaining zones, themostproductiveoptionswere two tidal barrage options (one termed as a‘tidalgate’),althoughseveral tidalstreamoptionswerealsostudied.

The capacity and estimated electricity outputfrom each option is shown in Table 3. The mostrecentpreviousestimateforelectricityoutputfrom

aMerseybarragewasfor1,450MWhperyear,butthis included gains from flood pumping, whichthe more recent studies do not. The constructioncosts of a Mersey barrage have been estimatedat £1.5bn (inflated to2006prices). This results inaunitcostofoutputrangingfrom12.27p/kWhto15.79p/kWhwhenacommercialdiscountrateof8-10%isapplied.Section4.8.2discussestheimpactandappropriatenessofusing commercial discountratesinrelationtoaSevernbarrage.However,evenafterallowingforcost reductionsandthebenefitsofcarbon-freeelectricity,thesecostsareunlikelytobecommerciallycompetitiveundercurrentmarketconditions.

Table3 ComparisonofmaintidalpoweroptionsfortheMerseyEstuary(source: Peel Environmental Ltd)

Technology option Rated capacity(MW) Annual electricity output(GHh)

Tidallagoon(Zone1) 350 650

Tidalbarrage(Zone2) 700 1,200

Centralreservation(Zone2) 20 40

Constrainedchannel(Zone2) 50 100

Tidalfence(Zone2) 35 80

Tidalgate(Zone3) 380 700

Waterwheel(Zone3) 200 500

LiketheSevern,theMerseyisahighlyprotectedestuary, and has international designations asa SPA and Ramsar site and a number of nationaldesignations–seeNWDAstudy48forfurtherdetails.LiverpoolBay,MerseyNarrows,andtheNorthWirralForeshoreareallproposedSPAs.Theestuaryhousesa number of intertidal and subtidal habitats thatsupportpopulationsofinvertebrates,althoughthesehabitatsarelesspronouncedintheMerseynarrows,where the tidal stream resource is strongest.The Mersey has seen considerable growth in fishandbird speciesas changes to industrialpracticeshave made the river less polluted, and there areover 40 species of fish, and large populations ofwaterbirds,whichcouldpotentiallybedisplacedbyanyproposedproject.

The NWDA-commissioned study identifies thebarrageproposalsas themostdisruptive in termsof environmental impact, but detailed up-to-dateanalysishasnotbeenconductedinrelationtohowaschemewould impactontheprotectedfeaturesandspecies.

TheMerseyisalsoanimportantshippingcorridor,and although a barrage could be constructedupstream of Liverpool port, it would impact onaccesstoGarston,EasthamLocks,theQEIIOilLockandtheManchesterShipCanal.Thestudiesdonebythe Mersey Barrage Company involved a detailedanalysisofshipmovementsbasedonshippingtrafficfrom1990,whichincludedconditionspredictedbythe hydraulic model. The results of this showedaverage increases in voyage times of around 40


minutes,resultingincostincreasesofaround£1.5mper year (1992 prices). In addition, maintenancedredgingrequirementswereestimatedtoincreaseby up to 60% in comparison to pre-barrageconditions. Naturally, this data would need tobe updated to take account of current and futureshippingrequirementsifabarrageoptionwastobedevelopedfurther.

Oneof themajordriversbehind investigationsinto exploitation of the Mersey’s tidal resourcehasbeenthepotentialforavarietyofnon-energybenefits. TheMerseyBarrage Company conductedaneconomicvaluationofthesebenefits,concludingthatabarragewouldresultinadditionalbenefitsofbetween£90mand£213m.Thepotentialforanewroad link is seen as one of the main non-energybenefits,aswellasincreasesintourismandamenity.However,theanalysisusesaverylowvaluationofthelossofintertidalhabitat,andthismaynottakeaccountoftheprotectednatureofthesesites,andtheresultingrequirementstoprovidecompensatoryhabitatforprotectedbirdspecies.

It isnotclearat this stagewhether the recentstudycommissionedbyNWDAandotherswillresultin furtherwork, or indeed a full project proposal.However, there does seem to be real enthusiasmforharnessingthetidalresourceintheMersey,anda consortiumof interests thatmightbewilling totakethisforward.

Loughor Estuary

TheLoughorEstuaryinWaleshasanannualmeanspring tideof3.9m,with theupperestuarybeingidentifiedasapotentialsiteforasmalltidalenergybarrageof5MW.TheproposedbarragewouldextendfromBurrypointattheentranceofCarmarthenBayto Pontardulais, a point where there is already anatural constriction where a railway line and theA484crosstheestuary.

A major incentive to the construction of thebarrage is the potential for amarina upstreamofthe barrage for recreational use. The barrage hasthepotentialtogenerate15.1GWh/yearifallowedtooperateallyearround.However,theuseofthescheme for amenity purposes (i.e. the marina)wouldreduceoutputtoaround9.7GWh/year,astheoutputwouldbelimitedduringthesummermonthsto retain high water levels upstream; the exactoutput penalty would depend on the operationof themarina.Whilst the inclusion of an amenity

element may reduce the output of the barrage,it also improves the economic justification for abarragebyspreadingsomeoftheconstructioncoststothebusinessesdevelopingthemarina.

Theunitcostofelectricitywherethebarrageisgenerating all year round compared towhen it isrunningatloweroutputduringthesummermonthsdependslargelyonthediscountrateused.Athigherdiscountrates,theunitcostofoutputislowerwhenthereisreducedoutputduringthesummermonths(duetoamenityuse),butatlowerdiscountratestheunitcostofoutputislowerifthebarragegeneratesallyearround.Thesmallscaleoftheprojectwouldmeanitcouldconnecteasilytotheunitedutilities11kVdistributionline.

As with many barrage proposals, the quantityof mobile sediment and its propensity to rapidlyerodeandaccreteisaseriousconcern,whichmayin turn change the hydrodynamic regime. TheLoughor Estuary inlet provides nursery areas forwhiting,plaiceandsole,andhasthreedesignatedproductionareasforcocklesandmussels.Abarrageinthislocationisalsoexpectedtodisturbbirdandinvertebratepopulations,as themid-shoremusselbeds are important bird feeding areas and majorwildfowlroostsarepresentonthesaltmarshesatWhiteford.Theimpactonthesehabitatsandspecieswouldbemorepronouncedduringtheconstructionperiod.

The mouth of the Loughbor Estuary overlapspart of the Carmarthen Bay and Dunes SpecialAreaofConservation(SAC),whichisadesignationundertheEUHabitatsDirective.Theestuaryisalsocontained within the Bury Inlet Special ProtectionArea (SPA) for avian features under the EC BirdsDirective. Additionally theBurry inlet is identifiedas a Ramsar site for wetland features under theRamsarConvention.

The Loughor Estuary has a small powergenerationcapacitycomparedtotheMerseyEstuaryor the Severn. This has a negative impact on theeconomicviabilityoftheproposals,notwithstandingtheenvironmentalconcernsthatwouldneedtobeovercomeforanyprojecttoproceed.

Duddon Estuary

TheDuddonEstuary,locatedontheCumbriancoast,hasarelativelyhighmeantidalrangeof5.8m,andinterest in itspotential forgenerating tidalpowerwas first identified in 1988. The local authorities


were interested inthepotentialofabarragebothforenergycaptureandanewroadcrossing,whichwouldimprovetheregion’stransportinfrastructure.

The proposed alignment of a barrage extendsfromthemouthoftheestuaryjustwestofHaverriggtoSandaleHawsdunesystem,spanningatotalof4.4km. This location was seen as favourable as itofferedthegreatestenergypotential.Theproposeddesign for the Duddon barrage would include ten10MWdouble-regulatedturbineswithanexpectedannualenergyoutputof212GWh/year.

The existing distribution network around theDuddon Estuary does not have capacity to allowconnectionoftheproject.Forconnectiontooccur,anew132kVlinewouldneedtobeconstructedfromtheconnectionpointnearBarrow,toHutton,adistanceof45km.Thecapitalcostofthislineconnectionwouldbeabout£5m, roughly1.4%of totalproject costs.The project would need to receive the appropriateconsents and financial backing before constructioncould begin on the line, meaning that connectionwouldprobablynotoccurbefore2020.

The proposed project would include a roadbetweenBarrowandsouthCumbria,whichwouldreducethejourneydistancebyapproximately20km,equaltoaround40minutes.ThiswouldallowbettertransportconnectionstoMillomandHaverigg,whichare not well served by the existing road networkbecauseoftheirrelativeisolation.

The major industrial towns in the area havesufferedasthecoremanufacturingeconomyoftheregion has declined. The proposed project couldinvolveaworkforceofsome1,200employeesduringconstruction,withafurther300jobssupportedbyindirect requirements such as accommodation.About30peoplewouldberequiredtooperatethebarragewhencommissioned.

The area is recognised as an area of nationalconservation value and forms part of a largerSpecialAreaofConservationundertheEUHabitatsDirective.Additionally,theentireestuaryisaSiteofSpecialScientific Interest,and isdesignatedundertheRamsarConvention.

Theestuarysupportsspawninggroundsforspratandanurseryareaforherring,whiting,plaiceandsole,withcodbassandrayscommerciallyexploitedinthearea.Itisalsoadesignatedproductionareafor cockles, and there are regular sightings ofharbourporpoise.Asaresult,therewouldneedtobein-depthanalysisoftheenvironmentimpactoftheproposal,andstepstakentocompensateforthedamagecaused.

Wyre Estuary

TheWyreEstuaryinLancashirehasahighmeantidalrangeof6.6m,whichmakesitanattractivelocationto generate tidal power. There are two possiblesites which are being considered for the locationof a barrage. The barrage would have an installedcapacityof60-64MW(dependingonthealignment)andwouldbeexpected to generate123-133GWh/year. There is also the potential for it to provide anewroadcrossingatthemouthoftheestuary;thiswouldrequirealinkroadtobebuiltacrossanexistinggolf course.Although the road link isnot regardedas central to the scheme, itmaybe viewedas anopportunitytoimprovelocalinfrastructure.

The total project cost is estimated at around£138m, resulting in a unit cost of output rangingfrom5p/kWhtojustover19p/kWhdependingonthediscountrateused.Therelativelysmallscaleoftheprojectwouldallowconnectiontotheexistingdistributionsystemviaa11kVline.

The Wyre Estuary has important conservationdesignations, and is a Site of Special ScientificInterest.Theestuaryisaspawninggroundforspratandanurseryareaforherring,whiting,plaiceandsole.VirtuallyalltheriversdrainingintoMorecombeBay are important for salmon and sea trout, sothe construction of a barrage would affect thesespecies, in addition to a potential impact on thecommercialisedcockleindustry.Theestuaryisalsoimportantforwinteringwadingbirdsandwildfowl.

Although the impacts to the environment havenotyetbeenaccuratelyquantified,thereisaconcernthatwith the change in theestuary’s profile therecould be localised erosion and loss of saltmarshhabitats. Subsequently thearea to thewestof theestuaryisdenselypopulatedandtherearenumerousotherusesofthecoastline,includingtourism,fishing,andoilandgasdevelopments,allofwhichcouldbeaffectedbytheconstructionofabarrage.

Thames Estuary

The current Thames Barrier, which was completedin 1984, is a major component of London’s flooddefences.Duetotheimpactsofclimatechange,suchassealevelriseandincreasedstorminess,itislikelythatLondonwillneedtoconsiderbuildingnewflooddefencestoprotectitoverthelong-term.Thisissueiscurrentlybeingstudiedaspartofalarge-scaleprojectcalled‘ThamesEstuary2100’todevelopatidalflood


riskmanagementplanfortheestuary.49

It is suggested that a new flood protectionbarrier could be designed to incorporate energygeneration (possibly up to 800MW), and a newriver crossing. The cost of a new flood protectionbarrier is already estimated at around £20bn,so incorporating additional features would help

improve theeconomicsofany scheme,and couldpotentially generate economic development andclimatechangemitigationbenefitsforLondon.

No further details are currently available, buttheSDCbelievesthatthereissignificantpotentialinenergygenerationfromtheThames,andthismeritsseriousconsideration.

A Severn Barrage

4


This chapter will focus on proposals for a Severnbarrage50 from a sustainable developmentperspective.ThisfocusisinrecognitionoftheSDC’sremitforthisproject,whichspecificallycallsontheSDCtoconsidertheresourceintheSevernEstuaryandtheissueofaSevernbarrage.ASevernbarrage,ifdeveloped,wouldbejustonerenewableenergyproject among the many that will be required.However, the SDC believes that our approach onthis issue is justified by the high concentration oftidal range resource, the unprecedented scale ofthe proposals, and the need for Government totakeastrategicdecisiononwhetherornotfurtherinvestigationshouldtakeplace.

Theneedforastrategicdecisiontobemadeonthisissueisbasedonourrecognitionthatanumberoffactorsareatplay.The2006EnergyReviewreferredin particular to concerns about the environmentalimpactofaSevernbarrage,andthisissuehasbeena key criterion in our review. The Severn Estuaryhas thesecondhighest tidal rangeofanyestuaryintheworld,andtheuniquehypertidalhabitatsitsupportsareprotectedbyUKandinternationallaw.These important protections point to the need togive careful consideration to alternatives and thecompeting public interests between conservationand biodiversity, and the provision of secure, lowcarbon energy supplies. A Severn barrage projectwouldrepresentamajorinfrastructureprojectonaninternationalscale.Ataregionallevel,suchalarge-scaleprojectwouldhaveprofoundimplicationsfortheeconomyand for society in thesouth-westofEnglandandsouthWales.

Inthecontextofclimatechangeandrenewableenergy targets, there is renewed interest in re-examiningaSevernbarrage.Butthecostsandriskswouldbe significant, anddevelopment isunlikelytooccurwithoutsomeformofGovernmentsupport,bothpoliticalandfinancial.Thesefactorsmeanthat

Governmentneedstodevelopalong-termpositionon this issue. The SDC believes that this positionmustbe informedby theprinciplesof sustainabledevelopment.

ThissectiondrawsprimarilyonResearchReport3,whichgoesintomoredetailonmanyoftheissuesdiscussedhere.

4.1.1 Chapter outline

OuranalysisbeginswithastrategicoverviewoftheSevernestuarytidalresource,includingasummaryofthevariousbarrageoptions,followedbya lookatthealternativestoabarrageandtheconflictsinresourceutilisationthatemerge.Wethenconsiderthe contribution that the two primary barrageoptions might make to UK electricity supply, andthe characteristics of electricity output and theimplicationsforgridmanagement.Thisisfollowedbya summaryof theevidencewehave collectedonthecarbonpaybackofthetwobarrageoptions,andtheestimatedcontributiontheycouldmaketoreducingcarbondioxideemissions.

The report then goes on to consider thephysical effects of a barrage development,including consideration of data uncertainty, soundscience, tides and currents, morphology, and thesedimentaryregime.TheseconclusionsareusedtodeterminethepossibleimpactsontheenvironmentandconservationstatusoftheSevernEstuary,andeconomicandsocial impactsataregional level.Aseparatesectiondealswiththeestimatedcostsofabarragescheme,andlooksatfinancingoptionsandhowthesefitwithincurrentenergypolicy.

Finally, the report summarises some of theresultsofourpublicand stakeholderengagementwork before commenting on the policy processgoingforwardandissuesofgoodgovernance.

4.1 Background

AstheshowninChapter1,theSevernEstuarystandsoutastheUK’slargestsingleconcentrationoftidalrange resource. This section summarises themainbarrageoptionsproposedforcapturingthisresource

and looks at any potential conflicts between thedevelopment of a tidal barrage and tidal streamdevices or tidal lagoons. It also considers thecompatibilityofmorethanonetidalbarrage.

4.2 Strategic overview of the Severn Estuary resource


4.2.1 The Severn Estuary

TheSevernEstuaryislocatedonthewestcoastofBritain, where the river Severn meets the BristolChannel, between south west England and southWales.InadditiontotheriverSevern,whichisthelongestandhasthehighestwaterflowofanyriverinBritain,theestuaryisalsofedbytheriversWyeandAvon.Theestuarysupportsanumberofmajorcities,includingBristolandCardiff,andisthesiteforanumberofindustries,includingportinstallations,

chemical processing plants, and nuclear powerstations.

The Severn Estuary is a hyper-tidal estuarysystemasaresultofhavingthehighesttidalrangeintheworldaftertheBayofFundyinCanada,witha mean tidal range of 8.2m at Avonmouth. Thishas resulted in around 200km2 of inter-tidal areaandahighlydynamicsedimentregimethatisinaconstantstateofflux.

Figure16 TheSevernEstuary51

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff

Source: Severn Estuary Partnership


4.2.2 Severn barrage options

The consideration of a Severn barrage has hada long and chequered history, with a number ofdifferent studies and proposals surfacing over thepast80yearsorso,alongwiththereportsfromtwoGovernment-backedCommittees.Thefirstofthesewas the Bondi Committee report in 1981 whichfavouredanebbgenerationbarrageschemeontheCardiff-Weston alignment. A subsequent two yearstudywasfundedandcarriedoutbytheDepartmentofEnergy,CentralElectricityGeneratingBoard,andtheSevernTidalPowerGroup(STPG)between1987and 1989 (Energy Paper 57, The Severn Barrage:GeneralReport.1989).

TheschemesidentifiedbytheSDC’sresearchareasfollows:

• Cardiff-Weston scheme:oftenknownasthemain‘SevernBarrage’proposal,thiswouldrunfromLavernockPoint,westofCardiff,toBreanDown,south-westofWeston-super-Mare

• Cardiff-Weston scheme with second basin:similartotheCardiff-Westonschemeabove,butwithasecondbasinontheseawardside,thusenablingutilisationofnearlythefullestuaryresourceandalsoprovidingsomefloodprotectionbenefitstotheSomersetLevels

• Dawson continuous power scheme:abarrageintheouterestuaryfromMinehead(seeabove),butwithanembankmentextendingtoBreanDown,thuscreatingasecondbasinandenablingcontinuouspoweroutput

• English Stones or Shoots scheme:thecurrentlyproposedalignmentwouldrunclosetothetwoSevernCrossingsandhasbeendesignedtofacilitateahigh-speedraillinktoreplacetheagingSevernTunnel

• Hooker scheme:similartoabovebutwithasecondbasintoseaward,enablingoutofphaseoperationonboththeebbandfloodtides

• Minehead-Aberthaw scheme:oftenreferredtoasthe‘OuterBarrage’,thisalignment

wouldmakemaximumuseoftheSevernEstuarytidalresource,andisthelongestbarrageproposalbecauseofitsdownstreamlocation;thisoptionisbeingexploredbySomersetCountyCouncilonfloodprotectiongrounds

• Severn Lake scheme:a1kmwidebarrageinthesamelocationastheCardiff-Westonscheme,designedtoallowtheconstructionofanumberofadditionalfeatures,includingawavefarmontheseawardside,andfourmarinas

• Shaw two-basin energy storage scheme:similartotheabove,butwithdeep-setpumpturbinestoenablesignificantpumpedstoragecapacity.

The cost of a Severn barrage is to a largedegreedependenton the lengthandscaleof theembankments, while energy output is dependentonthenumberofturbinesandlocationwithintheestuary.Incomparingconstructioncostestimatestothe estimated electricity output, the SDC’s reviewofpreviouswork indicatedthatthetwomostcosteffective schemes are the Cardiff-Weston and theShoots alignment and, for comparative purposes,decidedtofocusontheseinmoredetailandasastartingpointforreviewingSevernbarrageoptionsin terms of sustainable development. The Cardiff-Weston scheme is themostwell studied scheme,and the updated Shoots concept is based on anearlier scheme which was also studied in somedetail.

The SDC’s starting point in considering theseschemes is as renewable energy schemes, andnot, for instance, as flood defence barriers orregional development projects. However, theoverall sustainability assessment will dependon a holistic and integrated assessment of theschemes,havingregardtotheirimpacts,costsandbenefits.TheSDCstronglysupportsrenewablesandthe decarbonisation of the energy from a policyperspective(seeSection1.4).However,westartedthisprojectwithnopreviouspositiononaSevernbarrageandourobjectivehasbeento reviewtheavailable evidence and test the arguments forand against a barrage against the principles ofsustainabledevelopment.

It is clear that if a Severn barrage wereconstructed, regardless of the option chosen, itwouldbeahugecivilengineeringprojectthatwould

haveamajoreffectonthesurrounding landscapeand environment, and on the regional economy.This ismainlyasa resultof thescaleofaSevern

barrage.TheCardiff-WestonandShootsoptionsaresummarisedinTable4.

Table4 ComparisonoftheCardiff-WestonandShootsbarrageoptions


Length of embankments 16.1km 4.1km

Generating capacity 8.64GW(8,640MW) 1.05GW(1,050MW)

Annual average electricity output 17TWh(17,000GWh) 2.75TWh(2,750GWh)

Number of turbines 216 30

Number of sluice openings 166 42

Ship lock size 360mx50m(x2) 225mx37.5m

As this overview shows, the Shoots barrage issignificantly smaller in terms of size and outputthantheCardiff-Westonbarrageduetoitslocationmuchhigheruptheestuary(seeFigure17),wherethevolumeofwaterimpoundedismuchless.

The landfallsof theproposedbarrageschemesshouldbetreatedasindicativeratherthanprecise,and the potentially significant effects on theenvironmentandcommunitieslivinginthoseareasshouldberecognisedas issues thatwould requiresubstantialfurtherinvestigation.

Figure17 ProposedlayoutandlocationoftheCardiff-WestonandShootsbarrage

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4.2.3 Alternatives to a barrage

In order to properly consider a potential Severnbarrage it is important to first consider the otheroptions for exploiting the tidal energy resource inthe Severn Estuary and Bristol Channel. Althoughthe evidence on this subject is high level and insome areas incomplete, a number of conclusionshaveemergedfromResearchReports3and4.

4.2.4 Compatibility of options

InordertotakeastrategicoverviewoftheSevernEstuary resource, it is important to consider thecompatibility of the different options available.This includesboth thecompatibilitybetween tidalbarrages,lagoonsandtidalstreamdevices,andalsobetweendifferenttidalbarrageoptions.

Tidal stream

Due to the nature of the resource and thetechnologies, there does not appear to be anymajor potential conflict between the utilisationof the tidal stream resource in theSevernEstuaryand tidalbarragesor lagoons. This isbecause thetidalstreamresourceisconcentratedindeepwaterchannels, which, along with large sedimentarydepositsintheestuary,wouldpresentanumberofengineeringdifficultiesformostdevicesaswellasbeinganavigationalhazardforshipping.

Tidalstreamdevicesaremorelikelytobesitedfurtherdownstream fromabarrage, in theBristolChannel.This locationhasanumberofpotentiallyfavourablesitesthatareneartheshoreandoutsidethedeepwaterchannels.

However, if a Severn barrage were built then(regardlessoftheengineeringconstraints)itwouldnotbecommerciallyviable todeploy tidal streamdeviceswithin thebasinofaSevernbarrage,dueto a 50% reduction in tidal currents. A Severnbarrage would also reduce the tidal range (andhence the tidal current velocities) on its seawardsidebyabout10%fortheCardiff-Westonbarrage,reducing progressively with distance downstream;the effect on the output of tidal stream devicesismorepronounceddue to the fact thatoutput isproportionaltothecubeofthecurrentvelocity.

Nevertheless,theeffectontidalstreamdevices

in the Bristol Channel from a Severn barrage islikelytobeminor,withareductioninoutputoflessthan10%;fordevicesinstalledafterabarragewasdeveloped,thiscouldbemitigatedtosomedegreeby optimising their design. Conversely, the large-scale exploitation of the tidal stream resource inthisareacouldhaveanadverseaffectonapotentialSevernbarragebyreducingtheavailabletidalrange.However,basedoncurrentresourceinformation,thetidalrangeresource(usedbyabarrage)wouldbemuchgreaterthanthetidalstreamresource,whichhasmanypreferablelocationsinotherpartsoftheUK(seeSection1.3).

Tidal lagoons

The level of conflict between tidal lagoons and abarrage depends to a large extent on the scaleand location of any lagoon development that isproposed.Adirectconflictwouldoccurwheretidallagoons are being proposed in an area very nearto,orwithin thebasinof,a tidalbarragescheme.This is because both technologies utilise the tidalrangeresource.Forexample,atidallagoonbehindthe Cardiff-Weston barrage would have its outputreducedbyaround75%ofitsnormalvalueduetoa50%reductioninthetidalrange;thiswouldmaketidallagoonshereuneconomicincombinationwitha barrage. There would also be a 10% predictedreduction in tidal range just outside the Cardiff-WestonbarragewhichwouldreducetheoutputofatidallagoonintheBridgwaterBayareabyaround20%;theeffectfurtherdownstreamwouldbelesspronounced. It is not considered possible to placea tidal lagoon upstream of the proposed Shootsbarrageduetoalackofanappropriatesite.

Forsmall-scaletidallagoondevelopments,suchas the proposed project in Swansea Bay, conflictbetween these two options would be limited,withonlya small reduction inoutputexpectedatthis locationduetoabarrage.Theconflictswouldobviously increasewith thescaleofanyproposedlagoondevelopmentanditsproximitytoabarrage.Theimpactscouldalsobetwo-way,withapotentialreductionintheoutputofabarrageiftidallagoonsweretorestricttheflowofwaterfurtherupstream.

The effect of the Shoots barrage on potentialtidal lagoons would be less than for the Cardiff-Westonbarrage,withdevelopmentoftidallagoonspossibleinallthelocationsidentifiedabove.


Tidal barrages

Compatibilitybetweenbarrageoptionsalsoneedsto be considered in any strategic assessment. Ifthe Shoots barrage were built first, then it couldtheoretically be followed at a later date by theconstructionofthelargerCardiff-Westonbarrageinordertodevelopmoreofthetidalrangeresource.TheCardiff-Westonbarragewouldreducethetidalrangeinthebasintoaroundhalfitsnormalvalue,leading to a reduction of output in the ShootsBarrageofpossibly75%.TheShootsBarragewouldalso have an effect on the level output from theCardiff-Westonbarrage(andthetimingofcombinedoutputfrombothschemes),butmuchofthiswoulddepend on the method of operation and wouldneedfurtherinvestigation.

Although it is conceivable that the ShootsBarragecouldbe followedbydevelopmentof theCardiff-Westonscheme,itseemshighlyunlikelythatthiswould occur in reverse order as themarginalbenefitsoftheShootsschemeatthisstagewouldbe significantly reduced. However, it is possiblethatmoreofthetidalresourcecouldbedevelopedfollowingdevelopmentoftheCardiff-Westonsinglebasin scheme by constructing a second basinextension across Bridgwater Bay. This option isdiscussedinmoredetailinResearchReport3.

4.2.5 Dealing with data constraints

Thedesk-basedresearchhasallowedsomeof thesubstantialevidencebaseonSevernbarrageoptionstobeupdated,andforsomenewworkandthinkingto be developed. However, it was not within thescope of this project to conduct a comprehensivere-evaluationofaSevernbarrage.Alargenumberof uncertainties remain, particularly in relation todetailed modelling of environmental impacts, thecost of the proposed schemes, and the potentialeffectsonthelocalandregionaleconomy.

On environmental impacts specifically, whileahugevolumeofdataalreadyexists, the studiescarried out in the 1980s predate the HabitatsDirective and the UK regulations giving effect totheHabitatsandBirdsDirectives(seeSection4.6.2below). The impact of a barrage on protectedfeatures and the implications of the Directives’requirements fordevelopmentwere thereforenotconsideredinpreviousstudies.

Despite these uncertainties, the SDC believesthat there is enough evidence to take a strategicdecisiononwhetherornotaSevernbarragewarrantsfurtherinvestigation,bearinginmindthecostandeffortlikelytoberequiredtodothis.Thisreportwillbe the SDC’s contribution to this debate; thefinaldecisionistheresponsibilityofGovernment.

ThissectionconsidersthecontributionthatthetwoSevernbarrageschemesunderconsiderationwouldmake to UK electricity supply, their method ofoperation,andtheimplicationsofthisontheirload

factorandthetimingoftheiroutput.Itthenlooksattheimplicationsofabarrageongridmanagement,andtransmissionconstraints.

4.3 Electricity output and characteristics

Table5 ContributionofSevernbarrageoptionstoUKelectricitysupply

Cardiff-Weston barrage Shoots barrage

Annual average electricity output 17TWh(17,000GWh) 2.75TWh(2,750GWh)

Percentage of UK electricity supply (382.5TWhin2006)

4.4% 0.7%

Percentage of UK energy supply (235Mtoein2006)

0.6% 0.1%


4.3.1 Contribution to electricity supply

Table5showsthepotentialcontributionofthetwoSevern barrage schemes under consideration toUKelectricity supply. Figuresarealsoprovided fortheircontributiontoUKenergysupply,whichtakesaccountofalltheenergyusedintheUKeconomy,suchasforheatandtransport.Asonewouldexpect,the contribution to total energy supply is muchlower,whichillustratestheimportanceofreducingheatandtransportcarbonemissionsinadditiontothosefromelectricitygeneration.

Toputthesefiguresincontext,theannualoutputoftheCardiff-Westonbarragewouldbeequivalentto the output of around 2.2GW of conventionalbaseloadplant,suchascombinedcyclegasturbine(CCGT)plantornuclear(assuminga90%loadfactor–seeSection4.3.3below).Withatypical1GWplantsize,thisisequivalenttojustovertwolargepowerstations.TheShootsbarragewouldbeequivalenttotheannualoutputofa350MWconventionalpowerplant.

The impact on the UK’s targets for renewableelectricity would be more pronounced. The UKGovernmenthasanaspirationfor20%oftheUK’selectricitytocomefromrenewablesby2020.Morerecently, the UK has also agreed to an EU-widetargetfor20%ofallEurope’senergyconsumption(includingheat)tocomefromrenewablesby2020.52The Cardiff-Weston barrage would make a bigcontributiontowardsthe2020aspiration,assumingit couldbebuilt in time. Even the Shootsbarragewouldmakeasizeablecontribution,equivalent tothatenvisagedbyalargeoffshorewindprojectsuchastheLondonArray.

Mostoftheresearchontidalbarragesassumesaworkinglifeof120years,althoughitisconceivablethatelectricitycouldbegeneratedwellbeyondthedesignlifeifstructuralintegritycouldbemaintained,andifsiltationdidnotsignificantlyimpairoperationalefficiency.Theseconclusionsarewellsupportedbyexperiencewithlargehydropowerdams,andwiththe barrage at Rance in France, which is in goodcondition after 40 years of operational service.Within the lifecycle of the structure there wouldneedtobeperiodicmaintenanceandreplacementofsomeoftheplantandequipment,whichwouldmostlikelyoccurevery40yearsorso.

4.3.2 Method of operation

Tidalbarragesandlagoonscanbeoperatedontheebb or flood tide, or both, andwith the optionaladditionofflood/ebbpumpingtoincrease/decreasethe levelofwater in thebasin to further increaseoutput.TheseoptionsareexplainedinmoredetailinResearchReport3.

Modelling work on the Cardiff-Weston barrageindicates that the method of operation with thehighestpotential electricityoutputwouldbeebb-generationwithfloodpumping,withthepumpingcontributingtoanetgaininoutputofaround3%.The corresponding data on the Shoots barrageis incomplete,but the resultsare likely tobe inasimilarrange.

The research on output calculations has so farbeen from an engineering perspective, and takeslittleaccountoftherealitiesoftheUK’sliberalisedelectricitymarket,althoughthereisacknowledgmentofadegreeofflexibilityinhowabarragemightbeoperated.Thisislargelybecausetheexistingworkwascompleted inadifferentera,whenelectricitygeneration and the operation of individual powerplantswasunderthecontroloftheCentralElectricityGeneratingBoard.Under this scenario, the aimofmaximising theoretical electricity output for plantwithverylowvariablecosts(suchasnuclear,oratidalbarrage)makessense,asthesystemoperatorislikelytoscheduleconventionalplanttofitinwiththeresultingoutputschedule.

However,thisisnolongerthecase,anditisnowlikelythattheoperatorofaSevernbarragemayseektooperatetheplantonasub-optimaloutputregimeto take advantage of more attractive wholesaleelectricityprices.Integratingsucheconomicfactorsinto future electricity output models is a vitalconsideration.Thefiguresonoutputpresentedhereshould therefore be viewed as theoretical ratherthanaswhatmightoccurinoperation.

4.3.3 Load factor

Tidal power is by its very nature intermittent buthighlypredictable. This isbecause it isnot reliantonweathersystems,butontidalcyclesthatcanbecalculatedhundredsofyearsinadvance.

Theterms‘loadfactor’or‘capacityfactor’53areusedtodescribetheaverageoutputofanelectricitygenerator over a year in comparison to its ratedcapacity.Nogeneratorhasaloadfactorof100%,as


therewillalwaysbesomedown-timerequiredforroutinemaintenance,andtheoccasionalfault.

Conventionalthermalgeneration(e.g.fromcoal,gasandnuclear)willingeneralhaveamaximumloadfactorofaround80-90%,althoughtheactualfigurewilldependonwhethertheplantisusedtoprovidebaseload power, or to generate intermittently.Onshore wind power has a lower average loadfactor of around 27%, although individual windfarmsingoodlocationsmayrecordloadfactorsthataremuchhigherthanthisUKaverage.

Taking the installed capacity figures shown inTable 4 above, the Cardiff-Weston barrage wouldhave a load factor of 22.5%, with the Shootsbarrageatjustlessthan30%,althoughtheactualfigureswoulddependonthemethodofoperation,asdiscussedabove.Althoughlow,a loadfactoratthislevelisnotaprobleminitself;itsimplyfeedsthroughintothecostofelectricityoutput.

4.3.4 Output profile

The intermittent but predictable nature of tidalbarrage output is well illustrated by the outputprofile. This is a highly complex subject which isbriefly summarised here – further details can befoundinResearchReport3.

The timing of tidal range devices, as alreadydescribedinSection1.3.4,isprimarilyrelatedtotwotidal patterns: semi-diurnal tides, and the spring-neaptidecycle.Semi-diurnaltidesaretheregulardailytides,withtwofullcycleswithinaperiodof24hoursand50minutes.Thespring-neaptidecycleisthe29.5daycyclethataffectstheextentofthetidalrangewithineachdailytide,withawidevariationbetweenspringtides(maximumoutput)andneaptides(minimumoutput).

Asalreadyexplained,aSevernbarrageoperatedin ebb-generation mode will impound the waterat high tide and then allow the receding tide tocreateaheightdifferencebetweenthebasinwaterlevelandthesea levelbeforereleasingthewaterthroughturbines.Theoptimumtimeforgenerationoccursbetween2.5and4hoursafterhightide,withelectricity generationoccurring for 7-8hours after

commencing. However, within this period, outputfromabarragewouldnotbeconstant,particularlyatthebeginningandendofthegenerationcycle.

Over a seven day period, the timing ofgeneration from a Severn barrage will advanceby approximately six hours. This, along with thevariation in output due to the spring-neap tidecycle, means that there is a complex relationshipbetween the output of a barrage and electricitydemand.PeakelectricitydemandintheUKoccursduringearlywinterevenings(approximately6pm),with high demand occurring throughout the dayfrom around 7am onwards. Lowest demand isexperiencedintheearlymorninghours,particularlyinthesummermonths.

Onsomedays,peakbarrageoutputwillcoincidewith peak electricity demand, but the averageoutputfromaSevernbarrageisnotideallymatchedto UK electricity demand. On average, greateroutputfromtheCardiff-Westonbarragewouldoccurintheearlyafternoon(1-3pm)andtheearlyhoursofthemorning(1-3am),withminimumproductionoccurring between 7-9pm and 7-9am. As a resultof being slightly upstream, the Shoots barrageexperienceshigh tide, and thereforepeakoutput,around an hour later than the Cardiff-Westonproposal,puttingmaximumoutputataround2-4pmand2-4am.TheseresultsareillustratedinFigure23(notedifferentscales).

Expressed another way, average power outputduringthepeakelectricitydemandperiod(5pmto7pm)wouldbearound37%ofthemaximumhourlyaveragefortheCardiff-Westonbarrage,andaround55%ofthemaximumhourlyaveragefortheShootsbarrage. The higher figure for the Shoots barrageisexplainedbythefactthatoutputatthislocationoccursonehourlater,whichonaverageputsitclosertothepeakdemandperiodsonagreaternumberoftides.

However, average figures will also tend tounderstate the differences between spring andneap tides, and the variation in output that willoccurduringonegeneration cycle. Figure19 (a&b) illustrates thisusingactualdatacompared toatypicalelectricitydemandprofile.


Figure18 AverageoutputfrombothSevernbarrageproposalsincomparisontotheUKwinterelectricitydemandprofile

Overallthen,bothbarrageproposalswouldmakeasubstantialcontributiontoUKelectricitydemand,butonethat issub-optimal intermsofhelpingtomeetpeakelectricitydemandperiods,whencarbonsavingswouldbehighest.54Furthermore,thewidevariation in output both during and between

generation periods (from 0GW to 8.6GW for theCardiff-Weston proposal) combined with the dailychanges in theoutputprofileof a Severnbarrageposeanumberofseriousquestionsrelatingtogridmanagementandtransmissioncapacity.Theseareexploredbelow.

Figure19a SpringtidepowergenerationprofilefromCardiff-Westonbarrageovera24hourperiodduringspringandneaptides

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Figure19b NeaptidepowergenerationprofilefromCardiff-Westonbarrageovera24hourperiodduringspringandneaptides

4.3.5 Implications for grid management

Misconceptions over intermittency

As described in the SDC’s 2005 report on windpower,33 there are a number of misconceptionssurroundingtheintegrationofrenewablesintothenational electricity grid. It is commonly assumedthatintermittentoutput,suchasthatfromtidalorwindpower,causesaproblemforthegridoperator,and that such output requires dedicated backup,therebyoffsettingsomeofitsbenefits.

Both the SDC and the UK Energy ResearchCentre(UKERC)33,55haveshownthatsuchclaimsareunfounded,andarebasedonanumberofinaccurateassumptions regarding grid management. First,both the supply and demand of electricity areconstantly changing, even under a system basedentirely on conventional thermal generation,withlarge changes in both variables throughout theday.Forexample,majorsportingeventsresultinarapiddemandsurgefromthesimultaneousboilingofkettlesduringbreaks,whilstatexactlythesametime an unexpected fault could cause the loss ofover1GWofsupplyfromalargepowerplant.Thegrid operator has tools and strategies in place todealwith theseeventualities, and theadditionof

intermittent renewables to the grid needs to beconsideredinthiscontext.

All electricity generation plant is intermittentto some degree, and in many respects severalrenewable technologies are actually less prone tounexpectedoutagesthanthermalgenerationplant.Thisisbecausenotechnologyis100%reliable,soevenbaseloadthermalplant(suchasCCGTplantornuclear)willbeoutofserviceforsomeoftheyear,either for scheduledorunscheduledmaintenance.When this is unscheduled, thegrid operatormustcopewithaninstantaneouslossofupto1.3GWofsupply,orpossiblymore if there isa transmissionfailure.Most renewables, including tidalandwindpower, canhave their aggregateoutput predictedseveral hours in advance of generation, or in thecaseoftidalpower,yearsinadvance.Furthermore,in the case of modular renewable generators(suchaswind turbinesor tidal streamdevices), afaultinonedevicewillbeinsignificantintermsofoverall output. Finally, a fall in output from theserenewablesisunlikelytooccurinstantaneously–asexplainedbelowfortidalpower.

The integration of a large volume of onerenewable technology does present a numberof issues for grid operators, but there is no needfordedicatedbackupplant.What ismore likely is

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�0 Tidal Power in the UK SustainableDevelopmentCommission

thatduetothe lowercapacityvalue56attributableto some renewables, they are unable to displaceconventionalcapacityonamegawatt-for-megawattbasis,sotheplantmarginrises.57Thisisaneconomicconsiderationratherthananoperationalbarrier.33,58

The capacity value of a Severn barrage

ThisisparticularlytrueofaSevernbarrage.Becauseof the regular mismatch between the timingof greatest barrage output and peak electricitydemand,alongwithalowloadfactor,thecapacityvalueofaSevernbarrageislow.Thisisillustratedby

thedemandduration curve for the Cardiff-WestonbarrageshowninFigure20,whichshowsminimumelectricity demand being met by conventionalcapacity dropping from 25GW to 19GW, whereaspeak electricity demand falls from 70GW to68GW.TheeffectfortheShootsbarragewouldbeproportionatelysmaller.ThisimpliesthattheCardiff-Westonbarrageisabletodisplace2GWofconventionalcapacityintheyearmodelled, giving it anaverage ‘capacity value’ ofaround20-23%.Theequivalentdatadoesnotexistfor the Shoots barrage, but following from theconclusionsofSection4.3.4,itscapacityvaluemightbesomewhathigher.

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Figure 23: Demand curve with and without the Cardiff-Weston barrage(data from a single year)

When peak barrage output (8.64GW from theCardiff-Weston barrage) coincides with times ofminimum electricity demand (25GW), the typeof generating output displaced is an importantconsideration from a carbon-saving perspective.Thisdependsonthegridmix,andatpresent,theCardiff-Weston barrage would not displace anylow carbon output (e.g. output from nuclear orrenewables), as the total capacity of such outputislessthanthenetcapacityrequirementafterthebarrageoutputissubtracted.Inthelongerrun,withmorerenewablesand/orotherlowcarboncapacity,it is likely that tidal outputwouldoccasionally be

competing for demand with low carbon outputduringlowdemandperiods.

Overall,aSevernbarrageoperatedformaximumelectricity output would reduce the number ofhoursthatexperiencesmallchangesindemandforpowerfromconventionalgeneration,causeasmallincreaseinhoursthatexperienceamoderatelevelofdemandchange,andincreasetheextremehour-to-hourfluctuationsindemandthatwouldneedtobeaccommodated.Thismeansthattheconventionalcapacitywouldneedtobemorereactiveandbetterable to respond tovery large changes indemand(eitherpositiveornegative).

Figure20 DemanddurationcurvewithandwithouttheCardiff-Westonbarrage(datafromasingleyear)

SustainableDevelopmentCommission Tidal Power in the UK �1

Implications for system balancing

From a grid management perspective, thepredictabilityofthesevariationslessenstheimpactthese changes would have on the stability of thegrid. There would be a requirement for increasedload following capability from other generators–oftentermedas‘systembalancing’requirements–butthiswouldbeprovidedfromexistingcapacity,andtherewouldbenoneedfordedicatedreserve(orbackup)plant.Thisconclusionisconsistentwiththefinding that theCardiff-Westonbarragewoulddisplace up to 2GW of conventional capacity, andisalsoconsistentwiththeSDC’spreviousworkonwindpower.33

Anincreasedneedforsystembalancingcarriesan economic penalty. Under the current marketframework this cost is unlikely to fall to thegeneratorresponsibleforcausingtheincrease,andisthereforesharedbetweenallmarketparticipants.Asaresult,itisimportanttoconsiderthelikelyscaleofthesecostsinanyeconomicevaluation,astheywilleventuallybepassedontoconsumers.

Overall then, the SDC does not feel that thevariability or sub-optimal timing of output fromeither Severn barrage scheme are factors thatundermine their potential contribution to climatechange or energy security objectives. While theCardiff-Westonschemewouldundoubtedlyrequiremoreactivegridmanagement,weviewthisasaneconomicratherthanatechnicalconstraint.

It is also important to consider the possiblecontribution that increased energy storage anddemand management might make over the longtime period that a barrage would be operating.Future advances in large-scale electricity storagetechnologies, and developments in automateddemand response (sometimes referred to as‘dynamic demand’),59 could lead to a much moredynamicandsophisticatedelectricitygrid–andonethatisbetterabletoaccommodateintermittentorvariablesupply.

As our research shows, there are a number ofpotential ways that a barrage could be designedto provide some level of storage itself, throughsequential release of water into multiple basinsfor example. Our analysis of this is that such ascheme would need to be economically (andenvironmentally)justifiedbasedonthenetbenefitsitcouldprovide.Therefore,anymodificationofthebasicdesignwouldneedtobetreatedasanenergystorage project, and evaluated in comparison to

otherwaysofprovidingsuchstoragecapacity.Onepossiblevariationofamultiplebasisdesign

wouldbeifconstructionoftheShootsbarragewasfollowedatsomelaterdatebyconstructionoftheCardiff-Weston barrage. As this would create abasinwithinabasin,theremaybethepotentialforimproveddispatchabilityofthecombinedoutputofthetwoschemes.

4.3.6 Implication for the transmission system

The Severn Estuary area has significant networkcapacity for new generation, with negativetransmissionnetworkuseofsystem(TNUoS)chargescurrentlyinforceforgeneratorsinthesouth-westofEnglandduetoashortageofgenerationtheretomeetlocaldemand.However,anyassessmentofnetworkcapacity is only ever a snapshot in time, as thesituationcanchangerapidlythroughacombinationofnewcapacity(someofwhichmayonlybeattheconceptualstage),networkreinforcements,andthedecommissioningofexistingplant.

The current financial incentives through TNUoSchargestoconnectnewcapacityinthesouth-westand,toalesserdegree,insouthWales,couldhaveapositiveeffecton theeconomicsofanybarrageproposal. However, the TNUoS system is highlydynamic, and it is likely that the connection ofa large amount of new capacity in the form of abarragewouldreduceorevenreversethissituationfor all generators in these TNUoS zones, includingthebarrageitself.

Inadditiontohavingsufficientsparecapacityintheconnectionzones,anynewconnectiontothegridmustbeabletoidentifyasuitableconnectionpointtothewidertransmissionsystem.Forhighcapacityprojects,thereareanumberofconstraintsinplacethatare intended toensure system reliabilityandstability,withlimitsontheamountofcapacitythatcanbeconnectedtoasinglepoint.

AsshowninFigure21,thetransmissionnetworkaroundtheSevernEstuaryisquitedeveloped,withpossibleconnectionsatboth400kVand275kVonbothsidesoftheestuary,notfarfromthepotentiallandingpointsforabarrage.

The implications for a Severnbarrageareverydifferentforthetwoschemesunderconsiderationhere. For the larger Cardiff-Weston scheme, ourresearch indicates that two connections into the400kV network would be required at both thesouthandthenorthsidesofthebarrage(i.e.four


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Due to themuchsmaller ratedcapacityof theShootsscheme,theresearchindicatesthatalloftheconnectionoptionsseemtohavesufficientcapacitytoaccommodatethis through justoneconnection.AconnectiontotheHinkleyPoint–Melksham400kVdouble-circuit is considered the most appropriateduetoahighdemandfornewcapacityhere,whichcouldfurtherincreasewiththedecommissioningofthenuclearpowerstationatHinkleyPoint.

These conclusions show that both schemeswouldrequiresomenewtransmissioninfrastructuretoconnect intotheexistingnetwork,butthatthisrequirement is far higher for the Cardiff-Weston

scheme due to its higher rated capacity. Theremay also be a requirement for additional gridstrengthening in other parts of the transmissionnetwork if such a connection were to be made,although such requirements would need furtherdetailedstudy.

Thereisalsothepossibilitythatequipmentmaybe required to allow this additional output to beusedinsouthernEnglandtosubstituteforcapacitypresentlyprovidedbytheFrenchinterconnectortoavoid congestion in the central England network.This would have a negative effect on the carbonsavingsachievedbyaSevernbarrage,aselectricityimported from France has a low carbon intensitydue to thehighpercentageofnuclearpower thatisinstalledthere.

Figure21 Electricitytransmissionnetwork(400and275kV)aroundtheSevernEstuary


This section assesses the embedded carbonemissionsthatwouldcomefrombuildingaSevernbarrage (the ‘carbon payback’) before going onto look at the estimated carbon savings over thelifetimeofthescheme.

4.4.1 Carbon payback

The work commissioned as part of this projectincluded an assessment of the embedded carbonemissionsfromtheconstructionphaseofaSevernbarrageproject.Theassessmentexcludesemissionsfromthetransportofmaterialstosite,whichcouldbe significant, andemissions fromoperationsanddecommissioning. On this basis, it is not a fulllifecycle carbon analysis. However, constructionemissionsarelikelytooutweighsignificantlytheseother emissions. Emissions from operations anddecommissioning are also likely to decrease overtimeduetotheprogressivedecarbonisationofthewidereconomy.

The long lifecycle of a Severn barrage has apositive impact on the carbon ‘emissions factor’,as theembeddedemissions fromconstructionarecounter-balanced by 120 years of zero emissionelectricitygeneration.Theemissions factor for theCardiff-Westonbarrageisestimatedtobe2.42gCO

2/

kWh,withafigureof1.58gCO2/kWhfortheShoots

scheme (based on figures for the English Stonesscheme). This translates into a carbon payback ofaround5-8monthsforthetwoschemes.

TheemissionsfactorforaSevernbarrageputsitin thevery lowestcategory forpowergeneration,and it compares well against other low carbontechnologiessuchasnuclearpower(16gCO

2/kWh).17

There seems little doubt that, despite a numberof emissions that remain unaccounted for in thisanalysis,aSevernbarragewouldbea lowcarbontechnology.However,afullsustainabledevelopmentappraisalrequiresustoconsiderthecarbonimpactsofresultingdevelopmentinthesurroundingregion,and other effects such as the displacement ofcargomovements.ThisisconsideredinSection4.7below.

4.4.2 Carbon reduction potential

Oneof themain arguments for building a Severnbarrage is its potential contribution to reducingcarbondioxideemissions, and therefore its abilitytohelptheUKmeet itsnationaland internationalobligations on renewables and emissions ofgreenhouse gases.69 It is therefore important toknowwhat the likelybenefitsofabarragewouldbeontheUK’sclimatechangemitigationefforts.

ThereductionincarbondioxideemissionsfromaSevernbarragedependsheavilyontheassumptionsmade on the carbon intensity of the displacedelectricity. As the output from a tidal barrage isintermittent, highly predictable, and has a verylowoperationalcost,itislikelythatthiswouldbetreated as baseload generation by the electricitymarket,inasimilarcategorytonuclearpower.

As a result, tidal barrage output is most likelytodisplacetheoutputfromlarge,centralised,fossilfuelplant. Thereare twoways to thinkabout thecarbon impactofplantdisplacement:a) thatnewcapacitywilldisplacetheoutputofexistingplant,orb)thatitwilldisplacetheneedforsomeotherformofnewcapacity,andtheassociatedemissions.

It isassumedherethataSevernbarragewoulddisplace the need for some other form of newcapacity,whichwouldmost likelybeCCGTplantasthis is currently the preferred choice for new-buildbaseload generation. The reason for this is that aSevern barrage is unlikely to be operational for atleast10years,duringwhichtimemuchoftheUK’scoalcapacitywillbetakenoutofserviceduetotheLarge Combustion Plant Directive. This, along withthecontinuedretirementoftheUK’snuclearcapacity,willcreatetheneedforsubstantialamountsofnew-buildcapacity,towhichabarragewouldcontribute.AssumingthataSevernbarragewoulddisplacetheoutput of CCGT plant is consistent with the SDC’sanalysisofnuclearpower17andwindpower.33

Official figures show that average emissionsfor gas-firedplant are 100 tonnes of carbon61 pergigawatt-hour (tC/GWh).62 However, it is moreappropriatetoassumethataSevernbarragewoulddisplace new-build gas-fired plant, which has acarbonintensityofaround90tC/GWh.

4.4 Carbon emissions


Using this figure, alongwith the ‘averagegas’and the ‘gridmix’figures for comparison, Table6presentsthelikelyannualcarbonsavings(asbothcarbon and carbon dioxide) from the two Severnbarrageproposalsbeingdiscussed.

Althoughitispossiblefromthisdatatocalculatethe lifetime carbon savings (over the 120 yearsexpected life of a barrage), these figures are

unlikelytoberealisticbecauseoverthisperioditislikelythatthegeneratingcapacitybeingdisplacedwillbeprogressivelylesscarbonintensiveassocietyis ‘decarbonised’. As a result, the contribution, inpercentage terms, to UK electricity supply (asdescribed inSection4.3.1above) isseenasmoreuseful than calculating the total lifetime carbonsavings.


MtC MtCO2

MtC MtCO2

Annual carbon savings (basedon90tC/GWh)

1.53 5.60 0.248 0.91

Percentage reduction in UK carbon emissions (1990baseline)

0.92% 0.15%

For comparison

Annual carbon savings based on ‘average gas’ displacement (100tC/GWh)

1.7 6.22 0.275 1.00

Annual carbon savings based on ‘grid mix’ displacement (131tC/GWh)

2.23 8.15 0.36 1.32

Table6 PotentialcarbonsavingsfromaSevernbarrage

Theconstruction,presenceandoperationofaSevernbarrage would involve major physical changes towater levels, geomorphology, and sedimentaryprocesses. These physical changes underlie andhavesignificantimplicationsfor:

• theenvironment –theestuarineecosystem,intertidalandwetlandhabitats,birds,fish

• theeconomy and societyatalocalandregionalscale–portsandnavigation,landdrainageandflooding,waterquality,infrastructureandtransport,employment,industryandrecreation.

ASevernbarragewouldbeaverylargestructureacross the estuary with a significant physicalfootprint.TheCardiff-Westonbarrageisabout16kmlongandaShootsbarrageisabout4km.However,thechangesthatabarragewouldcauseextendwellbeyondthedirectphysicalfootprintofthestructure,and involve physical changes to the estuary as aresultofreducingthetidalrangeandchangingthewaterlevelswithinthebarragebasin(‘upstream’)and outside of the barrage (‘downstream’). Thephysical barrier across the estuary, together withthechangestowaterlevels,thetidalcurrentsandthe wave regime of the estuary, also mean thatthe sedimentary andmorphological characteristics

4.5 Physical implications of a barrage


andprocessesoftheestuarywouldbesignificantlyaltered. This section summarises someof the keyeffectsthatarepredictedtooccurwithdevelopmentofabarrage.Theissuesofthelifetimeofabarrageanddecommissioningarealsoconsidered.

4.5.1 Sound science and uncertainty

Thissectionaddressesthephysicalchangesthatabarragewouldhaveontheestuaryandsurroundingcoast. These physical changes underlie not onlythe environmental and conservation impacts of abarrage,butalsothe implicationsofabarragefortheeconomyandforsociety.Asoutlinedabove,theSDCconsidersthatwehaveenoughinformationtoreachahighlevelviewonthestrategicquestionofwhetheraSevernbarrageisanoptionthatmeritsfurtherinvestigation.However,weareconsciousthatthere are gaps in the information available abouttheeffectsthatabarragewouldhave,andthecostsand possible options for mitigating any adverseeffects.Further,weknowthatthereisnotenoughinformation to take a decision to proceed withdevelopmentortosatisfycommercialorregulatoryrequirements. Sound science and information areessentialtogooddecision-makingandtoensuringthatweoperatewithinenvironmentallimits.

The1980sstudiesprovideawideanalysisofthephysicalandecological regimesbeforeandduringtheconstructionandoperationalphasesofbarragedevelopment.Theresearchwasundertakenduringthe 1980s and early 1990s and focused on theCardiff-Westonalignmentofthebarrage.However,those studies and the review that the SDC hascommissionedidentifyalargenumberofunknowns,andalackofcertaintybothastotheestuaryasitisnow(theenvironmentalbaseline)and,toagreaterdegree, thepost-barragescenario.63Asmentionedabove,thestudiesalsopredatedesignationofmanyoftheconservationfeatures.Theymaynothaveusedthemostadvancedmodellingtechniquesorappliedthelatestknowledgeofestuarineecosystemsandprocesses,orinternationalexperience,totheeffectsofcoastaldefencestructures.

For example, information on the effects of abarrage on currents is based on modelling fromearly2-Ddepth-averagepredictions,whichprovidea limited basis for drawing firm conclusions. Howmorphological features of the estuary mightrespond, upstreamanddownstreamof a barrage,is a complex issue and has not been studied in

detail, and this considerable uncertainty makespredictions of the ecological response and theimpactsonhabitatsandbirdsverydifficultat thisstage.Predictionsofthelossofintertidalhabitat,forexample, arebasedmainlyonestimated changesto water levels, as comprehensive predictions ofchangestomorphologyarenotavailable.

Changes of ecology and ecosystems involvea complex set of interactions between physical,chemicalandbiologicalparameters.ForaschemeatthescaleofaSevernbarrageandthedifficultiesofmodellingadynamicandcomplexnaturalsystem,itislikelythatsomeuncertaintieswillremainevenafterfurtherdetailedstudiesarecarriedout.

Theseareasofuncertaintyalsohaveimplicationsforconsideringtheeffectsofdevelopmentonportsandnavigation,andfloodriskmanagement,whichare discussed further in Section 4.7. The functionof the estuary in supporting economic and socialstructures, and the value of ecosystem servicesprovided by estuaries – for example, as nurseriesfor fish, filters forwaste, and assistingwith floodmanagement–shouldbetakenintoaccount.64Thisdoes not mean that any change to the system isautomatically ‘bad’ or negative, but rather that aholisticapproachneedstobetaken.Italsoimpliesthatweshouldattempttounderstandthelongtermeffectsofanyproposeddevelopmentbecausetheconsequenceswillbefeltoverthe longterm,andthecostsofdealingwithproblemsofthisnaturearemorelikelytofallatalocallevelratherthanasanupfrontcostofdevelopment.

4.5.2 Water levels and currents

The high tidal range seen in the Severn is theproductoftheshapeoftheestuaryandthevelocityatwhich the tidewavepropagates,which causesaresonanceeffect.This‘hypertidal’natureiswhatmakes the estuary attractive for potential powerdevelopment,butitisalsoresponsibleforcreatinga series of unique conditions and habitats, suchas extensive mud flats and mobile sand banks.ExtractingenergyfromthisdynamicregimeintheformofatidalbarragewouldfundamentallychangethenatureoftheSevernEstuary.

Onthewhole,abarragewouldraisetheaveragewaterlevelinsidethebasinbyraisingthelowtidelevels to around present mean sea level and byreducinghightidelevelsbyupto1m(uptoabout0.5mforaShootsscheme).Themeansealevelin


theestuarywouldberaisedbysome2.5mto3mfortheCardiff-Westonscheme.Theoveralleffectisto reduce the tidal rangebyaround50%. For theCardiff-Weston scheme, the range would declinefrom11.5mto4.5monspring tides,and5.5mto2.5monneaps.For theShootsscheme, the resultwould be a similar reduction in tidal range, from12.5mto4.5monspringtides,and6.5mto3.5monneaps.

Downstreamofabarrage,modelpredictionsforthe Cardiff-Weston alignment are that low waterlevelswouldbe raised somewhat andhighwaterlevelswouldbereduced.Theseeffectswoulddeclinewithdistance,althoughthemodelspredicted thatthedecreaseinhighwaterlevelscouldbedetectedup to 75km seawards. However, Research Report

3 notes that these modelled results are counter-intuitive,andthathighwaterlevelscouldincreasedue to water being held up against a barrage.Ascertainingthecorrectpredictionusingadvancedmodelling,whichalsoconsiderssedimenttransport,wouldbeanimportantfactorindeterminingtheriskoferosiondownstreamofabarrage.

ThegeneraleffectofabarrageonthetidalrangeisshowninFigure22.

Thescaleofchangetothetidalrangewithinthebarragebasinisbestillustratedbyconsideringthelossof intertidalhabitat. The intertidalarea is thearea between high and low tide that is regularlyexposedtobothairandwaterasaresultofthetides.ThisisdiscussedfurtherinSection4.6.3below.

Asaresultofthehugetidalrange,theestuary

Figure22 Relativepositionoftidalbasinwaterlevelsunderanebbgenerationmodeofoperation65

Barraged inter tidal zone

Natural intertidal zone

Figure 25: Relative position of tidal basin water levels under an ebb generation mode ofoperation (source: Clark17)

Mean sea level

Natural high tide

Basin low tide

Mean basin level

High tide

Natural low tide

Mean sea level

Natural high tide

Basin low tide

Mean basin level

High tide

Natural low tide

Source: Clark


alsohasverystrongcurrents.Thecurrentsmaintaindeep channels and high loads of suspendedsediment. The reduced tidal range would reducecurrents in the estuary as a whole. Locally fasterflowswouldbeexperiencedclosetothesluicesandturbinesinthebarrage.

Inadditiontowaterlevelsandcurrents,changestothewaveregimeoftheestuaryarealsorelevantto the Cardiff-Weston scheme. With water levelsin the basin remaining more constant (from thereduced tidal range), waves might be generatedon the surface of the estuary with the risk thatincreasedwaveenergycouldaffectsoftshorelinesatthemarginsoftheestuary.

4.5.3 Morphology

Morphology refers to the form and developmentof the landscape, in this case also referring to theunderwater areas of the Severn Estuary. As Figure23 shows, the estuary is characterised by deepchannelsrunningthroughmoreshallowwaters,withanumberoflow-lyingareasonbothsidesthatwouldbe inundatedathighwater if therewerenofloodembankments.Thisalsoillustratesthepossiblethreatofsealevelriseandstormsurgestothisregion.

The Severn Estuary is a highly dynamicenvironment, with rapid (often daily) and longer-termchangesseeninthedepthsandpositioningofdifferentfeaturessuchassandbanksandchannels.Recentevidencesuggests that theadditionof theCardiffBaybarragehasresultedinthegradualsplitandmigrationoftheCardiffGrounds(asandbar),whichmaygivesomeindicationoftheimpactofamuchlargeSevernbarrage.

Changes to morphology and the sedimentregimehaveimplicationsfortheenvironment,theengineeringofabarrage,andalsoatasocialandeconomiclevel;forexample,inrelationtoportsandnavigation.

More detailed examination of the possibleimpactofabarrage,someofwhichiseitherhighlycontested or the subject of much uncertainty, isoutlinedinResearchReport3.66

4.5.4 Sedimentary processes

The muddy nature of the Severn Estuary is theproductofahighsuspendedsedimentload,whichis maintained by the strong currents that passthroughdeep channels in the estuary, particularlyonspringtides.Thecurrentsarealsoinfluencedby

Figure23 ElevationinandaroundtheSevernEstuary

�� Tidal Power in the UK SustainableDevelopmentCommission

thepatternof thetides.Thefloodtide isstrongerthantheebbtide,butthisiscounteredbytheebbtidelastingforalongerperiodoftime.

Althoughour knowledgeof these sedimentaryprocesses in the estuary is incomplete, it seemsthatthesecurrentsaretheprimarymechanismforsortingof seabedmaterials, leading togravelandrockypatchesinthechannels,andmuddydepositsin the inter-tidal areas. Other sediments presentintheestuaryincludeclay,sand,andshinglewithsediment supplies from a number of sources,including rivers, cliff erosion, saltmarsh erosion,mudflaterosion,theseabed,andseawardinputs.

There are a number of large sand bodies intheestuary,suchastheMiddleGround.Thesearedeposited through a ‘tidal pumping’ mechanism,which sees marine sands brought up the estuaryonthestrongfloodtideswhichtheslowerflowingebb currents are unable to remobilise. Muddysediments,ontheotherhand,appeartoremaininsuspensionformosttides,havingbeenintroducedfromupstreamfluvial(riverandstream)sources.

Theconstructionofabarragecouldbedesignedtolimittheeffectsonthesedimentaryregimeuntilclosure,althoughdredgingforconstructionmaterialscouldhaveasignificantdirecteffect.

Onceconstructed,abarragewouldhaveamajoreffect on sedimentary transport by reducing thetidalforceontheseabedoutsidethevicinityofthebarragebyafactoroffourduringfloodtidesandafactor of tenduring ebb tides. Thiswould lead toa significant reduction in sand transport (with thefreezingof currentlymobile sandbanks), and thelikelydepositionofmudsediments.

Closetothebarragestructure itself,wherethestrongcurrentspassthroughtheturbinesandsluicegates, sediment transport would continue, with anetaccumulationofsedimentpredictedonthebasinside. This sediment accumulation, and its abilityto significantly reduce the operating lifetime of abarrage,hasinthepastbeenofparticularconcernfor the Shoots proposal, but designmodifications(e.g.positioningthesluicegateshigheruptoavoidwaterflowswiththehighestsedimentloads)havebeen investigated to attempt to tackle this issue.Further investigationwould be required to ensurethatthesemodificationsweresufficient,asexcessivesedimentation could have serious implications fortheeconomicviabilityofthescheme.

Overall, a barrage might result in depositionofupto85%of themobilesediment load,whichin turn may allow sufficient light to penetratethe water column to create a viable photic zone.The consequences of this decreased sedimentconcentrationanditsroleincreatingconditionsforprimary production within the water column arediscussedfurtherbelowinrelationtoecologyandbirds.

4.5.5 Decommissioning

Thereisverylittlediscussionofdecommissioningintheexistingresearch,andthegeneralassumptionuptonowisthatthestructurewouldnotbeintentionallydismantled even if power generation were tocease.Despitetheobviouscostofdecommissioning(whichcouldbeashighastheconstructioncostinrealterms),theremaybeanumberofgoodreasonswhy this would be the preferred option, such asminimising disturbance to the environment andsomeofthebenefitsofadditionalfloodprotection(seeSection4.7.3below).

As the barrage structure would be largelybenign, and assuming the estuary systems wouldre-establishunderthealteredregimeoverthelonglifetime of a barrage, decommissioning does nothavethesamesignificancethatitmighthavewithsome other electricity generating technologies.Theonlypossibleexceptiontothisisiftheschemeturned out to have more serious environmentalimpacts than anticipated, and it was thereforedecidedthattheestuaryshouldbereturnedto itspreviousstate.However,thefeasibilityofreturningtheestuarytoitspreviousstateisunknown,andtheenvironmental impacts of decommissioning mightthemselvesposesignificantchallenges.

It would be possible to plan for the costs ofdecommissioning by placing a levy on the saleofelectricitywhich,due to the long lifecycleof abarrage,wouldhaveaveryminimalimpactonthecostofelectricity,particularlyifthisweredeferreduntilafteranyinitialcapitalwerepaidback.

However,duetothelonglifecycleofabarrageand the uncertainties over decommissioning, thepragmaticapproachwouldbetoviewanypotentialdevelopment as a permanent addition, and toconsidertheresultingimpactsasirreversible.


Basedonthisoverviewofpredictedchangestothetidalrange,morphologyandsedimentaryprocesses,theeffectsonecology,habitats,birdsandfish,andwater quality are now considered. Many of thehabitats and features of the Severn Estuary aredesignated conservation sites under internationaland UK legislation, and the key designations areoutlinedhere.

An environmental impact assessment (EIA)wouldalsorequirefullconsiderationofarangeofotherpotentialimpactsofaproposeddevelopment,includingthelandscapeandvisualeffectsofaSevernbarragewhicharealsodiscussedbelow.Thefutureevolution of the estuary system having regard topredictedsealevelriseandclimatechangeimpactsisalsoconsidered.

FurtherdetaileddiscussionoftheenvironmentalimpactsandthepolicyframeworkcanbefoundinResearch Report 3. The following discussion alsodrawsonapaperbyPrater67onbehalfoftheRoyalSocietyfortheProtectionofBirds(RSPB),andfromthe SDC’s discussions with the statutory natureconservationagencies–inparticulartheCountrysideCouncil forWales(CCW),NaturalEngland(NE)andtheEnvironmentAgency(EA).

4.6.1 Scope of environmental review

ThisreviewhasfocusedmainlyonthemarineandcoastalenvironmentalimpactsassociatedwiththeShoots and the Cardiff-Weston barrage schemes.Itisclearthatabarragewouldcausemajorchangesinthephysicalandbiologicalmarineenvironment,upstreamanddownstreamofthedevelopment,andthatthesechangeswouldalsoaffectcoastalland.

More information is available for the Cardiff-Westonscheme than for theShootsasa resultofpreviousinvestigations.Manyoftheenvironmentaleffectsoftheschemeswouldbequalitativelysimilarbut there are important differences in scale and,duetotherespectivelocationsofthetwoschemeswithin the estuary, the particular conservationfeaturesthatwouldbeaffected.

Thepotentialenvironmentaleffectsofabarrageon the terrestrial environment have not beenconsidered in any significant detail in this reviewor inpastresearch.The landuseplanningaspectsof the barrage schemes under consideration havenot been developed in detail by the proponents

todate,and thealignmentsof the schemeshavebeenselectedmainlyoneconomicandengineeringcriteria. In addition, the impacts of extracting,producing and transporting construction materials(for example, the extraction of aggregates) havenotbeenconsidered.Alloftheseissueswouldneeddetailedinvestigationifanybarrageproposalweretobeconsideredfurther.

The discussion also focuses mostly on theimplications of the expected changes in thepresenceofabarrage,ratherthantheconstructionand operating impacts of a barrage. Constructionwoulditselfhavesignificantenvironmentalimpacts,directlyfromthephysicalfootprintofthebarrageaswellasnoise,dust,trafficandwaterqualityissueswhich couldaffecthabitats,fishandbirdsaswellaslocalcommunitiesduringconstructionperiodsofseveralyears.Thereasonforfocusingonthepost-construction scenario is that these environmentalimpactsaremorecomplex,long-termand,inmanycases,mightbeirreversible.Thedirecthabitatlossfrom construction would of course be part of theconsiderationoftheimpactsofthedevelopmentonthe integrity of the European site, and the wholeconstruction sequence would need to be fullyconsideredintermsofitsimpacts,withmitigationandmanagementmeasuresputinplace.

WhiletheLaRancebarrageinFranceisagoodexampleoftheengineering,operationandenergyoutputofabarrage,comparisonsinenvironmentaland ecological terms are less helpful, for tworeasons:nobaselineenvironmentaldataexistsfrombeforethebarragewasbuilt,andtheestuariesaredifferenttypes.

4.6.2 Protected status of the Severn Estuary

TheSevernEstuaryandthesurroundingcoastalareasaresubjecttonumerousnationalandinternationaldesignationswhicharedesigned to recogniseandprotecthabitatsandspeciesaswellasfeaturesoflandscape, and of archaeological, geological andhistoric importance.Thisdiscussion focuseson theinternational designations, which are of centralimportance because of the strict legal tests thattheysetuptowhichabarrageproposalwouldneedtocomplyinordertoassess,reduce,justifyandthencompensate for any adverse impacts. Moreover,many of the same features that are protected in

4.6 Environmental impacts


national legislationandpoliciesarealsoprotectedintheinternationaldesignations.

The Severn Estuary is classified as a SpecialProtection Area (SPA) for birds under the EUBirds Directive and, following its submission tothe European Commission (EC) in 2007, is now acandidateSpecialAreaofConservation(cSAC)undertheEUHabitatsDirective.68TheriversWyeandUskarealreadyclassifiedasSACs.TheSPAareaisalsodesignatedasawetlandofinternationalimportanceundertheRamsarTreaty.69

Figure25provides furtherdetailson theareascovered.Thesites,whichtogetherformpartoftheEuropeanNatura2000network(explainedbelow),contain a range of protected species, includingwaterfowl, migratory fish and plants, as well asriver,estuarineandintertidalhabitats,andnaturalfeaturessuchassandbanks.

TheSevernEstuaryandtheadjacentareasalsocontain various sites of special scientific interest(SSSIs)andotherreserveandheritagedesignationswhich are protected under national legislation70– see Figure 26. These designations include areasbehind the existing seawalls such as the GwentLevelsaswellasgeological featuressuchasSullyIsland and Middle Hope. Further details of thesedesignationscanbefoundinTables6.2(1),(2)and(3)ofResearchReport3.

Habitats Directive and Natura 2000

TheHabitatsDirective(92/43/EEC,1992)addressestheconservationofnaturalhabitatsandofwildfloraandfauna.TheDirectiveexpresslyacknowledgesthebroaderobjectiveof sustainabledevelopment, and

Figure24 Natura2000networkofdesignatedsitesacrossbiogeographicregions

The EC Natura2000 network across biogeographical regions

Natura2000 site

Alpine

Anatolian

Arctic

Atlantic

Black sea

Boreal

Continental

Macaronesia

Mediterranian

Pannonian

Steppic

Outside data coverage

Note: Natura2000 data for Cyprus and Malta are not included.

Biogeographicalregions 2005

places the aim of maintaining biodiversity withinthat context. It stipulates that the maintenance ofbiodiversityshouldtakeaccountofeconomic,social,culturalandregionalrequirements,andrecognisesthatincertaincases,themaintenanceofbiodiversitymayrequiretheencouragementofhumanactivities.TheDirectivealsohighlightsthecontinueddeteriorationofnaturalhabitatsandtheincreasingnumberofwildspeciesthatareseriouslythreatened.

Themainmethod for securing thebiodiversityobjective is the creation of a coherent EuropeanecologicalnetworkofSACs:theNatura2000network(article3).Thenetworkis intendedtoensurethatthenaturalhabitatsaremaintained,andifnecessaryrestored,atafavourableconservationstatuswithintheirnaturalrange.TheNatura2000networkalsoincludes SPAs classified under the Birds Directive.At a European level, 18% of Europe’s land areais designated under Natura 2000, illustrating theintentionforselectedsitestobeuniqueorimportantinaEuropeancontext.71IntheUK,designatedsitescoveraroundtwoandahalfmillionhectaresoflandand coastal marine areas in the UK.68 The Severnestuary contains around 20,270ha of intertidalhabitat,around7%ofthetotalintertidalhabitatintheUK.72Figure24showstheextentoftheNatura2000networkasof2005.

The Habitats Directive establishes a processwherebyMember Statesmustproposeadraft listof sites, and the EC then adopts sites identifiedas of Community importance. In the UK, thereare a total 611 designated SACs, cSACs, and SitesofCommunity Interest (SCIs) (whicharesites thathave been adopted by the European Commission,butnotyetformallydesignatedbythegovernmentof each country).73 A further three estuaries, theSevern (as noted above), together with the Dee

andtheHumberestuaries,havebeensubmittedascandidateSACs.

MemberStatesmaytakeonlyaccountofscientificmattersinselectingsitesforsubmissiontotheEC.74Once a site is classified, proposed developmentsthatwouldadverselyaffecttheintegrityofthesitemustbeconsideredthroughtheprocesssetoutinarticle 6(4) of the Directive, as implemented UKlawthroughtheHabitatsRegulations.Thisprocess,which contains a series of ‘tests’ and includes arequirement for compensation to be provided, isoutlinedindetailinSection4.10.4.

Birds Directive

The Birds Directive is a long standing Directive(1979/409/EEC) specifically focused on theconservation of wild birds. Member States musttakemeasurestopreserve,maintainorre-establishhabitat for wild birds, and for certain Annex 1species,takespecialmeasures,includingclassifyingSpecialProtectionAreas(SPAs).

The Directive is less onerous in terms of theprocess for classifying SPAs,which is doneby theMemberStates.ThereisnoprocessforconsideringproposeddevelopmentswithinaSPA.However,theBirdsDirectiveisnowlinkedtotheHabitatsDirective,and SPAs are part of the Natura 2000 network.Furthermore, the Conservation (Natural Habitats&c.) Regulations 1994 apply the same tests thatapplytoaSACtoanyproposeddevelopmentwhichwouldadverselyaffecttheintegrityofaSPA.

The SPA and SACs are considered together inthisreportasbothwouldbesubjecttothetestssetout in theHabitatsDirective. They are referred totogetheras‘theDirectives’.

Box7 SummaryofkeystatutorydesignationsintheSevernEstuary

TheSevernEstuaryareaisrecognisedthroughanumberofinternational,nationalandlocaldesignationsincluding:

• SpecialProtectionArea(SPA)

• RamsarSite

• SpecialAreasofConservation(SAC)andacandidateSAC(cSAC)

• SitesofSpecialScientificInterest(SSSIs)

• NationalNatureReserves

• LocalNatureReserves

• SitesofImportanceforNatureConservation

• EuropeanMarineSite.


Figure25 MapshowinginternationaldesignationsintheSevernEstuary

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff

Ramsar

Special Area of Conservation

Special Protection Area


Defining biodiversity objectives

The Directives seek to protect biodiversity byprotectingcertainhabitatsandspecies.Understandingtheconceptofbiodiversityandhowitfitswithinthisframeworkiscritical.Atagloballevel,biodiversitylosscontinuestooccuratarapidrateduetohumanactivities,andthislossisdegradingtheecosystemservicesthatwerelyonforhumanwellbeinganddevelopment. In the past, Europe’s ecosystemshave suffered more man-induced fragmentationthanthoseofanyothercontinent.TheNatura2000networkofprotectedsitesisoneimportantwayofprotectingbiodiversityatthescaleofbiogeographicregionsacrossEurope.

Biologicaldiversityor‘biodiversity’isthevarietyoflifeonearth–comprisingecosystems,speciesandgenes.TheUNMillenniumEcosystemAssessment75definesbiodiversityas“thevariabilityamonglivingorganisms from all sources, including terrestrial,marine, and other aquatic ecosystems and theecological complexes of which they are a part.

This includes diversity within a species, betweenspecies,andofecosystems.”

The definition is important because it showsthatbiodiversityhasdifferentdimensions.Itisnotsimplyaboutnumbersofdifferenttypesofspecies,or‘speciesrichness’.Neitherisitsimplyameasureof the biological productivity of an ecosystem.Compare, forexample,anArctic tundrawhichhasveryfewspecieswiththeAmazonrainforestwherethenumbersofdifferentplantspeciesnumberinthetensofthousands.Bothareimportantecosystems.

The findings of the UN Millennium EcosystemAssessment,75whichwasinitiatedin2001inorderto assess the consequences of ecosystem changeforhumanwell-being,includethefollowingadvicefordecision-makers,whichisparticularlyaimedatavoidingthese‘conceptualpitfalls’:

“Differentinterpretationsofseveralimportantattributes of the concept of biodiversity canlead toconfusion inunderstandingbothsci-entificfindingsand theirpolicy implications.


Specifically,thevalueofthediversityofgenes,species,orecosystemsperseisoftenconfusedwith thevalueofaparticular componentofthatdiversity.Speciesdiversityinandofitself,forexample,isvaluablebecausethepresenceofavarietyof specieshelps to increase thecapabilityofanecosystem tobe resilient inthefaceofachangingenvironment.”

One of the messages from this work is theimportance of identifying the geographical scalebeing studied, and to recognise that biodiversityreferstodiversityatmultipledifferentscales.Inthecaseof theSevernEstuary, this thinking isbehindthedesignationoffeaturesthatmaybeimportantinthecontextofEuropeanorUK-widebiodiversity.The impact of a Severn barrage on species andhabitatsisconsideredinthefollowingsections,witha summary of the overall impact on biodiversityprovidedinSection4.6.10.

4.6.3 Habitats and ecology

The dynamic environment and large tidal rangeoftheSevernEstuarygiverisetoasetoffeaturesandhabitatsthatare,inanumberofcases,uniqueto the estuary – that is, that are not typical ofestuariesgenerally.EachcomponentofthemarineandcoastalenvironmentneedstobeevaluatedtobuildanoverallpictureofthelikelyenvironmentalimpactsofaSevernbarrage,andResearchReport3providesamoredetailedecologicalassessmentthatconsiders the baseline, predicted future evolutionandpotential impacts for thevarious componentsof the Severn Estuary environment. Here, thediscussionsummarisesandhighlightsthekeyissuessetoutinthatreport.Again,asdiscussedinSection4.5.1above,thisdiscussionisbasedonexistingdataandresearch,andconsiderableuncertaintiesremainastotheecologicalresponseoftheestuary.

The key ecological features in the marineenvironment are the intertidal mudflats andsandflats,saltmarsh,therockyintertidalarea,sand

Figure26 MapshowingnationaldesignationsintheSevernEstuary

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff

Site of special scientific interest

Site of importance for nature conservation

Welsh heritage site


dunes,andsubtidalhabitats.Thesehabitatswouldbedirectlyaffectedbythechangedphysicalregimeunder a barrage, as described above. In addition,a number of transitional coastal habitats such aswetlands,grazingmarshandreedbedsarepresentaround theestuaryabove thehigh tidemarkandbeyondtheexistingseawalls.Thesehabitatswouldbe affected with less frequent inundation and bychanges to land drainage and the water table.The populations of birds and fish within theseenvironments are also a central aspect of theecological picture. Marine mammals are less of aconcernalthoughsomespeciessuchastheharbourporpoiseandgreysealfeedintheBristolChannelandouterSevernEstuary.

Intertidal habitats

The most dramatic and noticeable change tohabitatscomesasaresultofthereducedtidalrange

andnewwaterlevelsinthepost-barragescenario,andthedirectreductionofintertidalareaupstreamofthebarrage.TheSevernEstuaryandBridgwaterBayhaveextensiveareasofintertidalmudflatsandsandflats, estimated at some 23,000ha in total.Figure 27 shows the location of the two barrageschemesinrelationtotheintertidalzone.

Thepredictedchangeinintertidalarealandwardofeachbarrageisalossofapproximately5,530haonaspringtideand3,372haonaneaptidefortheShootsscheme,and14,428haand5,842haof theequivalenttidesfortheCardiff-Westonscheme:seeTable7below.Thischangeispredictedonthebasisofexpectedwaterlevelchangealone.Inreality,thedistribution and extent of the intertidal mudflatsandsandflatswillalsobeinfluencedbythechangesto thesedimentary regimeof theestuary,aswellas other factors including sea level rise and theoperatingregimeofabarrage.

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff

Shoots Barrage


Mud

Mixed rock and shingle

Sand

Figure27 LocationofthetwoSevernbarrageschemesinrelationtotheintertidalzone


Scheme RangeCurrent intertidal area (ha)

Predicted intertidal area

Change in intertidal area (ha)

The ShootsSpring 7275 1745 -5530

Neap 4815 1443 -3372

Cardiff to WestonSpring 18898 4469 -14428

Neap 9881 4039 -5842

Table7 Predictedchangeinextentofintertidalarealandwardofthetwobarrageschemesbasedonpredictedchangesinwaterlevelsalone

In this dynamic environment, sediments arehighlymobileand theextremesofphysical stressmean that the intertidal habitats of the SevernEstuary are characterised by a species-poorassemblageof invertebrates(i.e.alownumberofspecies).However, thisdoesnotnecessarilymeanalowbiomass.Theassembledspeciestendtoexistin large numbers of relatively small individuals.The large tidal range, funnellingprocesses, strongtidalstreams,andhighsuspendedsediment loadscreate difficult conditions for the colonisation ofbenthicspecies(speciesthatliveontheseafloorsuchasinvertebrates).Inthesub-estuariesoftheriversWye,Bristol,AvonandUsk,thebenthicmacrofaunaissimilartothatfoundinthesoftsedimentsofthemainestuarybutinhighernumbers.

Invertebrates and biodiversity

Changes in the physical regime and the intertidalarea would have implications for the invertebratecommunities present in the intertidal area. The1980s studiespointed to invertebrateassociationsintheintertidalareasincreasinginabundanceandinbiomassofspecieswithabarrage.Speciestypicalofhypertidalestuarieswerepredictedtodecreasewhile other species might increase. The sizedistribution of individuals in these species wouldalsotendtoincrease.

Thispredictiongivesrisetooneofthemostcritical– and controversial – questions about the impactthatthesignificantlyreducedintertidalareawouldhave for ecology and birds, and the relationshipbetweenthis reductionandtheexpected increaseinbiologicalproductivity.Thereisbroadagreementthatthesepreliminaryassessmentsareaccurateas

tothedirectionofchangethatwouldbeexpected.However, there are fundamental differences anddisagreementsbetweenexpertsabouttheparticularimplicationsforbirdsandecologyingeneration.

Saltmarsh habitat

The Severn Estuary is an important location forsaltmarsh,aresourcethatisindeclinethroughoutEuropeandtheUK.Figure28showsthelocationofsaltmarshareasinrelationtotheproposedbarrageschemes.

A marked contraction of saltmarsh habitat isalsopredictedinthepresenceofabarrage.Thisisprincipallybecause,withthechangeintidalrangeandduration,existingestuarinesaltmarsheswouldbeinundatedlessfrequently.However,changestothehydrodynamic conditions, sedimentary regimeand morphology of the estuary would also affectthesaltmarsh.

For a Cardiff-Weston alignment, a reductionof around 540ha is predicted and for a Shootsalignment, about 133ha. These figures referonly to the expected reduction upstream of abarrage; reduction might also occur downstream.ThetotalareaofsaltmarsharoundtheestuaryandBridgwater Bay is about 1430ha. Although theexpected reduction is qualitatively similar for aShoots barrage, the actual reduction is of amuchlessermagnitudeduetotherelationshipbetweenthelocationofthesaltmarshesandthebarrage.

As the upper marsh zone becomes morepermanently exposed, it would be colonised bymoreterrestrialvegetation.Thepredictedterrestrialvegetation is expected to include increaseddistribution of Spartina, which is a type of grass


oftenfoundinfreshwaterswampsandsaltmarshes.TheincreasedpresenceofSpartinaontheuppertidalflatsisofconcernforbirds.Inparticular,thisraisesconcernsforoneofthe importantmigratorybirds,the Dunlin because studies in other UK locationshave found a correlation between the spread ofSpartinaanddecreaseinDunlin67.

Lossofsaltmarshesthroughacceleratederosionwouldmean thatevenas thehighwatermark isrestoredwithsealevelriseovertime,itispossiblethatre-establishmentofformersaltmarsheswouldnotbepossibleexceptoveraverylongtimeperiod(centuriestomillennia).76

Subtidal habitats

The muddy and sandy subtidal habitats wouldincreaseinareaasaresultofthedecreasedintertidalarea. The change in physical regime would affectparticularspeciesofhoneycombworm,Sabellaria,whichformsreefsandisaprotectedfeatureofthe

estuary. Subtidal sandbankswouldalso changeastheresultofthemorphological,hydrodynamicandsedimentarychangesdiscussedaboveatparagraphs4.5.3and4.5.4.

Rocks and shingles

In addition to the main mud and sandflats ofthe intertidal area, some rocky intertidal areaswould also become subtidal under a barrage,and some geological features including wave cutplatformswhichrelyoncontinuederosionfortheirmaintenancewouldbelost.

Themainshinglehabitatsintheestuaryarethelow shingle ridges in Bridgwater Bay. Changes tothesedimentregimeandphysicalprocesseswithintheestuaryhavethepotentialtoaffecttheshinglehabitatswithintheestuary.

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff

Salt Marsh

Figure28 Saltmarshareasinrelationtotheproposedbarrageschemes


Transitional habitats

Transitional habitats around the Severn Estuaryincludegrazingmarsh,reedbeds,saltings,drainagechannels, wetlands, grassland and woodlands,rivers and standing open waters, and agriculturalland and urban areas. As with the saltmarsh,theseareaswouldbeexpectedtoexperience lessfrequentinundation.Thechangeswouldaffectthecompositionand structureof thehabitatsand thespecies theysupport.Theoverallpicture for thesehabitats would need to be investigated in moredetailtounderstandtheimplicationsofchangestowater levels, land drainage, and the water table.Forexample,theexpectedincreaseinwaterlevelswould be generally expected to have a positiveeffect on freshwater wetland habitats. The earlystudiesalsoindicatedthatreedbedsmightdevelopextensivelyattheheadoftheestuaryinareasthatarepresentlyintertidal.

Plankton and marine algae

Thereislittlequantitativeorqualitativeinformationavailableontheplantcommunitiesofphytoplankton,microalgae,macroalgae,intertidalplantsordetritus.In the presence of a barrage, the early studiesindicated that there would be a general increaseinspeciesdiversity,standingcropandproductivityof these plant communities as result of reducedturbidity and greater substrate stability. However,theoverallconclusionwasthatasubstantialchangeintheproductivityoftheestuarywasnotpredicted.This is in contrast to thepredictions in relation toinvertebratesdiscussedabove.

4.6.4 Water quality

Water quality standards are set by UK legislation,although in many cases are determined by EUDirectives or international conventions that havebeen implemented via UK regulations. The mostimportantoftheseistheWaterFrameworkDirective,whichcameintoforcein2000,andrequiresallinlandandcoastalwaterstoachieve‘goodstatus’by2015.TheEnvironmentAgencyistheprimaryregulatorofwaterquality,andhasresponsibilityforthelicensing,monitoringandenforcementofsewageandindustrialwastedischarges.ItisalsoresponsibleformonitoringdesignatedbathingwatersinlinewiththeECBathing

WaterDirective(1976).Waterquality itself is dependentonanumber

of variables, including point source discharges ofsewageand industrialeffluent,diffuseagriculturalrun-off,highwaydrainage, spillage from industrialpremises and marine vessels, and contaminantsin rivers. The Severn Estuary is currently classifiedunder the National Water Council classificationsystem as good quality in the upper estuary andfairquality in themiddleand lowerestuary–seeFigure 29. The evidence suggests there has beena continual improvement in water quality for themajorcontaminants.Thehighsuspectedsedimentload in the estuary means that algal productivityis low, and eutrophication is not seen as a majorthreat.

The physical implications of a barrage oncurrents,water depths, and turbiditywill all haveimplications for water quality. Unfortunately,available assessments are based on limited dataandwerepreliminarystudiesundertakensometimeago, and prior to the Water Framework Directive.For the Cardiff-Weston scheme, a few preliminaryconclusionsareavailableasfollows:

• Abarragewouldreducethedispersionofseawateruptheestuaryandtheabsorptionofoxygen,whichwouldleadtothefreshwater/seawaterinterfacemovingseawardby5-30km,dependingonriverflow

• Theconcentrationsofconservativepollutants(thatremainchemicallyunchangedinthewater)suchasnickelandcadmiumcouldatworstdouble

• Concentrationsofother,non-conservativepollutantsbehindthebarragewerenotpredictedtochangesignificantly.Similarly,thenumberofbacterianearsewageoutfallsispredictednottochangesignificantly

• Theoxygenstatuswaspredictedtobelargelyunaffectedbythereducedtidalmixingandthesystemwouldtendtobecapableofretainingmoreoxygenbecauseofthereducedsalinity

• Thesuspendedsedimentconcentrationscharacterisingthewatercolumn,landwardofthebarragearepredictedtoreducetothosetypicalofotherhightideestuaries


• Itispredictedunlikelythateutrophicconditionswouldresult,althoughthereissomedisputeoverthisfinding.

For the Shoots scheme, variations on theaboveconclusions includeareduction incadmiumupstream of a barrage (due to the major sourcesbeingdownstreamoftheproposedlocation),butapossiblyinferiorsituationwithrespecttoammonia,BOD(biologicaloxygendemand),dissolvedoxygenandsomemetalcontaminantsincludingnickelandcopper.

Notwithstanding these initial predictions, andagreement that sediment levels would decreasesignificantly, water quality remains an area ofuncertainty.Theimpactonwaterqualityofabarrage,andeventhequestionofwhethertherewouldbean overall improvement or deterioration in waterquality is highly contested. An issue that wouldrequire further investigation based on updated

predictions would be how the Water FrameworkDirectivewouldapply.

4.6.5 Birds

TheSevernEstuaryisrecognisedasaninternationallyimportant estuary for birds, and international andnationaldesignationsprotectanumberofbirdspeciesandtheirhabitats.Fivespeciesareofinternationalimportance and nine or ten are of nationalimportance.Intotaltheestuaryhasanassemblageofsome65,000waterbirds.Anassemblageofbirdsis a measure of the abundance of birds using asite.ThethresholdforaninternationallysignificantassemblageofwaterbirdsundertheBirdsDirectiveis20,000.

The sitewas classified as a SPA based on theperiod1988-1993; thespeciesaffectedareshownin Table8.Birdnumbersare countedusingafive

Figure29 SevernEstuarywaterqualityandstatutorymonitoringsites51

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff

Class A National Water Classification

Class B National Water Classification

Dangerous substance directive

Bathing waters directiveDirective limits passed everyyear over the last four years

Bathing waters directiveFailure to meet directiveonce in the last four years

North Sea Conference Annex 1a



year mean peak average (to avoid exceptionalcounts affecting the assessment of importance).Sinceclassification,birdnumbershavechangedandworkbytheRSPBprovidesagoodoverviewofthenumbers, relative importance internationally andnationally,andhowspeciesnumbershavechanged

since the SPA classification67. An environmentalassessment of a barrage scheme would needto provide a more complete baseline picture ofbird numbers and patterns of use in the estuary.Thetablebelowshowsthekeybirdspeciesandtheassemblageofbirds.

Table8 BirdspeciespresentedintheSPAcitation(withnumbersinbrackets)67 Source: RSPB

Citation category

Species qualifying at citation (average numbers between 19��-93 in brackets)

Species qualifying 2000-2005 (average numbers between 2000-05 in brackets)

Internationally important populations of regularly

occurring Annex 1 species

Bewick’sSwan(289) Bewick’sSwanisjustbelowthe‘international’threshold(276)

Internationally important populations of regularly

occurring migratory bird species

Shelduck(2,892)

Dunlin(41.683)

Redshank(2,013)

EuropeanWhite-frontedGoose(3,002)

Shelduck(3.272)

Dunlin(23,312)

Redshank(2,566)

Teal(4,450)

Pintail(758)

An internationally important assemblage of waterfowl

Qualifies Qualifies

Nationally important bird populations within

internationally important assemblage of waterfowl

Wigeon(3,977)

Teal(1,998)

Pintail(523)

Pochard(1,686)

TuftedDuck(913)

RingedPlover(winter)(227)

GreyPlover(791)

Curlew(3,096)

Whimbrel(246)

SpottedRedshank(3)

Bewick’sSwan(276)

EuropeanWhite-fronted

Goose(942)

Wigeon(8,062)

Shoveler

Pochard(880)

RingedPlover(passage)(665)

Curlew(2,545)

Black-tailedGodwit

Whimbrel(passage)(222)

SpottedRedshank(10)

Existing bird population status

Two species have declined substantially in recentyears: theDunlin and the EuropeanWhite-frontedGoose.Thisdeclineisprobablyasaresultofclimatechange,andreflectsatrendforothersitesinWalesandsouthwesternEnglandwherewarmerwintersmeanthatbirdshavebeenremaininginmoreeasternareas.RingedPloverhasalsodecreased,probablyfor the same reason. Grey Plover has decreased

although the reasons are not clear. Decreases inPochard and Tufted Duck have also occurred butfor different, local reasons (possibly in responsetoimprovedlocalwaterqualityorchangesinfoodsupply).Otherspecieshaveincreasedconsiderablyoverthistime.Forexample,severalducks(Pintail,Shoveler,Teal,Widgeon)aswellasRedshankandBlack-tailed Godwits. Pintail and Teal are now atinternationallyimportantnumbersintheSevern.


Overall, if the estuary were classified as aSPA today individual species and total numberswould still be of international importance. Theestuary isusedasa feedingground, roostingandloafingsiteandsupportshighnumbersofbirdsontheir migratory passage. The intertidal area is ofparticular importance, althoughusage of the areaisnotdistributedevenly.So,forexample,countsinthe winter of 1987-1988 found that 50% of birdswerefeedingon just13siteswhichcover12%ofthetotalintertidalarea,andsixofthesesitesweredownstreamofthetwobarragelines,inBridgwaterBayandParrettEstuary.Thenext40%ofbirdswereatanother43sites.Mostbirdsroostnearthefeedingareasontheupperintertidalareabelowsaltmarshand,duringhighspringtides,intheuppersaltmarshorinfieldsaroundtheestuary.

IntertidalareasupstreamoftheShootsbarragelocationaregenerallyutilisedlessbyoverwinteringbirds.However,theintertidal,saltmarshandcoastalgrazingmarshareas in theupperestuary (aroundSlimbridge)arealsoareasutilisedbytheBewick’sSwan,whichcanoccuratinternationallyimportantnumbers and is listed in Annex 1 of the BirdsDirective.

Impact of a barrage

A number of studies have attempted to modelandpredict thepotential impactsof abarrageonbird populations. However, as has been discussedabove, predictions depend upon the physical andecological response of the estuary. The two keyfactors are the reduced intertidal area,where thebirds’preyresourceisfound,andareductioninthetimeavailabletofeed.

Oneofthekeyissuesiswhethertheincreasedproductivity of the estuary might offset some ofthe lossof intertidalarea. Thisprediction ismadeby Kirby.77,78 However, these predictions remainverycontroversialanduncertainintheabsenceofagreaterunderstandingofbasicphysical,hydrologicalandoperationalinformationandadvancedmodellingofmorphologicalchangeonwhichtobaseaccuratepredictions.67,79

Analysisaspartofthe1980sstudiesconcludedthatpreydensityand sizewere thekeyvariablesrather than foraging time, and even assuming a50% loss of feeding area, predicted increases inpreydensitywerefoundtobeoftheorderfoundinotherestuaries.80However,theexpectedincreasein

birddensities(asaresultofincreasedpreydensity)didnotapplyforsomespeciessuchasDunlinandpossibly Shelduck – meaning the makeup of birdpopulationswouldchange.

Theseconclusionscanbeseenasabroadindicatorbasedonconsiderationoftheexistingmudflatsandsandflatsunderthedifferentwaterlevels.Theactualimpactswoulddependonotherphysicalchangestomorphologyupstreamanddownstreamofabarrageaswell asbirdbehaviour in response to changes.Actual impactswouldvaryspeciesbyspecies,butwith interactions between different species ofbirds.Somebirdsmightusethereducedintertidalareainhigherdensities;othersmightmovetolessfavourable areas with less food sources. A rangeofotherparameterssuchas implicationsfromthespreadofSpartina,anddisturbanceeffectsonbirdsofsignificantinfrastructureworkswouldalsoneedtobeconsidered.Accordingly,theoverallpictureisverycomplex.

In relation to a Shoots barrage, the loss ofintertidalareawouldbeconsiderably lessandtheresultingimpactonbirdswouldbesignificantlylessthanforaCardiff-Westonscheme.Manykeyareasof bird usage are seaward of the Shoots barrageline. Dunlin, for example, is rarely found abovethis line so the impact on this species would beminimal.Again,amoredetailedassessmentwouldberequired.

4.6.6 Fish

The Severn Estuary supports a range of migratoryandmarine fish species. Themigratory species ofparticular concern are salmon, twaite, allis shad,seaandriverlamprey,eelandseatrout,whicharedesignated features of the estuary under the EUDirectives.

Theestuaryalsoprovidesfeeding,spawningandnursery grounds for a number of marine species.Forexample,flounders,bass,whiting,sprat,mullet,pollackandsolearefoundinconsiderablenumbersashighuptheestuaryasOldbury.

Abarragewouldaffectfishinanumberofways:principallyasaresultofitbeingaphysicalbarrierintheestuary,andbecauseofpotentialchangestowaterqualityincludingdissolvedoxygen,turbidity,andcontaminants.However,arangeofotherfactorswould also come into play – increases in prey onjuvenilesbybirdsandfish,changeinpreyresources,changes to spawning and feeding grounds, as


wellasdelays tomigrationandthemovementofsmolt(spawn)andtheidentificationofnatalrivers.Furthermore, fish would be sensitive to barrageconstruction,inparticularnoiseandwaterquality.

Forthebarragestructureitself,theissuesareitsphysical presence (the potential to delay or blockmigrationsroutes),thesafetyoffishpassingthroughturbines, and the possible mitigation measure offishpasses.Allthesefactorswillvarydependingonthetypeandageofthefish.

Theeffectsonfishareverymuchinfluencedbythe location of a barrage within the estuary. TheShoots barrage, higher up the estuary, would not‘block’theRiverUsk(aSACinitsownright)andsothe impacts forfish(especiallyshad, lampreyandsalmon)wouldbedirectlyreducedandtheoverallreductionofleavingoneofthekeyprotectedrivers‘open’couldbematerial.

Inrelationtopassagethroughturbines,a2001studycitedinResearchReport3involvedsimulationsusingspecificallytheturbineproposedbySTPGfortheCardiff-Westonbarrageandthispredictedinjuryrates for species including salmon (adult – 40%;smolt–10%),eel(28%)andshad(juvenile–53%)withvaryinginjuryrates(asindicatedinbrackets).However, the Environment Agency’s view is thatsalmon, sea trout and shad in particular, wouldpotentially face high to very high mortality rates.Actual injury rates would be sensitive to preciseturbinedesigns,rotationspeeds,fishpasssizeandlocationandpatternsofgeneration.

Largefishpasses,possiblyofdifferenttypestotargetdifferentspecies,wouldbeneededtotrytomitigatethepresenceofabarragebyprovidinganalternativerouteforsomefish.Furtherworkwouldberequiredtoconsideroptionsforfishpasses.

Furtherdetailedstudieswouldberequiredofthepossibleimpactsonspecies,especiallythosewhichare designated or of commercial or recreationalimportance. The implications of changes in waterquality and the sensitivity of different species tochangewouldalsoneedtobeconsidered.

International experience with fish passage atother barrages varies. The pilot barrage schemeintheBayofFundyresultedinaveryhighimpacton migratory fisheries. The barrage at La Rancehasbeendescribedashavinghadminimalimpacton migratory fish species, although other reportssuggest that the barrage has had an impact onmigratory species suchasTrout.ASevernbarragewould use turbines more closely resembling theRancebarrageintermsofthisaspectofoperation,

so theveryhighmortality ratesexperiencedwithturbines at Bay of Fundy would not be expected.Nonetheless,theadverseimpactonfishpopulationscould still be very significant, depending on thesuccessofmitigationmeasures.

4.6.7 Landscape and visual

AreportrecentlycommissionedbyNaturalEngland81hasconsideredtheeffectsof theconstructionandoperationoftheCardiff-Westonbarrageonarangeof landscapes and views. The landscape featuresconsideredwereprincipally locatedontheEnglishsideoftheSeverninaccordancewiththeagency’sremit, although the ‘zones of visual influence’identified cover the whole of the estuary andsurrounding areas. Figure 30 predicts the zone ofvisualinfluenceupto50kmfromtheCardiff-Westonschemewhennoroadlinkisincluded.

TheconclusionofthereportwasthataSevernbarrage at the Cardiff-Weston location wouldpotentially have a significant effect on someaspects of the landscape and seascape character,national landscape designations, and views.Both the physical presence of a barrage and thephysical changes to water levels and morphologywould affect the landscape. In addition to directimpacts, the infrastructure associated with abarrage could have a range of indirect effects; inparticular, road linksandnewpower linesaswellas possible new coastal development. The reportincludes suggestions for minimising or mitigatingtheimpacts,andenhancingthelandscapethroughlocation,layoutanddesign.

Goingforward,therewouldneedtobeagoodunderstandingofpublicperceptionsoftheexistinglandscape and seascape, and attitudes towards anewbuiltstructurelikeabarrage.Thiswouldneedtobeconsideredinanyfuturedesignworkandforacomprehensiveassessmenttobemadebefore,andas part of, an Environmental Impact Assessment.Accurateandrealisticvisualsimulationimages(staticorvideo)areimportantforpeople’sunderstandingof aproposal; theexisting imagesare verydatedand do not usemodern techniques or reflect theexisting landscape and seascape including, forexample, thesecondSeverncrossing.This typeofassessmentshouldbeaprioritytoinformpublicandstakeholder debate and engagement if a Severnbarrageweretobetakenforward.


4.6.� Climate change and the Severn

The Severn Estuary is not a static system, andpredictionsfortheevolutionofthebaselineestuaryenvironmentneedtobeconsideredinthelightofsealevelriseandclimatechange.ResearchReport3drawsonrecentworkbytheEnvironmentAgency82

to develop a coastal habitat management plan(CHaMP) for theSevern. There is also someotherresearch considering the implications of climatechange for the estuary although this is relativelylimitedandadevelopingareaofresearch.83

The Severn CHaMP confirms that the estuaryis changing and predicts that the change will

continue,lookingattimeframesof20,50and100years. Sea level rise will create ‘coastal squeeze’and eventually, some loss of intertidal habitat.Thegreatestpercentagechangeisexpectedtobeinsaltmarsh.In2025,changesintheupstreamareasoftheSevernestuarywillbeapparent,andby2055,achangeintheoverallestuarybedprofilecanbeexpected.By2105,thisislikelytobefurtherchangetotheprofileoftheestuarybedwithanoverallnetloss to the intertidal area. Theestimated changescomparedtothecurrentsituationarepresentedinthetablebelow.

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff

Figure30 Zoneofvisualinfluenceupto50kmfromtheproposedCardiff-Westonbarrage(witharoadlink)81

Source: Land Use Consultants


Total Estuary Change(Ascomparedto2005)

Estimate of Area in 2005(ha)(GISestimate)

20 year%change

50 year%change

100 year%change

Intertidal Area 22,500 -7 -7 -11

Intertidal mudflat and sandflat

20,000 -6 -5 -9

Saltmarsh 1,600 -13 -41 -38

Transitional grassland 1,600 +13 +6 +6

Subtidal 46,000 +3 +3 +5

Table9 Severnestuaryhabitatchangesasaresultofclimatechange

The predictions of the CHaMP will be used toinformdecisionsoncoastalfloodriskmanagement,and will inform the shoreline management planfor the Severn Estuary. The aim is to ensure thatpotential habitat loss is taken into account indecisionsoncoastaldefenceworks(maintenanceofexistingworksandconstructionofnewworks)inawaythatprotectstheintegrityoftheNatura2000networkandRamsarsites.84

In relation to birds, Prater67 indicates thatdecreases in Severn Estuary bird numbers forseveral important species (Dunlin, Ringed PloverandEuropeanWhiteFrontedGoose)areattributabletowarmerwinters–thetrendhasbeenforashifttoeasternestuaries (small species suchasDunlinwouldhavebeendisadvantagedbyasmallerbodyweightincoldereasterntemperaturesinthepast).However,thistrendcouldbereversedovertime(ashabitatavailabilityandconditionschange inotherareas),andwesternestuariescouldreceivehighernumbersinthefuture.ThispointstothepositionoftheSevernwithin thewidernetworkofprotectedsitesandaspartoftheEastAtlanticFlyway.

TherewillbewinnersandlosersamongthebirdsintheSevernEstuaryfromclimatechange.Sealevelrisewillhaveanimpactontheestuarybutitisnotclear that the levels of sea level rise and habitatloss predicted until the end of the century willhaveamajornegative impacton the currentbirdinterestofthesite.67EvenbirdspeciesintheSevernthat drop below the thresholds for internationalsignificanceareexpectedtoremainimportantinaUKcontext.Fish(inparticularsalmon),willalsobeaffectedbyclimatechange,butagainthedirection

ofchange(positiveornegative)dependsonarangeoffactorsandvariesunderdifferentclimatechangescenarios.

Overall, the picture is complex and involves anumber of interacting factors related to sea levelriseandanincreaseinaveragetemperaturesundervarious scenarios. Different habitats and speciesmay respond differently to both factors at a UKand international scale over the medium to long-term,meaningthattherelativeimportanceofasitewillvary fordifferentspeciesover time.However,theestuary,andconservationsitesingeneral,willremain important forhabitatsandspeciesas theyadapttoclimatechange.

4.6.9 Impact of a barrage on protected features

The first stage in applying the Directives is thatan ‘appropriate assessment’ must be made.An appropriate assessment for a scheme at thescaleofaSevernbarragewouldrequireextensivefurther studies and analysis. The following givesan indicativeassessmentof thepredicted impactsontheconservationfeatures.Thisoverviewshowsthatfeatureswouldbeaffectedtovariousdegreesby both of the two schemes under consideration.However, the scale of the different schemes, andhencetheimpacts,shouldalsobekeptinmind.

The conclusion of this preliminary assessmentis that either barrage would have significantimplications for the integrity of the sites. ThismeansthatthetestsinArticle6(4)oftheHabitats

Table10 AssessmentofimpactondesignatedSPAandpSACfeaturesfrombothbarrageschemes

Receptor Cardiff-Weston Scheme Shoots Scheme

SPAFeatures

•Annex1species–Bewick’sswan

•Overwinteringassemblageofwaterfowl

•Intertidalmudflatsandsandflats

•Saltmarsh

•Intertidalrockandshingle

•Nospecificassessmentavailable–possibleimpactstopopulation

•Speciesspecificassessmentsgenerallylacking;broadoverviewstudiessuggestthatoverallpopulationsmayberelativelyunaffected

•Potentiallossofuptoc.14,500haofintertidalhabitat

•Unquantifiedbutsubstantiallossofexisting539haresource

•Unquantifiedlossofintertidalrockandshingle

•Nospecificassessmentavailable–possibleimpactstopopulation

•Nospecificassessmentavailable;limitedimpactlikelybasedonexistinginformationonbirddistributions



•Unquantifiedlossofintertidalrockandshingle

cSACFeatures

•Atlanticsaltmeadows/saltmarsh

•Estuary

•Mudflatsandsandflats

•Reefs(Sabellaria)

•Subtidalsandbanks

•Fish(allisandtwaiteshad)

•Fish(riverandsealamprey)


•Reductionintidalrangeandflowsu/sbarrage;smalllocalreductionintidalranged/sofbarrage


•Unquantified,butsignificant

•Unquantifiedchange

•Veryhighriskofveryhighmortality.Potentialstockeradication.

•Mediumriskofhighmortality


•Reductionintidalrangeandflowsu/sofbarrage;smalllocalreductionintidalranged/sofbarrage


•Unquantifiedbutminor

•Unquantifiedchange

•Veryhighriskofveryhighmortality.Potentialstockeradication.


RiverUskSACFeatures



•Fish(atlanticsalmon)

•Veryhighriskofveryhighmortality.Potentialstockeradication


•Highriskofhighmortality

•Lowriskofimpact

•Lowriskofimpact

•Lowriskofimpact

RiverWyeSACFeatures



•Fish(atlanticsalmon)








Directive must be applied.85 In effect, given themajorchangesthatabarragewouldbringandthenatureconservationimportanceoftheestuary,anybarragedevelopmentmustmakeaverystrongcasetojustifyoverridingthepresumptionofprotection.Thetests–noalternativesolutionsandimperativereasonsofoverridingpublicinterest–aswellastherequirementtosecurecompensatorymeasuresareconsideredinSection4.10.4aspartofthediscussiononprocessandgoodgovernance.

4.6.10 Biodiversity impact of a Severn barrage

TheSevernisnotableinthatithasalownumberofspecies,relativetootherestuaries.Infact,theAtlanticregionasawholehas lower levelsofbiodiversityinpurespeciesnumbersthanotherregionswithinEurope–butitmakesupforthisintermsofanimalabundance.86Similarly, intheSevern,thediversityandabundanceofspeciesfoundwithintheestuarymayseemtoberelativelypoorincomparisonwithotherestuaries.But theSevernestuaryhostsverylarge numbers of individuals because of its sheersize,andalsoplaysanimportantroleaspartoftheoverallnetworkofestuariesinGreatBritainandinthe Atlantic biogeographic region of which it is apart(seeFigure29).

Moreover, the species in the Severn Estuaryoccur in different ways than in other estuaries;

theinvertebratesareanunusualmixandtheyaregenerally smaller than their counterparts in otherestuaries but occur in larger numbers. Therefore,from a biodiversity perspective, any changes tothediversityof theSevernEstuarywouldneed tobe assessed both in terms of their impact on theestuary itself, but also in terms of the impact onnationalandinternationalbiodiversity.

On a geographical scale, the species that usetheestuary–especiallymigratorybirdsandfish–fitintothewiderbiogeographicregionandsoitwouldbeimportanttoconsider implicationsofabarrageforthesepopulationswithinthiswidercontext–forexample,theEastAtlanticFlywayforwadersandtheAtlanticforsalmon,troutandotherfishspecies.

The initial predictions give a strong indicationthat large-scalebarragedevelopmentwouldhavean irreversible effect on some protected features,reduce the area of certain habitat types (mostnotably the intertidal area), and that therewouldbealossofexistingbiodiversity.Anincreaseintheproductivityoftheestuaryasaresultofabarragemay not, in the latter case, be seen as desirableif thiswere to replaceunique featureswith thosethat can be found in other ecosystems. There isalso significant uncertainty based on availableinformation of whether increased productivity inthe estuary would translate into increased birdnumbers.

This section reviews the available information onthe impacts that a Severn barrage would haveon the economy and society at a regional level.Unfortunately, the available information is out ofdate,andinsomecasesincomplete,asthedetailedstudiesdone in this areamainlydateback to the1980s,withsomeupdatesfromSTPG’s2002report,assummarisedinResearchReport3.

These significant limitations make it difficultto draw definitive conclusions on a number ofkey issues. Further work, including new primaryresearch,wouldbeneededtoaddressthesegaps.A full sustainability appraisal of the regional andlocal impacts would provide a framework forenhancing positive impacts and for mitigatingnegative impacts. In particular, the impact on the

region’sportsisidentifiedasasignificantissuethatwouldneedfurtherdetailedconsideration.

4.7.1 Ports and navigation

The Severn Estuary is home to four commercialports: Bristol, Cardiff, Newport, and Sharpness/Gloucester.Ofthese,onlySharpness(whichprovidesaccesstoGloucesterviaacanal)isupstreamoftheboth proposed barrage locations, along with theheritageharbourfacilitiesatChepstowandLydney.Theestuary’smajorportoperations–theBristolPortCompanyfacilities(whichcompriseAvonmouthandRoyal Portbury docks) and the Associated BritishPorts (ABP) facilities at Cardiff andNewport – are

4.7 Economy and society at a regional level


located upstream of the Cardiff-Weston locationbut downstreamof the Shoots location. The portsofBarryandBridgwaterarelocateddownstreamofbothbarragelocationsintheInnerBristolChannel.

Theportsandtheservicestheysupportareanimportantpartof the localand regionaleconomy,andareresponsibleforhandlingaround3%ofUKtrade(17.2milliontonnesoffreightin2004).Itisestimated that the Bristol and south Wales portsgenerate over 15,000 jobs between them, withmanymorejobsheldinport-basedcompanies.WiththeircloseproximitytocentresofpopulationintheWest Midlands, and good strategic transport linksthroughroadandrail, theports in thisareamakeanimportantcontributiontotheregionandareinmanycasessuccessfulbusinessesintheirownright.TheSevernEstuaryisalsousedbyfishingandleisureinterests, whose needs may be very different tolargecommercialusers.

In the case of Bristol port, there are existingproposals for a major expansion of the portsfacilitiesattheRoyalPortburysiteinordertoprovideincreased capacity for deep-sea container ships,whichareexpectedtobeanimportantcomponentoffuturegrowthintheshippingindustry.Thenewfacilities would have berths for four ultra largecontainer ships (often termed ‘post-Panamax’) ofupto16mdraughttoaccommodatethesevesselswhentheyenterservice.

A number of stakeholders from the marineand ports sectors have expressed concernsthat navigational requirements are sometimesoverlookedwhenmarineinfrastructureprojectsarecarried out, and in the case of a Severn barrage,that the potential impacts on the region’s portshavepreviouslybeendownplayedasanissue.ThemessageconsistentlypassedtotheSDCwasoftheneedforearlyengagementandconsultationsothatanyconflictscanbemitigated,andsafetyensured.

TheMarineBillpublishedbytheUKGovernmentshouldhelptoachieveamoreintegratedapproachtotheplanningofmarinedevelopments.

Impact of a barrage

A barrage in the Severn Estuary will create aphysical barrier to ship movements, requiring theinstallationofoneormorelocksinordertofacilitatepassage between the two different water levels.The operation of locks will inevitably have animpactonshipmovements throughanydelaysor

restrictions on capacity, as well as adding a costpenaltyasaresultofthetimetakentopassthroughthe locks. The design of locks is also an issue, ascurrentdesignsassumeamaximumshipsizethatwould be too small for the very large containershipsthatmightdockatBristolinthefuture.

No detailed studies have been carried out onshipmovements inrelationtobarrageoperations,andthisremainsasagapintheevidencebasethatwouldrequirefurtherworkaspartofcomprehensiveimpacts assessment. For example, earlier studieson the proposed Mersey Barrage (see Section 3)includedadetailedassessmentofshipmovementsand the likely economic impact of a barrage.In relation to construction, previous studies haveassumed that navigation would be maintainedthroughout theconstructionperiod,with the lockscompletedpriortobarrageclosure.

Changes to the tidal range as a result of abarrage could have mixed consequences forshipping,particularlyupstream.The raisingof lowtidewaterlevelscouldpotentiallybebeneficialforthenavigationofshallowdraughtedvesselsasanincreased period of time would be available fortransitintheestuary.However,thereductioninhightide water levels could have serious implicationsfor the navigation of large vessels upstream of abarrage,asthiswouldreducetheamountoftimeand/or capacity for transit. Thiswouldexacerbatethe current constraints at Sharpness,whichwouldbe upstream of both barrage proposals and canonly be accessed by large vessels (6,500dwt) onthespringtides.TheCardiff-Westonschemewouldalso have an impact on the ability of very largecontainershipstoaccessanexpandedBristolport,thusjeopardisingthisplanneddevelopment.

Changestotheseabedgeomorphologyandthesedimentregime(asdescribedinSection4.5)couldhave a direct impact on navigation in the wholeestuarythroughchangestothelocationofexistingfeaturessuchasdeepchannels,andthepossibilityof much greater siltation. A direct impact wouldbe greater requirements for dredging, an activitythatmayinfuturebemoretightlycontrollediftheestuaryisapprovedforSACstatusundertheHabitatsDirective.Itisimportanttonotethatthisisanotherareathatremainscontroversial,andmoredetailedstudieswouldberequiredtobettermodelthelikelyeffectsofabarragescheme.


Implications and mitigation measures

Therecouldbesignificantadverseeconomicimpactsonaparticularport,orsetofports,asaresultofaSevernbarrageduetoapotentialdisplacementofportactivityoralimitoncertainformsofexpansion.Thereisapointatwhichthedelaysandinconvenienceof having to pass through locks would affect theattractivenessandcompetitivenessofaport inaninternational market and therefore potentially toaffectthelongtermviabilityofoneormoreoftheports in the estuary. This could result in a loss oftradeandinvestmentfortheregionaleconomyandthepotentialforincreasedcarbonemissions,habitatloss,andotherenvironmentimpactsasaresultofportrelocationorfromatransferoftraffictoother(possiblylessoptimal)locations.

Mitigation measures might include increasingthe size and number of ship locks, and requiringsomedegreeofflexibilitytotheoperationalregimeofabarragetoaccommodateshippingtraffic.Thesetwomeasurescouldhaveanegativeimpactontheconstructioncost,orpotentialoutputofabarrage,which would need to be balanced against thelong-termbenefits.With regard to sedimentation,dredginghasalreadybeenidentifiedasapossiblesolution, but one that has its own negativeimplications, including a potential carbon cost asa result of increased activity. A reappraisal reportproducedbySTPGin2002indicatedthatanewportdownstream might be required to offset for theimpact on ports upstream of a barrage. However,thiswouldpresentawholeseriesofenvironmental,socialandeconomicissues,andwouldneedtobeconsideredfromastrategiclevel.

4.7.2 Transport links

Manyof theproponentsofabarragepoint to thepotentialfornewtransportlinks–eitherroadorrail– runningon topof thebarrageand thus gainingadditionalvaluefromthestructure.Theseproposalswere raised during our public engagementprogramme, and there was strong interest in thepotential for additional transport links, althoughsome concerns over the possible impacts ofimproved access and associated development onexistingcommunities.

The prospect of new transport links raises anumberofkeyquestions,whichcanbesummarisedasfollows:

• Isthereanidentifiedneedfornewtransportlinksateitherofthetwoprimarylocations?

• Consideringtheneedsofshipspassingthroughtheshiplocks,howwouldaroadorraillinkbeengineeredintoafully-functioningbarrageandwhichtrafficwouldgetpriority?

• Whatarethepossibleimpactsonlocalcommunitiesandtheenvironmentofbuildingnewtransportlinks?

• Wouldpublicsupportforabarragebeanydifferentifforsomereasontransportlinkswerenotaviableoption?

Identified need

TheSDChasnotbeenconvincedthat there isanyidentified need for a new road link either at theCardiff-Weston or the Shoots location, the latternowhaving two road crossings already. There areno existing plans that propose a further Severnroadcrossing,andinthecaseoftheCardiff-Westonbarrage it is not clear that the volumes of trafficthataroadlinkwoulddisplacewouldjustifysuchaproject.However,thisviewcontrastswiththeresultsof our public engagement work, where a roadcrossingattheCardiff-Westonalignmentwasfelttooffersignificantjobandleisureopportunities.

The most promising proposal seems to be forahigh-speed rail crossing runningoverabarrage.TheexistingSevernTunnelwascompletedin1885andprovidesasingle-trackrailconnectionbetweenBristolandCardiff.AccordingtoNetworkRail,87theSevernTunnelisaseriousconstraintonenhancingservices to and from south Wales, which includepassenger and freight traffic. Some stakeholdersarealsoconcernedatthelong-termviabilityofthisstrategicasset,whichisofcrucialimportancetotheeconomyofWales.

Neither road nor rail options have been fullyassessedand costed inpreviousassessmentsof aSevernbarrage,so there is limited informationonwhattheadditionalcostmightbe.Althougharailcrossingcouldbeaddedtoeitherbarrageschemeunder consideration, the most logical (and leastlengthy)optionwouldbeacrossingovertheShootsproposal,asthiswouldfollowtheexistingalignmentof theSevernTunnel,allowingeasyconnection toexistinginfrastructure.ArailcrossingontheCardiff-


Westonschemewouldalsobeabletolinkintothenationalrailsystem,butwouldrequiremuchmorenewtrackandanumberofnewconnections,thusincreasingthecost.

Engineering uncertainties

In addition to limited information on cost, thereseems tobea lackof informationonhowa roador rail crossing would be engineered. With theCardiff-Weston scheme in particular, the existenceofoneormoreshiplocksandthehighvolumesofcommercialshippingtrafficthatcouldbeexpected,presentanumberof challenges.A solutionmightbe to completely bypass the locks altogether bybuilding a viaduct over the barrage, but this isunlikelytoworkforaraillinkasthegradientswouldprobablybetoosteep.Asolutionforrailmightbeto build a link on both sides of the lock(s), thusswitching rail traffic to the side that is not beingusedbytheshiplocksystem.Ofthetwooptions,aviaductwouldappeartobemoreexpensive,wouldhaveapotentially largevisual impact, andwouldnotnecessarilybenefitfromhavingabarrageasitsfoundation.

Comparing the two transportoptions, it seemsthataroadlinkcouldposemoredifficultiesthanaraillinkduetothemorecontinuousnatureofroadtrafficandthegreaterwidthrequirement(assumingaroadlinkwouldbedualcarriagewayorgreater);a viaduct could be very expensive, although thiswould depend on its length, and whether it wasonlyrequiredforthelocksectionofthebarrage.Foraraillink,theShootsalignmentmaybepreferentialonengineeringgroundsduetothelowervolumeofshippingtrafficatthisupstreamlocation.

Community and environmental impacts

Any new transport infrastructure project can havesignificantimpactsonexistingcommunitiesandtheenvironment,bothpositiveandnegative,althoughthesedifferconsiderablybetweenroadandrail.

For a new road link, the positive impacts canincludeimprovedaccessforlocalcommunities(andthewiderregion),reducedcongestion,andshorterjourneytimesasaresultofmoredirectroutes.Thesebenefits, ifmaintained,canhavepositivebenefits

forthelocalandwiderenvironment,withpotentialfor reduced air pollution and carbon emissions.Onthenegativeside,anewroadlinkcanspoilthelocalenvironment,cutoffexistingcommunities,leadto an increase in traffic, congestionandpollution,andincreasecarbonemissions.

The impacts of a new rail link may be moreconfinedtotheland-takeoftheinfrastructureitself,andsomeofthismaydisplaceexistinginfrastructure.The benefits are likely to be inter-regional ratherthanspecificallylocal,withthepotentialforshorterjourneytimesandimprovedfrequencyontheCardifftoLondonroute.Thelocalenvironmentalimpactislikelytobelimited,althoughthisdependstosomedegreeonwhetherthenewlinkisaccompaniedbyelectrificationoftheexistingline.

Public support

The strong initial reaction among some membersofthepublictothepotentialfornewtransportlinkswas based to some degree on a perception thatthiswould represent greater value for theproject–twobenefits‘forthepriceofone’.If,however,itturnedoutthatanewtransportlinkwasnotviableforwhatever reason, thismay lead toa reductioninsupportforthebarrageprojectasawhole.Thisisparticularlytrueiftheprojectispresentedtothepublicwiththetransportoptionattachedfromthestart. The conclusion from this is that proponentsofabarragemaywishtopostponejudgementonthemeritsofnewtransportlinksuntilthecaseforoneisprovenandtheengineeringuncertaintiesareresolved.

Valuing transport proposals

The provision of new transport links as part of aSevern barrage project would appear to be an‘optionalextra’forwhichthereareuncertaintiesbothovertheneed,andtheengineeringpracticalities.Asaresult,transportproposalsshouldbeevaluatedasstand-aloneprojectsbasedontheadditionalcoststhattheymightaddtoabarragescheme.Forarailcrossing, this would necessitate an assessment ofthecomparativecostofbuildingalinkoverabarragecomparedtoanewbridgelinkortunnelthatcouldbeconstructedinthemostappropriatelocation.


4.7.3 Coastal defence and flood protection

TheoriginalproposalsforaSevernbarragewerenotconceivedordesignedwithflooddefenceinmind.But with the sea level rising and the prospect ofincreasedstormsurges–asadirectresultofclimatechange–thefloodmanagementandriskprofileofabarragearenowanessentialpartoftheanalysis.As the Foresight ‘Future Flooding’ report shows,88climatechangeisincreasingfloodrisk,particularlyfrom sea level rise and more stormy weather,and coastal flood risk is predicted to increase inproportiontofloodriskfromrivers.

Twoaspects of coastal andfluvial (river) floodriskneedtobeconsidered:

• Coastaldefenceandpossibleprotectionfromsealevelriseandstormsurgesforlow-lyinglandaroundtheestuary

• Floodriskfromriversthatflowintotheestuary

Thediscussioninthisreportisatahighlevelandfloodingisanissuethatwouldneedtobeconsideredcomprehensivelyinanyfuturestudies.Itisdifficult

tomake definitive statements based on availableinformation. Inparticular,more informationwouldbe needed on the operating and managementregimeforabarrageaswellashowchangestothemorphology of the estuary (discussed in Section4.5.3)couldaffectmanagementofcoastalerosionandfloodriskinthelong-term.

Severn Estuary flood defences and land drainage schemes

The vast majority of the coastline along theSevern Estuary is already protected by coastaldefences. Many of the defences have been builtover hundreds of years, and some date back toRomantimes.Thishasgenerallybeenaprogressiveprocess of land reclamation, with many low-lyingareasnowdependenton thesedefences to avoidinundationathightide.Inturn,thousandsofpeoplearenowreliantoncoastaldefencestoprotectlandandproperty.TheextentofcoastlineprotectedbydefencesisshowninFigure31.

Figure31 ExistingcoastaldefencesaroundtheSevernEstuary

Bristol

Gloucester

Weston Super-Mare

Newport

Cardiff

Coastal Defences



The main coastal flood risk is from very hightides combined with storm surge events, whichcanoccasionallycausewater levels to increasebyupto2m.Inupstreamareas,thereisafurtherriskof fluvial and surface flooding from high rainfall.In some instances, a combination of factors mayincreasetherisk,forexample,whereriverfloodingupstreamcoincideswithahighspringtide.

Theveryseverefloodingexperiencedincentralandwestern England in July2007wasa result ofheavy rainfall (rather than a storm surge), whichcausedhighriverlevelsandflashsurfaceflooding.Onthisoccasion, itappears thataSevernbarragewouldnothavebeenabletopreventanyfloodingbecause itoccurredduringaperiodofneap tides,which means there was no impediment to riverdischargeintotheestuary.

A further consideration is land drainagemanagement. There is around 800km2 of low-lyinglandupstreamoftheCardiff-Westonbarrage,including the Somerset, Wentlooge and CaldicottLevels;partoftheSomersetLevelsliedownstreamoftheproposedbarragelocation.UpstreamoftheShootsproposal therearealso largeareasof low-lyinglandaroundGloucester.Theselow-lyingareasare in many cases drained by a large number ofschemes, which help to provide land suitable foragriculture and human settlement in the region.Previousresearchidentifiedwellover100drainageschemes with outfalls into the Severn, and manyoftheseuse‘tidalflaps’(one-waydrains)toallowdischargeduringlowtideperiods.

Flood risk and coastal erosion policy

The Department for Environment, Food and RuralAffairs(Defra)setsGovernmentpolicyonfloodandcoastalerosionrisk inEngland,andgivesfinancialsupporttooperatingauthoritiesforfloodandcoastaldefence. These are the EnvironmentAgency, localauthorities,andinternaldrainageboards.InWales,the Welsh Assembly Government has devolvedresponsibility for policy and funding. In EnglandandWales,theEnvironmentAgencyistheprincipaloperatingauthoritywithresponsibilityforthemainriversandthesea.

UndertheGovernment’sstrategy‘MakingSpaceforWater’,89 theEnvironmentAgencywill takeona more strategic overview role for all flood andcoastalerosionissues,andtheroleofRegionalFloodDefenceCommitteeswillcoverbothcoastalerosion

and flooding.90 Local authorities have powers toundertakesomefloodprotectionworksforordinarywatercoursesandsomeelementsofcoastalerosion.Internal drainage boards (IDBs) are independentbodies, created under statute to manage landdrainageinareasofspecialdrainageneed.Planningpolicyalsorequireslocalauthoritiestotaketheriskoffloodingandcoastalerosion intoaccountwhenconsideringnewdevelopments.

Fundingdecisionsandstrategicplanningfornewflood defences and the maintenance of existingdefencesaremadethroughasystemofprioritisation.Priorities are determined according to the costeffectivenessoftheschemebeingconsidered,wherethe benefits are weighed in terms of protectingexistingassets,thevalueofthoseassets,improvingpublicsafetyandensuringthelong-termsustainabilityof the schemewith respect to climate changeandresultingsealevelrise.

Across England and Wales, the EnvironmentAgency is presently funded for an annual spendof approximately £600M for the construction andmaintenance of flood defences. Although in thelong-term this figure will no doubt rise, thereare nevertheless limited resources that must beprioritisedinordertoachievemaximumvalue.

Implications of a barrage

It is important to note that none of the originalbarrage schemes were designed with floodprotection inmind.However,dueprimarily to thethreatofclimatechangeimpacts,thissituationhasnowchangedand,asnotedinSection4.2.2,floodprotectionisnowviewedbymanyasasignificantpossiblebenefitofaSevernbarrage.Concernoverrisingsealevelshasledsometocallformoredetailedinvestigationintothe‘OuterBarrage’ortwo-basinschemes (where a second barrage could be builtfromtheCardiff-WestonbarrageacrossBridgwaterBay), as these would offer flood protection for amuchlargerproportionoflow-lyinglandthaneithertheCardiff-WestonortheShootsscheme.

The main benefit of a barrage would be asignificantincreaseinthelevelofcoastalprotectionfor low-lying areas upstream of a barrage. Theimmediate effect of a barragewould be to lowerthe level of the high tide within the basin. TheCardiff-Weston alignment would lower the highwater level by around 1m. This reduction wouldeffectivelyprotectthatareaofcoastfromsealevel


risewiththeexpectationthatassealevelrisesoverthenext50to100years,thehighwaterlevelwouldgradually increasetothepre-barragelevel.ForanOuter barrage (at Minehead), very large areas oflandwouldbeprotectedbehindthebarrage.Itmustbe recognised that a barrage would not replaceexisting coastal defences around the estuary. Thedesign and operation of a barrage would requirethesedefencestobemaintained.Abarragewouldalsogivesomeprotectiontotheareaupstreamofabarragefromstormsurges.

Downstream of a barrage, models indicatethat high water levels would decrease. However,these results are somewhat counter-intuitive, andasdiscussedinSection4.5.2,itcanbeseenthatabarragemightbeexpectedtoincreasewaterlevelsslightly. The correct position would need to beascertained using advanced modelling techniquesto predict more accurately the likely water levelsandwhethersedimentwoulddepositintheareaofBridgwaterBay(asaresultofdecreasedcurrents)orwhethercoastalerosioncouldoccurdownstreamofthebarrage,requiringremedialcoastaldefences.

Abarragecouldalsoallowhighwaterlevelsintheupstreambasintobemanagedtosomeextent.This would on occasion require a change in theoperating regime,and so therewouldmost likelybecostsincurredasaresultoflostelectricityoutput.Thisabilitytomanageabarragewouldassistfloodmanagementintheeventthatpeakriverfloodingwaspredictedtocoincidewithaspringhightide.Insuchanevent,theaimwouldbeclosethebarragetopreventwaterenteringthebasinandtopreventthehightidereachingitsmaximum.Thismodeofoperation would be similar to the Thames barrierwhich protects large parts of London. It is likelythat a condition would be placed on the barragerequiring the operator to operate the barrage topreventfloodingifrequired.

As well as the possible benefits, there areconcerns that a barrage may also have negativelong-term impacts on flood risk upstream of abarrage.One risk thathasbeen suggested is thatchangesinthesedimentaryregimeandmorphologyof the estuary could weaken the banks of riversandstreamsbydeprivingthemofsedimentflows,thuscausingerosion.Theconcernisthatthiscouldrequire expensive modifications and upgrades toflooddefencesupstream.

Landdrainageisonefurtheraspectthatneedsto be factored into consideration of a barrage.The original barrage studies indicated that the

impactofanincreaseinlowwaterlevelsasaresultof a barrage, combined with the increased timeat which water is held at high tide levels wouldmean that some existing drainage schemes willbe adversely affected due to shortening of thetime available for discharging. In addition, wheresea defences are on pervious foundations, extralocal drainagemight be required to control salineintrusion.Thepreviousresearchidentifiedwellover100drainageschemeswithoutfallsintotheSevern,andmanyoftheseuse‘tidalflaps’(one-waydrains)to allow discharge during low tide periods. Thesedrainage issuescanbedealtwithtechnicallybyaprogrammeofremedialworkstoupgradeandaddpumpingstationstoanumberofexistingoutfalls.ThecostoftheestimatedworkisaccountedforinthecostestimatesfortheCardiff-Westonschemeatbetween£24.5Mand£61.9M(1988dataescalatedto2006prices);thereisnoequivalentdatafortheShootsscheme.

Further investigation is needed to allow a fullassessment of the possible benefits and risksfor coastal defence, rivers, and land drainage. Onbalance,theobjectivewouldbethattoensurethatthereis,asaminimum,nonetincreaseinfloodrisktosocialandeconomicinfrastructurefromabarrage.This assessment would also need to be valued ineconomicaswellaswidersustainabilityterms.

Valuing flood risk benefits

Flood risk is an emotive subject, and one that isboundtoriseupthepoliticalagendaastheimpactsof climate change become more pronounced.However,theUK’scoastlineisextensive,anditwouldbeveryresource-intensivetoattempttoprotectallofitfromflooding.Asaresult,clearprioritisationisrequiredtoensurethattheavailableresourcesarespentinawaythatensuresthemostbenefit.Itisalso important todistinguishbetweencoastalandfluvialfloodrisk,andtheinterplaybetweenthem.

Evolving UK policy on flood risk managementis that physical, manmade structures are notnecessarilyanaffordable,oreventhebest,solutionfor long-term adaptation to climate change.89In some cases softer options, such as improvingthe capacity of saltmarshes and floodplains, maybe more appropriate. This may also need to becombined with a policy of ‘managed retreat’ or‘realignment’wherethevalueofassetsthatwouldrequire protectiondoesnot justify expenditure on


additionalcoastaldefences.Theseissuesdemonstratethatcoastaldefences

andtheadaptationresponsetoclimatechangearelinkedwithapproachestocoastalandwetlandhabitatmanagement. In the UK, the Essex Wildlife Trustproject91isanexampleofaschemelinkingcoastalrealignmentandwetlandhabitatrestoration:coastaldefenceswereshiftedinlandtoallow84hectaresoffarmlandtobecomeanaturaltidalwetlandandasustainablefloodprotectionmechanism.Thisprojecthasbeencitedasanexampleofadaptationpracticeby theWorkingGroup II of the IntergovernmentalPanelonClimateChange(IPCC).92

Wetlandscanplayanimportantroleinadaptation–literallymakingspaceforwater,allowingnaturalprocesses to take their course, and absorbing theforce of storm surges – but coastal and wetlandhabitatsarethemselvesatriskfromclimatechange(see, for example, a Defra-published guide on‘Conserving biodiversity in a changing climate’).93

Protectingthesehabitatsormakingnewspaceforthemcanofferopportunitiestoachieveconservationand coastal andfloodprotectionobjectives. Theselinksarestartingtofindaplaceatapolicylevel,butcritically,theymustbetranslatedintopractice.

In the case of the Severn Estuary, the viewofthe Environment Agency is that a barrage wouldnotsaveanymoneybecauseitwouldnotremovetheneedtokeepandmaintaintheexistingcoastaldefences.94 It is also clear that funding levels forcoastaldefenceandfloodprotectionintheUKareextremelyunlikelytocomeevenclosetothecostofinfrastructurerepresentedbyabarrage.

The most obvious exception is London whereexpensive flood protection mechanisms such asthe Thames Barrier can be contemplated becauseof the very high concentration of population andhigh value political, economic and social assetsthat would otherwise be at risk. Building capital-intensivecivilstructurestoprotecttheUK’scoastalareas on a large scale from sea level rise wouldbe economically unrealistic, as well as potentiallyunhelpfuland technicallydifficultor impossible todeliver. Sowhen it comes to assessing the futureriskandoptionsformaintainingcoastaldefencestoprovideasimilarlevelofprotectioninthefuture,averylarge,expensivebarragewouldnotbethetopofthelistofoptionsasacoastaldefenceproject.

ThispositionleadstotheEnvironmentAgency’sconclusion thatanyflood riskbenefits fromeitherthe Cardiff-Weston or the Shoots scheme wouldbe economically marginal. In effect, there is not

substantial public money available for coastaldefence which could be applied to part-fund abarrage.However,thispositiondoesnotnecessarilymeanthatabarragewouldprovideamarginallevelofadditionalprotection,as the levelofprotectioncouldinfactbesubstantial.

Theterminologyusedmayinsteadbeareflectionof the low asset value of some of these areas,rather than the level of protection provided. Thispointstoanotherissue:thatbyprovidingahigherlevelofprotectiontolandthatwouldnototherwisebe protected and might, without a barrage, belost to sea level rise, a barrage would have theconsequenceof increasing thevalueof such land.Thiscould increasedevelopmentpressures in low-lyingcoastalareasaroundtheestuary.ThisissueisdiscussedfurtherinSection4.7.5.

Accuratelycalculatingthenetfloodriskbenefit(after accounting for possible negative impactsand for the barrage operating regime) would beanimportanttask.Ifsuchabenefitcanbeproven,thentheremaybeacaseforcreditingthisbenefitto a barrage project in some way, although thiswould depend on how a barrage was financed.AschemeledbytheprivatesectormayseekagrantfromGovernment to ‘pay’ for thefloodprotectionbenefits, whereas a public sector scheme wouldbeabletotreatsuchbenefitsaspartoftheoverallscheme.

Thefloodriskbenefitsfromthe‘OuterBarrage’oratwo-basinschemewouldnodoubtbegreaterthan the Shoots or the Cardiff-Weston schemes,andwouldprovideagreaterdegreeof protectionto areas such as the Somerset Levels. However,such benefitswould need to be balanced againsttheadditionalcostoftheseschemesand,assumingthat these costswouldbemet frompublic funds,considerationwouldneedtobegiventothewiderpressuresonthefloodriskmanagementbudgetinEnglandandWales.

Itmaybe thecase thatsomeof the land thatwould receive additional protection would notnormallybeconsideredforcoastaldefencesduetoitslowvalueintermsofprotectinglifeandproperty.Implementationofsofteroptions,includingmanagedretreat, may be more appropriate in combinationwithagreaterdegreeofprotectionforhighvalueassets. It isalsopossiblethatabarragedevelopermayseek tousesomeof this land in formulatingacompensatoryhabitatpackage,asrequiredundertheEUDirectives.


4.7.4 Employment

A Severn barrage would result in the creation ofsubstantial numbers of new jobs, most of whichwould be concentrated in the construction phase.Previousstudieshavemadedetailedestimatesforthelikelyscaleofnewemployment,butmostofthedataandassumptionsforthisworkarenowlikelytobeoutofdate,sothefiguresquotedbothhereand elsewhere need to be treated with extremecaution.Forexample,productivitygainsmaymeana10-20%reductioninlabourrequirements,butthismaybeaccentuatedbyany shift of production toothercountries.Itisalsonotclearfromthepreviousstudies how the indirect employment impactswere calculated, and there is nodataonpossibleemployment disbenefits as a result of reducedvisitorspendatcertainsitesorfromareductioninportactivity.

ThemostrecentworkbySTPG(2002)estimatesemployment at 200,000 person years for theconstruction phase of the Cardiff-Weston scheme,peaking at 30,000-40,000 per year in Years 2 to5of theproject.STPGalsoestimated that50%ofthejobscreatedwouldbeintheSevernsideregion.This would most likely result in a substantial netmigrationoflabourintotheregionfromtherestoftheUKandinternationally.InthecurrentEuropeanjob market, a large percentage of this migrantlabourcouldbeexpectedtocomefromthenewEUmemberstates,orfromthenewmemberstatesofthefuture.

With any strategic assessment of employmentimpacts,considerationneedstobegiventothenetemployment effect of anyparticular developmentin the context of overall national employmentlevels,andthetypeandqualityofthejobscreated.The creation of jobs around the constructionand operation of a barrage will not necessarilyrepresentanet increase inemployment,as thesejobsmayotherwisehavebeencreatedelsewhere–forexample,intheconstructionofaconventionalelectricitygeneratingplant.More important is thebalance between the creation of skilled and non-skilled labour, their permanency over time, andthe potential for learning and innovation throughthe project. These factors need to be consideredin comparison with other electricity generationtechnologies.

A net migration of labour into the Severnsideregioncouldhaveasignificantimpactonthedemandforaccommodationduringtheconstructionphasein

anarea that isalreadyunderpressure fromrisingpopulation(thepopulationinthewestofEnglandisexpectedtoincreaseby117,000by2026).95Ifthisisnotadequatelycateredforthenthereisariskthatthesedemandscouldresultinanincreaseinurbansprawl and poor quality housing development,upwards pressure on the cost of accommodation,andcommunitycohesionissues.

Anydecision toproceedwithabarragewouldneed to be accompanied by detailed strategyfor the provision of both short and long-termaccommodationformigrantlabour,alongwiththeadditional services required. There may also be anumberofpossiblemeasuresthatcouldbetaken,includingprogrammestoup-skillthelocalworkforceand efforts to ensure the participation of existinglocalbusinesses,bothofwhichwouldhavewiderregionalbenefits.

4.7.5 Development and housing

A Severn barrage would have significant impactson local communities and housing, as well asthe potential to create new opportunities fordevelopmentatregionalandsub-regionallevelsinthesouthwestofEnglandandinsouthWales.

Atalocallevel,abarragewoulddirectlyaffectthe communities located at the landfalls of thebarrage. In particular, the Cardiff-Weston barragewoulddirectlyaffectthecommunitiesatLavernockPointon theWelsh sideof theestuaryandBreanDown/Weston on the English side of the estuary.Theextentof impactswoulddependontheexactlandfallofabarrageandonthedetaileddesignandplanningofthebarragealignmentandwhethertheprojectwouldincludeancillaryfeaturessuchasnewtransportlinks,whichwouldhavetobeintegratedintoexistingnetworks.

The barrage alignments chosen for study inthe past were mainly based on economic andenergy considerations, and the available studiesrecognise that land use issues would requirefurther consideration. Any project would need tominimise thedirect impacts on communitiesbothinthelocationanddesignofabarrage,andduringthe construction phase, and would also requireextensiveengagementandconsultationwiththesecommunities. Drawing on the conclusions of theWorld Commission on Dams,96 this process shouldaimtoreconcilecompetingneedsandentitlementsthrough an approach that recognises rights and


assesses the risks, particularly in relation to localcommunities.

The development of a Severn barrage couldresultinthecreationofamoreattractiveestuarineenvironment,whichcouldinturnleadtoanincreasein land values and the potential for prospectivedevelopment.Inaddition,thepotentialforabarrageto provide additional coastal defence around theestuarymaymean thatareasof coastal landgainahigher leveloffloodprotection(fromfuturesealevel riseandstormsurges),whichcould increasedevelopmentpressureonruralandgreenbelt landaroundtheSevern.Dependingonhowtheprojectwasfinanced, theremaybeastrong incentivefordevelopers to seek to enhance the commercialviabilityoftheprojectbylinkingittocommercialandresidential development, both in developing theirbusinesscase,andinseekingplanningpermissionandconsent.

Ensuring people have access to good quality,affordable and environmentally and sociallysustainable places to live is a fundamentalsustainable development policy goal. The SDCbelieves a whole-system approach is neededto tackle housing affordability, encompassingsupplyanddemandsides. Inthiscontext,theSDCrecognisestheneedtobuildadditionalhomes,andtodoso inareasthathelptorelievesomeoftheacutepressuresinotherareassuchasthesoutheastofEngland.Asour recent reviewofGovernment’sprogress on Sustainable Communities highlights,68we believe new homes should be built in waysthat tie inwith localandregionalplans toensurethat they are strategically located (ideally withinexisting communities), have high environmentalstandardsforenergyandwateruse,accesstopublicservices, and result in the creation of desirableand functioning communities rather than isolatedhousingestates.Developmentmustalsobeavoidedinareasatriskofcoastalorfluvialflooding.

Wehaveanumberofseriousconcernsoverthetypeofdevelopmentthatmightoccuralongsideabarrage.Thereisaseriousriskthatabarrageisseenasavehiclefordeliveringamuchlargerdevelopmentproject, due to political or economic priorities.While appropriate and sustainable developmentmaybewelcome, the risk is thatpoorly-designedandbadly-integrateddevelopment occurs, leadingto unwelcomepressures onexisting communities,incursions into greenbelt land, and a reduction inthecarbonsavingsthatabarragecouldachieveduetoan increase inancillaryemissions.Foraprivate

sector-led project, the relatively high discountraterequiredby investors(seeSection4.8.2)mayleadtoanadditional incentiveoncommercialandresidentialdevelopment,whichcouldfundamentallychangethedynamicoftheproject.

The context is of course important. Therewould need to be a strategic overview taken ofdevelopmentpressuresintheregionsborderingtheSevernEstuary, includinganestimateof the likelyinfluxofnewresidentsandbusinessesasa resultof barrage construction, and the long-term needsof the area both in terms of accommodation andservices. As Section 4.7.4 highlights, the labourrequirements during construction could be equaltothepopulationofawholetown,sotherewouldneedtobewell-developedplanstodealwiththisimpactinthemostsustainableway.

From the SDC’s engagement with regionalstakeholders, it was clear that, although there isa high level of awareness of possible costs andbenefitsfortheregion,theexistingstrategiesandplans for economic development, transport, andspatialplanninginsouthWalesandthesouthwestofEnglanddonotaccountforthepotentialimpactof a barrage. It would therefore be a priority toensure that any barrage proposal and associateddevelopmentareconsideredwithin thecontextofthesedocumentsaspartofacomprehensivereviewof the regional economic and strategic planningimplicationsofdevelopment.98,99,100,101

Thispoints toastrongrole forstrategicspatialplanning, and for the economic developmentorganisations(theSouthWestofEnglandRegionalDevelopment Agency and the Welsh AssemblyGovernment), working in close cooperation withlocal authorities, housing associations and otherregionalandlocalstakeholders.

A number of the negative impacts identifiedabove could lead to increased carbon dioxideemissionsinotherpartsoftheeconomy.Forexample,displacing shipping capacity could result in anincreaseintotalfreightmilesduetolessappropriatereplacement locations, and new transport links ormajor new housing developments could lead toincreased emissions. Some of these impacts maybecontainableinthelong-termthroughregulation(e.g. new standards for zero carbon homes from2016)oraneconomy-widecapongreenhousegasemissions.Butthecomplexityoftheissuesinvolvedmakes clear the need for a broad assessment ofthe net carbon balance of all the options underconsideration, and any associated development.

The potential for wider environmental impactswould also need to be managed strategically toensurethatincreaseddevelopmentpressureseekstominimisetheimpactsonbiodiversityandhabitats,bothcoastalandrural.

4.7.6 Leisure and tourism

TourismisoneofthelargestemploymentsectorsintheSevernsideregion,withseveralmillionvisitorsper year and a wide variety of leisure activitiestakingplace.Theseinclude:

• Anglinginrivertributariesupstreamofapotentialbarrage,withsome6,000participantsestimatedforsalmonalone

• Bird watching,particularlyaroundBridgwaterBayandintheupperestuaryatSlimbridge,thelatterhavingabout200,000visitorsayear

• Cardiff Bayrecreationduetothecompletionin1999oftheCardiffBaybarrage

• SurfingandtourismrelatedtotheuniqueoccurrenceoftheSevern Bore,whichisa

naturallyoccurringtidalwavethattravelsuptheRiverSevernandcanreachheightsof2m

• Tourist resorts,includingBarryIsland,Burnham-on-Sea,Clevedon,Penarth,Weston-super-MareandMinehead

• Wild-fowling,consistingof13wild-fowlclubswithupto500membersonbothsidesoftheestuary

• Yachtingintherelativelysmallnumberofyachthavens,includingthoseatBristol,Chepstow,PenarthMarine(insidetheCardiffBaybarrage)andPortishead.

Figure32 showsthetouristattractionsandrecreationalareasintheSevernsidearea.

Previous work by STPG suggests that thecombinationofahightidalrange,strongcurrents,andhighlevelsofturbidityservetolimitthelevelofrecreationalactivityintheSevernEstuary.However,the effect of this may allow or encourage theexistenceofotherformsofrecreation,suchasthoseassociatedwiththewildlifeoruniquecharacteristicsofthearea.

Figure32 TouristattractionsandrecreationalareasintheSevernsidearea

Bristol

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Sully Island

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Apreviousassessmentoftheimpactofabarrageconcluded that theremaybea5-20% increase intourism as a result of a Severn barrage, mainlyduetothecreationoflesssevereconditionsintheresultingbasinandthelikelihoodthatthebarrageitselfwouldbeavisitorattraction.TheincorporationoftwosmallboatlocksintotheoriginaldesignsfortheCardiff-Westonscheme is thought tominimisetheimpactonrecreationalsailingactivities.

Possiblenegativeimpactsfromabarragemightinclude a direct conflict with popular amenitybeaches (such as those at Barry and Weston-super-Mare),andtheeffectthatareductioninbirdnumbers might have on bird-watching activities.It seems likely that both barrage schemes wouldputanendtothespectacleoftheSevernBore,andtheleisureactivitiesassociatedwithit.

Thedataavailableontourismandleisureimpactsis incomplete and is likely to beout of date. Thiswouldbeanotherarea thatwould require furtherevaluation, including an economic assessment ofthelikelysectoralimpactsonthelocaleconomy.

4.7.7 Fishing activities

AsummaryofthefishspeciespresentintheSevernEstuary,andtheimplicationsofabarragefortheirlong-term survival, is presented in Section 4.6.6.Bothcommercialandrecreationalfishingactivitiestake place in and around the Severn Estuary andin the rivers that flow into the estuary, includingthe Wye and Usk special areas of conservation.Salmonandeelarethemostcommercialimportantspeciesalthoughtheimportanceofthesefisherieshasdeclined.Therecreationalexploitationofthesespeciesandprivatelyownedsalmonfishing rightscontinues to have significant social and economicvalue. Commercial fishing for white fish such ascod, whiting, bass, and sole also takes place ontheestuaryusingavarietyofmethods.Very littleshellfishingtakesplace.

The impact of a barrage on fishing activitieswouldbeasaresultofanumberoffactors,includingtheimpactonindividualspecies,restrictionsonthemovement of vessels, the commercial viability ofthefishingeffortandthefishingmethodsemployed.It is thought possible that a reduction in turbiditymay help support an increase in shellfisheries,althoughthiswoulddependonwaterqualityissuesassummarisedinSection4.6.4.

AfullappraisalofaSevernbarragewouldneed

toincludeareviewofcurrentfishingpracticesinandaroundtheEstuary, incorporatingawidespectrumof fishing activities, such as trawling, sea anglingandshellfisheries.Anevaluationoftheimpactsofa barrage should provide evidence on the likelyimpactsonfishstocksandwaterquality.Thisshouldalso consider the economic and social value ofrecreationalfishingactivities.

4.7.� Aggregates industry

TheSevernEstuaryishometoaregionally-importantaggregates industry, with around 1.5m tonneslandedannually.Muchof this ismadeupofwell-sorteddredgedsandtakenunderlicencefrominter-tidalsandbanksintheSevernEstuaryandthewiderBristolChannel.Ithasbeenestimatedthataround1,700jobsareeitherdirectlyorindirectlylinkedtoaggregatedredgingactivitiesinsouthWales.

Current or proposed plans anticipate thatdredging inWelshwaterswillmoveprogressivelyoffshore, with around 800,000 tonnes of materialexpectedtocomefromtheSevernEstuaryandinnerBristolChannelby2015.

A Severn barrage would have a number ofpotentialimpactsontheaggregatesindustry,bothongoing andduring construction. Importantly, anychanges in the sedimentary regime (see Section4.5.4)couldimpactonthequalityofsandresources,and therefore on the economic viability andenvironmentalimplicationsofextraction.Adecreasein turbidity as a result of a barrage would mostlikely leadtothemodificationof theseabedfrommainly sand-based substrate toamixed substrateofsandandmud.Ontheotherhand,abarragemayimproveaccesstosomesitesduetomodificationstoupstreamwaterlevels,andapotentialincreaseinthenumberofsitesthatarefullysubmerged.

Duringtheconstructionphase,abarragewouldalso require a very large quantity of aggregatesforfill andconcrete. Therewouldbeanumberofadvantagesfromsourcingthis locallyorregionally–most importantly, theminimisationof transport-related carbonemissions – and theSDCwouldbeconcernedifthiscouldnotbeachieved.Thiswouldbe a positive, albeit short-term, benefit for theregional aggregates industry, with the possibilitythatdemandcouldbemetthroughacombinationof existing and temporary licences. However,suchahigh levelofdemandmay lead toupwardpressuresonthepricesofaggregates,whichcould


havenegativeeconomiceffectsbothregionallyandnationally depending on the extent to which thisdemandcouldbemetfromincreasesinsupply.

Aswithotherregionaleconomicconsiderations,this issue would require further investigation ifa Severn barrage were to be considered in moredetail.

This section looks at the estimated capital costsfor the two Severn barrage schemes underconsideration,beforegoingontoanalysetheunitcostofelectricityoutputthatarisesfromavarietyofdifferentdiscountrates,andtheirrelevance.Itthenconsiders the level of Government involvementthatmightberequiredtodevelopaSevernbarrageproject, before commenting on possible financingoptionsandthetreatmentofancillarybenefits.

4.�.1 Cost of construction

Thelastdetailedestimateofthelikelyconstructioncost of the Cardiff-Weston and Shoots barrageschemes occurred in 1988 and 1990 respectively.In order to update these figures for inflation,ResearchReport3usedamultiplierbasedonapriceescalation index. It is important to note that thefigurespresentedbelowareanupdateofpreviousestimates and are not based on revised data.Changes since the 1990s, such as the likelihoodof being able to obtain some of the equipmentoverseasatreducedcost,andthereducedneedforlabour(alongwithpossibleincreasesinreallabourcosts),pointtotheneedfortreatingsuchestimatesasindicativeratherthandefinitive.

That said, the SDC’s research estimatesconstruction costs of £15,066M (updated to2006 prices) for the Cardiff-Weston barrage, and£1,498.8mfortheShootsbarrage.However,a10-15% margin of error should be applied to thesefigures to account for the uncertainties describedabove.

Both barrage schemes are highly capitalintensive, with construction times of up to sevenyearsfortheCardiff-Westonscheme.Privatesectorprojectsofthissizewilloftenbedebt-financed,anddue to the longdelaybefore revenuegeneration,interest payments can add significantly to overallproject costs. In the case of the Cardiff-Westonscheme,thecostofborrowingmightruntoseveralbillion pounds depending on the interest rate

applied. The calculations presented in ResearchReport3arebasedontheprojectsbeingfinancedover their lifetimes (120 years) in order to allowcomparisonwithothertechnologyoptions,butthismaybeunrealisticiftheprojectweretobefinancedbytheprivatesector.

4.�.2 Unit cost of output

Calculating the unit cost of output allows for asomewhatsimplisticcomparisonofabarragewithother electricity generating technologies. The unitcosts provided in Table 11 are calculated usingthe construction costs described above, whichare converted from their current cost estimatesto equivalent annual costs (EAC) by discountingrevenuesovertheexpectedlifetimeof120years.

Discounting isawayofaccountingfortherateof return an investor might expect from such aproject.Ahigherdiscountrateusuallysignifiestheexpectationofhigherrisks,whereasalowdiscountratemightbeapplied if theprojectwere seenaslowrisk,possiblyduetobeingproventechnology,orbecauseithadGovernmentbackingoraccesstoaguaranteedsourceofrevenue.Table10providesarangeofcommercialdiscountrates(8-15%),alongwiththediscountraterecommendedbyHMTreasuryforpublicsectorappraisals,whichisincludedheretogivean indicationof thepublicbenefitofbothSevern barrage schemes. In fact, HM Treasuryrecommendadecliningdiscount rate schedule forvery long-termprojects,witha rateof3.0%usedfortheperiodof31-75years,2.5%for76-125years,and2.0%for126-200years.102

Further,itshouldbenotedthatthecostsbelowarebasedontheoverallcapitalandoperatingcostsofthetwoschemes(includinginterestcharges),butdonot includeancillarycostssuchastransmissionnetwork upgrades or increased system balancingcosts. They do not include any allowance for thecostsofprovidingcompensatoryhabitataswouldberequiredundertheEUHabitatsandBirdsDirectives

4.8 Cost and financing


(see Section 4.10.4). This is standard practicewhen comparing different electricity generatingtechnologies in this way, although providingcompensatoryhabitatwouldbeacorepartofanybarrageprojectandthecostscouldbesubstantial.

Itwouldthereforebesensiblefordataontheunitcostofoutputtobepresentedasaconstruction-onlyestimatependingfurtherinvestigationintothelikelymagnitudeoftheseancillarycosts–inparticular,thecostofprovidingcompensatoryhabitat.

Barrage option

Discount rate

2% 3.50% 8% 10% 15%

Cardiff-Weston

5yearprogramme 2.27 3.56 8.54 11.18 19.1

7yearprogramme 2.31 3.68 9.24 12.37 22.31

Shoots

Lowcase 2.13 2.96 6.08 7.69 12.36

Midcase 2.35 3.29 6.8 8.62 13.87

HighCase 2.58 3.62 7.52 9.54 15.38

Table11 Unitcostofoutput(p/kWh(real))fordifferentbarrageoptionsatvariousdiscountrates

The first conclusion from this data is that thechoice of discount rate has a very considerableimpactontheunitcostofoutput.Thisisduetothehighup-frontcapitalcostofabarrage,andthelonglifetimeof thestructure.TheSDC’s researchpaperon the economics of nuclear power concludedthat a commercial discount rate of 9% might beappropriate for private sector construction of newnuclearplant.Recognisingthatthereareanumberofsimilaritiesbetweenalargetidalbarrageandthedevelopmentofnuclearpower,thisimpliesthatthe8and10%discountratesarethemostappropriatetouseifthebarrageweretobedevelopedbytheprivatesector.Aswouldbeexpected,usingasocialdiscountrate(2-3.5%)resultsinamuchlowerunitcostofoutputthanthecommercialdiscountrates.A low discount rate may be appropriate if theproject were viewed as a publicly-owned project,asthiswouldtakebetteraccountoftheverylong-termbenefits.

The second conclusion is that neither of theschemesiscostcompetitivewhencomparedagainstcurrentwholesaleelectricitypricesifacommercialdiscount rate is applied. However, this should notbeasurprisewithsuchcapital-intensiveproposals,

and the costs above do not take account of thelowcarbonpremiumthatelectricityoutputfromabarrage would attract. A full commercial analysiswouldincludeanassumptiononlong-termcarbonpricesbut, in theabsenceofsuchdata, there isagoodcaseforconsideringthetwobarrageoptionsagainstothersourcesoflowcarbonelectricity.

Table 11 shows how the two Severn barrageoptionscompareagainstotherelectricitygeneratingtechnologies,withtherangeincostsrepresentativeof thediscount ratesdescribedabove. This showsthat at an 8% discount rate, both options lie atthehigherendincomparisontoother lowcarbontechnologies;at15%,theyarewellabovethecostsof all other technologies except wave power; butusing low discount rates of 2 or 3.5% a barragebecomeshighlycost-competitive.

Evenallowingforthefactthatthebarragefiguresmay not be completely accurate, the conclusionfrom this comparison is that both Severn barrageoptions are unlikely to be economically viable forprivatesector investment inelectricitygeneration.ThishasconsistentlybeentheconclusionoftheUKGovernment.Furthermore,duetotheone-offnatureof barrage construction, there is only very limited


potential for learning effects from such a project,whichmeansthat it ishardto justifyGovernmentinterventiononinnovationgrounds.

However,optingsolelyfortheleast-costoptionsforgeneratinglowcarbonelectricityignoresanumberofotherconsiderations,includingconstraintsontheratethatanyonetechnologycanbedeployed,andthereducedriskandcostbenefitsfromhavingabroadportfolio of generating technologies.103 Researchdone by the Policy Studies Institute for the SDC104

highlights thehugegap that isemergingbetweenrequiredandplannedlowcarbonelectricitycapacityupto2030which,alongwiththenewEUrenewablestargets,maynecessitatethedevelopmentofawholeseries of technologies (both renewable and non-renewable)atarangeofcostlevels.Theconclusionfrom this is that electricity prices will need to risesubstantially in the long-run topay for lowcarbon

investment across a wide range of technologies,both insupplyanddemand.This issomethingthatGovernment is currently reluctant to contemplate,despitethefactthatoverallcostsasapercentageofGDPwouldberelativelysmall–asconcludedbytheSternReview.22

Itisalsopossibletoarguethatstandardeconomicanalysistendstounderstatethesocialandeconomicgains of projects with very long time horizons.Forexample,noneoftheUK’sfourpumpedstoragepower plants would be likely to go ahead on apurelycommercialbasis,becauseofthehighcapitalcost and long timescales involved. Nonetheless,theseplants,whichwereall commissioned in thenationalisederaofUKenergypolicy,haveproventhemselves as very reliable providers of instantlydispatchable reserve power, bringing significantenvironmentalandeconomicbenefits.

Figure33 Comparingthecostofatidalbarrageagainstothertechnologies

Comparison of fully built up cost of technologies 2006

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4.�.3 Level of Government involvement

AsstatedinSection1.4,currentGovernmentenergypolicyisbasedonliberalisedmarkets,andthereforeassumes thata Severnbarragewouldneed tobefinancedandconstructedbytheprivatesectorwithminimalGovernmentinvolvement.TheSDChasuptonowacceptedandworkedwithinthisframework,but this project has required us to expand ouranalysistoincludethefullspectrumofoptionsrightuptofullGovernmentinvolvementandownership.Anumberof reasons liebehind thisdecision,andareexplainedbelow.

Long-term public benefits

The120yearexpectedlifetimeofabarragemeansthatitwouldbeprovidingcarbon-freeelectricityforaverylongtime,andformanyfuturegenerations.There is a strong argument for suggesting thata commercial economic evaluation of a barrage(based on commercial discount rates) does nottake sufficient account of these benefits. Indeed,the Stern Review states that with climate changemitigationpolicies, itmaybemoreappropriate touseloworevenzerodiscountratestobetterreflectthelong-termnatureoftheproblem.22

Theprivatesectorisonlylikelytoacceptalowrateofreturnforaverylowriskproject,signallingsignificant Government backing. However, goingaheadwithapubliclyfundedprojectwouldremovetheseconstraintsaltogether,andwouldallowfortheconsiderationofevenlowerdiscountrates(downtozero) if thepublicwerewilling topay for theup-front capital cost of the project through generaltaxation. There are also a number of financingoptionsinbetweenthesetwooptions,allofwhichareconsideredinmoredetailbelow.

The long-term nature of the Severn barragedecision (and the time likely to be required for adecision tobemade)alsoconferson theSDC theresponsibility to consider options that are outsidetheframeworkofcurrentenergypolicy,asthiscouldchangewithinthetimescalesinvolved.

Mismatch between risk and reward

As with any large, high profile project, theGovernmentneedstobeawareoftheriskof‘moralhazard’, particularlywhere it has anoverridingor

well-publicisedinterestinsuccessfulcompletionoftheproject.AstheSDCexplainedinitsanalysisofnuclearpower,105moralhazardisthetermusedtoexplain the phenomenon whereby individuals ororganisations may intentionally engage in morerisky behaviour, safe in the knowledge that thecostsoffailurewillbeborneelsewhere.

In the context of a Severn barrage, suchbehaviour could manifest itself through appraisaloptimism,wherebypromoters of a barragemight(intentionally or unintentionally) underestimatethe true cost of a scheme, or systematically takeonhigherrisksintheexpectationofaGovernmentbail-outshouldtheschemefacedifficultiesorevencollapse. These are numerous examples of wheremajorprojectsandcompanieshaverequiredsomeform of emergency public expenditure, includingtheWestCoastMainlineupgrade,SizewellBnuclearpowerstation,BritishEnergy,andtherecentcollapseofMetronet.

TheconsequenceofthisisthattheGovernment,and therefore the taxpayer, is in the positionof underwriting the project, regardless of theirwillingnesstodoso.Tosomedegreethiswillhavetheeffectofreducingprojectcostsbyreducingthecost of capital, but it can also have the oppositeeffectbyencouragingorallowing inefficiencyandcomplacency.Ofgreaterconcernistheprospectthatanyseriousfinancialproblemswithsuchaprojectcouldresult ina largebill for thetaxpayer topickup,asoncestarted,noGovernmentislikelytoallowsuchaprojecttofail.

This inherent risk for Government and thetaxpayer, regardless of how a barrage might befinanced, leads to a potential mismatch betweenrisk and reward for a private sector-led project.So,despiteprovidingan implicitguaranteeof lastresort to the project (and possible public moneyintheeventoffinancialdifficulties),inadditiontothefinancialincentivesthatmightberequired,theGovernmentandtaxpayerwouldstandtogainlittleof the economic rewards once the project was inoperation,astheserewardswouldflowtotheprivatesector developer. An alternative, Government-ledfinancing package,whilst not likely to reduce therisks,mayenableafairerallocationoftherewards.

Ensuring the public interest

A private sector-led Severn barrage project wouldundoubtedly put huge pressure on the developer

tofindalternativesourcesofincometothecentralenergyprojectinordertoimprovetherateofreturnfor investors. As described in Section 4.7.5, thiscouldtaketheformofproperty,businessorleisuredevelopmentintheareatotakeadvantageoftheimproved aesthetic value of the resulting basin.Proposals to upgrade or construct new transportinfrastructure (e.g. ports, roads and rail) are alsopossible.

While these options provide a possibleopportunity for regeneration and sustainabledevelopmentintheregion,thisdependstoalargeextentonhowtheyarecarriedout.

Furthermore, in constructing the barrage itself,there is a potential conflict between the privatedeveloper’sdesireforreducedcostsandthepublic’sdesireforawell-designedandconstructedproject.A short-termist approach to construction risks theuse of sub-standard materials and methods ofconstruction that could negatively impact on theexpectedlifeofabarrageandonthesustainabilityofancillaryinvestments.

Itmaybepossible to limit sociallyundesirableoutcomestosomeextentthroughacombinationofgoodstrategicplanning,incentivesandregulation,buttheSDCbelievesitisalsoimportanttoconsiderthe impact that an alternative financing approachmight have in ensuring the public interest isupheld.

Considering all the options

TheSDCbelievesthat,forthereasonsgivenabove,thereisastrongcaseforconsideringalltheoptionsforfinancingaSevernbarrage,regardlessoftheirfitwithcurrentenergypolicy.Abroadrangeofoptionsfor the initiation andownership a Severn barrageproject in relation to the level of GovernmentinvolvementispresentedinFigure34.Thislistisnotexhaustive, but it does illustrate the considerablerange in Government involvement that might bepossible.

Figure34 DifferentoptionsforthelevelofGovernmentinvolvementinthedevelopmentofaSevernbarrageproject

Government initiates and leads project, which is publicly-ownedandfinancedfromgeneraltaxation.

Low level of Government involvement

High level of Government involvement

Private sector initiates and leads project with no Governmentinvolvementatanystage.

Government initiatesprojectbutprivatesector-ledwithfinancingobtainedfromprivatesectorinvestors.NospecialfinancialsupportfromGovernment.

Government initiates and financially supports project but privatesector leads with financing obtained from private (and possiblysomepublic)sectorinvestors.

Government initiates and leads project, with financing obtainedfromtheprivatesectorintheformofaPublicPrivatePartnership(assetsarepubliclyowned!).

Governmentinitiatesandleadsproject,withfinancingobtainedfromthecreationofanewcompanywithmajoritypublicownership.

Government initiates and leads project, which is publicly-ownedandfinancedfromabondsissueorlargeinstitutionalinvestors.


Under the current energy policy frameworka Severn barrage is likely to fall into one of thebottom two categories. However, considering thehigh cost of output associated with a project ledandfinancedbytheprivatesector,itdoesnotseemlikelythatitwouldevergoaheadwithoutconcertedGovernmentinvolvement.

A decision to promote a Severn barrage may,therefore,poseanumberofdifficultquestionsforthefuturedirectionofUKenergypolicy.TheGovernmentmaybeabletomakeacaseforsupportingabarragebasedonlong-termcarbonsavingsandsecurityofsupply;benefitsthatarenotadequatelyvaluedbytheelectricitymarket.Ontheotherhand,itwouldbedifficultfortheGovernmenttojustifytreatingatidalbarrageasanewrenewabletechnologythatrequiresinnovationsupport(thejustificationbehindthe establishment of the RO), as the technologyitselfiscertainly‘mature’,andthereisonlylimitedpotentialforlearningandfurtherreplication.

Regardlessofthejustificationused,Governmentmaybekeentoensurethatsupportforabarragewasdoneinawaywhichisconsistentwithwiderenergypolicy,andthesupportgiventoothertechnologies.Thismayrequireamajorre-thinkofenergypolicyifGovernmentweretotakeapoliticaldecisionthatabarrageshouldgoahead.Whilstsupportingaone-off special project would risk the charge that theGovernment is ‘pickingwinners’ – something thatithasexplicitlyruledout106–theremaybeagoodcasefortreatingaSevernbarrageprojectdifferentlytoothersforthereasonsgivenabove.

The conclusion from this section is that, afterconsidering andweighing up all these issues, thedecision whether or not to pursue construction ofa Severn barrage must eventually be a politicalone, as any scheme would require some levelof Government involvement for which a caseneeds to be made. It is also clear that a positivedecision would have much wider implications,requiringafundamentalreappraisalofGovernmentinvolvementintheenergysectorandtheincentiveson offer to support technologies such as carboncapture and storage (CCS) or nuclear power, rightthroughtootherrenewablesandmicrogeneration.

4.�.4 Financing options

Thissectionwilllookinmoredetailsatthefinancingoptionsavailableforconstructionofabarrage,andtheimplicationsoftheseonGovernmentpolicyand

the need for public support. Both private sectorandpublicsectorfinancingoptionsareconsidered,alongwithseveraloptions thatsitsomewhere in-between.

Private sector financing

AdecisiontosupportthedevelopmentofaSevernbarrage by the private sector presents a numberof challenges to Government, business and widersociety. For example, what economic frameworkwouldberequiredinorderfortheprivatesectortoinvest insuchaprojectandwhat formmight thisinvestmenttake?

Inmanyways,someof the issuessurroundingthe financing of a possible Severn barrage aresimilar to those that arise with nuclear power,exceptonaneven larger scale.Both technologiesarecapitalintensive,havelongconstructiontimes,andarenotlikelytobethefirstchoiceforprivatesectorinvestmentinnewelectricitycapacityunlessthey are able to obtain some formof low carbonpremium,ordirectsupportfromGovernment.

Assuch,muchoftheresearchcommissionedbytheSDContheeconomicsofnuclearpower107isalsorelevanttoaSevernbarrage,particularlyconsideringtheestimatesforunitcostsofoutputgivenabove,which show that neither barrage option is likelyto be commercially viable at present wholesaleelectricityprices.

The introductionof carbonpricing, in the formof the EU Emissions Trading Scheme (EUETS), isunlikely to offer the support needed to make aSevern barrage attractive to investors. Phase II ofEUETSrunsonlyto2012,andagreementonthenextphase isunlikely forseveralyears.However,evenwith this in place, it is unlikely that this schemewill be sufficiently long-term to provide the rightfinancialincentiveforsuchaninvestment.108

The Renewables Obligation (RO) requireselectricity suppliers to source an increasingpercentage of sales from renewables and iscurrentlysettoachieve15%renewablessupplyby2015.AlthoughaSevernbarragecouldbeincludedforsupportundertheRO,theROenddateof2027would probably be considered too short to justifysuch a long-term investment. Furthermore, theCardiff-WestonschemewouldbetoolargetoincludeintheROasitcurrentlystands,asaddingthislevelof output from one project would have a serousdetrimentaleffectonthesupportprovidedtoother


technologies by deflating the price of RenewableObligation Certificates (ROCs) and causing marketuncertainty. It is possible that the Shoots barragecould be accommodated within the RO, althoughthiswouldneedfurtherinvestigation,andconcernsoverthelongevityofROsupportwouldstillapply.

Withthisinmind,theSDC’sconclusionisthattherewouldneedtobesomenewsupportmechanismtoallowaSevernbarragetoproceed.Thiscouldtaketheformofanadditionalone-offpolicyinstrument,or the modification or replacement of existinginstruments.Possibleoptionsinclude:

• Extension of the RO:theexistingROcouldbesubstantiallyextendedtoprovidethecontinuityneededforabarrageproject,althoughthismaynotgetovertheproblemsidentifiedabove

• Feed-in tariff:aguaranteedpricecouldbesetforoutputfromaSevernbarrage,withtheadditionalcostpassedontotheenergysuppliers,oralternativelytothepublicsectorintheformofapowerpurchaseagreementbetweenthebarrageoperatorandpublicsectororganisations

• Government-backed bond:financecouldberaisedthroughabondissuebackedbyGovernment,whichwouldhelptolowerinterestrates;however,thiswouldtransfersomeoftherisktothetaxpayer

• Grant funding:theprojectcouldreceivedirectgrantfundingfromGovernmenttoalevelthatmakesitattractivetoinvestors;thiswouldrepresentadirectcosttothetaxpayer

• Long-term low-carbon electricity contracts:theGovernmentcouldawardcontractsthroughauctionthatsetaminimumpricefornewlowcarbonoutputtobedeliveredatafuturedate,withanyshortfallfromtheactualmarketpricebeingmetbythetaxpayerorothermechanism;suchcontractscouldbetargetedatalllowcarbontechnologies,justsome,orevenasingletechnology

• Modifications to EUETS:theintroductionofafloorprice,orsubstantialextensionofthecomplianceperiod,couldprovideadditionalcertaintyinthelong-termpriceofcarbon

• Public Private Partnership:theGovernmentcouldenterintoalong-termagreementwithaprivateconsortium,whowouldbuildthebarrageandownitforacertainnumberofyears,withtheGovernmentobligedtobuytheresultingpoweroutput,probablyatapre-determinedprice;ownershipofthebarragewouldeventuallypasstothestateattheendoftheagreement

• Severn barrage obligation:anewobligationonenergysupplierstosourceoutputfromabarragescheme

• Tax allowances:theGovernmentcouldprovidetaxincentivestoaprospectivedeveloper.

It is not clearwhich, if any, of these potentialoptions (or combination of options) would besufficienttoencourageaprivatesectorbidtobuildabarrage.Measuresthatsignificantlyreducetheriskassociatedwithsuchalargecapitalinvestmentarelikelytobemostsuccessful,asthesewouldreducethecostofcapitalandtherebyreducetheunitcostofoutput.

However,regardlessoftheoptionchosen,puttingin place the necessary economic framework tosupporttheconstructionofaSevernbarragewouldrequirea significant changeor addition to currentenergypolicy, andmost likelyprimary legislation.Thisraisestheissueofhowanynewmeasurewouldfitwithinthepolicylandscape,andwhetheritwouldrequireamorefundamentalreviewofpolicy.

It is worth noting that the recently agreed EUrenewablestarget(20%ofallenergyintheEUtobeobtainedfromrenewablesourcesby2020)mayrequireasubstantialevolutionofUKenergypolicyin order to meet the obligations that are finallyagreed.Thiscouldrequirethe introductionofnewmeasures, or changes to existing measures, andfinancial support for a tidal barrage schememayendupbeingseeninthiscontext.

If a sufficiently attractive economic frameworkwereputinplace,thentheSDC’sworkonnuclearpower107wouldsuggestthattherearetwopossibleroutesforprivatefinancingofsuchaproject:

• Corporate finance,wheretheprojectisfinancedonthebalancesheetofthedeveloperordevelopers


• Project finance,wheretheprojectisestablishedasaseparatelegalentitytowhichalargenumberofpartiesmaytakeaninterest

Corporatefinanceisthesimplerofthetwo,butin this case would require a substantial financialcommitmentfromtheprojectdeveloper(s).Projectfinance is inherently complex, but it does offersomeprotectionfrombankruptcyforthedevelopersandallowsamuchhighergearingratiofordebttoequity.ThelattermodelwasusedintheconstructionoftheChannelTunnel,aprojectthatalsohadsomeGovernmentinvolvement.

Public sector financing

As already stated, public sector financing or anysignificant Government involvement in a barragedevelopmentwouldbecontrary tocurrentenergypolicy.Nevertheless,thereisalonghistoryofpublicsector financing of large infrastructure projects.Virtually all of the UK’s generating capacity andtransmissioninfrastructurepriortotheprivatisationoftheelectricitysectorinthelate1980swasbuiltinthisway.Furthermore,consideringthehighlevelofGovernmentinterventionthatwouldberequiredtostimulateprivatesectorinterestinabarrage,theoptionofpublicsectorfinancingdoesnotlookquitesoradical.

Although previous models of public sectorfinancing relied heavily upon taxation andGovernment-backedbonds, thereareanumberofotherapproachesthatmayalsoberelevant,suchasashareofferaimedatindividualinvestorsorsomeformofcommunityownership.

Publicsectorfinancingwouldremove,orattheveryleastlimit,theextenttowhichtheGovernmentwould need to make any changes to the marketframeworkforelectricitygenerationorrenewables,as a Severn barrage could be dealt with outsideexisting measures as a one-off project. Uponcommencement of generation, the Governmentcouldallowoutput fromabarrage tobesold intotheelectricitymarketbyapublicly-ownedoperatingcompany.ThismaybeattractivetoGovernment,asit would avoid the need for new measures in analreadycrowdedpolicyenvironment.Buttheremayalsobeconcernsoverthesignalsthiswouldsendtoother technologies, and it is possible therewouldbeaccusationsofinconsistencyandspecialpleading

fromotherelectricitygenerators.Ifchosen,abarragefinancedbythepublicsector

wouldenableaneconomicevaluationbasedonalowdiscountrate.ThisisbecausetheGovernmentcanobtaindebtfinanceatvery lowinterestrates,andtherewouldbenoneedto justifyahighrateof return from the project due to the absence ofany incentive to maximise short-term profits. Forexample, HM Treasury recently released index-linkedbondsat anominal interest rateof1.75%.AsillustratedinSection4.8.2,usingadiscountrateof2%reducesthecostofelectricityoutput(excludinganyancillarycosts, suchashabitat compensation)to less than 2.5p/kWh, making a barrage verycost-competitive with other forms of electricitygeneration.Theactualrateofreturnrequiredfromtheprojectwoulddependon thefinancingmodelchosen, with options that attempt to bring inexternal funding likely to require a higher return,andthereforetheuseofahigherdiscountrate.

Possible options for raising the required fundsforapublicly-ledprojectinclude:

• Consumer levy:theGovernmentcouldintroduceanewlevyonconsumers’billstoraisethecapitalrequired;thiscouldbedoneovera10yearperiod,thuslimitingthepriceimpactonconsumers

• Community ownership:similartoshareownership(seebelow)orlinkedtoabondissue,theGovernmentcouldtargetinvestmentopportunitiestolocalcommunitieslookingforasecureandstablereturn

• Government-issue bond:theGovernmentcouldissuealong-termbond(or‘gilt’),whichwouldraisethecapitalneededforconstructionatcomparativelylowinterestrates

• Grant funding:abarragecouldbefundedsolelyfromgeneraltaxationrevenueorbyincreasingthenationaldebt,althoughthiswouldeitherrequiretheGovernmenttoraisetaxesortocutexpenditureinotherareas

• Public company with minority share issue:theGovernmentcouldestablishanewpubliccompanyandraisethefinancepartlythroughabondissueorgeneraltaxation,withthe


remainingfinanceraisedfromthesaleofaminoritystakeofthecompanytotheprivatesector

• Public private partnership:theGovernmentcouldallowtheprivatesectortoraisethemajorityofthefinancefortheprojectandleadonconstructionandprojectmanagementinreturnforaguaranteedreturnfromtheelectricityoutput,possiblyintheformoffixed-termoperationallease

Thisisnotintendedasacompletelistofavailableoptions,andthereissignificantpotentialforneworhybridfinancingmodels,outsideof ‘publicprivatepartnerships’, thatmaintaintheprincipleofpublicownership. One possibility is that dividends (fora community ownership or shareholding financemodel) or coupons (for a bond model) mightbe payable in delivered electricity, which couldbe particularly attractive for future participants(whether organisations or individuals) in carbonmarkets. This is an area that would benefit fromfurtherinvestigationandstakeholderinput.

4.8.5 Consideration of ancillary benefits

As part of the SDC’s engagement programme onthis project we have heard a number of claimsbeingmadeas to possible ancillary benefits from

the construction of a Severn barrage, or throughconsiderationofadditionalfeatures,manyofwhicharediscussedinSection4.7.Themainthemesareasfollows:

• Floodprotectionfromabarrage,aswellasenhancedprotectionfrom‘outerbarrage’options

• Anewroadand/orraillinkovertheCardiff-Westonbarrage

• Anewhigh-speedraillinkovertheShootsbarragetoalleviatecapacityconstraintsthroughtheSevernTunnel

• Developmentopportunitiesaroundthebarragelandingpoints,oronthebarrageitself

• Additionalrenewableenergygenerationaspartofthebarragestructure,suchaswindturbinesorwavedevices

Where ‘optionalextras’ to theprimarybarrageproposalareputforward,theSDCbelievesthattheyneedtobeconsideredonthebasisoftheadditionalcostsandbenefitsthattheyrepresent.Thismeansthat they should be considered separately to theprimary aim of electricity generation, with anyadditional costs to the main project justified bythe benefits they would bring. Moreover, thealternativestoandjustificationfortheseelementsofaproposalwouldneedtobeconsideredaspartof the appropriate assessment where they wouldadverselyaffectdesignatedconservationsites.

As described in Section 1.2, a major part of theSDC’s review of tidal power was an extensiveprogrammeofpublicandstakeholderengagement.Aspartofthisprocess,theengagementconsultantswereaskedtoelicitviewsspecificallyontheSevernbarrage proposals, which was done through allthreestrandsofpublicengagement–local,regionalandnational –aswellas through thestakeholderengagement.

4.9.1 Public attitudes and opinions

TherewassomeawarenessofproposalsforabarrageintheSevernEstuaryamongstregionalparticipantsduetosustainedpresscoverageintheBristoland

Cardiff area. Those living near the proposed sitesfor theCardiff-Westonbarragehadagreater levelof knowledge. On a national level there was lessawareness,with63%havingnoknowledgeofanybarrage proposal and another 18% having only alittleknowledge.

After being given top-level information on abarrageproposalandthepotentialadvantagesanddisadvantages as part of a national opinion poll,58%of people across theUKwere in favour of abarrageand15%against.ThemajorityofthepublicconsultedintheworkshopsthattookplaceinBristolandCardiff(wheremoredetailedinformationwasprovided)werealsoinfavourofabarrageastheyfeltthebenefitsoutweighedthedisadvantages.

4.9 Public and stakeholder opinion

Figure35 PublicattitudestoaSevernbarrage

Nothing at all

Slightly against

Neither for nor against

Slightly in favor

Strongly in favour

20%10%0% 30% 40% 50% 60% 70% 80% 90% 100%

“Given these potential benefits and disadvantages, on a scale of 1 to 5, where 1 is strongly in favour and 5 is strongly against, how do you feel about a tidal barrage across the Severn Estuary?”

Base: All National – 1010

Public attitudes to a barrage across the Severn Estuary

The production of carbon-free electricity wasperceivedtobethemostimportantbenefitofthebarrage in the regional workshops and the mainreasontosupport it.However,a fewpeoplewereagainstabarrage,mainlyduetotheenvironmental

effectsonthehabitatsandwildlifeinthearea.Thisconcernwas also seenat thenational scale,with56% of people seeing it as the most importantdisadvantage.

Figure36 MostimportantbenefitofaSevernbarrage

The potential for increased protection from flooding forsome parts of South West England

Potential for new jobs and economic development inSouth Wales and parts of South West England

Don’t know

Large contribution to the UK’s electricity needs

Reduces the UK’s reliance on imported fossil fuels andimproves the long term security of electricity supplies

A CO2 – free source of electricity generation

20%10%0% 30% 40% 50% 60% 70% 80% 90% 100%

“Which benefit of a barrage across the Severn Estuary do you consider to be the most important?”


Most important benefit of a barrage across the Severn Estuary

Figure37 MostimportantdisadvantageofaSevernbarrage

Don’t know

The noise and disturbance created by theconstruction of a barrage over several years

The economic impact on some ports of restrictedship movement in the area

The landscape and visual impact of a barrage

The potential high cost of a barrage

Negative impacts on internationally significant naturalhabitats and species such as birds and fish

20%10%0% 30% 40% 50% 60% 70% 80% 90% 100%

“What disadvantages of a barrage across the Severn Estuary do you consider to be the most important?”


Most important disadvantage of a barrage across the Severn Estuary


When given information specifically about theCardiff-WestonbarrageandShootsbarrageproposal,thepublicintheSevernareaweremainlyinfavourof the construction of a large barrage across theestuary.Themainreasonsforthiswere:

• Theproductionofasignificantamountof‘clean’energyovera100+yearperiod.Alargerbarragewouldusemoreofthepotentialtidalresourceandcoulddeliver5%oftheUK’senergyneeds

• Therewereconcernsasmallerbarragewouldbereplacedbyalargeroneatalaterdate,whichwasseenasawasteofresources

• Theancillarybenefitsofaroad/railcrossingandthereductionofjourneytimesbetweenCardiffandBristol

• Thecreationofnewjobs,althoughtherewereconcernsthatlocalareasandinfrastructuresmightfindithardtocopewithalargeinfluxofpeople

• Betterfloodprotection• Thepotentialforpositiveimpactsontourism

inthesurroundingarea.TheCardiff-WestonBarragewasseenasasignificantvisualpresence,andonethatcouldbecomeasourceofcivicpride.

4.9.2 Stakeholder attitudes and opinions

Thestakeholderengagementcomprisedtworegionalworkshopswithkeystakeholdersrepresentingarangeofinterestsandsectors,includingenvironmentalNGOs,tidal device developers, Government departmentsandagencies, and shipping interests. The southernworkshop inCardiffpaidparticularattention to theSevernEstuarybarrageproposals.

Stakeholdersrecognisedthecontributionthatalarge barrage couldmake in producing significant

amountsofcleanrenewableenergy,butwantedtoensurethatnegativeimpactswouldbeminimised.Stakeholders generally felt the impacts couldpotentially be more negative than the public andhad greater conditions of acceptability. Thereforemany were inclined towards the smaller ShootsbarrageschemeovertheCardiff-Westonscheme.

Oneof themain concernswas the irreversibleimpactontheenvironment,ecologyandnationallyand internationally designated sites and manyfelt there was a need for more reassurance thatenvironmental impact would be mitigated. Whilsttherewasapositiveattitudetowardstheidentifiablecontributionabarragewouldmaketo renewablestargets inWalesandtheUKmoregenerally,therewasalso concern thatanydevelopmentmightbeenergyintensiveinitsconstruction.

Fromaneconomicperspective,alargenumberofstakeholdersfeltthatinvestinginabarragecoulddetract from investing in other renewable energyprojectsandthat itwouldbetooexpensive,havetoohighanimpactandwouldtaketoolongtobuild.TheseconcernswerelesspronouncedfortheShootsbarrage proposal which was seen to have no orsignificantlylessimpactonmajorports.

Socially,therewasrecognitionthattherewouldbedisruptionduringtheconstructionphaseandthatlocalcommunitieswouldhavetolivewiththelegacyof the barrage. Some identified possible tourismopportunities,andthepotentialtoregenerateareasandbreakdowntheEnglish/Welshculturaldivide.Othersfeltitcouldhaveanegativeimpactonruralsettingsand,asacounter to itsability toproducecarbon-freeelectricity,wouldnotencouragepeopletothinkaboutreducingenergyconsumption.

Due to the potentially huge impacts that abarrage would have, there was a strong call forbroadpublicandcross-stakeholder involvement inanyfuturediscussionsordecisions.

AstheSDC’sanalysisshows,itisveryunlikelythatabarrageproposalwouldeverbebroughtforwardwithout concerted intervention by Government.This is because a fully-developed proposal wouldrequireasubstantialamountofresearchandpolicy-relatedwork,butwithnoguaranteeoftheeventualoutcome.Itisthereforenotaprocessthataprivatesectordeveloperwouldbelikelytoinitiate.

ThemajorroleforGovernmentintakingforwardsuch a scheme contrasts significantlywith currentenergypolicy,whichassumesahands-off,market-based approach. However, the unique scale of aSevernbarragescheme,combinedwiththepressingneedsofcombatingclimatechangeandimprovingenergysecurity,mayjustifyanexception.

Thissectionlooksatthepolicyprocessthatmight

4.10 Policy process and good governance


berequiredinordertoproceedtothenextstageofdevelopmentofaSevernbarrage,bearinginmindtheprincipleof‘goodgovernance’.Itconsidersthelikely research and assessment stages, and theimportance of early public engagement, beforecommentingonrelevanceoftheEUDirectives,andtheprocessthattheydictate.

4.10.1 Research and assessment stages

ForaSevernbarrageproposaltobetakenforward,itwouldneedtosuccessfullypassthroughanumberofdistinctstages:

1 Pre-feasibilitystudiestolookatanumberofpotentially‘deal-breaking’issues,forexamplecompensatoryhabitatrequirementsandfinancingmodels.Thisstagemayalsoneedtoincludeafinaldecisiononthepreferredalignment.

2 AStrategicEnvironmentalAssessment(SEA)couldberequiredtoassesstheproposalinthecontextofthewidertidalrangeresource,includingfullconsiderationofalternativeoptionsaspartofatidalenergyplanorprogramme.

3 Comprehensiveanddetailedfeasibilitystudiesforthepurposeofevaluatingtheviabilityoftheproject,coveringdetailedcostestimates,materialsourcingandlogistics,updatedoutputpredictions,gridupgrades,sedimentarymodelling,impactonotherusers,impactonlocalandregionaleconomy,mitigationandcompensationoptionsforlosthabitat,andimpactonbirdsandfishspecies.

4 ComprehensiveanddetailedenvironmentalstudiesaspartoftheEnvironmentalImpactAssessment(EIA)andAppropriateAssessment,andotherstudiesasrequired,inordertosubmitaplanningapplicationandapplyforconsentunderSection38oftheElectricityAct1989.

Dependingonthescaleoftheproposal,specialprimary legislation, a ‘SevernBarrageAct’, is oneoption fordrawingtogetheroneormoreof theseprocessesinacoherentway.Legislationcouldsetupasingleprocessfortheconsentingofaproposal,oritcouldgofurtherandalsoestablishfinancingandinstitutionalarrangementsforaproject.

There may be some scope for one of more of

these stages to be combined or run concurrently,but this does give some broad indication of theprocess that would apply. Effective engagementandconsultationwouldberequiredthroughoutthisprocess,asdiscussedfurtherbelow.

4.10.2 The importance of engagement

TheUKGovernment(andwidersociety)isincreasinglyrecognising the important benefits to decision-making that can be gained through good publicand stakeholder engagement. Recent experienceclearly demonstrates where good engagementcan support and inform policy decisions,109 andwhere inadequate or no engagement results in afailure or derailment of political processes.110 Theentrenchment of positions and subsequent delayto (or abandonment of) policy that ensues canconfoundanyattemptstowardsamoreprogressive,efficientandeffectivedecision-makingprocess.

As more critical and complex issues, such asaSevernbarrage, cometo the topof thepoliticalagenda,thereisagrowingneedforanewmodelof engagementwithin our society to tackle thesechallenges. This model aims to bring togethergovernment,stakeholdersandthepublicinamorecollaborativeapproachtodecision-making.Ifwearetoaddress‘wholesystems’issues,toacknowledgescientificcomplexityandtorecognizethepotentialtrade-offs between competing needs, we need awhole systems approach for collective decision-making.

The issue of a Severn barrage is not currentlyhigh on the public’s list of concerns, but thatwould quickly change if a decision was taken infavouroftheconcept,withthepotential forhigh-profile campaigns on both sides of the debate.The complexity and interdependency of issuesandpotentialimpactsoftheSevernBarragemakeeffective engagement an intrinsic part of anydecision-making process relating to the barrage.This thinking lies behind the SDC’s own work onpublic and stakeholder engagement around tidalpowerintheUK.

Good governance and sustainable development

The SDC places great importance on promotinggood governance, which is one of the threeprinciplesunderpinningtheUK’ssharedframework


for sustainable development (see Section 1.2).Ourresearch,policyandpracticepointconsistentlyto the need to shift from old style governmentto governance. In otherwords,weneed tomovefromamodelwhereitissimplyexpertsthatdecide(andthencommunicatetheirdecision),toamodelwhere responsibility and ownership is distributedbeyondGovernmenttowidersociety.Theprinciplesofgoodgovernanceareconsistentacrossanypolicyor decision-making process, and are as applicableto the Severn barrage as to any other criticalsustainabledevelopmentissue.

Attheheartofgoodgovernanceistheneedtoengagethepublicandstakeholderssystematically.A two-way engagement process deepens theunderstanding and commitment of both decision-maker and participant. In doing so stakeholdersandwidersocietywillnotonlybemorepreparedto make changes themselves, but they will alsobe much more likely to permit, and not resist,the significant shifts in policy that sustainabledevelopmentrequires.

The benefits of engagement

From the Government’s perspective, public andstakeholderengagementoffersthefollowingdirectbenefits:

a) It informsthepublicandkeystakeholders,notonlythroughdirect/indirectprovisionofinformationbutalsobystimulatingfullerpublicdebateonkeyissues

b) Itensuresacceptable consultation processeswhichgenerateafullandusableunderstandingofthefullrangeofopinionsandaspirationsaroundkeyissuesanddecisions

c) Itallowstheinformationgainedtoincreasethevalidity and robustnessoftheresultingdecision,andthelikelihoodofitssuccessfulimplementation.

Inaddition,effectiveengagementprogrammeswould deliverwider, strategic benefits that are inlinewiththeGovernment’sprioritiesonsustainabledevelopmentanddemocraticrenewal:

d) Generatesharedownership and responsibilityacrosssocietyforaddressingthecriticalchallengesweface.Thiswillraise

thelikelihoodofsuccessfulimplementationofsustainablepolicies,ratherthanleavingGovernmentinadefensivepositionsearchingfor‘quick-fix’measures.

e) Understandhowtoengage and mobilise the nationoncritical,long-termstrategicdecisionsandchangeinvolvingsignificantcomplexityanduncertainty.Policy-makerswillincreasinglybepresentedwithcomplexissuesofstrategicimportance,whichneedtobedealtwithaswholesystemratherthansingleissues,takingintoaccountconflictingdepartmentalobjectives.Afull‘publicengagement’programmewouldenablesignificantshiftsinpolicyandaction.

To grasp the full range of benefits thatengagementcanbring,itshouldnotbeconceivedas a single activity. It is about applying a rangeof approaches to establishing new relationshipsthroughout the decision-making process, frominceptiontoimplementation.Furtherdetailscanbefound in theSDC’spositionpaperonengagementandsustainabledevelopment,111whichdescribesasetofbroadprinciplesforeffectiveengagementbyGovernmentandotherpolicy-makers.

Further engagement on a Severn barrage

There is a clear need for substantial public andstakeholder engagement if a decision is taken tofurther investigateproposals foraSevernbarrage.The SDC’s own engagement programme on tidalpowerwasnecessarilyhighlevel,andwasnotableto go into the depth that would be required on,forexample,thedifferentbarrageoptionsandthelikelyenvironmental impacts, for adecision tobemade.

Any further engagement process would needto ensure that there is a real chance to influenceGovernmentpolicyand theconditionsattached tothedevelopmentofaSevernbarrage.

4.10.3 Relevance of the Directives

As described in Section 4.6.2, the Severn Estuaryis protected by multiple designations, the moststringentofwhicharetheEUDirectivesonHabitatsandBirds,bothofwhichhavebeentransposedintoUKlegislation.TheaimoftheDirectivesistostem


biodiversitylossacrossEuropeasaresultofhumandevelopment.

ThepreambletotheHabitatsDirectivereaffirmsthe connection with the aims and principles ofsustainable development, with the implicationthatthelegislationisnotintendedtosimplyblockhuman development from occurring. Instead, thelegislation was established to protect unique andimportanthabitatsandspeciesbyplacingaseriesofconstraints to support environmental conservationobjectiveswhennewdevelopments areproposedonprotectedsites.

Supporters of the Directives argue that theyallow environmental conservation interests anequalvoiceatthetablewhendecisionsarebeingtakenonproposeddevelopmentsatprotectedsites.This is seen as progressive, as environmentalconcerns have historically been overlooked infavour of economic or social objectives. TheDirectives lay out a process by which prospectivedevelopmentsareassessed,withfullconsiderationofthealternativesandmitigationoptionsbeforeapolitical decision can be made. For the protectedhabitatsandspecies,anydecisiontoproceedmustthenbeaccompaniedbyacomprehensivepackageof compensatory measures designed to maintainoverallcoherenceoftheNatura2000network.

However, the SDC has heard from a numberof stakeholders who believe that the Directivesno longer reflect modern conservation prioritiesin light of the challenges represented by climatechange. The argument is that first, the Directivesmakenoallowanceforaprojectthat,byitsnature,seeks to mitigate against climate change; andsecond,thattheydonottakeintoaccountthefactthat ecosystems andhabitatswill be altered as aresultof thechangingclimate, regardlessofwhathumans do. These two arguments are used inrelationtoaSevernbarragetoquestionwhetheraspecialexceptionshouldbemadeforabarrageasaclimatechangemitigationmeasure,andwhetheritwouldbenecessarytoprovidecompensationwhenthe habitats being protected are already likely toundergochange.

Against this background, recent commitmentstostopfurtherbiodiversitylossarerelevant.Ataninternational and European level, the increasingurgency of stopping biodiversity loss has beenrecognised, and political commitments have beenmade to take action. In 2001, EU Heads of Stateagreed tohaltbiodiversity loss in theEUby2010andtorestorehabitatsandnaturalsystems.In2002,

they joined some 130 world leaders in agreeingto significantly reduce the rateofbiodiversity lossgloballyby2010.In2006,theEuropeanCommissionadopted a Biodiversity Communication and ActionPlan2006withanambitiouscommitmenttohaltthelossofbiodiversityby2010.112TheCommunicationparticularly recognises that climate change isone of the key priority areas for biodiversity, andthat strategic measures would be needed to helpbiodiversity adapt to unavoidable climate change.AstrongandcoherentNatura2000networkisalsoarecognisedpartofthisstrategy.

Interestingly, the 2006 Communicationparticularlyrecognisesthatweshouldbealerttotheriskthatclimatechangemitigationmeasuressuchasenergydevelopmentscoulddepletebiodiversity,andthatanypotentialdamageshouldbeminimisedandoffset.ThissuggeststhatthecurrentapproachoftheDirectiveshasbeenaffirmed,evenasclimatechange impactsandthe implicationsofmitigationformaintainingbiodiversityarerecognised.

The SDC believes that these issues arefundamental to taking a decision on a SevernbarrageandwediscussthemfurtherinChapter5.

The political dimension

Satisfyingthetestsofalternativesand’ImperativeReasonsofOverridingPublic Interest’ (IROPI), anddetermining appropriate compensatory measures,would need to be undertaken in part throughnegotiationanddiscussionsataEuropeanlevel.Atanearlystage,thelegalprocessandtheevidencerequired to inform thatprocesswouldneed tobeagreed.Forexample,adiscussionofalternativesinthecontextofUKenergypolicyandbetterevidenceofwhattheimpactsofbarragedevelopmentwouldbeontheprotectedfeatures,wouldbeapriority.

The SDC’s engagement with GovernmentofficialsandotherssuggestsincreasingrecognitionofthechallengeofclimatechangeamongMemberStatesandpotentiallysomepragmatism in theECin agreeing compensatory measures, particularlywith regard to large-scale renewable energydevelopments. However, this is untested and notnecessarilyuniversalwithintheEC;thereistheriskthatalegalchallengewouldleadtotheissuebeingdeterminedbythecourts.

The clear challenge of achieving satisfactorycompensatory measures has led a number ofcommentatorstosuggestpossiblewaysforwardon


aSevernbarragethat lieoutsidethecurrent legalframework:

• ReformoftheDirectivestogivegreaterimportancetothedevelopmentofrenewableenergyprojectsindesignatedareas

• DerogationfromtheDirectives,wherebytheUKcouldunilaterallydecidetoexemptabarrageschemefromtheenvironmentallegislation

Theseoptionsarenowdiscussedinmoredetail.

Reform of the Directives

The SDC has on several occasions heard the viewthattheEUDirectivesonHabitatsandBirdsdonottakeadequateaccountofthechallengeofclimatechange.Theassertion is thatasclimatechange isseenasagreaterenvironmentalthreattohumanity,any action that helps to mitigate climate change(such as renewable energy projects) should beviewed differently under the Habitats and BirdsDirectives,andgreaterflexibilityshouldbeshown.Anotherviewisthatclimatechangeprocesseswillalready cause irreversible damage to protectedsites,therebyrequiringamoreflexibleapproachtoconservation.

In the context of the Severn Estuary, thestatutoryconservationagencies’andothergroups’view is that the protected sites remain importantdespitethepotentialimpactofclimatechange.Forexample,althoughsomebirdsorplantspeciesmaymigrateordisappear,theexistenceoftheseuniquehabitatsmayprovideahometootherspecies,someofwhomwillthemselvesbemigratingfromfurthersouth.

Finally,tryingtoamendtheEUDirectivestodealwith one project could be a risky strategy, as theeventual scope of possible amendments would,once the process got going, be outside any onecountry’s control. As a result, the final outcomecouldbequitedifferent,andpossiblymuchweaker,than the instigator intended. Moreover, seekinglegislativeamendmentwouldnotbeaneasyoptionintermsoftimeandcost,andcouldbeseenasanunusualstepforaGovernmenttotakeinitssupportofasingleproject.

Derogation

TheSDChasalsoheardtheviewthattheimportanceofaSevernbarragemayjustifyaone-offderogationfromtheEUenvironmental legislation,possiblybyfailingtoprovidetherequisitecompensation(andamendingdomesticregulationsthattransposetheprovisionsoftheDirectiveintonationallaw).Thereis no mechanism within the Directive for doingthis.

This approach would represent a very seriousstep.AnimportantconsiderationwhenconsideringsuchanoptionistheUK’spositionwithinEuropeonbiodiversityandconservationissues.TheUKhasuptonowprideditselfonits leadershiproleonbothclimatechangeandbiodiversity,andasnotedabove,hasaffirmeditscommitmenttohaltingbiodiversitylossbysigninguptoand implementingmeasuressuchastheDirectives.

The SDC understands from senior Governmentofficials that theDirectivesarealready threatenedor overlooked by a number of Member States,andhavebeena significanthurdle for somenewMemberStatesenteringtheEU.Thereisthepotentialto jeopardise or open up important protectionsby seeking toderogate from theDirectives in thecontextofamajor renewableenergyproject.Thiscould have negative carbon consequences in thelong-run, by allowing projects to go ahead thatwouldotherwisehavebeenprevented(e.g.airportsormotorwaysinsensitivelocations).

4.10.4 Complying with the environmental legislation

ItisclearfromtheavailableevidencethataSevernBarrage would have a significant adverse effecton the integrity of the protected sites, althoughdifferent features would be affected to differentdegrees,andtheoverall impactwoulddependonthe particular barrage scheme. This triggers therequirementfortheUKtoundertakean‘appropriateassessment’oftheimplicationsofaprojectforthesite’sconservationobjectives.

It is the responsibility of the UK Government–ormorespecifically,the‘competentauthority’,forexample, the responsible Minister – to undertakeanappropriateassessment.Inpractice,theprojectdeveloper would prepare the evidence baseand submit all the relevant information to theconsentingauthorityaspartof theenvironmental


impactassessment.Iftheassessmentindicatesthatthe proposal may have negative implications forthesite’sintegrity,theprojectcannotbeapprovedwithout first going through the process describedbelow.

It is clear from the evidence, and from ourengagement with stakeholders, that a Severnbarrageproposalwouldhavea rangeof negativeimpacts that would require it to comply with thisprocess.

Step1 Consideration of alternatives

The Regulations require authorities to establishthat there are no alternative solutions before aprojectcanbeapprovedfor“imperativereasonsofoverriding public interest” (IROPI). Article 6(4)(4)referstothe“absenceofalternativesolutions”.

Government policy on the Habitats Directivestates that authorities should consider alternativesuitableandavailablesitesfordevelopmentwhichwould be reasonable alternatives, or identifypracticable approaches such as adapting workingmethods which would have less impact. On thisbasis, ‘alternative solutions’ seems to cover bothmitigation methods (ways to reduce or avoidaffectingsiteintegrity)aswellasalternativesinthesenseofotheroptionsandotherlocations.

European Commission (EC) guidance onexaminationofalternativesindicatesthatthisshouldinclude the ‘zero option’, and the conservationobjectivesandstatusoftheNatura2000siteshouldoutweigh consideration of costs, delays and otheraspects.TheMemberStateratherthantheprojectpromoter is responsible forconsideringalternativesolutions.

The requirement for a Strategic EnvironmentalAssessment would also mandate a wide-rangingconsiderationofalternativesaspartofconsiderationofaSevernbarrage.113ResearchReport3concludesthat the requirement foranSEAwouldapply toaSevernbarrageprojectandwouldneedtoincludeahighlevelreviewofUKenergypolicy.

Step2 Imperative reasons of overriding public interest

In theabsenceofalternativesolutions,authoritiescanonlyapproveaprojectbasedonIROPI.Reasonscan include the social and economic justificationfor a project. The UK Government states that it

“… expects there to be few cases where it willbe judged that IROPI will allow a developmentto proceed which has an adverse effect on theintegrityoftheinternationallyimportantSPAorSACdesignations”.114

AtaUKlevel,guidingprinciplesforconsiderationof IROPI include the provision of a clear anddemonstrable direct environmental benefit on anational or international scale. Other principlesinclude national security and defence, and a vitalcontribution to strategic economic developmentor regeneration. Theprinciplesadoptedby theUKGovernmentfavourprojectsofnationalandpossiblyregional importance.RecentEuropeanCommission(EC) guidance confirms that a long-term publicinterest is necessary to make a strong case.115The potential for a proposal to contribute togreenhouse gas reductions is cited as a particularexample of a relevant overriding public interest(for example, the EC refers to an example of aport development in the Netherlands involving atransportnodalshift).115

Step3 Compensatory measures

In the event that the overriding public interestof a project is judged to outweigh the natureconservation importanceofthesite,theDirectivesrequire compensatory measures to offset thenegative impacts of a project and to ensure theoverall coherence of the Natura 2000 network.Compensatory measures are independent of theactual project. This is in contrast to mitigationmeasures, which are undertaken as part of theprojecttominimiseadverseimpacts,suchasdesignandconstruction.

The issue of compensatory measures hasemergedasakeyissueforthestatutoryconservationagencies,butalsohassignificantpracticalandcostimplicationsforanySevernbarrageproposal.

Research Report 3 indicates that considerablefurtherworkwouldberequiredtopredictwhattheimpactswouldbeontherangeofNatura2000andRamsar features, and therefore what mitigationand compensatory measures might be possible.The report concludes thatprovisionof appropriatemeasures to satisfy the test of overall coherencewould be very challenging, “possibly to thepointofnotbeingdeliverable”,particularlyinthecaseoftheCardiff-Westonproposal.


Theconservationagenciessharethisview,94orgoevenfurtherandsuggestthatitwouldbeimpossibletoachieve,basedonavailableinformationaboutthescaleofaSevernbarrage(withreferencetoaCardiff-Westonalignment),knowledgeoftheNatura2000network of sites within the UK (number, locationandtype)andexperienceoffindingcompensatorymeasuresinthecontextofotherdevelopmentssuchasportdevelopmentandtheCardiffBaybarrage.

Article6oftheHabitatsDirectivedoesnotdefineprecisely what ‘compensatory measures’ mightmean, and appropriate measures are determinedonacasebycasebasis.GuidancefromtheEuropeanCommissionprovidessomeassistance,andindicatesthat the measures must ensure that the relevanthabitatsandspeciesareconservedatafavourablestatus within the biogeographical region.115 Theoverall aim is to prevent net loss to the networkintermsofqualityandquantity.Thecompensationshouldaddressthehabitatsandspeciesnegativelyimpacted, in comparable proportions, and shouldprovide ecological functions comparable to theoriginalsite.Distanceisnotnecessarilyanobstaclebut this depends on the function of the site, forexample,theSevernEstuary’slocationonthewestcoast of Great Britain and how it fits within theAtlanticregion.

There are a range of possible views as towhatmightbeacceptable inthecaseofaSevernbarrage. At the highest end, compensation mightbe approached on the basis that features mustbe replaced on a like-for-like basis, and that inthe caseofunique featuresor setof featuresnotexistinginanyotherlocation,compensationcannotbe provided. The implication is that developmentwhich destroys unique or irreplaceable features,suchas theuniquelyhypertidalestuarysystemoftheSevernEstuary,cannotproceed.

However, a less stringent interpretation couldseektoidentifycompensationforspecificattributes,suchascertainfishspeciesorintertidalhabitattypes.TheSevernEstuary’shightidalrangeisnotexplicitlyincluded in the features identified for under thecSAC, and the individually protected habitats andspecies are found in other locations and are notuniquetotheSevern.TheSevern’sstatusasaverylargeandhypertidalestuaryanditspositiononthewest coast of Great Britain would nonetheless berelevantfactors.

In practical terms, options for compensationinclude:

• creatingnewhabitat• restoringahabitatthatisinapoorstate• recreatinghabitatswithinthesite• recreatinghabitatsinotherdesignatedsites• recreatinghabitatsatnon-designatedsites

andthendesignatingthosesites• designatingotherUKestuariesnotcurrently

designatedasspecialareasofconservation.

It is clear that habitat creation (or recreation)at the scale of a Severn barrage would be costlyandtechnicallychallenging.Thesheerscaleofthechallengecanbeseenbycomparingcompensationthat has been provided for other projects.AtWallaseaIslandonEngland’seastcoast,amajorwetland habitat creation project established awetlandascompensationfortwoportdevelopmentsundertakeninthe1990s.116Theprojectisanexampleofusingmanagedrealignment(breachingaseawall)tocreatecompensatorycoastalhabitatandprovidesustainablecoastalfloodmanagement.Theprojectcost£7.5millionfor115haofnewhabitat.116

Compulsorylandpurchasecouldwellberequiredto provide space for habitat creation, and thecompensationwouldbeamajorprojectinitsownright.TheCardiff-Westonschemewouldinvolvethelossofsome145km2(14,500ha)ofintertidalhabitat(around70%ofthetotal),whichisindicativeofthescale of habitat creation that would be required.ClassificationofUKestuariesnotcurrentlyclassified(orrequiredtobeclassified)couldbeamorefeasiblewayofdeliveringcompensation.However,otherUKestuariesaresmallerthantheSevernEstuary,andmanyarealreadyclassifiedorbeingconsideredforclassification or development – for example theMersey.117

TheSDChasnotattemptedtoprovideanestimateofthetotalcostofprovidingcompensatoryhabitatas this would be a lengthy and complex processthat would require a substantial body of researchfollowedbynegotiationsbetweentherelevantUKorganisationsandtheEC.DuetotheimplicationsforaSevernbarrageproposalifadequatecompensationcannotbe foundoragreed, there isastrongcaseforprioritisingthiswork;ahighcostcompensationpackagewouldneedtobeconsideredalongsidethecapital costestimates forabarrageaspartof theeconomicviabilityassessment.

Conclusions and Recommendations

5


This chapter presents the SDC’s conclusions andrecommendationsontheroleoftidalpowerintheUK,andoutlinesourpositiononaSevernbarrage,takingaccountoftheanalysisandconclusionsfromChapter4.

Our consideration of a Severn barrage hasinvolved a staged process of evidence gatheringand engagement, through to final analysis anddiscussion.TheSDCstartedtheprojectwithakeeninterestinunderstandingtheuntappedpotentialoftidalpowertechnologiesinalowcarbonelectricitysystem – and with no fixed views on the issuesaround a Severn barrage. This has enabled us totake a completely fresh look at the opportunitiesandissuesinvolved,whilsttestingtheprinciplesofsustainabledevelopmentonarealandcontroversialquestion–whethertheGovernmentshouldfurtherconsideraSevernbarrage.

One of our aims with this report, and bypublishingourevidencebaseonourwebsite,isto

beastransparentaspossibleinhowwereachedourconclusions.Themainbodyofthereportisintendedasasummaryandanalysisofall theresearchwehavedrawnon,with a series of conclusions on awiderangeof issues.Thiswasusedasthesourcematerialforthediscussionsthattookplacebetweenthe SDC’s Commissioners, which focused on asmaller number of more controversial, high levelissues.Thesediscussionsculminated inaseriesofintensive SDC sessions in Cardiff over twodays inJuly2007,andincludedafieldtriptothebanksoftheSevernEstuaryandtheCardiffBaybarrage.TheminutesoftheSDC’splenarysessionsarepublishedonourwebsite.

This chapter is the product of these finaldiscussions,and represents theconsensusviewoftheSDC’sCommissionersonanumberofhighlevelissues. It laysouta clear setof recommendationsand challenges to Government to ensure theexploitationoftidalpowerinasustainableway.

5.1 A consensus view

TheUKhasaconsiderabletidalpowerresourcethatcouldbeexploitedtoproducerenewableelectricity.Although thedata is somewhatuncertain, currentestimatessuggestthatourtotalresourceisdividedroughly equally between tidal stream and tidalrangepotential,with a combinedoutput equal toaround10%ofUKelectricitysupply.

Thisillustratestheimportanceofconsideringalltheoptionsforexploitingthisresource,asanarrowfocusonjustoneproject(aSevernbarrage)couldbedetrimentaltothedevelopmentofawholeclassof emerging tidal stream technologies, some ofwhich could be sizeable generators of renewableelectricity in the UK, with great export potentialoverthelongterm.

5.2.1 Tidal stream

Long-term potential

TheSDCisenthusiasticaboutthepotentialoftidalstream technologies, subject to the constraintsthatmightbe imposeddueto locationally-specific

impactsupontheenvironmentandnaturalmarineprocesses,andthelong-termcostsbeingacceptable.TheUKisinauniqueposition,withasuperiortidalstreamresourcecombinedwiththelargestcollectionofdevicesbeingdevelopedortestedanywhereintheworld.ThisUKsuccessstoryistheproductofanumberoffactors,butthestrongleadershipshownbytheUKGovernmentandtheScottishGovernmentin providing support for marine renewables since1999isalsoanimportantfactor.

Tidal stream technologies could make asubstantial contribution to the sustainable energystrategiesoftheUK’sthreeDevolvedAdministrations.The UK’s tidal stream resource is concentrated inScotland, Wales and Northern Ireland and recentdevelopments in Scotland show the potential forpolicyinterventionatthedevolvedlevel.TheSDCisverywillingtoofferfurthersupporttotheDevolvedAdministrationstohelpmaximisethispotential.

Considering the progress that has been made on tidal stream, the objective now must be to ‘stay the course’. Inmanyways the tidal streamindustryisatthesamestageofmarketdevelopmentaswindpowerwas20yearsago,andthetimescale

5.2 Tidal power in the UK


for bringing prototype technologies to large-scaledeploymentneedstobeasfast-trackedaspossible.This will require continued support and politicalcommitmentforatleastthenexttwodecades,anda willingness to invest widely in the knowledgethat not all the devices under development willsucceed. The challenges for this nascent industryare considerable: securing the necessary publicandprivate investment,achievingcost reductions,accessing the grid, satisfying environmental andregulatoryrequirements–alongwithworkinginthedifficultmarineenvironment.

But the rewards are potentially large: thegenerationofasizeablepercentageofUKelectricitysupply, the long-term contribution to highlyskilledjobsandaknowledgeeconomy,theexportpotential, and as a contribution to global effortstoreducecarbondioxideemissions.Itisthislong-term perspective that must be adopted whentaxpayersareasked to invest in thedevelopmentofsuchtechnologies.Furthermore,consideringtheimportance attached to innovation policy by theStern Review, Government should ensure that itappliesanylessonslearnedfromthissectortothedevelopmentofotherlowcarbontechnologies.

Policy improvements

Ourengagementwithtidalstreamdevelopersandthose close to the industry suggests there are anumber of areas where Government policy couldbe improved. The support and funding structureswill need to be reviewed and improved in linewith circumstances as they develop and change.Forexample,aflexibleapproachshouldbetakenonthefutureofBERR’sMarineRenewablesDeploymentFund (MRDF), which has so far not had anyapplicants due todelays ingettingdemonstrationprojectsofftheground.ThesedelaysshouldnotbeviewedbyGovernmentasfailureofthetechnology,butasan indicationof the challenges facing tidalstreamdevelopers.Lessonscouldbelearntfromthesuccessof theScottishGovernment’s£8msupportpackage for marine energy technologies, whichhas had strong interest fromboth tidal andwavedevelopers.Increasedsupportformarinerenewablesunder a banded Renewables Obligation is alsovery welcome, and may provide an opportunityto revise the support available under the MRDFso that it focuses on providing grant funding forprojectdevelopmentand testing,with theaimof

stimulatingprogresstowardsinitialtidalarraysandpre-commercialschemes.

The European Marine Energy Centre in Orkneyis an excellent example of public sector fundingbeingused to stimulateprivate sector investmentand innovation in a strategic and efficient way.But theopportunity to realise the fullpotentialofEMECmustnotbemissed.Nowthattheinvestmentis made, there may be significant potential todevelop the services offered by EMEC, such asbaselineenvironment studiesand the certificationof devices, and to develop the centre’s marineresearchcapacity.ThiswouldrequireanincreaseinthecorefundingforEMEC,buttheSDCbelievesthatsuchanexpenditurewouldrepresentagooduseofpublicfunds.

Looking to the future, the SDC believes that there is potential to exploit the activity centred around EMEC to develop a regional ‘hub’ around Orkney and parts of the Caithness coastline away from the Pentland Firth for commercial testing of devices beyond the prototype stage.Theseasaround Orkney and Caithness represent an idealenvironment for testing inconditionsthatare lessseverethanthePentlandFirth,withthepossibilityofcreatingadditionalgridcapacityviaanotherlinktothemainland,andbyutilisingsparecapacityatDounreay.

In the long-term, a lack of transmissioncapacitywouldappeartobeaseriousconstraintondevelopmentoftheUK’stidalstreamresourceinthefarnorthofScotland.This isawiderproblemthatalsohasimpactsontheonshorewindindustryandwavepowerdevices.TheSDC’sreviewofOfgem,13

which looks at the ability of renewable energytechnologiestoconnecttothegrid,concludesthatthere are a number of problems with the current regime for connecting renewable generation and a real absence of long-term thinking on the solutions to overcome them. This has serious consequences for the UK’s ability to meet its targets for renewable electricity, let alone the more ambitious EU targets that will eventually be implemented.ThisisanissuethatbothOfgemandGovernmentwillneedtogettogripswithasamatterofurgency.

Strategic planning and consenting

Onstrategicplanningandconsenting,theframeworkmustbeclearandrobust.Thelackofgoodbaseline


informationonthemarineenvironmentandontheeffects of large-scale deployment of the differentdevices is a real issue. The gaps will have to befilled over time through research of a strategicandgenericnatureaswellasbydevelopers–butwill ultimately also be resolved through trial andperhapssometimeserror.Thiswillrequirearealisticapproach to risk in recognition of the big pictureenvironmental benefits of developing this lowcarbon technology. In the short term, the realityis that developers may need extra support withtheenvironmental impactandconsentingprocess.Therealsoneedstobemorecoordinationbetweenenergypolicyandtheconsentingregimetoensurethatappropriatesitesareselectedfordevelopment,thuslesseningthetimeandcostinvolvedingainingconsent.

Finally, the need for a strategic environmentalassessment(SEA)tobeundertaken–incombinationwitha leasingcompetitionfordevelopmentrightstoseabedownedbytheCrownEstate– isalreadyrecognised as a step that will be taken whenthe industry reaches the stage of commercialdeployment.Butthetimingwillbecrucial.AnSEAcanbeseenasanopportunitytointegrateinterestsinmarineconservationandpotentialconflictsofusein themarineenvironmentwithfishing, shipping,andrecreationalactivities,whileatthesametimeproactively influencingand supportingappropriatesiteselection.Thisapproach–whetherintheformofanSEAorinamarinespatialplanningframeworkunder a new Marine Act – will have a long-termimpactonhowtheindustrydevelops.TheScottishGovernment is in the process of completing astrategic environmental assessment for marinerenewables around the west and north coasts ofScotland, and the Welsh Assembly Government isalsodevelopingamarinerenewablestrategy.

5.2.2 Tidal lagoons

It is very difficult to come to a clear viewon thelong-term potential of tidal lagoons due mainlyto the lackofauthoritativeevidence,and the factthat the concept remains unproven. The pictureis exacerbated by the controversy around costestimates,and the tendencyofsometidal lagoonproponents to position the concept in opposition,andasanalternative,toaSevernbarrage.

The SDC’s analysis of tidal lagoon potentialindicates very few direct conflicts with barrage

proposals, with the exception of large-scale tidallagoon development, or a Russell Lagoon typescheme,intheSevernEstuary.Thereislittleevidencetosuggestthatsuchlarge-scaleproposalswouldbeeconomicallypreferabletoaSevernbarrage,anditispossiblethattheywouldcumulativelycauseatleastas much environmental disturbance. Conversely,there are a number of potential sites around theUKwheretidal lagoonsmaybetechnicallyviable.These are generally areas of relatively shallowwaterwhere there isagood tidal range resource,andincludepossiblesitesaroundtheSwanseaBay(forapossiblesmall-scaledevelopment),LiverpoolBay,andthemouthoftheMerseyEstuary.

Despitetherebeingnoexamplesoftidallagoonsanywhere intheworld, thetechnologiesusedarenotinthemselvesneworinnovative;theinnovationisintheconcept,designandconstruction.Thisplacestidallagoonsinadifficultpositioninrelationtotheavailablefinancialincentivesforrenewableenergytechnologies, which are currently justified on thebasisof innovationand long-termcost reductions.Thesituationisnothelpedbytheinsistenceofsometidal lagoon proponents that the technology doesnotrequiresubsidiestobeeconomicallyviable.

A lagoon concept does offer some obviousbenefitsoverabarrage;dependingon itspositionand size, fish and navigation passage might beaffectedtoafarlesserdegree.However,anoffshorelagoonstillinvolvesasubstantialcivilstructureinacoastalbayorestuary,and it followsthat lagoonswouldnotnecessarilybetheenvironmentallybenignsource of tidal energy that is sometimes claimed.The impact of a tidal lagoon structure on coastalprocesses and sediment transport needs carefulevaluation to test the environmental acceptabilityofpotentialschemesincoastalareas.

Theconceptalsohasmeritinofferingpotentialopportunities for community involvement inownershiporpartnershipofascheme;thisisbeingactively investigated in north Wales. But publicacceptabilitywouldneedtobeaddressedthroughengagement around information and awarenessgaps inenvironmentalandsocial impacts,aswellasthe importantquestionofvisualand landscapeeffectsatalocallevel.

The SDC’s conclusion is that there is a strongpublicinterestinseeingthedevelopmentofoneormoretidallagoondemonstrationprojectstotesttheconcept,andprovide real-lifecost,energyoutput,and environmental data. Demonstration projectscouldhelpidentifycost-savings–forexample,inthe


useofinnovativematerialsorimprovedconstructionmethods–andthismayjustifyfinancialsupportfortidallagoons.Anyproposalswouldneedtocomplyfully with the relevant environmental legislationandconsentingprocesses,andthisprocessinitselfcouldbeausefullearningexperience.

We therefore recommend that the Government investigates options to encourage one or more tidal lagoon demonstration projects. This could take the form of inclusion intheRenewablesObligation,oranopencompetitionto solicit private sector or community interest.The additional expenditure would not need to belarge,butthepotentialbenefitscouldbeextensiveconsidering the resourceavailable,both in theUKandinternationally.

5.2.3 Tidal barrages

Ouranalysisoftidalbarrageshasinevitablyfocusedon the question of a Severn barrage. This reflectsourremitonthisproject,theextensiveinformationalreadyavailableontheseproposals,andthepractical

realitythattheSeverncontainsthemajorityoftheUK’s tidal range resource. We have also reviewedanumberofothertidalbarrageoptions, includingproposals for theMersey. Theredoesnot seemtobeanextensiveoverlapbetweentidalbarragesandtidalstreamdevices,leadingtotheconclusionthattheycan,onthewhole,beconsideredseparately.

TheUK’spotential fordevelopinganumberofdifferenttidalbarrageoptionsotherthantheSevernisextensive.Themainreasonwhythispotentialhasnotbeendevelopedinthepastisthattheschemesstudiedhaveappearednottobeeconomicallyviable.Moreover, tidal barrages, like large hydropowerschemes, can be hugely disruptive to the localenvironmentandestuarysystems,andcanhaveanumberofregionaleconomicandsocialimpacts,allofwhichneedtobeconsidered.The SDC is therefore supportive of further investigation into UK tidal barrage options outside of the Severn Estuary,althougheachshouldbeconsideredonacase-by-casebasisasthepotentialbenefitsandimpactswilldifferconsiderably.Furthermore,theconclusionswehavedevelopedona Severnbarrage (seebelow)maybeapplicabletootherbarrageproposals.

Theproposal fora tidalbarrageacross theSevernEstuary brings into sharp focus all five of the UKGovernmentprinciplesofsustainabledevelopment.There isnodoubtthat itwouldmakea long-termand significant contribution to reducing carbondioxide emissions from electricity generation,andwould help improve theUK’s energy securitythroughitspredictabilityofoutputandbyavoidingthe import of fossil fuels. At the same time, itwould have profound and irreversible effects onan internationally important hypertidal estuarysystem.

The SDC began its in-depth discussions on aSevern barrage from a general position in favourof thedevelopmentof renewableenergysources,recognising that renewable energy has a crucialrole to play in mitigating against climate change.Our approach, therefore, was to examine theconditionsunderwhichaSevernbarragemightbesustainable.118Wethenworkedthroughtheissuestoseewhethertheidentifiedbenefitswererealandmaterial,andwhichofthenegativeimpactsmightbe ‘deal-breakers’ unless dealt with adequately.

Our discussion of deal-breaking issues led toagreementonasetofconditionsthatwouldneedto be fulfilled for any project to be sustainable.A number of these conditions represent majorchallengesforcurrentGovernmentpolicy.

The subtlety of this approach is important.The SDC is neither advocating unquestioningGovernment support forabarrage,nor isouraimtosuggest conditions thatwouldeffectivelymakeitsdevelopmentimpossible.Instead,werecognisethe importance of giving serious consideration toa Severnbarrage,within a framework thatplacesa high value on the long-term public interestand on maintaining the overall integrity of internationally recognised habitats and species.

This section draws on the analysis andconclusions from Chapter 4 to present the SDC’sconsensuspositiononaseriesofhigh-level issuesthat are fundamental to ensuring a sustainableSevernbarrage.Wedonot takeapositionon therelativemeritsofthevariousbarrageschemesbuthaveinsteadconsideredtheissuesgenerically,withan inevitable focus on the larger Cardiff-Weston

5.3 Conditions for a sustainable Severn barrage


scheme due to the availability of more detailedevidenceandthegreaterdegreeofimpactitwouldhave–environmentally,economicallyandsocially.

5.3.1 Energy policy context

In considering the benefits of a Severn barrage,wehaveanumberofconcernsaboutitsimpactonwiderenergypolicy. Inparticular, there is the riskthat sucha largeproject coulddivertGovernmentattentionawayfromthehugeeffortthatisrequiredin reducing energy demand, encouraging otherrenewables,developingsustainableheatnetworks,andoncarboncaptureandstorage.TheSDCisalsoconcernedthatsuchaprojectcouldsendthewrongkindof signals to consumers,with the risk that itcouldfurtherentrenchcitizens’separationfromthesourceoftheirenergyandtheresultingimpacts,andcouldthereforeencouragecomplacencyinreducingenergydemand.

Someoftheseissuesemergedduringourreviewofnuclearpower,leadingustoidentifythenegativeimpactthatanewnuclearprogrammemighthaveon reducingenergydemandandon technologicallock-in as two of our five key disadvantages.A Severn barrage could also have thesedisadvantages,andwouldnotmoveusanyclosertoamoredecentralised,flexibleenergysystem.

The SDC has been encouraged by the positiveattitude shown in the 2007 Energy White Papertowards tackling energy demand and sustainableheat issues, but we remain concerned that theGovernmentisnotyetwillingtomatchitsambitionswith the radical policies needed to deliver them.And while there have been a number of positivedevelopments on climate change policy moregenerally–inparticular,theClimateChangeBill,andthecommitmenttomandatezerocarbonstandardsfornewhomesby2016–theGovernmentdoesnotyet seem to have policies in place to deliver therequiredcarbonsavingsoverthenext15years.

Encouragingly, public awareness of climatechangehasincreasedoverthelastcoupleofyears,providingagreaterdegreeofpoliticalspacefornewmeasures to reduce emissions. This is particularlytrue when action on climate change can bedesignedtoachieveothergoals,suchascombatingfuelpoverty,increasingeconomiccompetitiveness,andimprovingpeople’squalityoflife.Forexample,proposals to break the link between increasedenergy consumption and the profits of energy

supply companies (the ‘Supplier Obligation’) havethepotentialtoimprovetheinformationprovidedtohouseholdsthroughsmartmetersandaccuratebills,whichalongwithgreaterprovisionofenergy-savingmeasures (suchas insulationandmicrogenerationoptions) could potentially save them money.For commercial organisations, emissions tradingschemessuchastheCarbonReductionCommitmentortheEUEmissionsTradingSchemecanhelpintheidentification of energy savings, whilst rewardingthosewhoarelowemitters.

InthiscontextwebelievethatitispossiblefortheGovernmenttotakeonalargeprojectsuchasa Severn barrage without diverting its attention(and associated resources) from other priorities.But developing a Severn barrage option wouldundoubtedlybeabigtestofGovernment’swillingnesstotacklethechallengeofclimatechangethroughawholerangeofpolicyinterventionswithoutsimplyoptingforthe‘onebigsolution’approach.Instead,Government could use the symbolic nature of aSevernbarrageasanexampleofthescaleofactionrequired.

ASevernbarragewouldneedtobejustonepartofamajor, long-termstrategyforreducingcarbonemissions,withconcertedactionatalllevelsoftheenergy hierarchy. It would also need to developoptions for both centralised and decentralisedtechnologies,asregardlessoftheprogressmadeonthe development of decentralised energy sourcesand reducingenergydemand, theUKwill requirelarge-scale, centralised electricity generation fora very long time. A Severn barrage would be arelativelywell-placedcentralisedsupplyoptionduetothecloseproximityoftheSevernEstuaryresourcetolargecentresofelectricitydemand,whichwouldlimittheneedformajorgridreinforcementsandanypotentialconflictwithdecentralisedsupplyoptions.

5.3.2 Ensuring the public interest

If pursued, a Severn barrage would be a majorinfrastructure project and a long-term addition tothelandscapeandtheregionaleconomy.Thismeansthat,regardlessofhowitisfinanced,itwouldbeanimportantpublicassetformanygenerations.Gettingitbuiltwouldalsorequiresubstantialpoliticalcapitalduetothecomplexityoftheprojectandtheneedtonavigateanumberoffinancialandlegalhurdles.As a result, the SDC believes that any decision infavourofaSevernbarragemustbeconditionalupon


upholding the long-term public interest, both intermsofhowtheprojectisdesignedanddelivered,andinitsownership.

Apportionment of risks and benefits

OuranalysisinSection4.8concludesthatabarrageschemecouldnotbefinancedbytheprivatesectorwithoutsignificantGovernmentinterventioninthemarket(andastrongleadonprojectinitiationandconsents) to create an attractive set of conditionsfor investment. However, the SDC has a numberof concerns over the apportionment of risks andbenefitsforaprivatesector-ledproject.

Inadditiontotakingtheleadonprojectinitiation,which would involve substantial expenditure onenvironmentaland feasibilitystudies,Governmentwouldmostlikelyhavetounderwriteprivatesectorinvestmentthroughtheprovisionofnewincentivesorguarantees.ThisisbecausetheelectricityoutputfromaSevernbarragewouldnotbeeconomicallycompetitive with other forms of low carbonelectricitygenerationifacommercialrateofreturnisrequired,particularlyintheabsenceofarealisticandstablepriceforcarbon.

Despite taxpayers and/or consumers takingontheserisksanddirectcosts,therewouldbenoguarantee that the project would proceed to theconstructionstage,particularlyconsideringthelargenumber of hurdles to pass along the way. Thereis also a high risk of moral hazard, which meansthat those involved in building a barrage mighttakeonhigherrisksthantheymightotherwise,orsystematicallyunderestimatecosts,inthe(probablycorrect)expectationthattheprojectwouldnotbeallowed to fail. This could lead to a Governmentbail-outinthecaseofcostoverrunsorconstructionproblems.

As a result, a private sector-led project wouldpass all the additional costs, anda large shareofthe risks, to thepublic sectorwithout providing acommensurate share of the benefits. Conversely,the private sector owners would stand to enjoyownership of a sizeable public asset offering aguaranteedreturn.Inourview,thisisnotconsistentwithensuring the long-termpublic interest and itwouldnotprovidegoodvalue for the taxpayerorconsumers.

Avoiding short-termism

Therequirementforthehighrateofreturnnecessarytoattractprivatesectorinvestmentwouldbehighlylikelytodriveadangerouslyshort-termistapproachtothedesign,deliveryandoperationofabarrage.Thisdoesnotappeartousasanappropriatewaytofundacapital-intensiveprojectwithsuchlong-termbenefits.

Tomaintainahighrateofreturn,privatesectordeveloperswouldhavea very strong incentive tomaximise overall revenues, and would want toattract complementary investment around theproject.There isaserious risk that thiscould leadtowiderdevelopmentpressuresthatwouldnotbeinthelong-termpublicinterest;forexample,badlydesignedor constructedhousingdevelopments ormultiple new roads, both of which could increasenet carbon emissions and pressures on the localenvironment.

Thereisalsotheissueofconstructionmethods:aprivate sectordevelopermaynotbesufficientlyincentivisedtospecifythehighestqualitymaterialsor constructionstandardsas theirpaybackhorizonisunlikelytoextendmuchbeyond40years,ratherthantheexpected lifetimeof thestructureof120years.Thiscouldleadtothedesignandconstructionofasub-optimalstructurethatwouldbelesslikelytostandthetestoftime.Finally,therewouldbenodirectincentivestodesignandoperatethebarragetomaximise coastal flood protection benefits andtomanagetherisk fromupstreamfluvialfloodingevents where these coincide with high tidalconditions.

Approaching the financing issue through thelensofprivatesectorownershipwouldnot, inouropinion,takeadequateaccountofthevalueofthesecure,lowcarbonelectricitythatabarragewouldproduce over the long-term. For example, thereis an obvious mismatch between the timescalesbeing considered for cap and trade schemes orrenewables incentives, and the expected lifetime(andconstructiontime)ofabarrage.Acomplianceperiod of 20 years is currently seen as long-termforcapandtradeschemes(aUKmanifestoonthefutureof the EUETS calls for emissions trajectoriesupto2030),119andtheRenewablesObligationonlyoperatesupto2027.Thisalsoimpactsonsomeotherlow carbon technologies, but would particularlyapply to a barrage with its construction period ofat least 5-7 years and an operational lifetime of120years.


Regional impacts and priorities

Inadditiontoshort-termism,theSDChasconcernsover the ability of private sector developers toadequately take account of economic and socialconsiderations, or the need for an integratedapproach to strategic planning at a regional andlocal level. Thishas implications for the impactofaSevernbarrageonexistingports,thepotentialfornewtransportlinksusingabarrage,andtheimpactduring the construction phase on housing, localbusinesses,andthesupplyofaggregates.

The complexity of the issues underlines theneed for a coordinated approach to the planningofabarrageandits impactonexistingandfuturedevelopment.Forexample,abarragecouldhaveanegativeeffectonthelong-termeconomicviabilityof existing ports in the region, leading to a lossof business and possibly the creation of new orexpanded capacity elsewhere. This could in turnhave implications for net carbon emissions (as aresultof lessefficient freightmovements)and forthepressureonhabitatsinotherlocations.Itwouldthereforebe importantforaSevernbarragetobeconsideredinthecontextofotherpoliciesandplans–inthiscase,portspolicy,andthelong-termoutlookforshippingintheUK.

Private sector developers are less likely toconsidersuchissuesvoluntarily,leadingtoaheavyrelianceontheregulatoryandconsentingfunctionsof Government and the economic developmentorganisations to ensure that regional interestsareupheld.TheSDCbelievesthatthisapproach isproblematicforsuchalargeandcomplexproject.

5.3.3 Complying with the environmental legislation

The Severn barrage proposals are located in anestuary that has high levels of environmentalprotection under national and internationallegislation, and its construction would involvelarge-scaleandirreversiblechangetothehypertidalestuaryecosystem.Thisdynamicraisesaparticularset of scientific, moral and legal questions thatare relevant to the strategic consideration of theschemes.

Natura 2000 and biodiversity

Chapter 4 summarises theprotected status of the

Severn Estuary, including the aims and objectivesof the European environmental legislation, andanalyses the likely impacts that a Severn barragewould have on the protected features based onavailable information. The overall integrity ofthe Natura 2000 network, and the biodiversityobjectives it upholds, is central to the science-ledapproachtoconservationthatallEuropeancountrieshaveadopted.

A number of commentators have suggestedthattheobjectivesembodiedinthelegislationmaynotbefitforpurposeduetothechallengesposedby climate change, because in a rapidly changingclimatethenaturalrangeofmanyspecies,oreventheirveryexistence,maychange.TheSDChasnotbeen persuaded by these arguments. It is simplyuntruetoclaimthattheHabitatsandBirdsDirectivesare based solely on the approach of protectingexistingsiteswithfixedboundaries.

The Directives are founded on the principle ofmaintainingviablepopulationsofsometimeshighlymobilespecies,suchasmigratoryfishandbirds,andofensuringaseriesoffunctioninghabitattypesoveran extensive biogeographic range spanning manyMemberStates.Designationofsitesisavitaltool,butonlyonetool,todelivertheseends.HabitatlossintheSevernEstuaryneedstobeconsideredwithinthe context of the biogeographic region of whichtheestuaryisapart,andwithinawiderEuropeanandinternationalcontext.

First, it is important to clarify what is meantby biodiversity. As discussed in Section 4.10.3,biodiversity is a measure of both quality andquantity, and therefore of distinctiveness. Somehabitatsareglobally importantbecausetheyhaveauniqueassemblageofjustafewspeciesinlargenumbers (e.g. arctic tundra), others because theyhave smaller numbers of a very wide range ofspecies(e.g.tropicalrainforest).Replacingadistinctassemblageofasmallnumberofthreatenedspecieswith a larger number of common species doesnot constitute an increase in global biodiversity.So,althoughaSevernbarragemayresultinagreaterquantity of animal and plant life developing in aless extreme environment, this does not of itselfcompensateforthelossoftheexistinguniqueandenvironmentallyimportanthabitatsandspecies.Theaimofenvironmentalconservationis,inthewordsoftheRSPB,“toconservethespecial,notmakethespecialordinary”.67

Second,itisclearthatclimatechangeisalreadyhavingameasurableimpactonsomespeciesinthe


estuary,butthereisnoevidencetosuggestthatthehabitatsitcontainswillbeanylessimportantinthefuture.Numbersofsomebirdspeciesoverwinteringintheestuaryhavedecreased,insomecasesquiteconsiderably, and this is attributed to warmerwinterswhichpresentlymakeestuariesfurthereastmoreattractive.Thenumbersofotherbirdspeciesusing the Severn Estuary have increased. Theestuarycontinuestosupportpopulationsofbirdsatinternationally important percentages, and it willcontinuetobeimportantinconservationtermsevenif its importance for different species increases ordecreasesovertimeinresponsetocomplexclimaticchanges.Inthewiderglobalcontext,theimperativeto protect biodiversity will take on an increasedimportance as action is needed to ensure thatspecieshavespacetomoveinresponsetochangingclimateandcoastalregimes.Despitesomechanges,conservation and biodiversity protections shouldnot be abandoned or ignored because of climatechange.Rather,environmental conservationpolicyneedstoconsiderbiodiversityobjectivesinalong-termcontexttotakeaccountofclimatechange.

Although the hypertidal nature of the SevernEstuary createshabitats that to somemayappearmuddyandunattractive,itisexactlythesefeaturesthatmakeituniquefromabiodiversityperspective.Thehabitatsitcontainsarelikelytocontinuetobehugely important as a feeding site for migratorybirds and for fish species, and are therefore anessential element of the Natura 2000 network.The SDC therefore accepts that maintaining the overall viability of these habitats and species is a statutory obligation that should be vigorously upheld.

Applying environmental limits

The SDC has given careful consideration to therelevance of the EU environmental legislation(‘theDirectives’) tothe issueofaSevernbarrage.Our conclusion is that the Directives are a legalembodiment of ‘living within environmentallimits’, which is one of the five UK principles forsustainabledevelopment.TheDirectivesareguidedby ‘soundscience’,andestablisha cleardecision-makingprocessthat is intendedtofacilitate‘goodgovernance’ whilst recognising the importance ofeconomicandsocialgoalsindevelopmentdecisions.TheyestablishclearenvironmentalprotectionsforasmallpercentageoftotalUKlandandmarinearea,

andareintendedtoensurethatbiodiversitywithinEurope and internationally is maintained and,ideally,enhanced.

The practical implementation of ‘living withinenvironmental limits’must eventually lead to theestablishmentofabsolutelimitsoncertainaspectsofhumandevelopment.Notdoingsowouldrenderthetermmeaningless.Therefore,theDirectivesshouldbe seen as representing an enlightened approachtodealingwithenvironmentalconstraints,andonethatisattheheartofsustainabledevelopment.

TheDirectivesalso setan importantprecedentforotherareasofenvironmentalpolicy.Forexample,the introductionofcapandtradeschemesfor theregulation of greenhouse gas emissions, alongwith the proposal for binding annual targets forreductions inemissionsunder theClimateChangeBill,showshow‘livingwithinenvironmentallimits’can be applied to climate change. The regulationofwaterbornepollutants from industrialprocessesandsewagetreatmentisanotherclearexampleofenvironmental constraints being given a statutorybasis.

Asaresult,theSDC’sviewisthatany proposal for a Severn barrage must fully comply with the Directives and adhere rigorously to the process they set out. We would be firmly against any moves to revise or derogate from the Directives to facilitate proposals for a Severn barrage.

Thisconclusiondoesnotmeanthatdevelopmentcannotoccur.TheDirectivesexplicitlyacknowledgethattherearecircumstancesinwhichdevelopmentmightbejustifiedinprotectedareas,andestablishaclearprocessformakingthatjudgement.

Very simply summarised, the process beginswith a requirement for Government to undertakean ‘appropriate assessment’, supported by goodevidence, of how the site would be adverselyaffectedby theproposeddevelopment.Assumingtheresultoftheappropriateassessmentshowsanadverseeffectat thesite, thentheproposalmustpassthroughaseriesofthreetests,asfollows:

4. Consideration of alternatives:Thefirsttestthenrequiresanassessmentofthealternatives,includingthe‘zero’(no-development)optionandwaystomitigateagainstanyadverseimpacts.

5. Overriding public interest:Iftherearenoviablealternativestothedevelopment,thenapoliticaldecisioncanbetakentoproceedonthebasisof‘imperativereasons


ofoverridingpublicinterest’.ThisdecisionwouldnormallybetakenbyaGovernmentMinister.

6. Compensation requirement:Ifthisisthecase,thereisthenacompulsoryrequirementtoprovidecompensatoryhabitattoensuretheoverallcoherenceoftheNatura2000network.Thepracticalityandcostofthisrequirementrepresentsthefinaltestoftheoverallviabilityoftheproposal.

Webelievethatabarrageproposalwouldmeetthe first two tests of the Directives with relativeease. Although a broad interpretation of ‘viablealternatives’ could be taken, a more realisticinterpretationmightbetoconsiderthealternativesfor harnessing the tidal range resource in theSevern Estuary on a large scale. This would needto consider the relativemerits of large-scale tidallagoondevelopment, although there seems tobelittle evidence to suggest that this would be lessdamagingthanalargebarrage.EvenifaverybroadinterpretationweretakenthatlookedatthewholeUKenergysystem,itishighlylikelythatacompellingcasecouldbemadeforaSevernbarragebasedonitsrenewablecredentialsandreliability.

Assumingthisfirsttestcouldbemet,thentheGovernmentwouldneedtobeconvincedthatthereare‘imperativereasonsofoverridingpublicinterest’forabarragedevelopmenttoproceed.Basedonitspotentialcontributiontorenewableenergytargetsandtoreducinggreenhousegasemissions,itseemshighlylikelythatthissecondtestwouldbemetaswell.

This leadsdirectly to a requirement toprovidecompensatory habitat, reflecting the importanceof the Severn Estuary within the Natura 2000network.

Providing compensatory habitat

The aim of the compensation requirement of theDirectives is to ensure overall coherence of theNatura2000network.Thescaleofhabitatcreationrequired to provide adequate compensation for aSevern barrage project would be unprecedentedwithin the UK. Nevertheless, the SDC considers ittechnically,legallyandfinanciallypossibleforawaytobefoundgivensufficientpoliticalwill.

A habitat compensation package on thisscale would be a major project in its own right.

Therewouldalsobea substantial up-front capitalcostsattachedtosuchaschemewhichwouldraisethe cost of electricity output for a Severnbarrageasthesewouldneedtobeabsorbedaspartofthedevelopment. It is clear that the compensationrequirement would be the biggest test that anybarrageproposalwouldhavetofaceandmayevendeterminetheoverallviabilityoftheproject.

However, the SDC believes that it would beuntenablefortheGovernmenttotakeadecisioninfavourofaSevernbarrageunlessitispreparedfortheUKtodemonstrateitscommitmenttoupholdingthe integrity of the environmental legislation andtheprocesses ithassignedupto.Failuretodosowould undermine the Directives, set a dangerousprecedenttootherEUMemberStatesandcountrieselsewhere in the world, and would not deliver aSevern barrage consistent with the UK’s agreedframeworkforsustainabledevelopment.

Asaresult,theSDCrecommendsthatdiscussionoverthecapitalcostofaSevernbarrageassumestheinclusionofthefullcostofprovidingcompensatoryhabitat, pending further investigation into itsscientific, practical and economic feasibility. Inthemeantime, thecapitalcostfiguresprovided inChapter 4 should be treated as construction-onlycoststoavoidasystematicmisrepresentationofthetotalcostofasustainableSevernbarrage.

5.3.4 Our advice to Government

Ourconclusionsontheenergypolicycontextforabarrage,theneedtoconsiderthelong-termpublicinterest, and the importance of upholding theenvironmental legislation lead the SDC into newterritory.BelowweoutlineouradvicetoGovernmentontheconditionsnecessaryforasustainableSevernbarragedevelopmentbasedontheseconclusions.

Wider action on climate change

ThepolicycontextforanydecisiontakenonaSevernbarrage is important. The benefits of a barrage(equivalent to just over two large conventionalpowerstations,butoperatingforaverylongtime)areextremelysubstantialfromaclimatechangeorenergysecurityperspective.Nevertheless,aSevernbarragewouldstillrepresentjusta5%contributiontothedecarbonisationofelectricitysupply,fallingtolessthan1%asacontributiontototalenergyuse.


The Government would need to ensure that a decision in favour of a Severn barrage was only part of a major effort to deliver at least a 60% cut in greenhouse gas emissions by 2050,120implyingalmost completedecarbonisationof theelectricitysystemandradicalactiontoreduceenergydemand.AshighlightedbytheSternReview,22thiswillrequireacombinationofcarbonpricing,astronginnovationpolicy,andactiontoremovebarrierstobehaviouralchange.FromtheSDC’sperspective,thewillingnessofGovernment toput inplace the radicalpoliciesneeded on energy demand, greater decentralisedsupply and technology innovation should be aprerequisiteforanydecision infavourofaSevernbarrage.

An environmental opportunity

The requirement to provide compensatory habitatisgenerallyseenasadeal-breakingobstacleforaprospectiveSevernbarragebybothproponentsanddetractorsalike.TheSDCbelievesthatthisaccountsformuchoftheratherdangerousdiscussionaroundreform of, or derogation from, the Directives, orconversely, for the view that a barrage schemewouldbeimpossibleunderanycircumstances.

Instead,thereisclearlyauniqueopportunitytodevelopacompensatoryhabitatspackagethatseekstorespondtothechallengesofclimatechangeinapositiveway.Ratherthanaprocesswhichattemptstocreateequivalenthabitatonanarrowly-definedbasis, a progressive strategy would look at thelong-term coherence of the Natura 2000 network(the legal test tobesatisfied),and the typesandlocationsofhabitatrequiredtosupportitwithintherelevantbiogeographicregion.Thiswouldexplicitlyaimtoadapttoclimatechangebyusingthefundingavailable from the compensation package (whichinturnismadeavailablebyanincome-generatingenergyproject)tocreatenewcoastalandwetlandhabitatsonanationalscale,aidingbothbiodiversityandcoastalprotectionobjectives.Inreality,theUKalreadyfacesthischallengeintacklingsealevelrisewith implications for coastal defences and loss ofintertidalhabitat.

The SDC believes that such a strategy wouldrepresentasignificantadvanceintheimplementationof European environmental legislation by joiningbiodiversity and climate change objectivestogether,andbylinkingclimatechangemitigationandadaptationaspartofa long-termframework.

Itthereforerepresentsasubstantialenvironmentalopportunity, but one that would be a huge testof the Government’s commitment to sustainabledevelopment,andtotheevolutionofenvironmentalconservationinthefaceofclimatechange.

The need for public ownership

Wedonotbelieve itwouldbepossible todelivera sustainable Severn barrage through the privatesector. Considering the scale of the project, theassociated risks, and the complexity of the issuesinvolved,webelievethatabarragewouldneedtobepublicly-ledasaprojectandpublicly-ownedasanassettoensurelong-termsustainability,compliancewiththeenvironmental legislation,andmaximumpublic benefit. This does not rule out innovativefinancingoptionstohelplevercommunityorprivatesectorinvestment;infact,theremaybeanumberof innovative financing options that Governmentcouldexplore.

Therearesomesignificantbenefitstoaprojectfinancedandownedbythepublicsector. Itwouldenabletheuseofalowdiscountrate(possibly2%),justifiedbythelong-termpublicbenefitstheprojectwouldbring.ThisissupportedbytheSternReview,which recommended that a very low discountrate be used when evaluating long-term climatechangemitigationmeasurestotakeaccountoftheintergenerationalbenefits.Usingalowdiscountratewould substantially reduce the cost of electricityoutput,makingithighlycostcompetitive.

The benefits of a low discount rate could alsobe applied to other aspects of the scheme – andin particular, the cost of a compensatory habitatspackage. The costs of large-scale habitat creationbecome much more manageable when they arevaluedinawaythatbetteraccountsfortheirlong-term benefits to the country. The SDC believes that a public sector-led approach would be the best way to reconcile the need for low carbon electricity generation with the protection of internationally important habitats and species.

Wearenot calling for theUK’s energy systemto be renationalised, nor do we believe that ourrecommended approach should necessarily beappliedtoother technologiesorsectors.However,foranumberof reasons,aSevernbarrageprojectisunique,andtheconsequencesofgettingitwrongwouldbelong-livedandpossiblydisastrous.Thereare a number of precedents for the approach we


prescribe, including the London 2012 Olympics,whichisbeingdeliveredbyapublicagencythroughdedicated legislation, but with financing frommultiplesources.

Our recommendations may be relevant toother large infrastructure projects, and the modelsuggestedcouldcertainlybeappliedtoothertidalbarrage proposals, but we are not proposing aone-size-fits-all solution. Instead,weare issuingachallengetoGovernmentthatwillrequireacompleterevisionofattitudestowardsaSevernbarrage.Thiswill not be comfortable territory, but we believethat a publicly-owned approach is essential for asustainable, economically viable Severn barragethatreducestherisktotaxpayerswhilstupholdingthelong-termpublicinterest.

Avoiding a ‘decide-and-deliver’ approach

DespitebeingverypositiveoverthepotentialforasustainableSevernbarrage,theSDChasoutlinedaseriesofimportantconditionsonhowsuchaprojectshouldbedeveloped.NavigatingthroughtheissuesandagreeingontheseconditionshasbeenadifficultprocessfortheSDC’sCommissioners,particularlyduetotheinevitableriskthatourrecommendationsmaybeselectivelyappliedonceadecisionismade.

The SDC believes that on such an importantissue,Governmentmustavoidadecide-and-deliverapproach. There are a number of crucial areas ofuncertainty that will need to be resolved beforea final decision can be made – in particular, theachievability and cost of providing compensatoryhabitat. Thiswill requirea sequential processandone that is genuinely open to the possibility thattheremaybeobstaclestodevelopmentthatcannotbeovercome.

5.3.5 Moving forward

A number of the SDC’s recommendations – inparticular theneedforpublicownershipandforaradicalapproachtoprovidingcompensatoryhabitat–representmajorchallengestoGovernmentpolicy.This isbecauseaSevernbarragedoesnotfitwellwithincurrentpoliciesonenergyorenvironmentalconservation,whichwerenotdesignedwithsuchalarge,one-offprojectinmind.Ourrecommendationsmayalsohaveimplicationsforotherareasofpolicy,particularlylargeinfrastructuredevelopments.

Asaresult,werecommendthatanydecisiontofurther investigateaSevernbarrage is takenwithdueregardforthecomplexityoftheissuesinvolved.TheGovernmentshouldnotrushintoadecision,norshouldproponentsofabarrageencourageittodoso.It ishugelyimportantthatthewholedecision-makingprocessistransparentandopen,withpublicengagement as a major element from the start.Notonlywouldthisadvancetheprincipleof‘goodgovernance’, but itwould significantly reduce therisk of a public backlash or legal action at a laterdate.

Belowweconsidersomeofthekeyconsiderationsfor Government if it is in favour of developing asustainableSevernbarrageproject.

Policy appraisal

If the Government is minded towards developinga sustainable Severn barrage, then it will needto consider the implications for energy andenvironmental conservation policy in light of theSDC’s advice, and to decide whether it is willingto take on the role of project lead thatwould berequired. This will involve a detailed examinationofthemostappropriateorganisationalsetupforthefurtherworkrequired,andacleartimelineforhowtheworkshouldproceed.

Anearlydecisionmayneedtobetakenonwhichofthebarrageoptionsshouldbeselectedforfurtherinvestigation. This would need to take account ofthe results from any ongoing engagement work(seebelow) toavoidanapproach that isdictatedsolelybyengineeringandeconomicfactors.

Compensatory habitat requirements

As already stated, the SDC has not conducted ananalysisofthecompensatoryhabitatpackagethatwouldberequiredtosatisfytheconditionsoftheEUHabitatsandBirdsDirectives.

Considering the overwhelming importanceof this particular factor, it would be prudentfor Government to focus on obtaining an earlyindicationofthefeasibilityofcompliancewiththeDirectives,andthecostofdoingso.Thiswouldneedtoincludeanassessmentoftheimpactsofabarrageon protected habitats and species, leading to aquantificationof thecompensationrequiredandadecision(followingnegotiationswiththeEuropean


Commission) on whether this could be providedinawaythatmaintainstheoverallviabilityoftheNatura 2000 network. Following the SDC’s adviceonpursuingthisasan‘environmentalopportunity’,thisworkshouldalsolookathowtheprovisionofcompensatory habitat could be linked to the UK’slong-termclimatechangeadaptationstrategy.

AstheSDChasclearlystated,ifcompliancewiththeDirectivesisfoundtobescientificallyorlegallyunfeasible, then proposals for a Severn barrageshouldnotbepursued,asthedevelopmentwouldthennotbeable to satisfy theprincipleof ‘livingwithinenvironmentallimits’.

Detailed project evaluation

An important secondary process would inevitablyinvolve a comprehensive research programmeto tackle the outstanding technical, economic,environmental and social issues. It would not beappropriatefortheSDCtobeprescriptiveabouthowthis research should be carried out, or by whom.However, considering the SDC’s recommendationson the financing of any barrage, we believe thiswouldbebestledbyGovernment,orbyacommitteeappointedbyGovernment.

Engagement

Running alongside the processes discussed aboveshould be an in-depth public and stakeholderengagementprogramme focusedon tidal barrageoptions in the Severn Estuary to help identify therights,opportunitiesandrisksassociatedwithsuchadevelopment.

IdeallyrunindependentlyfromGovernmentandbuildingontheSDC’sengagementwork,thisshouldseektogainagreaterconsensusontheconditionsforpublicacceptability,withastrongfocusontheimpacts on local communities. Thiswould help toprovideaninsightintowhatfactorswouldbemostimportantindevelopingproposalsinthelong-termpublic interest. A whole range of barrage optionscouldbepresented,alongsidenon-barrageoptionswhere direct conflicts emerge. This work would,in our view, be essential in deciding how best toproceed further and could help to shape researchpriorities.

A cross-Government approach

BecauseofthelocationofaSevernbarrage(linkingEnglandandWales),andduetoenergypolicybeingareservedmatter,theUKGovernment(throughtheDepartmentforBusiness,EnterpriseandRegulatoryReform (BERR)) would need to take the lead intakingforwardanyproposals.BERRwouldneedtoworkcloselywiththeDepartmentforEnvironment,Food and Rural Affairs (Defra) on issues such asclimatechange,marinespatialplanning,andnatureconservationpolicy,withDefraandtheEnvironmentAgencyonfloodandcoastalprotectionpolicyandstrategy, and with HM Treasury on economic andfinancingissues.

Nevertheless, there is a crucial leadership andstrategicroleatanational level inWalesandataregionallevelinthesouthwestofEngland.ThiswouldneedtobeledbytheWelshAssemblyGovernment(WAG) and the South West of England RegionalDevelopmentAgency(SWRDA)astheorganisationsresponsibleforeconomicdevelopment.Theywouldneedtoensurethatanybarrageproposalsarefullyintegratedintorevisedspatialplanningandregionalstrategies, and that the proposals maximise thelong-term public benefit in a sustainable way.They would also need to involve other keystakeholders, including local authorities, ports,shipping and surface transport interests, and localcommunity and business groups within existingSevernEstuarynetworks.

Therewould alsobean important role for thestatutory conservation agencies, and in particulartheCountrysideCouncilforWales,theEnvironmentAgency,andNaturalEngland.Theirexpertisewouldberequiredtoassist inthedesignanddeliveryofanyenvironmental researchprogramme,andtheywouldhaveanimportantroletoplayinspecifyingand ensuring the creation of any compensatoryhabitat that might be required. This work wouldrequireaconstructiveapproachtotheproposalsandone that seeks touphold the requirementsof theenvironmentaldesignationswhilstmaximisingtheenvironmentalopportunity thatmightbeaffordedunderacompensatoryhabitatscheme.


The SDC’s role

Our advice to Government is based on ourassessmentofthecurrentevidence,anditisuptotheGovernmenttodecidehowtoproceed.

As theGovernment’s independent advisor andwatchdogonsustainabledevelopment, theSDC iscommittedtoworkingwiththeUKGovernmentandtheDevolvedAdministrationstointegratesustainabledevelopment approaches into all decision-makingand policy processes. Our conclusions present anumber of challenges for Government, for theprivatesector,andforBritishsocietyasawholeandwewillbelookingtoseehowthesearedealtwithandactedupon. Inassessingschemesofthiskind–whichhave long lead timesandvery long-termbenefitsandimpacts–anewapproachisrequiredwhichexplicitlyrecognisesthattherearerisksanduncertaintiesatascalehithertounrecognised.Theassumptionsunderliningthoserisks–ofgoingaheadwithaprojectofthiskind,ortheimpactsofclimatechange – must be laid out in a very transparentway.

TheSDCwouldthereforebeinterestedinworkingwith Government and other key stakeholders toexplore some of the substantive issues we raise,drawing on the expertise of our Commissionersand staff.Weareparticularly interested in furtherexploration of the ‘environmental and ecologicalopportunities’affordedbyaSevernbarrageproject,and in improving decision-making processes,planning, and citizen engagement connected topromoting and securing sustainable developmentoutcomeslinkedtoschemesofthiskind.

Wearealsokeentoexploreinnovativefinancingmodels that are public sector-led, incorporatinglong-termdiscountingapproaches,butwitha rolefor the private sector, to help deliver sustainableinvestmentoutcomesovertheverylong-term,andfor fresh ways to secure sustainable and reliablefutureenergymarkets.

We look forward to working with a range ofinterestedpartiesinevolvingaconstructivedebateontheissuesraisedbythisreport.

1 The term ‘Government’ is used when referring to UK-wide, or generic governance issues. The term ‘Devolved Administrations’ is used when referring to the role of the Scottish Government (previously Scottish Executive), the Welsh Assembly Government, and the Northern Ireland Assembly, and the term ‘UK Government’ is used when referring specifically to issues or areas that are ‘reserved’ (i.e. not devolved).

2 The Department of Trade & Industry (DTI) prior to July 2007.

3 HM Government (2006). The Energy Challenge. Energy Review Report 2006. www.DBERR.gov.uk/energy/review/page31995.html

4 The following statutory agencies gave direct input into the peer review process: Countryside Council for Wales, Environment Agency, Joint Nature Conservation Committee, and Natural England. Defra officials also provided useful advice on policy and legal matters.

5 HM Government (2005). One Future – Different Paths. The UK’s shared framework for sustainable development. www.sustainable-development.gov.uk/publications/uk-strategy/framework-forsd.htm

6 Further details on the role and composition of the SDC are available on our website: www.sdcommission.org.uk/

7 See www.pol.ac.uk/home/insight/tidefaq.htm for a useful Q&A on the tides.

� ABPmer (2007). Quantification of Exploitable Tidal Energy Resources in UK Waters. www.abpmer.co.uk/files/report.pdf

9 Salter, S. H. (2006). DTI Energy Review – Question 2: Possible under-estimation of UK tidal resource. www.dti.gov.uk/files/file31313.pdf

10 MacKay, D. (2007). Under-estimation of the UK Tidal Resource. www.inference.phy.cam.ac.uk/sustainable/book/tex/TideEstimate.pdf

11 World Energy Council (2004). 2004 Survey of Energy Resources. www.worldenergy.org/documents/ser2004.pdf

12 NGET (2007). GB Seven Year Statement. www.nationalgrid.com/uk/Electricity/SYS/current/

13 SDC (2007). Lost in Transmission? The role of Ofgem in a changing climate. www.sdcommission.org.uk/pages/ofgemreview.html

14 Further details can be found at www.defra.gov.uk/environment/climatechange/uk/legislation/index.htm

15 Further details can be found at www.scotland.gov.uk/News/Releases/2007/06/21152519

16 HM Government (2007). Meeting the Energy Challenge. Energy White Paper 2007. www.DBERR.gov.uk/energy/whitepaper/page39534.html

17 SDC (2006). Paper 2: Reducing CO2 emissions

– nuclear and the alternatives. From the SDC project ‘The role of nuclear power in a low carbon economy’. www.sd-commission.org.uk/pages/060306.html

1� Centre for Alternative Technology (2007). Zero Carbon Britain: an alternative energy strategy. www.zerocarbonbritain.com/images/zerocarbonbritain.pdf

19 WWF (2007). Climate Solutions: WWF’s vision for 2050. www.wwf.org.uk/filelibrary/pdf/climatesolutionreport.pdf

20 Greenpeace (2006). Decentralising UK Energy: cleaner, cheaper, more secure energy for the 21st Century. www.greenpeace.org.uk/files/pdfs/migrated/MultimediaFiles/Live/FullReport/7441.pdf

21 Mayor of London/Greenpeace (2006). Power London into the 21st Century. www.london.gov.uk/mayor/environment/energy/docs/powering-london-21st-century.pdf

22 HM Treasury (2006). Stern Review on the Economics of Climate Change. www.hmtreasury. gov.uk/independent_reviews/stern_review_economics_climate_change/stern_review_report.cfm

23 The Energy White Paper16 proposes a ‘Supplier Obligation’ scheme for the period post-2011. One of the options proposed would place a cap on the quantity or energy, or carbon, that energy suppliers could sell to domestic customers. There is also the potential for this to cover small and medium enterprises.

24 See www.sd-commission.org.uk/pages/sd_panel.html for further details.

25 BWEA/npower Juice (2006). The Path to Power. www.bwea.com/pathtopower/index.html

26 Carbon Trust (2006). Future Marine Energy. Results of the Marine Energy Challenge. www.carbontrust.co.uk/Publications/publicationdetail.htm?productid=CTC601

27 DTI (2005). Guidance for consenting arrangements in England and Wales for Pre-commercial demonstration phase for Wave and Tidal Stream Energy Devices. www.berr.gov.uk/files/file15470.pdf

2� FREDS (2004). Harnessing Scotland’s Marine Energy Potential. www.scotland.gov.uk/Resource/Doc/1086/0006191.pdf

29 CCW (2005). Potential Nature Conservation and Landscape Implications of Marine Renewable Energy Developments in Welsh Territorial Waters. CCW (2006). Potential Nature Conservation Impacts of Wave and Tidal Energy Extraction by Marine Renewable Developments.

30 SNH (2004). Marine Renewable Energy and the Natural Heritage: An Overview and Policy Statement. Policy Statement No 04/01. www.snh.org.uk/data/boards_and_committees/main_board_papers/040207-policy.pdf

31 European Court of Justice (2004). Opinion C-127/02 (Wadden Sea case). http://curia.europa.eu/en/actu/activites/act04/0404en.htm#ToC9

32 See Research Report 2 for summary comparison tables.

33 SDC (2007). Wind Power in the UK. www.sd-commission.org.uk/publications.php?id=234

6 References

34 IEA (2006). Energy Policies of IEA Countries (Compendium). www.iea.org/textbase/publications/free_new_Desc.asp?PUBS_ID=1850

35 IEA R&D Statistics database www.iea.org/Textbase/stats/rd.asp

36 Defra (2007). A Sea Change – A Marine Bill White Paper. http://defraweb/corporate/consult/marinebillwhitepaper07/marinebill-whitepaper.pdf

37 Scottish Executive (2007). News release (19/06/2007): Marine Bill planned. www.scotland.gov.uk/News/Releases/2007/06/19112631

3� Scottish Executive (2007). Recommendations of the Advisory Group on Marine and Coastal Strategy Subtitle: A Follow up to Seas the Opportunity: A Strategy for the Long Term Sustainability of Scotland’s Coasts and Seas. www.scotland.gov.uk/Publications/2007/03/08103826/0

39 Scottish Executive (2007). Scottish Marine Renewables – Strategic Environmental Assessment (SEA): Environmental Report. www.seaenergyscotland.co.uk

40 JNCC (2007). Scottish Marine Renewables Strategic Environmental Assessment – consultation response.

41 Crown Estate (2007). Annual Report 2007. www.thecrownestate.co.uk

42 EMEC (2005). Performance assessment for wave energy conversion systems in open sea test facilities. www.emec.org.uk/pdf/EMEC_Performance_Assessment.pdf

43 See www.wavehub.co.uk

44 The World Commission on Dams published a two-year comprehensive study into the positive and negative impacts of dams, including hydropower dams, in 2000.96

45 RWE npower (2007). Presentation on Rhyl tidal lagoon proposal (10/09/07). Personal communication with Bill Langley.

46 Unfortunately has not been possible to include the RWE npower cost estimate in the unit cost of output calculations, as this information was received after Research Reports 4 and 5 were completed.

47 BERR (2007). CCS Demonstration Competition. Website text (19/09/07). www.dti.gov.uk/energy/sources/sustainable/carbon-abatement-tech/ccs-demo/page40961.html

4� Peel Environmental Ltd. (2007). Mersey Tidal Power Study. www.merseytidalpower.co.uk

49 See the websites of the Environment Agency www.environment-agency.gov.uk/te2100/ and the Thames Estuary Partnership www.thamesweb.com/page.php?page_id=60&topic_id=9 for further details.

50 The term ‘Severn barrage’ will be used generically to describe all of the proposals for building a large tidal barrage across the Severn Estuary.

51 Severn Estuary Partnership (2001). Strategy for the Severn Estuary. www.severnestuary.net/sep/Publications/severn.html

52 Defra (2007). News release: EU agrees renewable energy target. www.defra.gov.uk/news/latest/2007/climate-0309.htm

53 Sometimes the term ‘capacity factor’ is used instead of load factor. This should not be confused with the term ‘capacity value’, which is defined below.

54 The carbon intensity of electricity generation is highest during peak demand periods because this is when marginal fossil-fuel powered plant is utilised, which will tend to be the least efficient plant available. Actual carbon intensity is also affected by relative fuel prices.

55 UKERC (2006). The Costs and Impacts of Intermittency. www.ukerc.ac.uk/content/view/258/852

56 The term ‘capacity value’ (sometimes also known as ‘capacity credit’) refers to the ability of new plant to contribute firm capacity to the overall system. High availability plant such as gas-fired CCGT can have a capacity value of up to 90% (meaning that 1GW of new plant would be treated as providing the system with 0.9GW of firm capacity), whereas wind plant has a capacity value of around 35% at low penetrations, falling to around 20% when the contribution of wind generation to overall supply rises to 20%.

57 This is explained in some detail in Annex B of the SDC report ‘Wind Power in the UK’.

5� Carbon Trust / DBERR (2004). Renewables Network Impacts Study. www.carbontrust.co.uk/Publications/publicationdetail.htm?productid=CT-2004-03&metaNoCache=1

59 BERR (2007). Dynamic Demand. Government response to Clause 18 of the Climate Change and Sustainable Energy Act 2006. www.berr.gov.uk/files/file41011.pdf

60 This report assumes that under the recently-agreed EU target for 20% of all energy requirements to come from renewables by 2020 www.defra.gov.uk/news/latest/2007/climate-0309.htm, the UK will need to commit to developing at least this amount. On greenhouse gases, this report assumes that the UK will need to make substantial progress in its goal for a 60% reduction in carbon dioxide emissions by 2050, and that the UK’s commitment will most likely need to rise to a 80-90% cut in line with the scientific evidence.

61 In accordance with the UK Government approach, the SDC reports carbon data in terms of tonnes of carbon (tC) rather than tonnes of carbon dioxide (tCO

2). To

translate carbon data into its equivalent in CO2, the

result should be multiplied by 3.66.

62 DBERR (2007). Energy Trends – March 2007. www.DBERR.gov.uk/energy/statistics/publications/trends/index.html

63 See Prater67 for comment on scope of analysis and conclusions from STPG studies on environment, ecology and implications for birds, and the view that although some preliminary assessment has been made, additional, extensive, and up-to-date environmental studies would be required to make even an inprinciple decision to proceed with a barrage proposal.

64 For a discussion of ecosystem services valuation approaches, see ‘Marine Biodiversity: An economic valuation’ by Plymouth Marine Laboratory (Nicola Beaumont, Michael Townsend, Stephen Mangi and Melanie C. Austen) (July 2006) which is part of Defra’s evidence base for the Marine Bill. www.defra.gov.uk/environment/water/marine/uk/policy/marine-bill/index.htm

65 R. H. Clark (2007). Elements of Tidal-Electric Engineering. Wiley. IEEE Press.

66 See also Pethick76 for a recent discussion of geomorphological issues related to a Severn barrage.

67 RSPB (2007). Ecological aspects of the Severn Barrage. A review by Dr Tony Prater.

6� Defra (2007). News release 31/08/07: Estuaries in bid for special conservation status. www.defra.gov.uk/news/2007/070831b.htm

69 The Convention on Wetlands, commonly known as the ‘Ramsar Treaty’, was signed in Ramsar, Iran, in 1971 and is an intergovernmental treaty which provides the framework for national action and international cooperation for the conservation and wise use of wetlands and their resources. There are presently 155 Contracting Parties to the Convention, with 1674 wetland sites, totalling 150 million hectares, designated for inclusion in the Ramsar List of Wetlands of International Importance. Further information is available at: www.ramsar.org

70 Wildlife and Countryside Act 1981.

71 European Environment Agency (2005). The European environment - State and Outlook 2005. http://reports.eea.europa.eu/state_of_environment_report_2005_1/en].

72 CCW (2007). Pers. comm.

73 JNCC figures as at 31 March 2006 www.jncc.gov.uk/page-1456.

74 Refer European Court of Justice decisions on the Birds Directive in R v Secretary of State for the Environment, ex p RSPB (Case C-44/55) [1997] Queen’s Bench 206 (concerning the Lappel Bank at Sheerness) and on the Habitats Directive in R v Secretary of State for the Environment, Transport and the Regions, ex p First Corporate Shipping Ltd (Case C-371/98) [2001] Common Market Law Reports 19, 511. A detailed description of the selection process can be found at www.jncc.gov.uk/page-1480.

75 Millennium Ecosystem Assessment (2005). Ecosystems and Human Well-Being: biodiversity synthesis. www.millenniumassessment.org/en/Reports.aspx

76 Pethick, J (2007). Severn Barrage Proposal: Assessment of Geomorphological Impacts (Report to Natural England).

77 Kirby, R (1988). The ecological implications of possible changes to sedimentological regime caused by the proposed Severn Barrage. Refer also discussion in Research Report 3 at para 6.7.11.

7� Kirby, R and C Retière (2007). Comparisons between environmental and water quality issues at the tidal power scheme at La Rance France, and those expected in the Severn estuary, UK.

79 RSPB (2007). Commentary Paper concerning “Comparisons between environmental and water quality issues at the tidal power scheme at La Rance France, and those expected in the Severn estuary, UK”. A paper by Dr Tony Prater.

�0 Refer to discussion in Research Report 3.

�1 Land Use Consultants (2007). Advice on Potential Landscape/Seascape and Visual Impacts of a Severn Barrage. Report commissioned by Natural England. www.naturalengland.org.uk/regions/southwest/default.htm

�2 Environment Agency (2006). Severn Estuary Coastal Habitat Management Plan.

�3 A research advisory group has been established to consider the impacts of climate change on the Severn estuary: www.severnestuary.net/sep/pdfs/impactsofclimatechangeonthesevernestuaryreport.pdf

�4 Defra (2005). Coastal Squeeze Implications for Flood Management – Requirements of the European Birds & Habitats Directives – Policy Guidance. www.defra.gov.uk/environ/fcd/policy/csqueeze.htm

�5 Where ‘priority’ habitats or species in a SAC would be affected by a proposed development the reasons of overriding public interest are more restricted. The preliminary assessment for either of the two barrage options indicates that no priority habitats or species would be significantly affected. The impacts to the Ramsar site are essentially similar to those for the SPA and cSAC, and therefore have not been considered separately.

�6 European Commission (2005). Natura 2000 in the Atlantic Region. http://ec.europa.eu/environment/nature/nature_conservation/useful_info/documents_publications/pdf/atlantic.pdf

�7 Network Rail (2006). Network Rail Business Plan 2007 – Route 13. www.networkrail.co.uk/aspx/3085.aspx

�� Office of Science and Technology (2004). Future Flooding. www.foresight.gov.uk/Previous_Projects/Flood_and_Coastal_Defence/Reports_and_Publications/index.html

�9 Defra (2005). Making space for water. First Government response to the autumn 2004 ‘Making space for water’ consultation exercise. www.defra.gov.uk/environ/fcd/policy/strategy/1stres.pdf

90 Defra (2007). News release 22/06/07: Strengthened coastal flood and erosion role for Environment Agency. http://defraweb/news/2007/070622a.htm

91 www.essexwt.org.uk/sites/Abbotts%20Hall%20Farm.htm

92 IPCC (2007). Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. www.ipccwg2.org/index.html

93 Defra (2007). Conserving biodiversity in a changing climate: guidance on building capacity to adapt. Published by Defra on behalf of the UK Biodiversity Partnership. www.ukbap.org.uk/Library/BRIG/CBCCGuidance.pdf

94 Environment Agency/Countryside Council for Wales/Natural England (2006). Position Statement: A Severn Barrage.

95 Bristol City Council (2007). Shaping Bristol over the next 20 years. Bristol Development Framework – Core Strategy: Issues and Options Paper. www.bristol.gov.uk/ccm/cmsservice/download/asset/?asset_id=19019124

96 World Commission on Dams (2000). Dams and Development: a new framework for decision-making. www.dams.org/report/contents.htm

97 SDC (2007). Building Houses or Creating Communities? www.sdcommission.org.uk/pages/200507.html

9� Welsh Assembly Government (2004). People, Places, Futures – The Wales Spatial Plan. http://new.wales.gov.uk/about/strategy/spatial/sppublications/walesspatial?lang=en

99 Welsh Assembly Government. South East Wales Economic Development Strategy. www.cardiff.gov.uk/content.asp?nav=2866%2C3386%2C4709&parent_directory_id=2865&positioning_article_id=&language=&sortkey=

100 South West Regional Assembly (2006). Draft Regional Spatial Strategy. www.southwestra.gov.uk/nqcontent.cfm?a_id=836

101 South West of England Regional Development Agency (2006). Regional Economic Strategy. www.southwestrda.org.uk/downloads/sub-section.asp?sectionid=57&SubSectionID=13&lang=

102 HM Treasury (2003). The Green Book: appraisal and evaluation in central government. http://greenbook.treasury.gov.uk/

103 UKERC (2007). Investment in electricity generation: the role of cost, incentives and risks. www.ukerc.ac.uk/ImportedResources/PDF/06/0706_Investing_in_Power.pdf

104 SDC (2006). Unlocking the power sector. www.sd-commission.org.uk/publications.php?id=496

105 SDC (2006). The role of nuclear power in a low carbon economy. SDC position paper on nuclear power. www.sd-commission.org.uk/pages/060306.html

106 Despite the Government’s desire to avoid picking winners, analysis of the 2007 Energy White Paper by Dieter Helm www.dieterhelm.co.uk/publications/Commentary_May07.pdf suggests that it is doing exactly that by banding the RO.

107 SDC (2006). Paper 4: The economics of nuclear power. From the SDC project ‘The role of nuclear power in a low carbon economy’. www.sd-commission.org.uk/pages/060306.html

10� Even if the next phase was designed to run for 10 years, this is unlikely to be sufficient for a barrage project, which may require over half this time for construction.

109 Examples include: National Pensions Debate; Committee on Radioactive Waste Management (CoRWM)

110 Examples include: Judicial Review of the 2006 Energy Review consultation process (focusing on nuclear power); Tomlinson Inquiry on Education

111 SDC (2007). Engagement and sustainable development. www.sdcommission.org.uk/publications.php?id=560

112 European Commission (2006). Halting the Loss of Biodiversity by 2010 – and Beyond: Sustaining ecosystem services for human well–being. http://eurlex.europa.eu/LexUriServ/site/en/com/2006/com2006_0216en01.pdf

113 Strategic Environmental Assessment Directive 2001/42/EC.

114 Defra (2007). The Birds and Habitats Directives: Outline Government Position (May 1998). Available on Defra webpage titled ‘European Union Wild Birds and Habitats Directives’. www.defra.gov.uk/wildlife-countryside/ewd/ewd09.htm

115 European Commission (2007). Guidance document on Article 6(4) of the habitats Directive (92/43/EEC). http://ec.europa.eu/environment/nature/nature_conservation/eu_nature_legislation/specific_articles/art6/pdf/guidance_art6_4_en.pdf

116 Defra (2006). News Release: UK’s largest man-made wetland created in Essex. http://defraweb/news/2006/060704a.htm

117 The Mersey is a SPA and Ramsar site for birds although the estuary itself is not a SAC.

11� This approach has parallels to the one adopted by the World Commission on Dams, which recommended that a series of conditions be applied to future dam projects to ensure improved outcomes for all stakeholders.96

119 Defra (2007). UK Manifesto for the EU Emissions Trading Scheme (EUETS). www.defra.gov.uk/environment/climatechange/trading/eu/pdf/manifesto-uk.pdf

120 Current Government targets are for a 60% cut in emissions by 2050, but the science now suggests cuts of 80-90% will be required in the most developed countries if we are to have a high probability of limiting the increase in average global temperatures to 2ºC.

121 When used in conjunction with Directives that were enacted prior to the creation of the EU.

BERR DepartmentforBusiness,EnterpriseandRegulatoryReform(UK)(previouslyDTI)

BETTA BritishElectricityTradingandTransmissionsAgreements

CCGT Combinedcyclegasturbine

CCW CountrysideCouncilforWales

CEC ConnectionEntryCapacity

CHaMP ClimateChangeMarineProtection

CO2 Carbondioxide

Defra DepartmentforEnvironment,FoodandRuralAffairs(UK)

DETI DepartmentofEnterprise,TradeandInvestment(NorthernIreland)

DNOs DistributionNetworkOperators

DTI DepartmentforTradeandIndustry(nowBERR)

EA EnvironmentAgency

EAC Equivalentannualcost

EC EuropeanCommissionorEuropeanCommunity121

EIA EnvironmentalImpactAssessment

EMEC EuropeanMarineEnergyCentre

EU EuropeanUnion

EUETS EuropeanUnionEmissionsTradingScheme

GW Gigawatt(=1000MW)

GWh Gigawatthour

IEA InternationalEnergyAgency

IROPI ImperativeReasonsofOverridingPublicInterest

IPCC IntergovernmentalPanelonClimateChange

JNCC JointNatureConservationCommittee(UK)

kV Kilovolt(=1000V)

kW Kilowatt(=1000W)

kWh Kilowatthour

MRDF MarineRenewablesDeploymentFund

MW Megawatt(=1000kW)

MWh Megawatthour

NE NaturalEngland

NGET NationalGridElectricityTransmissionplc

NGOs Non-governmentalorganisations

NWDA NorthWestDevelopmentAgency

Ofgem OfficeofGasandElectricityMarkets

R&D Researchanddevelopment

RO RenewablesObligation

ROC RenewablesObligationCertificate

RSPB RoyalSocietyfortheProtectionofBirds

SAC SpecialAreaofConservation

SEA StrategicEnvironmentalAssessment

SDC SustainableDevelopmentCommission

SNH ScottishNaturalHeritage

SPA SpecialProtectionArea

SWRDA SouthWestofEnglandRegionalDevelopmentAgency

tC Tonnesofcarbon

TEC TransmissionEntryCapacity

TNUoS TransmissionNetworkUseofSystem

TW Terawatt(=1000GW)

TWh Terawatt-hour

UKERC UKEnergyResearchCentre

UN UnitedNations

WAG WelshAssemblyGovernment

Glossary of terms

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DraftingTeam OliverKnightandKarlaHill

ArtDirection AndyLong

Design AndyLongandJeromeDutton

Photography JeromeDutton

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