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THE WATT COMMITTEE ON ENERGYREPORT NUMBER 15

SMALL-SCALE HYDRO-POWER

Papers presented at the Sixteenth Consultative Council meeting of the WattCommittee on Energy, London, 5 June 1984

The Watt Committee on Energy Ltd

A Company limited by guarantee: Reg. in England No.1350046

Charity Commissioners Registration No. 279087MARCH 1985

Contents

Members of the Watt Committee v

Members of Watt Committee Working Group onSmall-Scale Hydro-Power

vii

Foreword ix

Introduction xi

Section 1 Potential for small-scale hydro-power in the UnitedKingdomE.M.Wilson

1

Section 2 Hydro-electric plant and equipmentJ.TaylorC.P.Strongman

8

Section 3 Civil engineering aspectsN.A.Armstrong

37

Section 4 Institutional barriersE.C.ReedD.J.HintonA.T.Chenhall

48

Section 5 Economics of small public and private schemesA.T.ChenhallR.W.Horner

57

Section 6 Conclusions and recommendationsJ.V.CorneyH.W.Baker

78

Appendix 1 Sixteenth Consultative Council meeting of the WattCommittee on Energy

81

Appendix 2 Government grants and funding availableP.J.Fenwick

83

Appendix 3 Use of water for milling or power generation:circumstances in which a licence is required

86

Appendix 4 National Association of Water Power Users: Paperfor the Watt Committee

93

Appendix 5 Abbreviations 99

THE WATT COMMITTEE ON ENERGY

The Watt Committee on Energy 102

Policy

Members of Executive, March 1985

Recent Watt Committee Reports

102

103

103

Member Institutions of the Watt Committeeon EnergyMarch 1985

* British Association for the Advancement of ScienceBritish Ceramic Society* British Nuclear Energy SocietyBritish Wind Energy Association* Chartered Institute of Building* Chartered Institution of Building Services* Chartered Institute of Transport* Combustion Institute (British Section)* Geological Society of London* Hotel Catering and Institutional Management Association* Institute of BiologyInstitute of British FoundrymenInstitute of Ceramics* Institute of Chartered Foresters* Institute of Cost and Management Accountants* Institute of Energy* Institute of Home Economics* Institute of Hospital EngineeringInstitute of Internal Auditors (United Kingdom Chapter)Institute of Management Services* Institute of Marine EngineersInstitute of Mathematics and its Applications* Institute of Metals* Institute of Petroleum* Institute of Physics* Institute of Purchasing and Supply* Institute of RefrigerationInstitute of Wastes Management* Institution of Agricultural Engineers* Institution of Chemical Engineers* Institution of Civil Engineers* Institution of Electrical and Electronics Incorporated Engineers

* Institution of Electrical Engineers* Institution of Electronic and Radio EngineersInstitution of Engineering Designers* Institution of Gas EngineersInstitution of Geologists* Institution of Mechanical Engineers* Institution of Mining and MetallurgyInstitution of Mining Engineers* Institution of Nuclear Engineers* Institution of Plant Engineers* Institution of Production Engineers* Institution of Public Health EngineersInstitution of Structural Engineers* Institution of Water Engineers and Scientists* International Solar Energy Society—U.K. SectionOperational Research Society* Plastics and Rubber Institute* Royal Aeronautical Society* Royal Geographical Society* Royal Institute of British Architects* Royal Institution* Royal Institution of Chartered Surveyors* Royal Institution of Naval Architects* Royal Meteorological Society* Royal Society of Arts* Royal Society of Chemistry* Royal Town Planning Institute* Society of Business EconomistsSociety of Chemical Industry* Society of Dyers and ColouristsTextile Institute

* Denotes present and past members of The Watt Committee Executive

vi

Members of Small-Scale Hydro-PowerWorking Group

J.V.Corney Institution of Civil Engineers, ChairmanN.A.Armstrong Institution of Electrical Engineers and Institution of

Mechanical EngineersH.W.Baker Institution of Civil EngineersA.T.Chenhall Institution of Electrical EngineersD.J.Hinton Institution of Civil EngineersR.W.Horner Institution of Public Health EngineersM.J.Kenn Institution of Mechanical EngineersE.C.Reed Institution of Water Engineers and ScientistsJ.Taylor Institution of Electrical EngineersProf E.M.Wilson Institution of Civil Engineers

Acknowledgements

Commander G.C.Chapman, Mr J.A.Crabtree and Mr O.M.Goring attendedseveral meetings of the working group as representatives of the NationalAssociation of Water Power Users.

The Watt Committee working group on Small-Scale Hydro-Power is indebtedto many individuals and organisations in the United Kingdom from whominformation and comments were obtained in the course of this project, includingthe Central Electricity Generating Board, North of Scotland Hydro-ElectricBoard, South of Scotland Electricity Board, regional Water Authorities and (inScotland) regional councils and River Purification Boards.

The Watt Committee on Energy acknowledges with thanks financialassistance by the Department of Energy, which helped to defray the costs of theproceedings of the working group, and the advice given by Dr P.J.Fenwick ofthat Department.

NoteThe data included in this Report were correct, to the best of the authors’

knowledge and belief, in January 1985.

Foreword

At any moment in time the Watt Committee has four or five working parties,each tackling a specific project. Those under discussion at the meeting of theWatt Committee Executive of 24th January 1985 were technician education,waste disposal in the energy industry, the second phase of our study of acid rainand passive solar building design. Two other projects awaited firm proposals,and a further two were temporarily suspended because they would be more realisticat a later date.

The present Report on Small-Scale Hydro-Power contrasts strongly with its twoimmediate predecessors, which dealt with nuclear energy and acid rainrespectively.* It shares with them, however, the desire to clarify what at themoment could hold up development. Our only previous report devoted entirely torenewable energy sources was No. 5 Energy from the Biomass. Reports No. 1and, to a less extent, No. 2 include sections on renewable sources; Report No. 4Energy Development and Land in the United Kingdom contains two colouredmaps showing alternative source distribution in the United Kingdom andsuggests locations for wind, solar, wave, tidal and geothermal installations.

Discussions with a number of individuals about small hydro-electricgenerating capacity suggested that it was something of a Cinderella in that it wasunlikely to save much fossil fuel, and the cost per kilowatt could vary greatlywith the site and with the amount of outside help that would be required.Furthermore, there was no simple statement of the legal obligations.

Like windmills (now elevated to ‘aero-generators’), small hydro-power hassuffered a long period of neglect illustrated by idle water-mills and mill-pondsused to supply fish rather than energy. A great deal of money has been spent onaero-generator design and a full-scale unit is under construction in the OrkneyIslands. If it comes up to expectations we shall see more schemes being built andused to save energy. The same should be true of hydro-power.

To add to this Foreword would mean drawing on the Report itself. I end,therefore, with my personal thanks and those of the Executive to the numerous

February 1985J.H.Chesters

Chairman, The Watt Committee on Energy

* Particulars of previous Reports of the Watt Committee on Energy are given on pages 61–62.

x

people who have given information, time and voluntary effort to add to ourunderstanding of the problems and the wider potential of small-scale hydro-power.

Introduction

Despite the abundance of sites in the United Kingdom where small-scale hydro-power could be exploited, only a very small proportion of such potential is atpresent developed.

The Watt Committee on Energy was concerned at this lack of exploitation of avaluable resource and therefore decided to establish a working group to examinethe potential for development of further small-scale hydro-power as a usefuladdition to the energy resources of the United Kingdom. Its object was toidentify obstacles which may have inhibited development in the past and to makesuggestions for further study/action, with the eventual objective of helping toovercome the main obstacles and stimulate new schemes.

The working group was free to make its own definition of what was impliedby ‘small-scale’, and decided, in broad terms, that this should be any resourcebelow the size which the electricity boards had themselves considered worthdeveloping. In electrical terms we considered this to be from 5 to 5000kW.

We also decided, in order to limit the field of our study, that we would notinclude wave or tidal power, as these could properly form the subject of separatestudies. The papers forming this Report have been prepared by various membersof the working group and explore the potential for small-scale hydro-powerdevelopment in the whole of the United Kingdom. Topics covered include thetechnical problems and legal, institutional, environmental and economic aspectswhich may have inhibited development in the past.

The working group has been greatly helped and encouraged by the informationand assistance provided by members of the National Association of Water PowerUsers who have direct experience of constructing and operating small privateschemes. The number and variety of such schemes provide concrete evidence ofthe practicability of such development. The members of this Association areenthusiasts and have for the most part constructed and operated their schemesthemselves. Whilst clearly beneficial to their owners as they stand, they wouldnot all necessarily satisfy current economic criteria.

Our studies have been purposely limited to developments in the UnitedKingdom, but many aspects will be equally applicable to developing countries,particularly where a public electricity supply is not available in the vicinity and

the choice lies between hydro-electricity or, as an alternative, diesel generationwith high-cost fuel. The papers in general deal with water power for thegeneration of electricity, as it is in this form that it is easiest to assess its value asa power source; however, where an alternative use for the power exists it may besimpler to harness the power for such use, as was done in the past, rather than touse it for electricity generation.

The technology involved in the development of water power is not new, butthere are few people who have experience of both the engineering and the legalaspects, which are complex and varied. It is the hope of the working group that,by bringing together these subjects in one report, the problems facing potentialdevelopers of hydro-power will become better understood and many moresuccessful schemes will result.

J.V.CorneyChairman, Watt Committee Working Group on Small-Scale Hydro-Power

xii


REPORT NUMBER 15

Section 1Potential for small-scale hydro-power in the

United KingdomE.M.Wilson

Department of Civil Engineering

University of Salford

Salford

Potential for Small-Scale Hydro-Power in the United Kingdom

1.1Introduction

The United Kingdom is not a country rich in hydro-electric resources. Only inScotland and Wales are there mountains and rainfall on a scale large enough tooffer opportunities for hydro-electric development of tens of megawatts.However, over the whole country there are hundreds of sites where modestamounts of hydro-electric energy could be generated, at powers measured in tensof kilowatts.

The problem of assessing potential requires, first, some arbitrary definition ofwhat ‘small-scale’ means, since many of the surveys made in the past haveconsidered schemes only if their power capacity exceeded fixed values,frequently in megawatts. So far as this paper is concerned, ‘small-scale’ meansfrom 5 to 5000kW. An arbitrary sub-division can be made to mini- and micro-hydro, with capacities above and below 500kW respectively.

During the last five years several studies have been made of small-scale hydro-power in various parts of the U.K. These have supplemented many previousinvestigations: for example, there have been at least six sets of estimates ofScottish hydro potential in one form or another, though most of them did notinclude small-scale projects by the definition above. The range of such estimatesreflects uncertainty about the premise on which they should be based. Francis, ofthe Department of Energy,1 has suggested that there are three broad categories inwhich estimates may be placed, namely:

(a) Gross river potential is approximately the summation of annual runofftimes potential head.

(b) Exploitable technical potential is Category (a) less that energy which it istechnically impossible to exploit; it includes, for example, losses due toefficiencies of plant less than 100%, and heads too low for available plant.Category (b) tends to move towards Category (a) with time.

(c) Economic exploitable potential is Category (b) less the energy which it isuneconomic to develop. Economic circumstances differ from case to case, sothere is no firm boundary separating Categories (b) and (c). Much depends on thecost of energy being displaced: for example, displacement of public supply at 4p/kWh enhances the value of a scheme compared with sale to the Electricity Boardat 2p/kWh.

It is worthwhile to recall an extract2 from the Report of the MackenzieCommittee (1962) in assessing hydro-electric potential in Scotland: ‘To have anyreal meaning, the estimates of potential water power must be related to economicconsiderations…’

Most published studies deal with Category (b), and, since regionalinvestigations cannot by their nature deal with site-specific details and economicanalyses, guidelines based on minima for flow and head have to be adopted.

In trying to assess the small-scale potential of a region the researcher has touse all the evidence he can find. For this paper, the existing hydro-electriccapacity has been determined, together with published and unpublishedassessments of further moderate potential; from these, an estimate has been madeof small-scale potential. In the case of Wales and England there is betterevidence, in the form of recent small-scale potential surveys,3,4 and these havehelped in the extrapolations required. However, it must be said that in all thatfollows there is room for considerable error and the judgements made areinevitably subjective.

1.2Hydrology

Estimates of the occurrence and volume of flow passing a proposed hydro-electric site must be made if the development is to be properly sized andassessed. River flows are determined by the hydrology of the catchment and theconsequent runoff and groundwater contributions.

The river flow from a catchment is dependent upon area, location, orientation,rainfall, climate, topography and geology. In considering small hydro sites it isimpracticable to consider all these variables in detail, and it is usual to resort toone of a number of estimating techniques. However, in some locations there maybe an established Water Authority gauging station nearby where daily flowrecords over several years are available. Provided the gauging point (usually aweir or a calibrated river section) is not very far distant, a simple areal correctionmay be all that is required to adjust the measured flows to those at the requiredsite. An HMSO publication5 details the location of established gauges—most arelocated on larger well-developed rivers. The local Water Authority may have

2 SMALL-SCALE HYDRO-POWER

additional gauges which could prove useful, and in every case an approach to theWater Authority is worthwhile to obtain flow data and to establish if there areany requirements for compensation flow.

For run-of-river hydro-electric projects, the daily flow duration curve (FDC)provides the required data. The FDC shows the percentage of time that certainvalues of discharges are equalled or exceeded. Duration curves for long periodsof runoff (in excess of 5 years) are utilized in deciding what proportion of flowshould be used for generation, since the area under the curve represents volumeand hence directly affects energy output. Figure 1.1 shows FDCs for the RiverItchen at Allbrook, near Winchester, and the River Ogwen, near Bethesda, NorthWales.

The shape of the curve is also of importance: a generally flat curve representsa river with few flood flows, probably extensively supplied from groundwater; asteep curve indicates a ‘flashy’ river with frequent flood flows and comparativelylow flows during dry weather. Such characteristics indicate the system of flowadjustment that is required to utilise the flows available. In cases such as theRiver Itchen where flows are relatively steady, a daily adjustment of flow may beall that is necessary. However, for ‘flashy’ rivers such as the Ogwen, continualflow adjustment may be necessary to utilise all that is available.

In general, where there are no constraints on the scale of development, the 30%exceedance flow from the FDC may be adopted as a first estimate of thedesigned capacity for the scheme. Following the evaluation of costs, energyoutputs and value of energy production for several capacities, both above andbelow that corresponding to the 30% exceedance flow, the design parametersmay be modified to optimise the size of installation. For run-of-river sites, theFDC is fundamental to the calculation of energy output.

Where long-term flow records at a particular site are not available, it isnecessary to estimate the FDC from other readily available data, using anempirical method. Such methods of flow estimation depend on physical andclimatic conditions affecting the catchment. Rainfall data are often utilised, asthey are generally widely available and cover longer periods than riverdischarges.

One such method is through the use of unitised FDCs.6 FDCs from establishedgauging points are unitised by dividing through the relevant catchment area andannual rainfall so that they represent flow from 1km2 of catchment with anannual rainfall of 1 metre. Such unitised curves can be used to represent the generalflow conditions of a particular region. When applied to a specific catchment withinthat region, the unitised curve is factored by the appropriate catchment area andweighted annual rainfall. This method has the advantage that FDCs are producedfrom which energy can be directly calculated. The accuracy of the FDC producedis dependent on the similarity of the particular catchment to the gaugedcatchment, since even within the same region significant hydrologicaldifferences can exist.

POTENTIAL FOR SMALL-SCALE HYDRO-POWER 3

1.3Scotland

The first published estimate of hydro-power potential was that of the WaterResources Committee in 1921.7 The potential was estimated at 1700GWh perannum. This is the lowest of the Scottish estimates, probably because of therudimentary nature of Scottish electrification in 1921 and, perhaps, the stronglobbying of non-resident Scottish landowners.

In 1942, the Cooper Committee suggested a potential of 4000GWh perannum, and shortly afterwards the Hydro-Electric Development (Scotland) Act1943 was passed setting up the North of Scotland Hydro-Electric Board(NSHEB). When NSHEB published its development scheme in 1944, it foresaw102 projects producing 6270GWh per annum. This figure was revised again byWilliamson,9 who suggested that the annual output could exceed 8000GWh.

In 1962, the Mackenzie Committee reported a technically viable potential of7250GWh per annum, and in 1981, with a resurgence of interest in hydrodevelopment—after a 20 year lull—NSHEB re-estimated the Scottish potentialand concluded in a paper to the Economic and Social Research Council that thetechnical potential was 8500GWh per annum (2700MW installed) and that the

Figure 1.1 Flow duration curves: river with few flood flows (left); ‘flashy’ river (right).


economic exploitable potential was 5100GWh (1630MW installed). Since thislast study considered the lower power limit to be 50kW, it is clear that there is alarge number of quite small sites in Scotland that have not yet been assessed.This is hardly surprising, since small schemes do not justify the transmissionlines and access roads which are necessary in many parts of the country.

From such evidence as exists already, it is probable that small-scale schemesin Category (b) with a total potential output of at least 180MW are technicallyexploitable, though the proportion of these which would also merit a Category(c) classification, as being economically viable, could only be an informed guess—perhaps a third, or 60 MW, producing, say, 260GWh per year.

Table 1.1 Total potential hydro-electric power in the United Kingdom

Existing hydro-electricinstallations

Further majordevelopmentsproposed but notbuilt

Estimated small-scale (5kW–5MW)sites

Technicallyexploitable*

Economicallyexploitable*

MW GWh/y MW GWh/y MW GWh/y MW GWh/y

Scotland

1270 4000 350 1100 180 790 60 260

Wales 120 246 2308 390 70 300 25 110

England

9† 20 – – 32 160 14 75‡

NorthernIreland

Negl. 1 40 110 35 150 18 75

Total 1399 4267 620 1600 317 1400 117 520

Notes* Power capacity estimated at 30% exceedance, which on most British rivers gives a 50%

plant factor or thereabouts,†includes Kielder scheme (under construction).‡These values reflect the high utilisation factors of water supply schemes, which are

typically >60%.

1.4Wales

In Wales, as in England, public electricity supply is the responsibility of theCentral Electricity Generating Board. The present installed capacity of CEGBhydro-power stations in Wales is 114MW, producing annually about 215GWh.In addition, there are Water Authority schemes totalling about 5.7MW,producing 41GWh per annum. The load factors represented by these figures, 0.22 and 0.82 respectively, demonstrate only that the CEGB values peaking


capacity highly, whereas Water Authorities are using near-constant discharges toproduce and sell energy to their Electricity Boards.

The hydrometric areas covering Wales have recently been examined for theirsmall-scale potential for the Department of Energy by Salford University.3 Some565 sites were identified: they would have a combined capacity of about 70 MWand an annual energy output of 300GWh. The arbitrary lower power limit in thisstudy was set at 25kW and the estimate of scheme capacities ranged from thatfigure to 3200kW, It is estimated that up to 50% of these sites might come withinCategory (c).

1.5England

The first published data about the hydro-electric resources of England were againthose of the 1921 Water Resources Committee, which suggested an energyproduction of 180 GWh per annum. The Committee made it clear that this wasby no means the total potential, which they were unable to estimate.

A recent study4 of the English water industry commissioned by the Departmentof Energy, and again limited to powers of 25kW or above, has revealed 66 siteswith power potential of 8.4 MW and potential energy of 48 GWh per annum.The economically exploitable proportion of these is indeterminate, but it may beabout two-thirds. There are, in addition, certainly some hundreds of sitesunconnected with the water industry that could be developed, and many otherswould generate powers of less than 25kW, the total of which has not been estimatedsince data are widely dispersed and have not been systematically examined. Toprovide a first indication, it would be reasonable to quadruple the water industrypotential and to assume that one-third of these extra sites would be economic.These assumptions lead to Category (b) and (c) figures of 32MW, 160GWh and14MW, 75GWh respectively.

1.6Northern Ireland

There has been no recent study of small hydro potential in Northern Ireland.More than 200 existing weirs are technically exploitable, but there are fewexamples where electricity is being generated. There are several excellent siteson the Six Mile Water and Blackwater Rivers which would almost certainly beeconomic also.

The western part of Ulster was not fully developed for water power during theindustrial revolution; nor were the upland sites on the Antrim plateau. It isestimated that there may be up to 100 new sites for small-scale installations.Based on topography, rainfall and comparison with similar areas moreintensively studied, it would be reasonable to assume a technical potential of


about 150GWh per annum. This is equivalent to about 3% of current NorthernIreland electrical generation. A Category (c) figure might be about half of this.

Two larger schemes on the Lower Bann and the River Mourne have been wellresearched and would certainly now be economic. They would have a totalinstalled capacity of 40MW and would generate 110GWh per annum.

1.7Summary

The information given in this paper is summarised in Table 1.1.The estimates in this paper are based on the sources cited, on the references

and on private communications from A.T. Chenhall and F.G.Johnson of theNorth of Scotland Hydro-Electric Board and Dr S.R.Cochrane of Queen’sUniversity, Belfast, which dealt, respectively, with Scotland and NorthernIreland.

It is now reasonable to assume that there are upward of 500 sites in the U.K.where small-scale hydro-power could be developed with a better-than-evenchance of economic viability.

References

1. Francis, E.E. Small-scale hydro-electric development in England and Wales. InConference on Future Energy Concepts, Institution of Electrical Engineers,London, Jan 1981.

2. Electricity in Scotland: Report of the Committee on Generation and Distribution inScotland. HMSO, Cmnd 1859, London, November 1962 (the ‘Mackenzie Report’).

3. Department of Energy. Report on small-scale hydro-electric potential of Wales.University of Salford, Department of Civil Engineering, Oct 1980.

4. Department of Energy. Report on the potential for small-scale hydro-electricgeneration in the Water Industry in England. University of Salford, Department ofCivil Engineering, April 1984.

5. Department of Environment. Surface Water: United Kingdom, 1976–80. HMSO,London, 1981.

6. Wilson, E.M. Engineering Hydrology, 3rd Edition, p. 117. Macmillan, 1983.7. Report of the Water Resources Committee. HMSO, London, 1921.8. Hydro-electric works in North Wales. Further developments. Report to North

Wales Power Company, September 1944. Freeman, Fox & Partners and JamesWilliamson, 25 Victoria Street, London SW1. Internal Report No. 54.

9. Williamson, J. Water power development in Great Britain. I.C.E. Joint SummerMeeting, Dublin, 1949.



REPORT NUMBER 15

Section 2Hydro-electric plant and equipment

J.Taylor

and

C.P.Strongman

Merz and McLellan

Newcastle upon Tyne

Hydro-electric plant and equipment

2.1Introduction

The Watt Committee working group on small-scale hydro-power was set up toexamine the potential for development of further low-head hydro-electric poweras a useful and economical addition to the energy resources of the UnitedKingdom and to make suggestions for further study and action. When theworking group discussed its terms of reference, consideration was given toextending its examination to overseas potential. A decision was made, however,to limit the study to development in the U.K., but with the thought that it wouldbe welcome if, in doing so, the working group could encourage developments byU.K. plant and equipment manufacturers for which there might be salesopportunities overseas. Subsequently, the scope of the examination was changedfrom ‘low-head’ to ‘small-scale’ hydro-power, thus covering the entire headrange of installations of small capacity. This Section of this Report is confined tothe mechanical and electrical plant and equipment, although it excludes penstocksand gates (normally considered as part of the civil works) and the civilengineering aspects, statutory and legal matters, potential in the U.K.,environmental considerations and so on, which are dealt with in other Sections.

2.2Definitions

There are many definitions of small-scale hydro-power, and it is not possible tobe precise about them because the concept is somewhat subjective. The electricalengineer thinks of a definition in terms of the output of the generating set,

whereas the hydraulic engineer places more emphasis on head and flow, whichdefine the selection and size of the plant and whose product gives output. Thecivil engineer, although inextricably bound by the head and flow, is alsoconcerned with the physical dimensions of the plant and equipment insofar asthey affect the design of the civil works. For the present purpose, it is proposedto consider a definition in terms of electrical output. Output of the generating setin the range 0–10MW, and even higher, has been quoted in several papers andpublications; consequently there is a tendency to avoid defining what small-scalehydro really means—perhaps the International Electrotechnical Commission(IEC) should give some attention to this. The present working group decided toconfine itself to an upper limit of 5 MW, largely because of the anticipatedpotential for future small-scale hydro-power in the U.K. Within this range otherdefinitions are referred to, as indicated in Table 2.1, but there can be no hard andfast rule.

Table 2.1 Definitions of hydro-electric schemes

Small hydro 2–5MW

Mini-hydro 500kW-2MW

Micro-hydro � 500kW

Figure 2.1 Vertical Francis turbine.

HYDRO-ELECTRIC PLANT AND EQUIPMENT 9

A further category was suggested by one source, namely pico-hydro, coveringsets of � 15 kW; but in fact there is no real logic in using ‘pico’—or indeed‘micro’—unless these terms are related mathematically to the size of the plant.

Although generating set sizes in the � 15 kW range are not likely to be ofinterest to utilities for possible connection to the Grid,* such hydro-electricdevelopment should be encouraged. Many potential and existing privatedevelopers, such as members of the National Association of Water Power Users(NAWPU), find this to be a very useful range for domestic, farm and small local‘cottage industry’ applications in rural areas of the U.K.

This paper is confined to small-scale hydro-power installations designed forthe generation of electricity. It is acknowledged, of course, that directmechanical energy can be provided more cheaply than electrical energy. Theconcept of harnessing water for mechanical energy goes back for centuries,during which the water-wheel was used to produce small amounts of power forgrinding corn and later was developed for direct-drive industrial uses: thereremains a large number of old water-mills in the U.K. which could be developed.Indeed, many of them have been developed already, as publicised by NAWPU,and are used for stone-grinding, processing grain for animal feedstuffs, corn-milling, paper manufacture, flour-milling, snuff-grinding, the manufacture ofcloth and textile products, wood working, forestry work, farm machinery etc.

2.3General

The technology of hydro-electric power is well established in the U.K., andincludes plant that is in service, the design and manufacture of plant andconsulting engineering services. The scope of the technology extends from smallto large generating sets and includes their associated valves and ancillary plant.Manufacturers of plant such as water turbines, pump-turbines, waterwheelgenerators and generator-motors have supplied their equipment for power stationsin the U.K. and abroad. Whereas many of the schemes were landmarks in hydro-power development on account of size or design innovation, others were for ‘run-of-the-mill’ schemes. There are numerous examples of plant that is now regardedas being in the category of small-scale hydro.

Consulting engineering services for hydro-electric power have also beenprovided in the U.K. for many years. Again, a full range of types and sizes ofscheme has been covered; notable major schemes have been engineered as wellas small ones, the extent of the service and the design and engineering resourcesbeing adapted as required. Many of the small schemes in fact constitute the

* The legal and financial conditions for connection of private electricity generatingcapacity to the national public electricity supply network (the ‘National Grid’) aresummarized in Sections 4 and 5 of this Report.


initial power developments in the country or region. The associated plant andequipment can originate from companies abroad as well as from British firms;consequently, experience in the application of suitable plant is both shared andextensive.

Examples of small-scale hydro-power installations in the range presentlyconsidered are numerous in Scotland, operated mainly by the North of ScotlandHydro-Electric Board (NSHEB) but also privately (for example, the aluminiumworks at Lochaber and Kinlochleven). There are also a few small schemes inEngland and Wales, but few in Northern Ireland. Most of the possible types andarrangements of generating plant are already well represented in the U.K.installations. Although some plants have been in service since the turn of thecentury, the 1920s saw an increase in activity; then, with the formation of theNSHEB in 1943, many small schemes were planned and installed until about theearly 1960s. Currently the NSHEB is proceeding with a number of small run-of-river developments.

With regard to design and manufacture, most large generating-plantmanufacturers in the U.K. also cater for the small-scale hydro-power market, and

Figure 2.2 Horizontal Francis turbine.


there are smaller companies that specialise exclusively in this field. In view ofthe limited U.K. potential for the development of hydro-power, much of thisplant has been manufactured for installation abroad.

The selection of generating sets and plant for small-scale hydro-powerapplications is firmly based. Likewise, the selection of water turbines to suit thehydraulic conditions and of generators compatible with the loads or systems towhich they are connected is made generally in accordance with establishedprocedures. Nevertheless, there is scope for simplification and standardisation.This also applies to the ancillary plant.

2.4Water Turbines

All the available conventional types of water turbine are suitable for small hydro-power applications. The most common turbines for low- to medium-headapplications are the Francis and the Kaplan or propeller type. Apart from thevertical-shaft arrangement, the latter may be arranged as a bulb turbine, in whichthe turbine and generator are accommodated in an enclosure within the waterpassageway itself, as a tubular turbine, where the generator is located outside thewater passageway, or as a straight-flow turbine (Straflo), in which the generatorrotor is mounted on the periphery of the turbine runner. In addition, the cross-flow turbine, which is a partial admission (impulse/reaction) type, can be usedfor low- to medium-head applications. For high-head applications, Pelton andTurgo impulse turbines, which can be supplied for very small outputs, areemployed.

Figure 2.3 Kaplan turbine.


In the selection of the type of turbine there are overlaps between the differentdesigns that can be adopted for a given head; therefore other factors, such asspeed, submergence and efficiency, have to be compared.

Other possibilities are centrifugal pumps in reverse rotation and marine bow-thrusters (ships’ propellers). Further possibilities, such as river-current turbinesand commercial lift hydro-engines, are at the experimental stage, and have beendisregarded in the present study.

2.4.1Francis turbine

The Francis turbine (Figures 2.1 and 2.2) is of the reaction type, in which therunner receives water under pressure in an inward radial direction and dischargessubstantially in an axial direction. The main components of the Francis turbineare the fixed-vane runner, spiral casing, adjustable guide vanes and draft tube.The Francis turbine is suitable for a head range of about 10–300 m and ratings of� 100kW. The shaft arrangement can be vertical or horizontal.

2.4.2Kaplan/propeller turbine

The Kaplan turbine (Figure 2.3) is an axial-flow reaction turbine and is basicallya propeller type with adjustable blades. The water enters the spiral casing andafter passing the runner blades flows through a draft tube to the tailrace. Thistype of turbine has a high efficiency over a wide range of heads and output andhas a high specific speed. Governing is achieved by means of adjustable guidevanes and runner blades.

The propeller turbine is similar to the Kaplan but does not have adjustableblades.

2.4.2.1Bulb turbine

With the bulb-turbine arrangement (Figure 2.4) the generating set is contained ina capsule accommodated in the water passageway. It is a very compact and self-contained unit. There can, however, be problems with cooling the generator andaccess to the generator itself, although for small units the generator can beremoved in its entirety for maintenance. For reasons of economy the generatormust be of small diameter and therefore low inertia, thus limiting the applicationof bulb sets to connection with electrical systems of adequate size to maintainelectrical stability. The bulb turbine is suitable for a head range of about 5–20 mand ratings of � 300kW.


2.4.2.2Tubular turbines

With the tubular turbine (Figure 2.5), the generator is located outside the waterpassageway with a long shaft drive and a simple seal arrangement; the generatoris therefore easily accessible for maintenance. A gearbox can be accommodatedbetween the generator and turbine if required to enable a high-speed—and thuscheaper— generator to be employed. It is suitable for heads up to about 15m andratings of 50kW and upwards.

2.4.2.3Straight-flow turbine

The Straflo turbine (Figure 2.6) is a development of an earlier design in whichthe generator is located on the periphery of the runner; there is thereforeadequate space for a large generator with large rotational inertia. The arrangement is compact, and there is no drive shaft. Consequently, the size of thewater passageways, and hence the extent of the civil works, can be considerablyreduced. This type of turbine is suitable for a head range of about 2–30 m andratings of � 500kW.

2.4.3Cross-flow turbine

The cross-flow turbine (Figure 2.7) is a radial/impulse type of low-speed turbine.Its dimensions at low head and high flow are greater than those of comparableconventional turbines. It has simple blade geometry and lower construction coststhan the conventional turbine. For low heads, the blades can be manufactured

Figure 2.4 Bulb turbine.


from cheap materials because the bending forces are low. Efficiency is modestbut the curve is flat over a wide flow range. Gear boxes can be employed toincrease speed to suit economical generator designs; however, they reduce theefficiency.

This type of turbine is suitable for a head range of about 2–200m and ratingsup to about 1MW. Accordingly, it is quite suitable for the lower end of the micro-hydro range, because of its versatility and relatively low cost.

2.4.4Pelton turbine

The Pelton turbine (Figure 2.8) has an impulse wheel on which are mounted cup-shaped buckets that have a radial partition or splitter in the centre to divide theimpinging water-jet which issues from a nozzle on the end of the penstock. Thewheel is encased to prevent splashing. The governing mechanism is an adjustablespear or needle and a jet deflector. This type of turbine is suitable for high heads— within the range 20–1000m—and ratings from 10kW upwards. For lowoutputs one or two jets would be employed and a horizontal shaft arrangementwould be appropriate.

Figure 2.5 Tubular turbine.


2.4.5Turgo turbine

The Turgo turbine is an impulse turbine actuated by a water jet in which thewater enters on one side of the runner and discharges at the other. It is suitable forheads of up to about 300m. The Hydec unit, manufactured by Gilbert Gilkes andGordon Ltd. (see Table 2.4) is a turbine and generator package incorporating aTurgo water turbine.

2.4.6Pumps running in reverse

Conventional water turbines, as described here, with the exception of the‘domestic’ types, are expensive compared with centrifugal pumps run as turbines.Consequently pumps running in reverse as turbines are commonly employed onmicro-hydro installations in developing countries. This has prompted pumpmanufacturers to investigate the turbine characteristics of their pumps.

Since a centrifugal pump lacks guide vanes, other means have to be used forstarting, stopping and loading the set, for instance by adjustment of inlet-valveopening. Developments in this regard are taking place, and for sets usinginduction generators connected to the grid pumps run in reverse appear to besatisfactory. The lower runaway speed compared with a Francis turbine shouldgive cost advantages.

Figure 2.6 Straight-flow turbine.


2.4.7`Domestic turbines'

Some manufacturers are turning their attention to the ‘domestic’ user sector, i.e.consumers in the range � 10/15 kW. Although this is at the bottom of the rangeconsidered by the working group, the market, both in the U.K. and overseas, islikely to be substantial, but generally only for private purposes or for small ruralcommunities. Indeed, a large majority of installations listed by the NAWPU fallsinto this category; none is connected to the Grid, undoubtedly because the costsof connection and of complying with the technical and other regulations couldnot be recovered. Other Sections of this Report refer to these institutionalbarriers. Of the 120 or so installations listed by the NAWPU, only three are grid-connected and these are sets in the range 80kW–100kW. Nevertheless, whatevertheir size and for whatever purpose they are built, they all contribute to thetapping of a renewable energy resource.

Whereas the domestic range of turbines, some of which are made fromengineering plastics, will no doubt be marketed at relatively low prices, theycannot be compared with the more conventional turbines in the upper range of setsizes considered here. The standards to which these turbines are manufacturedand installed, although adequate for their purpose, may be somewhat differentfrom those for an installation that might be designed to supply a local isolatedcommunity of several consumers for which a charge might be made and forwhich some cognizance would have to be taken of the various regulations. The

Figure 2.7 Cross-flow turbine.


domestic-type turbine referred to, when available, may well be competitive, bothtechnically and economically, with standard pumps used as turbines.

2.4.8Waterwheels

Waterwheels—as stated earlier, in the past the traditional method of harnessingwater primarily for mechanical energy —appear to be no longer manufacturedexcept by a small firm in Cornwall. Many existing wheels have, however, beenrefurbished, some as museum pieces; but others have been put into service forgeneration and direct-drive purposes.

2.5Generators

Two types of generators are employed in hydro-electric installations:synchronous and asynchronous (or induction) type. In addition, for microinstallations, standard induction motors may be employed.

Figure 2.8 Pelton turbine.


2.5.1Synchronous generators

Synchronous generators are normally employed for generating sets connectedeither to an isolated system or a grid system. If they are connected to a grid,synchronising equipment is required.

2.5.2Induction generators

An important factor in the employment of asynchronous or induction generators,which are basically induction motors driven above synchronous speed, is thesystem to which the generator will be connected and the capability of that systemto supply the necessary magnetizing power. The fact that the induction generatorderives its excitation from the system and cannot therefore run completelyisolated (capacitor bank excitation excepted) is a disadvantage where a suitablesystem is not available. It also suffers from the disadvantage that the naturalinertia of the generator is considerably less than that of the equivalent, speciallydesigned, synchronous generator. This can, however, be compensated for byadding a flywheel. These disadvantages are to some extent offset by thefollowing important advantages.

A separate excitation system is not necessary: this relieves the unit of sliprings,brushes, field circuit breaker, discharge resistor and automatic voltage regulator.Expensive synchronizing equipment is also not needed; the generator circuit-breaker is simply closed at or near synchronous speed and the machine pullsitself into step. As a consequence, the machine is generally without stabilityproblems. Because of these factors the generator may require less maintenancethan the equivalent synchronous generator; it is also cheaper. Its efficiency issomewhat lower than that of a synchronous generator, but this is relativelyunimportant when considering hitherto uneconomic installations. There are speedand output limitations but they would probably not apply within the output rangeof small hydro.

Although, generally, experience on induction generators of large size islimited, a number have been installed by the NSHEB in the range 50kW–5MW.

2.5.3Standard induction motors

The use of standard squirrel-cage induction motors, instead of the wound-rotortype, as generators is a possibility and, provided that care is taken to avoidoverspeeding, this is a cheap solution for small-scale hydro-power. Overspeedingcan be avoided by the use of overspeed release clutches.


2.6Excitation Systems and Automatic Voltage Regulators

Existing types of excitation systems can be supplied to synchronous generatorsused for the generating-set range that is considered here. Such systems includeshunt excitation using a controlled rectifier, compound excitation and brushlessexciters. The choice depends upon the performance required.

Figure 2.9 Excitation systems: (a) static compound excitation; (b) brushlesscompound excitation.

Figure 2.10 Basic governing system.


For unattended machines thet supply a local load the selfregulating generatorisan obvious choise. In principle, it derives its excitation from the armature voltageand current of the generator via a compounding circuit. An important benifit ofthis arrangement is that excitation is sustained when the generator is subjected toashort circuit. It is usual for a compound sysyem to include an automatic voltageregulator in order to achieve closer voltage control and assist rapid voltagecorrection following sudden load chnages. In the case of mini- and micro-installations, the excitation and regulation equipment can with advantage form agenerator-mounted package. A brushless generator may also be preferred so thatmaintenance requirements are minimised (Figure 2.9).

Larger machines, especially those connected to the grid, need an excitationcontrol system matched to the requirements of the generator and supply system.

2.7Governing

The principles that apply to the governing of large hydro-electric generating setsare relevant to small sets. The objective is to maintain constant speed orfrequency by controlling the turbine flow to match changes of load; it is assumedhere that the plant is needed to supply an isolated system or local load, or to playa major part in the frequency control of a small system. Associated factors arethe time taken to achieve the desired flow and the flywheel effect of the set.Governing requirements therefore have an influence on plant costs. In addition totheir basic function, governors also facilitate starting, stopping, synchronising,parallel operation of generating sets and load sharing between them, and providesecurity against prolonged overspeeding.

Should the small generating sets feed into a large system, governing may notbe considered necessary, particularly in the case of induction generating sets.Then the governor actuator could be dispensed with, leaving the remainingmechanism to serve as an output or load controller. However, means for starting,running-up and shut-down of the set must still be provided.

The main elements of governing systems (Figure 2.10), which apply equally tolarge and small hydro sets, and alternative possibilities are itemised below.

2.7.1.Governor system

2.7.1.1Actuator

The actuator is a stable device or mechanism located on the governor head whichsenses a speed change and converts it into the displacement of a collar or othercomponent serving as a signal to an amplification system. The actuator can be


driven directly from the set by gears or belt—which is common on very smallsets—or by an electric motor supplied from a permanent magnet generator on theset. A variation on this is the electronic governor head, in which the speed signal,obtained from a toothed-wheel pick-up, is processed by electronic means. Theoutput from the actuator is then applied to a hydraulic servomotor via a pilotvalve.

2.7.1.2Servomotor

Since the forces available from an actuator are small (in relation to those requiredto alter turbine spears, deflectors, guide vanes, runner blades etc.) it is necessaryto amplify by employing servomotors. These are controlled by a pilot valve withoil as the pressure medium.

The servomotors can be single-acting, opposed by a spring, as often employedfor Pelton turbines, or double-acting, as applied on Francis and Kaplan turbines.On micro sets and where the operating forces are reasonably low, independenthand-wheel control may be sufficient.

Figure 2.11 Oil supply for governing system.


2.7.1.3Pressure oil

For spring-opposed servomotors, a storage receiver for the oil supply is notalways necessary. For double-acting servomotors, providing large forces over ashort operating time, pressure-oil receivers are needed (Figure 2.11). In bothinstances, a pumping set provides the pressure-oil supply.

2.7.2Alternative possibilities

2.7.2.1Output controller

The application of a microcomputer to the output control of a hydro-electricgenerating set is an economical alternative to the conventional mechanical orelectronic governor; this has been done by the NSHEB at Sloy power station. Inaddition to providing continuous control of the frequency and power output ofthe generating set, the controller can cater for sequential control of the run-upand shut-down operations and the monitoring of the plant. The output controlleracts on the conventional servomotor equipment of the governing system.

It is perhaps too early to say whether or not the microcomputer governor willmatch the reliability of the conventional mechanical or electronic governors. Onthe other hand, improved speeds of response can be achieved without loss ofstability.

2.7.2.2Load controller

A wholly electrical system for speed governing that has recently been introducedfor micro installations may possibly be extended to the low-power end of themini-installation range (Figure 2.12). It is applicable to installations that operateindependently of a public supply network or other parallel connected generators.

Speed is regulated by maintaining constant active load on the generator. Theflow through the turbine is constant at constant head at the full load value, andthe available hydraulic energy is converted to electrical energy at all times,leaving no imbalance to cause significant speed changes. Any positive differencebetween generator output and supply-system load demand is absorbed in adumping or ballast resistor. The only back-up that may be necessary is an inletvalve to isolate the turbine in the event of failure of the speed/load regulator orof a bypass valve.

The ballast resistor and its regulator can take various forms. For example,discrete resistor sections can be selected by electromagnetic or solid-stateswitching; alternatively, a phase-controlled triac, or anti-parallel thyristor pair


with a single ballast resistor, may be employed. The regulator unit comparesspeed, and load, against fixed references to provide switching signals.

Power dissipated in the ballast resistor need not be wasted. For example, watercan be heated for use in a space-heating system or for a hot water supply. Even ifthe surplus energy has to be wasted, there will be no cost penalty, since for suchan installation it has to be accepted that there must be a constant flow, whichwhen not needed for energy would run to waste.

Where water economy has to be practised, some form of secondary governingor water-flow regulator may be necessary if the normal demand is considerablyless than the rated output of the machine. If sudden load increases of anysignificance cannot occur, or are not allowed to, such regulation can be quitesimple.

2.7.2.3Hydraulic brake

The hydraulic brake incorporates a fly-wheel brake, on to which the water isdiverted in the event of load rejection. The tendency to overspeed is therebyopposed and the rate of flow can remain constant. The system is applicable toimpulse turbines.

2.7.2.4Eddy-current brake

An older form of electrical governing is the eddy-current brake, in which theload is adjusted to suit the output of the set. The power absorbed by the braking

Figure 2.12 Constant load controller.


device plus the system load equals the power output of the turbine. The brakingdevice consists basically of a series/shunt-wound magnetic frame, similar to ad.c. motor, in which the main shaft revolves. On the end of the shaft a ferrousdrum is mounted which rotates in the magnetic field set up by the frame. Theshunt winding is connected to the generator terminals, and the eddy currents thatare set up in the drum as it rotates absorb power and cause a braking effect. Asthe load on the generator varies, so does the current in the series winding of thebraking device, partially neutralizing the shunt field. Accordingly, the power ofthe turbine is shared by the system load and the braking device.

2.7.2.5Variable-speed operation

An alternative method of electrical governing for small-scale hydro, now madepossible by the development of large power static-variable frequency converters,is to allow the turbine to ‘free run’. This is a method adopted for wind-drivengenerators and considered for some wave-energy systems. The generatorsoperate at variable frequencies according to the load, and the output is convertedto direct current controlled at a constant value by a current regulator, and backagain to alternating current (Figure 2.13). In effect, the power is transmitted tothe a.c. system via a back-to-back d.c. link. The disadvantages are the need tovary a number of units to suit the constant flow as the load varies, the lowefficiency at part load and the need to design for fairly frequent runawayconditions.

2.8Electrical System Design

In order to limit total costs and thus assist in the justification of small hydroprojects, economies have to be made, not only in the selection of turbine,generator, governing and excitation, but also in the electrical system itself.Although a unitised system, comprising a generating set connected directly to itsown step-up transformer, is common for most large installations, it is sensibleand rational with small hydro-electric installations, if there is more than one set,to connect them through circuit breakers to a common busbar at generatorvoltage with a single step-up transformer to the transmission system. Not only isthis cheaper than the unitised scheme, but it provides good operationalflexibility. It should be mentioned that reactive power sharing is more easilyaccomplished with the unitised arrangement, however. When bussing at generatorvoltage, care must be taken not to exceed the fault-carrying and breakingcapacity of the switchgear and connections; the method of generator earthing andprotection must also be carefully studied. Off-site supplies for station auxiliariescan, however, be provided relatively cheaply.


2.9Protection

When small generating sets are connected to an Electricity Board’s network,obligatory electrical protection is necessary to safeguard the network(Figure 2.14). This obligatory protection is set out in EngineeringRecommendation G47/1 issued by the Electricity Council. In addition someguidance is given in Engineering Recommendation G26.*

Figure 2.13 Variable-frequency generator method of load control.


Figure 2.14 Typical protection diagram for asynchronous generator connected toGrid. Asterisk (*) indicates obligatory protection.


Figure 2.15 Typical protection diagram for synchronous generator connected toisolated system.


For a micro-hydro installation connected to an isolated system, simpleovervoltage, undervoltage and restricted earth fault protection would probably besufficient (Figure 2.15). The great dilemma facing the developers of such aninstallation is that they may well find that the cost of protecting the plant isalmost as expensive as the equipment that it is protecting.

2.10Control

Programmable sequence controllers/microprocessors are almost universallyavailable for starting, stopping and controlling the generating set. They useprogramming languages that are relatively simple to understand and are user-orientated, so commissioning and subsequent programme changes can beeffected by the operating personnel. The use of microprocessors also reduces engineering and commissioning time, since control logic can be modified duringthe course of engineering and at commissioning without the need for wiringchanges. The use of microprocessors can extend from simple start/stop controlinitiated by a single pushbutton operation to full remote operation, in which thegenerating sets can be controlled and monitored fully automatically by signalsreceived from a central control command (if the station is connected to a gridsystem) or by means of local water level or flow detection equipment (if it is anisolated station).

At present, micro-processors are relatively expensive for micro- or mini-hydroinstallations. For such installations, simple manual starting and stopping with theminimum of monitoring may be the right solution. However, if a micro-processor is employed it can carry out sequential control of starting and shut-down as well as continuous control of the frequency and power output of thegenerating set. It may therefore be economic for the upper range of small hydroinstallations.

2.11Design and Engineering

Large hydro-electric projects require specialists in almost every discipline ofengineering. They are usually headed by a project manager, who supervises andcoordinates these disciplines, with a team of engineers, each of whom isresponsible for a section of the work. Careful monitoring of the engineering andprogress in the manufacturer’s works and during construction, with computerisedcritical path scheduling and cost control, is necessary.

* Recommendation G59, revising these recommendations, is expected to becomeavailable about March 1985.


By contrast, this treatment cannot be given to small installations, as theircapital costs are not sufficiently high to warrant expensive engineeringmanagement. Consulting engineers, specialising in hydro-electric project designand engineering, have therefore adapted to this situation by

Table 2.2 Small hydro-electric installations in Scotland

Station Gross head,m

Plantcapacity, kW


Plantcapacity, kW

Sron Mor 52 1×5000 Glenmoriston

14 1×160

Cuaich 27 1×2500 Beannachran 10 1×160

Loch Ericht 55 1×2200 LoyneTunnel

26 1×550

Mullardoch 28 1×2400 Stronuich 10 1×210

Achanalt 20 1×2400 Pitlochry 14 1×50

Lochay 182 1×2000 Orrin 42 1×200 and1×56

17 1×54 Meig Dan 15 1×76

Lubreoch 30 1×4000 Tobermory 42 1×200 and1× 80

Dalchonzie 28 1×4000 Luichart 18 1×85

Lednock 92 1×3000 Torr Achilty 14 1×100

Ceannacroc 91 1×4000 Clunie Dam 18 1×175

Lairg 10 1×3500 Elvanie 35 1×300

Cassley 114 1×1 500 Duchally 26 1×325 and1× 125

Striven 124 2×3000 Quoich 38 1×350

Loch Gair 110 2×3000 Misqeach 37 1×350

Lussa 117 2×1200 Kerry Falls 57 1×500

Storr Lochs 138 2×950 and1×800

Gaur 30 1×160

Kilmelfort 112 1×2000 and1×83

Invergarry 64 1×285

Mucomir 7 1×1750 and1×200

10 1×30

Kerry Falls 57 2×500 and1×250

Vaich 7 1×320

NostieBridge

151 2×625 Culligran 60 1×2000

Loch Dubh(Ullapool)

167 2×600 Gorton 79 1×100

Morar 6 2×375 Errochty 92 1×525



Plantcapacity, kW


Plantcapacity, kW

Chliostair(Harris)

126 2×500 Claddoch 197 1×100

Gisla(Lewis)

48 1×540 *Bonnington – 2×5000

Shin 6 1×100 *Stonebyres – 2×3000

Awe Barrage 7 1×433

The schemes listed here are those operated by the NSHEB and SSEB that give output of5 MW and below.

* South of Scotland Electricity Board.

employing a small number of experienced staff on these projects, so as toeliminate time spent on optimisation of alternative designs: the choice is left tothe general engineering experience of the engineers assigned to the work. Simplespecifications together with standard conditions of contract should also beemployed. This reduces not only the manufacturer’s works and constructioncosts but also tendering costs.

Clients also have a responsibility for keeping the engineering costs of aninstallation to a minimum. Some may get deeply involved and place heavydemands on the man-hours allocated to the engineer responsible for the design.In addition, much time and expenditure can be wasted in discussion of thetechnical requirements with the public utility to whose grid the installation maybe connected. For example, the interpretation of obligatory protectionrequirements may have to be set against different system configurations. TheRecommendations of the Electricity Council, referred to in section 2.9, are by nomeans clear and definitive for every situation, and developers have found that theadoption of these Recommendations is time-consuming.

For auxiliaries systems, it is not always possible to simplify the specificationsto the same extent as for the generating sets, since details of auxiliaries circuitshave to be calculated and scheduled irrespective of the size of the generating set—except perhaps for micro-installations. There is, however, considerable scopefor producing what have come to be regarded as ‘mini-specs’.

2.12Conclusions

To summarise, the turbine type is determined by the hydraulic conditions,operating requirements and economic considerations.

Standardisation of water turbines in general is difficult because they are ‘site-specific’, and it is rare that site conditions match those which are best for astandard turbine. However, for micro installations there is a case for givingserious consideration to standardisation, since the plant and equipment represent


a large proportion of the total cost and these costs can be reduced by somemeasure of standardisation—even though some sacrifice in operational flexibilityand efficiency may be the consequence. Such standardisation might extend to the

Figure 2.16 Cost envelopes.


selection of materials and of runner sizes for specific head ranges, resulting instandard casings, shaft and bearing arrangements etc.

With regard to generators, whenever possible only standard generators shouldbe specified. The employment of standard induction motors run as generatorsshould be considered for grid-connected mini- and micro-installations.

Where small synchronous generators are employed, the self-regulating set or abrushless system may be the best solution for the excitation.

For the mini- and micro-range of sets, manual start-up and stopping withappropriate auto-trip facilities should be adequate. A micro-processor maypossibly be employed, however, to cater for sequential starting and stopping andcontinuous frequency and power output control if the cost is right.

Protection of the installation should be as simple as possible and the minimumnecessary to safeguard the plant. If the sets are grid-connected, cognizance mustbe taken of the Electricity Council’s Recommendations.

From studies made, the future development of small-scale hydro in the U.K. islikely to be mainly in the mini- and micro-hydro range of set sizes and thesummary and conclusions (Section 6 of this Report) have been biased towardsthis. Whilst Section 2 is confined to small-scale hydro in the U.K., it isrecognized that in developing countries a considerable degree of improvisation inhydro-electric engineering is practised. It is unlikely, however, that suchimprovisation would be tolerated in the U.K. for grid-connected installations.

Finally, what are the costs of the electrical and mechanical equipmentassociated with small-scale hydro?—an easy question to ask, but a difficult oneto answer. Much depends on the country in which the equipment is manufacturedand installed. If it is in a developing country, with relatively inexpensive labour,it will be cheaper than in a developed country. Indeed, U.K. manufacturers areknown to arrange for some of their heavy engineering and sub-assembly work tobe done in the Far East because of the high cost of labour in Europe. Figure 2.16indicates the form of cost envelope, showing cost per kilowatt plotted against setoutput across the head range. The curve has been derived from actual installationcosts and budgetary information provided by manufacturers and public utilitiesin the U.K. It does not pretend to be definitive, and many installers will say thatthe work could be done much more cheaply. These claims must, however, bemeasured against the institutional barriers that may or may not apply; thestandards of engineering that are set also affect the cost. The cost curveillustrated in Figure 2.16 most certainly does not claim to represent the installerwho buys a small ‘domestic’ turbine for private use: he is not bound to providesophisticated control and protection requirements, and may not be hampered bytoo much bureaucracy. As to the costs of installations in the U.K. that are connectedto the Grid, the envelope of costs shown in Figure 2.16 is realistic.


Table 2.3 Small hydro-electric installations in England and Wales

Station Plant capacity, kW

Cwm Dyli 1×2000

1×1000

1×2000

Dolgarrog 1×5000

1×5000

Mary Tavy 3×220

2×650

Morwellham 2×320

Chagford 1×31

The schemes listed here are those operated by the CEGB that give output of 5 MW andbelow.

Table 2.4 Suppliers of water turbines in the United Kingdom

Supplier Address and telephonenumber

Types of turbines

Boving & Co. Ltd. Villiers House, 41–47Strand, London WC2N5LB (01) 839 2401

Francis; Pelton; Kaplan;Propeller; Tubular

Gilbert Gilkes & GordonLtd.

Canal Iron Works, Kendal,Cumbria LA9 76Z

Francis; Pelton; TurgoImpulse; Hydec

Weir Pumps Ltd. Cathcart Works, GlasgowG44 4EX (041) 637 7141

Francis; Pelton; Tubular;Reversed pump; Kaplan

GEC Energy Systems Ltd. Cambridge Road,Whetstone, Leicester LE83LH (0533) 863434

Francis; Pelton; Kaplan;Propeller; Deriaz; Tubular

Armfield Engineering Ltd. Ringwood, HampshireBH24 1 PE (04254) 2405

Francis; Pelton; Cross-flow; Kaplan

Newmills Hydro Ltd. Mill Lane, Island Road,Ballycarry, Co. Antrim,Northern Ireland (09603)78610

Francis; Pelton; Propeller(Kaplan); Turgo Impulse

F.Bamford & Co. Ltd. Ajax Works, Whitehill,Stockport, Cheshire SK41NT (061) 4806507

Propeller (Kaplan);Tubular; Francis; Pelton(micro)

MacKellar Engineering(Grantown-on-Spey) Ltd.

Forest Road, Grantown-on-Spey, Morayshire, Scotland

Micro-hydro propeller;Cross-flow; Pelton

Hayward Tyler PumpCompany

PO Box 2, Luton LU1 3LW(0582) 31144

Reverse pump(submersible generator andother types); Pelton

Evans Engineering &Power Company

Priory Lane, St Thomas,Launceston, CornwallPL15 8DQ

Reaction and impulseturbines up to 100 kW;water turbines (under 1200


Supplier Address and telephonenumber

Types of turbines

(0566) 3982 kW); U.K. Patent holdersfor electronic load-governing systems

Flygt Pumps Ltd. Colwick, Nottingham NG42AN (0602) 614444

Submersible propeller

Dorothea RestorationEngineers Ltd.

Southern Works, 68Churchill Road,Brislington, Bristol BS43RW(0272) 715337

Reconditioned Francisturbines

Portmore Engineering Ltd. Portmore Road, LowerBallinderry, Lisburn, Co.Antrim BT28 2JS,Northern Ireland(0847) 651528

Cross-flow

Swift IndustrialDevelopments Ltd.

PO Box 8, Romsey,Hampshire SO5 OGT(0794) 40714

Axial flow impulse withflow control

Water Power Engineering Coaley Mill, Coaley,Dursley, Glos. GL11 5DS(0453) 89376

Cross-flow; Reaction;Second-hand andoverhauled turbines

Westward Mouldings Ltd. Greenhill Works, DelewareRoad, Gunnislake,Cornwall

Water-wheels

Disclaimer. The particulars given in Table 2.4 are given in good faith, but the WattCommittee on Energy takes no responsibility for their accuracy or for anyomissions or for the fitness of the equipment listed either generally or in anyspecific scheme. Developers should discuss their requirements with thesuppliers and seek appropriate advice.

In Tables 2.2 and 2.3, small hydro-electric installations (5MW and below)operated by the NSHEB and CEGB respectively are listed. In addition to these, alarge number of private hydro-electric installations in the U.K. operate at headsfrom about 0.5m to 220m and outputs between 1.5 kW and 200kW: amongthem, most of the recognised turbine types are employed. Only two or three ofthese are connected to the electricity boards’ systems. The remainder are usedfor private purposes only, and some have direct drive applications. NAWPU cansupply reasonably complete lists of them.

Details of suppliers of water turbines in the U.K. are given in Table 2.4.The authors are indebted to the Partners of Merz and McLellan and to their

colleagues in the firm, as well as to the other members of the working group, fortheir valuable help in the preparation of this paper.


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Conference, New Delhi, 1983.7. Micro Hydro Developments. Hydro Power, December, 1980/January 1981.8. Energy Department gives qualified ‘Yes’ to small hydro. Electrical Review, April,

1979.9. Teichmann, H.T. International standardization of small hydro schemes. Water

Power and Dam Construction, May, 1983,10. Generating profits on a small scale. The Engineer, 11/18 August, 1983.11. Giddens E.P. et al. Small hydro from a submersible pump. Water Power and Dam

Construction, December, 1982.12. Generators for small hydro applications. Hydro Power, December, 1980/January,

1981.13. Pereira, L. Induction generators for small hydro plants. Water Power and Dam

Construction, November, 1981.14. Water Power from Weissenburg-Ossberger-Turbinenfabrik GmbH.15. Garman, P. Development of a turbine for tapping river current energy. Appropriate

Technology, September, 1981.16. Submersible generator. Electrical Review, 23 September, 1983.17. Friedlander. Reviving low-head and small hydro. Electrical World, August, 1980.18. Makansi. Equipment options multiply for small-scale hydro. Power, May, 1983.19. Small hydro needs its own experts. Water Power and Dam Construction,

December, 1982.20. Marshall, A.F. et at. Microcomputer control of hydro turbines. Proc. I. Mech. E.,

April, 1983.21. Nair, R. Development potential for low-head hydro. Water Power and Dam

Construction, December, 1982.



REPORT NUMBER 15

Section 3Civil engineering aspects

N.A.Armstrong

North of Scotland Hydro-Electric Board,

Edinburgh

Civil engineering aspects

In most cases, the end-product of a hydro-electric scheme is electricityproduced by the generator and driven by the turbine prime mover. Although thegenerating plant is vitally important, it is nevertheless usual that the major part ofthe capital cost of a hydro-electric scheme is absorbed by its civil engineeringaspects. This Section brings to the attention of the developer of a potential smallhydro-electric scheme the salient questons of civil engineering to which heshould be giving consideration when assessing the feasibility of the scheme.

3.1Aqueducts

There is a large variety of types of hydro-electric schemes. The upper end of atypical scheme (Figure 3.1) is dealt with first here, and other aspects are dealtwith progressively, working downstream to the tailrace, the civil aspects of mostof the types that are normally encountered being briefly described.

The beginning of a conventional hydro-electric scheme is at a point wherewater collects, usually a loch or lake, a headpond or a river, providing a head ofwater. This is what the developer has noticed to make him interested in itspotential for power development. This collection point is fed by run-off fromrainfall or snow, falling over its upstream catchment area and draining naturallyuntil it reaches this point. It is often possible, and if so generally worthwhile, toincrease the amount of natural water that is available by tapping adjacentcatchment areas that would not naturally drain into the selected point. This isusually done by constructing some form of aqueduct system.

A first basic point for the developer, therefore, is that the aqueduct system willalmost certainly require planning permission.

Next, if it is relatively small and does not create a safety hazard for people orlivestock, the aqueduct can be left open; otherwise, it requires to be eithercovered or fenced (Figure 3.2). A buried aqueduct eliminates these hazards, andoverall is generally less expensive.

An open aqueduct’s gradients should permit the water to flow at a reasonablespeed to achieve a self-cleaning capability if grit, debris or stones can gainaccess; if the rate of flow is slow, the aqueduct is liable to become blocked and tooverflow, particularly on curves or bends. The presence of large boulders whichcould readily block the aqueduct if they enter the system should be checked withcare.

Consideration should be given to making the aqueduct as impermeable aspossible by lining it with suitable material, such as slate, flagstones, granite slabs,bitumen, concrete or steel plate etc.

Problems may arise if the aqueduct is open and liable to spill; this mightseriously affect its banking, which could then be breached and far progressively.Provision should therefore be made to allow the aqueduct to spill automatically atpredetermined points so that excessive water is ejected safely. Alternatively, ifpossible, the amount of water allowed into the aqueduct system may be limited;for example, the aqueduct may be fed from a river through a pipe which limitsthe entry of water. A rough guide to the size of the aqueduct, if it feeds a storagereservoir, is that it should be capable of handling five times the average flow ofwater.

It may be necessary to bridge the system where it is crossed by rights of way.

Figure 3.1 Main features of typical scheme.


A last consideration with regard to the aqueduct is the possibility of tunnellingto tap an adjacent catchment area. Tunnelling is likely to be expensive. Theminimum practical tunnel diameter is approximately 2m, and the current cost ofconstruction is around £1000000 per kilometre.

3.2Storage Reservoir

The provision of the storage reservoir may necessitate the building of a dam. Themost important aspect of this in the U.K. is whether it is liable to come within theterms of the Reservoirs Acts. At present, the Act in force is the 1930 Reservoirs(Safety Provisions) Act.1 A new Reservoirs Act was passed in 1975, but its firstphase is only now being brought into operation.

A reservoir comes within the scope of the new Act if its stored water exceeds25000 m3 (883000 ft3 or 5500000 gallons) in volume. This is about the same asthe quantity of stored water that came within the scope of the 1930 Act. It is nota large quantity: for example, if the average depth of the reservoir were 3 m, thedimensions of the area containing this volume would only be around 90 m×90m. Every new dam that is subject to the Reservoirs Acts has to be designed, andits construction must be supervised, by a civil engineer from a panel appointedby, for England, the Secretary of State for the Environment, and the Secretaries

Figure 3.2 Concrete-lined aqueduct, with bridge for sheep.

CIVIL ENGINEERING ASPECTS 39

of State for Scotland and Wales, and on completion a certificate is issued. A listof the appointed engineers can be obtained from the Institution of CivilEngineers1 or the Department of the Environment.3 The dam must then beinspected not less than once every 10 years, again by an engineer selected fromthe panel of appointed engineers.

A new feature of the 1 975 Reservoirs Act is that every dam that is subject tothe Act is required to have, in addition to the 10-yearly inspecting engineer, asupervising engineer selected from a further panel of appointed engineers;1,3 heis appointed to keep a watchful eye on the dam and to ensure that anyrecommendations made at the inspections are carried out. He reports to anenforcing authority. In Scotland this is the local regional or islands council, andin England and Wales it is the Greater London Council or appropriate countycouncil.

From 1 April 1 986 it will be necessary for all undertakers of large raisedreservoirs to appoint a supervising engineer and to be responsible for payment ofhis fees in respect of each dam that he supervises. It is probable, in the case of asupervising engineer’s duties, that the payment, including travel and otherexpenses, for a dam inspection at the present time can be expected to be in theregion of £1000 to £1500.

3.3Dam

Small dams are usually constructed on the gravity or embankment principle(Figure 3.3) and are of earth or rockfill. The type of dam selected may depend onits locality: for example, there may be a ready source of suitable material nearby.Alternatively, the type of dam may be determined on environmental grounds if itmust be of a type that blends with the surrounding terrain. The likely severity offloodwater could be another influence on the choice: for example, a concretegravity dam might be considered superior to an embankment dam.

An embankment dam requires a waterproof membrane. If the dam is relativelysmall, the membrane could be a simple wall with fill on either side; it would alsorequire an upstream protection face, such as stone or rock, to counteract anyeroding wave action.

Some possible weaknesses of an embankment dam are as follows.(1) There is a danger that the dam may be overtopped with flood water, which

could then affect its vulnerable downstream face.(2) If it is necessary to have an opening through the dam for flushing out

gravel and stones etc., the opening could create a permanent potential source ofleakage.

By contrast, the small concrete gravity dam does not suffer these problems: itcan probably be constructed using standard deliveries of ready-mixed concretebut care is needed to ensure that it is well founded on bedrock to prevent itsbeing overturned.


A serious operational problem could be the build-up of gravel, sand etc.behind the dam, especially in river schemes. The scheme must thereforeincorporate means to flush out this material. Usually this is done by running aculvert through the dam, with a flushing gate. The gate can be on either theupstream or the downstream face of the dam; if the gate is on the upstream face,it may be difficult to clear gravel from the gate’s tracks, and this might prevent itfrom operating correctly; if on the downstream face, the culvert is always underfull pressure and water will certainly ultimately find any weakness.

The following are practical suggestions if it is proposed that the dam shallscour through a culvert.

(1) The culvert can be continued upstream of the dam to act as a scouringchannel.

(2) The optimum gradient is 1:20.(3) The width of the culvert should exceed its height by a ratio of about 5:3. It

is important to ensure that when the gate is opened water does not prevent accessfor the purpose of reclosing the gate.

Figure 3.3 Embankment dam prior to installation of 1-m high top wave-wallgabions.


(4) When scour is operated, the rate of flow must not be too low; otherwise,gravel may collect under the gate and consequently it will be difficult to close it.

(5) Conversely, if the rate of flow is too high, only local scouring will takeplace around the entrance to the culvert.

(6) Some arrangement should be made to enable the dam to be deliberatelydrained.

Dams must be designed to cope with floodwater—by discharging usually overa spillway, or occasionally by opening gates.

Guidelines for the quantity of floodwater for which the design of the dammust provide are contained in a Floods and Reservoir Safety booklet,2 publishedin 1978 and obtainable from the Institution of Civil Engineers. Although itsrecommendations are not mandatory, the inspecting engineer would generallyexpect its requirements to be met. The guide requires that the dam be categorisedas follows:

(a) by location, that is, in terms of the risk to life and property downstream;(b) by type, that is, in terms of its ability to withstand overtopping.

The booklet gives guidelines on the period of time in years which, once the damhas been categorised, must be considered for determining the maximum possibleflood that may occur. The longer the period, the more severe the flood that canbe expected. A small dam would possibly be based on a 150-year flood, or on aneven shorter period if the affected community is small and the risk negligible;but a dam may be required to contain a 10000-year flood, or even more, if acommunity with a higher density would be at risk.

The probable maximum flood (pmf) that can be realistically expected at thedam is dependent on the probable maximum precipitation (pmp), rain plus snowif applicable, for a given duration over the relevant catchment or drainage basinunder the worst flood-producing conditions in the catchment area.

Using these data, the booklet provides guidelines on the amount of flood waterthat the dam must safely discharge.

If in any circumstances the dam would prevent water from going down theresidual river section (between the dam and the place where the power station islocated), it may be necessary to discharge ‘compensation water’—that is, tomake good the shortage of water in that section of the river. This could be tomeet fishery requirements or to maintain a summer amenity, for which the riverbed must be kept wet and fresh. About 5% of the average flow is normallyconsidered to be an adequate discharge for these requirements.

3.4Pipeline

If the water is conveyed to the power station through a pipeline, the cost can berelatively expensive. Nevertheless, a good choice of types of pipes is available. It


may be necessary to bury the pipeline for reasons of amenity. A small hydro-electric scheme may have the pipeline above ground: that requires theconstruction of supports.

Pipes suitable for small-scale hydro-electric schemes may be of steel (to BS3601), ductile cast iron, glass fibre, reinforced plastic or asbestos cement (to BS486). Steel pipes are the commonest. The pipes are usually internally protectedby a spun bitumen or epoxy pitch coating. If below about 1m in diameter, theyare difficult to recoat internally, as a painter cannot readily gain access.Corrosion effects can be reduced if the pipeline is always full of water, but steelpipes require periodic attention to contain corrosion. Standard sizes are available—up to 2m in diameter—but there is no limitation on size. The working pressureof the available pipes is virtually unlimited. The pipe joints may be flanged orwelded, or Viking Johnson couplings may be used. Supports are required aboutevery 12m for an above-ground pipeline.

The painting of a steel pipeline requires some care. If a bitumen type of paintis used, the pipes may require to be recoated internally every 5–8 years. The paintshould last longer if it is applied by means of a spun bitumen process— that is,

Figure 3.4 Fibre-glass penstock pressure pipe; diameter, 0.4 m.


when applied to new piping. A bitumen coating usually suffers abrasion damage,particularly on the base. When repainting, it is often difficult to apply the paint tothe invert owing to leakage and condensation, even when dehumidificationequipment is used.

External paint has a life of around 12–15 years; the more sunlight it is exposedto, the shorter its life. Normally, micaceous iron oxide paint is used.

Ductile cast iron pipe is now becoming a very serious competitor: it isavailable in standard sizes up to 1.6 m in diameter. Its working pressure issuitable for a head of around 250m of water at <1.2-m diameter and for a slightlylower head at a larger diameter. It is either flanged or has an O-ring spigot andsocket. Its anti-corrosion characteristics are good. Supports are required every 5–8 m.

Glass-fibre reinforced plastic pipe is available in standard sizes at up to 2m indiameter. Its working pressure is around 160m head if used above ground and200 m if buried; higher pressures are possible. The joints are either O-ring spigotand socket or Viking Johnson coupling. This kind of pipe requires to besupported at intervals of 3–5m. Its advantages are that it is light in weight andeasy to erect, that it can be transported in long lengths, so fewer joints areinvolved, and that it is non-corrosive. Its disadvantages are that it may be proneto accidental damage and may degrade with age, particularly if exposed tosunlight, and that any repair costs could be high.

Asbestos cement pipe is available in standard sizes to about 1.2-m diameterwith working pressures to around 120-m head. It is joined by sleeve couplingswith an O-ring. It requires to be supported at 4- to 5-m intervals. It is liable to beeasily mechanically damaged if installed above ground, so is better buried.

Concrete pipe is available. One type has a steel core with a spun concretelining and a prestressed mortar casing. It is available with diameter < 1.4 m and aworking pressure of 120-m head at 1-m diameter and 60-m head at the largestdiameter. In a hydro-electric scheme, the possible reason for concern about thistype of pipe is that a faulty section of the concrete lining might come adrift anddamage the turbine.

The delivered cost of these various pipes is surprisingly uniform—within arange of some 20%. The ductile cast iron type is the least expensive. Deliveredcost to the north of Scotland is about £ 100 per 1-m length for a pipe of diameter1m.

The NSHEB has one glass-fibre reinforced plastic pipe in service (Figure 3.4).This is a pipe of diameter 0.4 m under a head of 70 m and some 1000 m long,installed in 1 962 to replace a corroded steel pipe that had been in service for almost40 years. Plastic was chosen because of the difficult road access, and the plasticpipes were in fact taken to the site by helicopter. The only operational troubleexperienced was in the jointing—a spigot-and-socket type with a plastic fill—which had cracked as the result of thermal expansion and contraction effectswhen the pipe was left empty for a length of time. The new pipe, as installed,


was in fact too rigid; once that problem had been cured, it has given excellentservice.

For the occasions when a pipe is filled or emptied, means must beincorporated to allow the ingress or egress of air. This is especially importantduring emptying—either planned or accidental—to avoid the danger that the pipemay collapse as a result of vacuum effects.

3.5Screens

Screens are generally installed upstream and at the intake of turbines, but are alsoneeded on occasions at the discharge of turbines for fishery requirements. Theyare installed for the two following basic reasons:

(1) To prevent debris—leaves, grass, twigs, heather roots, stones etc.—whichmay block the passages of the turbine, especially the jets of Pelton and Turgoturbines and the guide vanes and runners of Francis turbines. This blockage

Figure 3.5 Concrete intake dam, incorporating self-cleaning overshot screen.


causes reduction in output, and it is time-consuming to dismantle the turbine toclear it.

(2) To prevent access by fish to the turbine (if fish regulations are in force).The area of screening in this case must be large enough for the flow-rate of thewater to be kept down to the region of 0.25–1 m/sec.

The spacing of the screen is dependent on the size of the debris that can bepermitted to go through the turbine and the size of fish to be encountered.

Screens have to be cleaned. This can be a particularly onerous and time-consuming task, especially in the late Autumn. It may be advantageous to installan oversize area of screening so that the frequency of cleaning is reduced. Forthe operator of a small hydro-electric scheme to have to rake out the screen in themiddle of the night is no fun! Hand-raking is usual on small schemes. Trashrakes are available, but they require manual supervision; at least one firmproduces a relatively inexpensive automatic screen-cleaning device, however.

A particularly troublesome problem is presented by the debris carried inaqueduct systems. Aqueduct intakes can be designed as self-cleaning devices byallowing the water to pass through a slightly upward- or downward-slopingscreen. This traps the debris, which is then pushed up or down the screen by thewater-flow or by gravity. Eventually the debris tips over the end of the screen,and it is then led to an area away from the path of the water (Figure 3.5). An upward-sloping screen can be used where there is an abundance of water, as in a riversupply.

3.6Power Station

To house the generator and associated equipment, the power station can be afairly simple structure, but it must be weather- and vandal-proof (Figure 3.6).The foundations for the machinery are relatively straightforward, although itshould be kept in mind that it is rotating machinery that they support, so theremay be a certain amount of vibration. It may be necessary to install some form ofcrane or lifting device within the station.

The station should be on a site where it is not liable to be flooded by externalwater. If possible, arrangements should be made for the station to drainautomatically if an internal pipe fractures: this ensures that the generator,bearings, control panels and electrical gear are not submerged, as repairs in thisevent would be lengthy and costly.

The water from the turbine is discharged along a simple channel or tail-race. Itmay be necessary to fit a gate at this point to prevent back-flooding of the stationif the turbine is dismantled for overhaul or repair.

Two final basic points for the developer of a small hydro-electric scheme arethat he should take into consideration the siting of the station for road access, andif he proposes to feed excess electricity into the National Grid a suitable gridconnection point must be relatively close.


References

1. Reservoirs (Safety Provisions) Act 1930 (includes Reservoir Floods Standard).Reprinted 1960, 70 pp., Institution of Civil Engineers. Thomas Telford Ltd., 1–7Great George Street, Westminster, London SW1P 3AA.

2. Floods and Reservoir Safety (an engineering guide), 58 pages. Institution of CivilEngineers (address as above), 1978.

3. Department of the Environment, Seymour House, Whiteleaf Road, HemelHempstead, Hertfordshire HP3 9DE.

Figure 3.6 Compensation water-power station, housing 350-kW horizontal Francismachine operating under head of 32 m automatically controlled by headpond levelequipment.



Section 4Institutional barriers

E.C.Reed

Northwood, Middlesex

D.J.Hinton

Anglian Water Authority, Cambridge

and

A.T.Chenhall


Edinburgh

Institutional Barriers

Besides the undoubted economic and financial obstacles likely to face thedeveloper of a small potential hydro-electric source in the United Kingdom, it isrecognised that there are a number of legal and institutional barriers. Indiscussions with the National Association of Water Power Users (NAWPU), apaper produced by the Association for the Watt Committee working group

(

Appendix 4) identified these legal and institutional barriers as ‘factors inhibitingdevelopment’.

To some extent, recent legislation, in particular the Energy Act 1983 (whichreceived the Royal Assent in June 1983) has altered the situation to such a degreethat the working group believes that an examination of the new circumstances isjustified.

The amount of legislation that might apply to a hydro-power developer couldbe vast, depending upon the scale and intent of the development. Most of thislegislation, however, is common to anyone constructing a building or running asmall enterprise. Examples would be the need to obtain planning permission(under the Town and Country Planning Acts in England, Wales and Scotland) or

a

Building Warrant. If the scheme is to be run as a small business, legislationsuch as the Health and Safety at Work Act has to be considered. Since thesematters are not specific to hydro-electric developers, and are at least moderatelyfamiliar, they are not considered further in this Report. Nevertheless, it should beremembered that they remain part of the overall picture and that they add to thegeneral burden of legislative procedures with which any developer must comply.

The remainder of this Section covers only those aspects of legislation thathave particular relevance to small-scale hydro-electric developments, althoughsome of it may also be of relevance to other electricity ‘autoproducers’. Since

separate legislation and institutions obtain in Scotland, Northern Ireland, Englandand Wales, the significant differences applicable to each region are indicated.

4.1Water

4.1.1England and Wales

The legislation that may face a small-scale hydro-power developer with regard towater could be considered to be formidable. The matters that are covered bylegislation are: abstraction; pollution prevention; land drainage; impounding; andfisheries. Furthermore, there are ten Water Authorities that administer theapplication of the legislation in their respective areas in England and Wales.These authorities and various other bodies were consulted by the working group.

(a) AbstractionThe licensing of, and the charges for, the abstraction of water are certainly the

most complex part of the water problem for small-scale water-power users, andit is worth noting that NAWPU was formed, among other things, to ease theconstraints with regard to abstraction caused by the Water Resources Act 1963.Under Section 23(1) of that Act, no-one may abstract water from a source ofsupply except in pursuance of a licence. The 1963 Act gave powers ofenforcement to the river authorities, and, as a result of differing interpretationsamong these authorities as to the licensability of use for power generation,representations were made to the Parliamentary Commissioner forAdministration particularly in relation to charges arising from the licences. Thisled in 1 974 to the issue of a memorandum by the Department of theEnvironment and the Welsh Office entitled ‘Use of Water for Milling or PowerGeneration: Circumstances in which a Licence is Required’, which is included asan appendix to this Report (pages 53–55).

The Water Authorities are entitled to levy a charge on the whole of thelicensed abstraction in accordance with charging schemes made under Section 31of the Water Act 1 973. All the Water Authorities, however, drew attention tonew legislation which was introduced in the Energy Conservation Act 1981, andparticularly to Section 16 which revises Section 60(2) of the Water ResourcesAct of 1963. Broadly speaking, the 1 981 Act refers to the need to conservesources of energy and the desirability of preventing water charges frominhibiting the use of water as a source of energy. All Water Authorities wereprepared to give consideration to this by allowing reduced charges in appropriatecircumstances, but the discretionary nature of these powers has led to widedifferences in interpretation, and a degree of uncertainty for the small hydro-powerdeveloper.

(b) Pollution prevention

INSTITUTIONAL BARRIERS 49

Most small-scale schemes for the discharge of water from a turbine would notbe such as to be considered a trade effluent, and therefore a consent to dischargein accordance with the Rivers (Prevention of Pollution) Act 1951 may not berequired. It would be necessary to establish this point with the relevant WaterAuthority. Under the Rivers (Prevention of Pollution) Act 1951, the definition ofa trade effluent reads as follows: ‘Trade effluent includes any liquid (either withor without particles of matter in suspension therein) which is discharged frompremises used for carrying on any trade other than surface water or domesticsewage’.

(c) Land drainageMost hydro-electric schemes that are installed entail the construction of either

under- or over-water courses. If these are constructed on ‘main’ rivers, consentwould be required from the water authority in accordance with Section 28 of theLand Drainage Act 1976. If, on a ‘non-main’ river, the proposed constructioncauses an obstruction to flow, a similar consent is also required in accordancewith Section 29 of the 1976 Act.

(d) ImpoundmentIf in a scheme there is to be impoundment of water, it is necessary under

Section 36 of the Water Resources Act 1963 to apply for a licence to impound, inaddition to any licence to abstract which may otherwise be required. In the eventthat the impoundment entails storage of more than 5000000 gallons of waterabove local ground level, in accordance with the Reservoirs (Safety Provisions)Act 1930, both the design and periodic inspection of the impounding structurewould need to be carried out by qualified engineers as specified under that Act.New legislation under the Reservoirs Act 1975 is soon to be implemented andwill strengthen certain sections of the old legislation.

(e) FisheriesThe Salmon and Freshwater Fisheries Act 1975 requires any scheme which

interferes with river discharge by impoundment or by abstraction to have regardfor the safety and passage of fish. Sections 12 to 15 of that Act refer to sluice-gate operation gratings for protection of fish at intakes, discharge points andconsents.

It can be seen from the above that the legal/institutional requirements of theWater Authorities in England and Wales are very comprehensive and that someconsultation with these authorities is required before proceeding with any small-scale power development.

4.1.2Scotland and Northern Ireland

Compared to the situation in England and Wales, the situation in Scotland andNorthern Ireland appears relatively straightforward. The Pollution Preventionand Land Drainage legislation must be complied with as in England and Wales,but, where a landowner owns the water rights to a resource (generally by owning


the river or loch) and the salmon rights (which can in some instances beseparately held), there are no special legal barriers to the use of that water forsmall hydro-electric development. In particular, there is no legislation that resultsin the levying of abstraction charges, which the NAWPU seem to regard as oneof the most damaging elements in the current batch of legislative barriers tohydro-power development. There is, however, a common-law requirement thatthe developer should not alter the use of the water to the prejudice of users belowhim, which might in some circumstances affect the way in which the scheme wasdesigned. Normally, however, the passing of water through a turbine, with itssubsequent return to the water course within the developer’s own estate, wouldnot be considered prejudicial to other use.

The Reservoirs (Safety Provisions) Act 1930 applies as in England and Wales,as will the Reservoirs Act 1975, but the limit of 5000000 gallons is not likely tobe breached by the majority of small hydro-electric developments.

4.2Electricity

4.2.1England and Wales

With the passing of the Energy Act 1983, many of the obstacles to the privategeneration and sale of electricity have been removed. It has always been the casethat anyone can generate electricity for his own private use, or as an activitysubsidiary to his main business, but prior to the 1983 Act generation as a ‘mainbusiness’ was the preserve of the electricity supply industry (Section 23 of theElectric Lighting Act 1909). It was also possible for a private developer toarrange to generate in synchronism with mains supply, and to sell as well as buyelectricity from the public supply network. The technical requirements for suchinterconnection were not, however, published, and tariffs were a matter fornegotiation (with the balance of negotiating power lying with the public supplybody). It was not permissible to transfer power from one location to another overthe public supply network.

The 1983 Act repeals or modifies those sections of the Electric Lighting Act1909 and the Electricity (Supply) Act 1919 that restricted private supplies, and itcreates new rules for potential small hydro-electric developers.

The only restriction now placed upon such a developer is that, if he intends tobuild or extend a station with a capacity exceeding 10 MW, he must give theArea Electricity Board written notice of his proposals. (The form and noticerequired for such proposals has recently been published as Statutory Instrument 1984 No 1 36.) Since the 10-MW limit is in excess of the range considered by theWatt Committee working group, this restriction is unlikely to be relevant.


In addition to removing restrictions on construction, the new Act placescertain duties on Electricity Boards which will facilitate connection of smallhydro-electric suppliers to the National Grid and allow the sale and purchase ofpower surplus to local requirements. Unless it is technically not feasible, theElectricity Boards must purchase surplus power and must permit the use of thepublic transmission and distribution network as a common carrier for the supplyto any premises. In addition, the Boards must fix and publish tariffs for suchtransactions on principles laid out in the Act. These principles are that buy-backtariffs should not increase prices payable by the Board’s ordinary consumers, andthat they should reflect the costs that would have been incurred by the Board butfor the purchase of the privately generated power. A disputes procedure is also laiddown and has been published as Statutory Instrument 1984 No 135.

Thus, provided a private hydro-electric developer complies with Section 2 ofthe Energy Act 1 983 (which in practice he would almost certainly do by virtue ofhis capacity being less than 10 MW), no legal obstacles prevent his constructingthe scheme. If he wishes to sell power and to use the public supply network,tariffs have now been published and the technical specifications likely to berequired have been available for some time (Electricity Council EngineeringRecommendations G47 and G26).*

As for hydro-electric development by the Central Electricity Generating Boardor any Electricity Board, these Boards would have to obtain consent forconstruction from the Secretary of State for Energy in compliance with eitherSection 2 of the Electric Lighting Act 1909 or Section 6 of the Electricity Act1957.

4.2.2Scotland

By and large, the situation in Scotland is now similar, but not identical, to that inEngland and Wales. Until 1983, Section 35 of the Electricity (Scotland) Act1979 required anyone desiring to build a hydro-electric scheme in excess of50kW to obtain the consent of the Secretary of State for Scotland (which wouldin practice be given only after consultation with the Scottish Electricity Boards).The Energy Act 1983 amended this situation by replacing the 50 kW limit withone of 1MW. Thus, although the limit for a private developer in England andWales is now for most practical purposes 10MW, in Scotland ministerial consentprocedures have to be followed for a scheme over 1MW. Apart from this, theposition for the private developer, at least relative to the sale of electricity andthe use of the public supply network, is identical to that described for Englandand Wales.

The two Scottish Electricity Boards, in the event that they wish to develophydro-electric schemes, must obtain consent from the Secretary of State forScotland under Section 10 of the Electricity (Scotland) Act 1979.


4.2.3Northern Ireland

In Northern Ireland, the relevant statutory instrument is the Electricity Supply(Northern Ireland) Order 1972, which establishes the Northern Ireland ElectricityService—a body similar in function to the two Scottish Electricity Boards, whichboth generate and distribute electricity.

In most respects relating to private production of electricity, this piece oflegislation is similar to that superseded in England, Wales and Scotland by theEnergy Act 1 983. For example, Section 30 prohibits any person other than theNIES supplying electricity as his primary business, and Section 33 prohibits theconstruction of private generating stations without the consent of the Ministryunless regulations made by the Ministry are complied with. The order alsocontains regulations regarding the provision of stand-by supplies to privatesuppliers by the NIES.

Overall, the position in Northern Ireland is much as it was in Scotland,England and Wales prior to the passing of the 1983 Act. The presentadministration has not, as yet, announced plans to pass parallel legislation to the1983 Act for Northern Ireland, although it has been stated that the spirit of the1983 Act will be adhered to by the NIES in its dealings with private producers.

4.2.4Powers to acquire land and wayleaves

It is perhaps worthwhile noting in passing that, whereas the various ElectricityActs confer wide powers upon the various public supply bodies to acquire land,acquire transmission and distribution wayleaves, dig up roads and enter premises(also to acquire water rights in Scotland), no such powers are available to privatedevelopers of small hydro-power schemes. By and large, this is very unlikely topresent any obstacles, since the size of most schemes would dictate primarilylocal use of the power. It might in some circumstances (more probably in remotelocations in Scotland or Wales) make it difficult for privately promoted smallschemes to be developed to the full where local load was smaller than potentialcapacity.

4.3Environmental Considerations

Until the recent promotion of the Kielder Dam hydro-electric development (andsubsequently the Drumjohn and Kinlochewe schemes in Scotland), there hadbeen no significant hydro-power development since the early 1960s. As a

* Recommendation G59 will replace Recommendations G26 and G47/1 from aboutMarch 1985.


consequence, much of the argument about the environmental impact of suchschemes had been forgotten, to be replaced by the currently more popular themes(at least as far as power generation is concerned) of nuclear safety, acid rain andthe storage of radioactive waste. In the U.K., therefore, hydro-power is oftenthought of as clean, renewable and environmentally benign—an attitude notshared by the environmental lobby, particularly in the numerous countries withmore active hydro-power development programmes, such as Norway, Sweden,Canada and New Zealand.

Environmental considerations enter the field of institutional barriers by way ofeither the Town and Country Planning Acts, the Energy Act or any of several ofthe various Electricity Acts. All of these acts contain clauses demanding that thedeveloper of small hydro-power resources, whether private or public, submits thescheme to the appropriate national or local government department for approval.It is normal at this stage for the department concerned to open the application toobjections by outside bodies or individuals, which can be on a variety of groundsincluding those generally described as environmental. Once objections have beenreceived they are resolved if possible, and if not resolved they are generallysubmitted to some form of public inquiry before a final ruling on the scheme’sacceptability can be made.

The time and effort required by a developer in going through the appropriateconsents procedures is very variable. Consents for very small schemes obtainedunder the planning acts are unlikely to receive much attention other than locally,and may be issued within a matter of months. On the other hand, larger schemesmay receive much wider attention, resulting in public inquiries, the wholeconsent procedure taking over a year and demanding much effort from proposersand objectors alike.

Although grounds for objections to a particular development can rangeextremely widely, environmental objections are particularly important to hydro-electric developers. It is an unfortunate fact of life that the majority of terrainsuitable for hydro-power projects is also terrain considered to be of high amenityvalue. This seems to apply almost universally to any large area of standing wateror any stretch of running water, be it lowland or highland, and is doubly truewhen combined with mountainous, rugged or wilderness landscape. Such areasare therefore highly likely to be considered as scenic heritage and may support alarge body of tourist interest (which in turn may affect the local economy). Inaddition, the terrain may support agricultural or forestry interests and mayprovide important land or water habitats for flora and fauna. A hydro-powerproject can affect such interests in many ways in both its constructional andoperational phases. In the construction phase, the excavation and deposition ofspoil and the storage of construction materials and equipment are likely to have aconsiderable impact. In both phases a number of the scheme’s components cancause such impact, including the dam or intake, the pressure pipeline if notburied, the power station building, the substation, the high-voltage connections ifprovided by overhead line, and most particularly the access roads. In addition, in


the operational phase, effects on the water level of the upper (and lower)reservoirs may expose silt margins, and the watercourse between intake andpower station (which is likely to include waterfalls in areas with favourableterrain) may lose much water.

Typical small hydro-power terrain can also support a wide range ofrecreational activity besides tourism. Thus climbers, hill walkers, bird watchers,naturalists, fishermen, canoeists, dinghy sailors and hunters may all have aninterest in the area to be developed, and are all likely to see various aspects of thescheme as affecting their interests. Some features, such as access roads, may beconsidered an advantage by some groups and an abomination by others. Featuressuch as overhead lines or pressure pipelines are likely to be universallyconsidered bad. The most serious objections are likely to be those affecting thenatural habitats of flora or fauna, such as trout and salmon spawning reaches, orinterference with deer movements or nesting areas. Less serious may beobjections concerning interference with access, such as footpaths, which canusually be accommodated without too much difficulty. In some cases, therecreational impacts may also have a significant effect upon the local economywhere the activity supports hotels or specialist shops or other local employment.In addition, the scheme may interact with the interests of local forestry oragriculture.

4.4Conclusions and Recommendations

Preliminary investigations into the existence of institutional barriers to small-scale hydro-power development led the working group to the conclusion thatParliamentary legislation had placed on the Water Authorities in England andWales a number of statutory requirements that were complicated to administer.However, the fact that there are fewer inhibiting factors in Scotland and that theScottish terrain lends itself more to development of hydro-power does not seemto have brought about a surge in the utilisation of small-scale hydro-power.

During the proceedings of the Consultative Council Meeting* held at the CityConference Centre, London, on 5 June 1984, it became clear that these statutoryrequirements were of themselves an impediment to progress for the smalldeveloper. Furthermore, the administration of the legislation was in certain casesdifficult to interpret and therefore, also, an impediment to progress.

An example of the problems of interpretation arose at the meeting when thediagrams in the memorandum by the Department of Environment and WelshOffice entitled ‘Use of Water for Milling or Power Generation: Circumstances inwhich a licence is required’ (reproduced here as Appendix 3 on pages 53–55) wereprojected. The resulting discussion revealed that the learned audience heldmarkedly conflicting views on the interpretation of these diagrams—which hadbeen intended to improve the understanding of the problem.


Major developers have the resources to surmount the problems caused by thestatutory legislation, but the working group has concluded that the individualdeveloper or small business is concerned at the impediment to progress that iscreated by the legislation and its administration.

The Energy Act 1983 has significantly altered the position with respect tosmall hydro-electric development; new statutory rights to the use of the gridsystem and to the sale of surplus power tend to a further reduction of the risk ofinvestment in small schemes by providing a guaranteed outlet at a predeterminedprice. The small developer with limited resources requires a simple solution fromthe Water Authorities to make the promotion of his scheme viable.

It is understood that one Water Authority has instituted a flat charge forabstraction and that this arrangement has caused no problems. We recommendthat consideration be given by all Water Authorities, in conjunction with otherinterested parties, to the identification of a simple list of principles that arerequired to be observed by the user. Bearing in mind the limited influence thatsmall-scale hydro-power use would have on the Water Authorities’ operations,the payment of a reasonable set fee should prove workable.

* See Appendix 1. page 51.



REPORT NUMBER 15

Section 5Economics of small public and private

schemesA.T.Chenhall


Edinburgh

and

R.W.Horner

Stoke Poges, BuckinghamshireEconomics of small public and private schemes

5.1Introduction

The central question that faced the Watt Committee working group from itsinception was quite simple: why is small hydro-power potential not being fullyexploited in the United Kingdom? Other papers in this Report examine fouraspects of that problem: (a) the potential; (b) legal, statutory and other barriers todevelopment; (c) civil engineering aspects; and (d) the availability of suitableplant. Before an answer to the question can be attempted, it is necessary toconsider economics, finance and risk.

It may be worthwhile to consider, first, the other side of the question explicitly.Why develop the potential at all? Why not leave the weirs and waterfalls aspleasant visual attributes of our landscape? After all, they are not (nationallyspeaking) a very significant resource. The whole U.K. hydro-power potentialcould be replaced by a single full-size nuclear- or coal-fired power station.

The first answer is that the fuel is free and potentially everlasting. The popularimage of hydro-electric power is that once the hurdle of finding the money andbuilding a scheme has been overcome, the consumer can enjoy virtually freeelectricity for a very, very long period indeed. This may not be as close to realityas some people might like, but it does embody the essence of why hydro-electricity is seen as worthwhile.

In addition, of course, in pollution-conscious times the relatively benign natureof the environmental impact of small hydro-power is seen as a very positiveadvantage, and it undoubtedly accounts for some of the support that small hydro-power attracts. By the same token, it also tends to attract support from those who

believe in individual and consequently small enterprise rather than the provisionof services by national or multi-national organisations.

With these answers in mind, the economic picture for small hydro-power isconsidered here in more detail under three headings: costs, benefits andeconomics.

5.2Costs

The capital cost of building a small hydro-electric scheme can be convenientlybroken down into four broad categories: (a) weir or dam and intake; (b) pressuretunnel, pipeline, headrace or penstock; (c) power station and other civil works(building, tailrace, access roads etc.); (d) mechanical and electrical plant. Thecosts are broken down in this way to clarify a simple point: with most generatingor power-producing plant, the capital cost is related, often almost linearly, to sizeor capacity. This means that over a wide range of different types of prime moverthe capital costs can be typified as, say, so many pounds sterling per installedkilowatt (or horsepower). For example, the Central Electricity Generating Boardrecently published figures of £664/kW for coal-fired power stations and £1033/kW for a nuclear power station. For hydro-electric power these generalisations

Figure 5.1 Typical arrangement of scheme with high-level catchment.


are not even approximately true, because the topography, geology and hydrologyof the individual site predominate among the costs. This can be illustrated bygoing through the four categories above, noting the design process and theinfluence of site-specific variables.

5.2.1Weir/dam/intake costs

The first essential in any scheme is to provide a basic intake point for water atsome point above the potential site for the turbines. Consider, first, the situationof a high-level catchment on, say, a Scottish or Welsh mountain, such as thatshown in Figure 5.1. It is a relatively straightforward matter, given a relief map ofthe area and a rainfall map, to work out the potential water run-off from such asite. There are, of course, complications due to the permeability of the rock, thetype of vegetation over the catchment and the surface characteristics of the area.So, first, where should the intake be placed? If it is placed low down thecatchment, the catchment area is increased and water capture is maximised; if itis higher, that capture is reduced but the head available to drive the turbines isincreased. The output of the scheme is obviously a function of the volume ofwater captured, but the energy available from any given volume is also afunction of the head. There is thus a quantifiable trade-off between the twowhich is primarily influenced by the catchment topography and hydrology. Inaddition, suitable geological conditions must be found if the intake is to include asizable weir or dam; the site must permit the catchment to be blocked withoutextending too far on either side.

Next, the height of the weir or dam must be decided. It must be rememberedthat rainfall is an intermittent event, and that run-off will not be a constant fromday to day or season to season. If a hydro turbine is large enough to take thehighest flows, it will operate inefficiently on the lower flows during the majorpart of the year. If the turbine is smaller, it will not be able to cope with highflows, which will have to be spilled and lost. One solution is to store the highflows and release them at low run-off times by building a high weir or dam. Thebigger the weir, and greater the storage, the smaller the turbine that must beinstalled and the more of the potential run-off can be captured. The amount ofstorage for each 1m of the height of the dam is a function of the catchmenttopography, and the whole equation depends upon how ‘flashy’ the run-off is.

The situation that might occur on a lowland river in England is very similar.Once again, water flow is unlikely to be constant throughout the year, and siteconditions will decide for any required capture of water how much must be spenton weir and intake, how deep the foundations need to be, what materials can beused and how high and wide the dam needs to be. A complication is that mostsuitable sites in England and Wales have probably been developed at some timein the past. There may well be existing weirs and races, built from a variety ofmaterials, for use by pre-existing water-mills of many types. The cost of

ECONOMICS OF SMALL SCHEMES 59

development may therefore include the possibility of refurbishing or utilisingdirectly existing facilities.

Figure 5.2 Typical designs of hydro-electric power units with approximately 2 MWoutput.


5.2.2Pressure tunnel, pipeline or headrace

The next stage of the design is to connect the intake to the turbines in the powerstation. For any given volume of water collected at the intake, the maximumamount of energy is extracted by increasing the head—the height differencebetween intake and turbine—as far as possible. Unfortunately, for this purposethe length of the connecting pipe must be increased, which is often veryexpensive. There is a trade-off between increasing output and increasing cost,which is primarily affected by the slope or gradient between intake and powerstation. High gradients generate greater heads for a given length and favourlonger pipelines, whereas low gradients dictate shorter ones.

Allied to the question of length is that of the diameter of the pipe. As pipelinediameter increases, so does cost; but for any given diameter, length and head, thereis a maximum possible flow and a frictional loss in head available at theturbines. The frictional losses in the pipe increase dramatically as this flow isapproached. Once again, there is a trade-off which is a function of length andhead and thus of gradient.

Finally, whether tunnelling is feasible or not, whether or not the pipeline can beburied and which materials are suitable for a given situation will also dependupon geological, topographical and environmental factors.

5.2.3Mechanical and electrical plant

Having decided on the intake and connecting pipeline, the influence of siteconditions on the choice of plant must be considered. Much of this ground iscovered in the Section of this Report that deals with mechanical and electricalplant. The principal determining factor is the head (and hence the gradient of thesite). At very high heads, impulse turbines of the Pelton or Turgo type arefavoured. At lower heads, reaction turbines of the Francis type are suitable, andat very low heads bulb, tube or Kaplan turbines. Each has differentcharacteristics in terms of size, simplicity, robustness, abrasion resistance,controllability and efficiency over a range of flows. Catchment characteristicssuch as head, flow variability and solids in suspension all influence the choice ofthe turbine plant, and hence the cost for a given power output.

By and large, the relationship between installed capacity and cost is fairlylinear for the electrical equipment, but as sets approach the micro sizes the costrelationship becomes distorted by the fixed costs associated with the equipmentthat is needed to comply with connections to the National Grid.


5.2.4Power station and other civil works

The last design question is the cost of the power station building itself, togetherwith such things as tailraces, screens and access roads.

Figure 5.3 Capital cost distribution of hydro-electric schemes in Scotland.


The cost of the power station depends primarily on size, and thus upon turbinetype and upon head. As head increases, the power output for any given physicalsize of turbine increases, so the power station building can be proportionatelysmaller per kilowatt of output. Similarly, different turbine types demanddifferent physical layouts and thus different costs (see Figure 5.2). It goes almostwithout saying that the provision of such items as access arrangements andelectrical conductors to points of demand are themselves site-dependent. Remotelocations with little local demand will necessarily be more expensive to reachand to carry power away from.

5.2.5Other site-specific considerations

The site conditions are thoroughly inter-related with the engineering design andcapital cost; but there are other site factors which could also affect the final cost.For example, are compensation flows needed from the dam to irrigate the oldwatercourse for environmental reasons? Are there other water interests betweenthe intake and discharge sites? Will the pipeline have to be buried or must thepower station be built in a special way to meet environmental legislation? Theseand other matters all affect the capital-cost/output equation.

5.2.6Typical costs

It has been shown above that it is difficult to generalise about the costs of hydro-electric installations and that it is misleading to talk in terms of pounds sterlingper installed kilowatt, since the design and catchment characteristics of thescheme determine how many kilowatt-hours are generated by each 1kW ofinstalled capacity. For example, a study of 65 schemes in Scotland showsaverage costs of about £1200/kW installed, or, more meaningfully, 31 pence perannual kWhr (Figure 5.3). The costs range from £700 to £2000/kW and from 16to 70 pence per annual kWhr. These were all ‘green-field’ schemes, and nodoubt wider ranges are possible where some of the civil works pre-exist, as at oldmill sites. Francis, in his paper on low-head and run-of-river schemes,6 quotes costranges of from £300/kW to £1500/kW installed (at 1978 levels), which is broadlyin line with the Scottish findings, given inflation between the two dates.

Figure 5.4 shows the percentage cost breakdown for two real schemes ofidentical installed capacity, illustrating the differences in annual output, capitalcost and cost breakdown which result from differing site conditions.


5.2.7Oncosts

The question of the costs of designing, engineering, managing and obtainingconsents for the project must be briefly considered. These costs may be vieweddifferently, depending upon whether a private individual is constructing theproject or the developer is a firm or nationalised body. To the private individualthe provision of these services may well be something that he undertakes himself

Figure 5.4 Breakdown of capital costs of two hydro-electric schemes with identicalinstalled capacities.


and is not charged to the project financially. The time and effort involved may beconsidered a free resource, although the obstacles met in acquiring theknowledge or skills required, and particularly in overcoming the consentsproblems, are often cited as tangible reasons that prevent more widespread hydro-power development.

To a private firm or nationalised body these aspects are not cost-free, and mayinvolve not only ‘in house’ resources but the use of specialist consultants. Forlarger schemes these costs may account for from 10 to 30% of the total capitalcost, but as the size of the scheme diminishes the proportion may increase, sincethe basic design effort remains the same regardless of size. This is at least onereason why firms and nationalised industries see a lower size limit toeconomically viable schemes.

The consents procedures also bear upon different developers in different ways.To a private developer the acquisition of planning permission and water licencesmay be his main concerns, possibly combined with the procedure for obtainingconsent to run in parallel with the public electricity supply network. For largerschemes it may also be necessary to obtain wayleaves or other consents.Nationalised bodies, on the other hand, will be more concerned with obtainingstatutory consent to build the scheme and acquiring transmission wayleaves.These procedures, together with the generally larger impact of such schemes,may also lead to public inquiries—a very time-consuming and cost-raisingactivity. Such bodies have access to extensive powers for the acquisition of landrights and wayleaves which are not available to private firms or individuals.

The nature of the developing body, and thus the treatment of these costs, has afairly significant impact upon the perceived viability of any individual scheme.

5.2.8Running costs

Once the hydro-power plant has been designed and constructed, the annualrunning costs must be considered to obtain a true picture of the overall cost ofpower production. Again, the situation is dependent upon the size of the schemeand the type of developer. By and large, the routine running and maintenancecosts for small hydro-electric schemes are very low. With careful design,schemes can be built to operate virtually automatically for long periods and torequire very little in the way of annual maintenance. At the limit, attendanceonce per week or so for the cleaning of screens and filters may be all that isrequired.

For the private individual these activities, like the oncosts, may be considereda zero cost resource and not figure in the economic equation at all. Firms andnationalised bodies, concerned with larger schemes, will have to set asideresources to ensure the safety, integrity and smooth operation of the plant. Asschemes decrease in size, these costs become relatively larger per unit output


until they contribute to making even the most promising of very small schemesuneconomic.

At the very low end of the small hydro-power scale, say under a few tens ofkilowatts, the fixed costs of Water Authority abstraction charges and LocalAuthority rates become particularly important. These charges are one frequentlycited reason for the non-development of small resources by private individuals.The Water Authority abstraction charges are (perhaps justifiably) seen by thesmall developer as unfair, bearing in mind that the water is not diminished inquantity or quality on return to the river course a little further downstream.

5.2.9Electricity Board regulations

The final aspect of costs to be considered here is compliance with ElectricityBoard regulations. Because runoff into hydro-electric schemes varies from day today and season to season, it is very rare to find total correspondence betweenoutput and local efectricity demand. Thus, at sizes above a kilowatt or two, theaverage developer finds himself forced to consider either foregoing productionor finding some other outlet for his surplus. This surplus may occur at certain times(most likely at night) despite the fact that he still remains a net importer ofelectricity from a public supply network (Figure 5.5). The most obvious courseof action from the developer’s point of view is, then, to run his generator inparallel with the public supply network, and import or export as water conditionsdictate. Two problems immediately arise: first, that of buyback tariffs, and,second, that of technical compliance with engineering standards, particularlythose for protection.

Not unreasonably, the Electricity Boards demand compliance with certainstandards, particularly for protection, to safeguard their own plant and, moreimportantly, the lives of their staff who work on the system (see ElectricityCouncil Engineering Recommendations G47/1 and G26). The problems for theprivate producer are twofold. First, he must have the expertise, or must buy theexpertise, to design the protection installation, and, second, he must, of course,purchase and install a fairly sophisticated set of protection equipment. The cost ofdoing so may be out of all proportion to the benefits to be gained byinterconnection unless significant exports of power are expected. It is to behoped that wider application of parallel generation (by say micro-CHP units)will result in packaged and standardised protection equipment whose cost will beappropriate to small-scale hydro-power producers, and that future updates to theregulations will simplify the situation. Recommendation G59, to be publishedabout March 1985, is such a simplification of Recommendations G47/1 and G26.


5.2.10Importance of fixed costs

Given the broad range of costs, it is fairly obvious that some schemes are goingto be worthwhile and others not. The roles of fixed costs, such as operation andmaintenance, design and engineering, Electricity Board and Water Authoritycharges, have been highlighted, in that they often set lower limits to the size ofviable schemes; a figure of 40 kW has been quoted as the lower limit forconnection to the National Grid.

5.3Benefits

It follows that the next question is that of the benefits from a hydro-electricscheme, what are they worth, and at what cost are such schemes economic.

The direct and indirect financial benefits from the operation of small hydro-power schemes in the U.K. derive predominantly from the supply of motivepower, which is almost (although not quite) invariably transformed intoelectricity before use. A secondary benefit, particularly in parts of Scotland, isthat of flood control; a well operated storage scheme can go a long way towardsregulating flood flows and containing potentially damaging volumes of run-off.

In passing, it should be mentioned that in countries other than the U.K.substantial benefits may arise from other water-related aspects. The provision ofpotable water supplies, the irrigation of crops and the provision of areas of waterfor recreational interests, such as fishing or sailing, are all seen as significantsources of benefit. Since in the U.K. (at least for small schemes) these aspectsare not usually important, they are not considered further here. The same is trueof the flood-control aspects, since direct payments are seldom attributable to thisservice.

There are a number of options for the direct use of mechanical power fromwater turbines, including the drive to heat pumps, where the powercharacteristics and heat-source availability are particularly attractive.Nevertheless, the predominant option is the supply of power for electricity, andonce again this is considered here under separate headings for private individualsand for Electricity Boards.

5.3.1Private individuals and firms

To the private developer of a small hydro-electric scheme, the principalattraction will be the replacement of units of electricity that he would otherwisehave to purchase from the public supply network. Since the tariff for unitssupplied on this network includes both the capital cost of plant on the publicnetwork and the running costs of the predominantly thermal plant, it is relatively


high—typically well in excess of 4p per unit for domestic consumers duringdaylight hours.

Problems begin to arise if the output of the scheme does not match thedeveloper’s demand for power at all times. He then has one of three mainchoices.

Figure 5.5 Shortfall and surplus power generated by an independent scheme.


First, he could choose to dump units at times when his demand is less thanproduction, to do without power when his output was less than his demand, andoperate in isolation from public supply. By spending more on water storage andplant control he may be able to tailor his output to match his needs more closely,but this will involve greater capital cost. If he designs his plant to match hishighest demands, he is likely to spill water for a great deal of the time, and if hedesigns for average conditions he is likely to be short of power at inconvenientmoments.

Second, he could operate in parallel with the public supply, importing at timesof high demand/low output and exporting at times of low demand/high output.This will simplify his control arrangements and need for water storage, andsatisfy his demand at all times. On the debit side, he will have to install additionalprotective gear and meet Electricity Board engineering standards. Perhaps moreimportantly, he will find that the tariff situation has changed. The units that hetakes from the Electricity Board will cost him more, since the Boards have torecover their fixed costs of supply from a smaller number of units sold, and theunits he sells to the Board will be valued at less than the units he buys, since theonly avoided cost (to the Electricity Board) is the cost of fuel needed to producethose units at a large power station.

The final main option is that of split-system running, where part of thedeveloper’s load is met by the public network and part by the hydro-electricinstallation on a completely separate circuit. In this way it may be possible tomatch demand to output (using storage radiators or water heaters to soak upsurplus output and avoid too much spillage) whilst maintaining public suppliesfor essential services at times of low output. The main problems here are the costof having two entirely separate electrical networks and the inconvenience ofhaving to juggle appliances from system to system in order to maximiseutilisation of the scheme.

5.3.2Electricity Boards

By the public Electricity Generating Boards the benefits are seen slightlydifferently. Since they have a statutory obligation to supply electricity of a givenquality (frequency and voltage) wherever and whenever it is demanded, they areinterested not only in the units supplied by the small hydro-electric scheme butalso in whether or not those units will be available at times of peak demand. Ifthe units will not be available at times of peak demand, and demand must

Table 5.1 Megawatt-size scheme: development by private company or ElectricityBoard

Private company Electricity Board

Capacity, MW sent out 8.5 8.5


Private company Electricity Board

Output, GWh/annum 21.7 21.7

Capital cost, £×106 4.68 4.68

Capital charge at 5% TDR over 30 years, £×106

per annumN/A 0.30

Financial cost at 10% interest rate over 10 years,£×106 per annum

0.47 –

Depreciation charge, £×106 per annum 0.24 –

Cost of operation and maintenance, £×106 perannum

0.03 0.03

Perceived total cost of scheme, £×106 per annum 0.79 0.33

Cumulative benefit over 30 years, at displacedthermal cost (at 2p per unit), £×106

– 6.67

Cumulative benefit per annum at tariff rate (at 3.5p per unit), £×106

0.76 –

Cumulative NPV, £×106 0.0 1.60

PP, years 6 –

IRR, % 10 7.6

Verdict Not worthwhile Viable

NA, not applicable.

Table 5.2 Micro scheme: development by private individual or Electricity Board

Private individual Electricity Board

Capacity, kW 10 10

Output, kWh 44000 44000

Cost—Equipment, £ 9000 9000

—Engineering and design, £ 0 1000

Total, £ 9000 10000

Financial cost (30 years, 5%), £ per annum – 650

Financial cost (10 years, 10%), £ per annum 1465 –

Operating cost: Materials, £ per annum 200 200

Labour, £ per annum 0 300

Total costs, £ per annum 1665 1150

Benefits at 2p per unit, £ per annum – 880

Benefits at 4p per unit, £ per annum 1760 –

Cumulative NPV over 30 years, £ – 5841

Cumulative NPV over 10 years (5% inflation), £ 12046 –

Verdict Profitable Uneconomic

still be met, one of three measures must be adopted: (a) other plant with firmerresources (coal, oil or nuclear plant) must be installed as well, or (b) more


storage will have to be added to the hydro-electric scheme (if possible) to ensurethat it will have water at peak times, or (c) more hydro turbines will have to beinstalled to achieve a probability that at least one will be available. A plantwhose output is always available at time of system peak is termed ‘firm’,whereas one whose output may not be available is termed ‘non-firm’. Firmoutput is worth more than non-firm output, since non-firm output must be backedup by additional firm capacity. The difference in value is sometimes known asthe ‘firm capacity credit’.

Hydro-electric schemes in general in the U.K., and particularly small schemeswhich typically include very little storage, are generally non-firm. The value oftheir output is therefore considered to be the value of the coal, oil or nuclear fuelthat would otherwise be used to produce that same output at conventional thermalstations, together with an allowance for other marginal output-related costs (suchas some maintenance and fuel-handling charges) at thermal stations.

Compared to an individual who evaluates the scheme’s benefits againstcurrent domestic or industrial tariffs, an Electricity Board is likely to value suchunits at only about half of the tariff rate as the portion attributable to marginalthermal running costs.

5.4Economics

From the foregoing discussion of costs and benefits, it is apparent not only thatcosts are site-specific, but that some elements will be treated differently,depending upon whether the potential developer is a private individual, a privatefirm, or a nationalised Electricity Board. It is also apparent that the same is trueof the treatment of benefits. Put at its very simplest, an economic assessment isthe process of balancing costs against benefits, and measuring the result againstsome standard to decide whether or not a venture is worthwhile. As the treatmentof costs and benefits differs depending upon the body involved, it is predictablethat the standard or yardstick for the balance also varies from body to body.

Economic results can be expressed in many different ways. Net present value,internal rate of return, payback period and cost-benefit ratio are just four of theways in which the same numbers can be presented in the search for an index ofworth for a project. In all of these, two factors are explicitly or implicitlyimportant: first, the length of time during which a project is or remainsremunerative, and, second, the developer’s ‘time preference for money’expressed as a discount rate or as a desired internal rate of return (IRR) orpayback period (PP). Both vary significantly between private and publicdevelopers, and from body to body and project to project within those categories.One of the reasons for these variations is the ‘riskiness’ of a venture.


5.4.1Private bodies

Private bodies vary substantially from individual to individual in their methodsof economic assessment, although a great many appear to put emphasis on PP asthe prime economic yardstick. The biggest distinction within this group is oftenbetween individual householders or landowners, who may be interested in smallhydro-power for other than purely financial reasons, and who may take a fairlylong view of asset lives and PP, and other organisations interested in small hydro-power as a commercial proposition. In the latter case it is not unusual to findshort PP (3–6 years) and high IRR (20–30%) used as yardsticks for prospectiveschemes.

5.4.2Public bodies

Public bodies, by comparison, are relatively well regulated and hence uniform.For the Electricity Boards the framework for economic assessment is laid downin a Government white paper entitled ‘The Nationalised Industries’ (Command7131).17 This states that the Boards must use methods that ensure an overall realrate of return of 5%. This, then, is the basic rate used for the majority ofeconomic assessments, although higher rates may be considered appropriate forprojects that might be considered ‘risky’ or ‘optional’ (in the sense that they arenot strictly necessary to maintain safe and secure supplies of electricity toconsumers, although they may contribute to cheaper or more economicalsupplies).

As far as length of life is concerned, the nationalised industries are concernedwith supplying services to the public over long periods as cheaply as possible.They therefore take a long-term view when assessing a scheme, and commonlyconsider lives for hydro-electric schemes in excess of 20 years. A typical figurefor many installations would be 30 years, with some elements (dams forexample) being amortised over periods up to 60 years.

Methods of assessment vary a little, but in the majority the principle of thediscounted NPV of the cost and income streams is by far the most important,although IRR and PP are also used. The minimum criterion is often a positiveNPV at a 5% test discount rate (TDR) over (say) a 30-year life.

5.4.3Examples

The variations in the treatment of costs and method of assessment may lead toidentical schemes being accepted or rejected, depending upon the body that doesthe assessment. Tables 5.1 and 5.2 illustrate this by showing typical values for amegawatt-size scheme (Table 5.1) and kilowatt-size scheme (Table 5.2) as they


might be assessed by various private or public bodies. In both cases the schemedesign and cost are identical. Table 5.1 shows how the use of high discount ratesor short PP can prejudice the economic outcome, and Table 5.2 illustrates howthe treatment of some cost elements and a differing perspective on prospectivebenefits can affect the calculation.

5.4.4Finance

Related to the question of economics is that of finance. Obviously, if a potentialdeveloper has his own internal sources of funding, his methods of economicassessment and financial management need satisfy only himself. In many cases,however, capital must be borrowed from outside sources, and the developer hasto consider real interest rates (as opposed to economic discount rates), cashflows, grants and financial limits. Such matters are once again highly specific toeach individual case, and are likely to change over time. Interest rates may befixed or variable, and have to be considered in relation to the current inflationrates. Cash flows have to take account of future inflation in the electricity tariff oralternative fuels. Grants or reliefs may be available to some projects for someindividuals but not others. Even assuming that all these criteria can be met,capital may be rationed so that projects cannot be undertaken.

5.4.5Risk

Risk has already been mentioned briefly in the economics section of this Reportas one of the factors that affect a developer’s economic criteria for passing orfailing a particular project. Risk in a hydro-electric development appears in manyways. Will the resource (run-off, river flow) be as big as estimated, and will it beunaffected by influences outside the developer’s control (afforestation, diversionupstream etc.)? Can the resource be developed without cost over-runs, and willthe completed scheme perform to expectations with regard to efficiency andavailability? Will the benefits (electricity tariffs, alternative fuels) maintain theircurrent real price over future years?

One of the ways of dealing with risk is to increase the economic yardstick(increase the TDR or IRR, decrease the payback period) to a level where the riskis felt to be reasonable (and the rewards for success high enough) for projectswhich meet the yardstick. This method is frequently used by private firms andindividuals, and goes some way to explain the high rates of return and short PPdemanded.

A more sophisticated means of assessing the problem is to attempt to defineprobability bands for each of the risk-bearing elements and to perform sensitivitystudies of the economic results given the probabilities of the events concerned.These methods are more likely to be used by large organisations and nationalised


bodies and are used in conjunction with the basic (or central case) economic resultsin deciding whether or not to develop a resource.

5.5Conclusions

This Section of the Report began by asking why small hydro-electric potential isnot being exploited more widely. In the past, nearly all the suitable sites forwater-power extraction in England, and many in Wales, have been exploited.Today few are used. In 1 947 there were 27 small hydro-electric installations thatprovided public supplies of electricity. Seventeen of these in England and Walesare now (it is thought) closed.

Undoubtedly one of the reasons for this state of affairs has been the rise in theready availability and relative cheapness of alternative forms of energy fromcoal, oil or nuclear sources. The steady rise in the burden of capital costs,particularly those with a large civil cost element, together with the falling realcost of coal and later oil/nuclear power, has swung the economic balance awayfrom hydro-electric power. Relatively recent sharp upswings in the price of allthese alternative fuels have not yet produced the expected swing in the oppositedirection.

In conclusion, the issues raised in the Section of this Report that deals withcost and economics are now examined, highlighting those points (in no particularorder) that contribute to the lack of momentum in small hydro-powerdevelopment, and thus indicating where improvement in the situation isrealistically possible.

5.5.1Water Authorities

The plethora of regulations relating to water supply, particularly in England andWales, is referred to in a different Section of this Report. These regulations inthemselves can be considered an obstacle to development. The principal amongthem are the need (again only in England and Wales) to obtain a licence forabstraction and the levying of abstraction charges. Many potential developerscite these as two of the most important of the numerous small obstacles todevelopment, particularly since hydro-power development may not interfere withWater Authority objectives, and such charges are not made elsewhere.

On the other hand, it must be stated that many authorities either overlook thecharges or make minimal charges to domestic water-power developers, and thatthe authorities are obliged to protect the interests of the general public in thematter of water supply. It may also be noteworthy that in Scotland (where nosuch abstraction charges are made) there does not appear to be a markedly greaterlevel of small hydro-power development.


5.5.2Electricity authority

In the Section on institutional barriers, and in the previous pages, reference ismade to the situation where a developer wishes to run his scheme in parallel withthe public supply network. Two issues are important here: first, the need to complywith certain standards, principally those concerning protection; and, second, thesituation regarding ‘buyback’ and ‘standby’ tariffs. Until 1983 it wasundoubtedly the case that the low buyback tariffs and lack of interest generallyby the Electricity Boards in promoting autoproducers were obstacles todevelopment. The Energy Act 1983 sought to redress that balance by givingautoproducers certain rights and laying out principles for autoproducer buybacktariffs. These regulations have been in force for a relatively short time, and it isprobably too early to assess their likely impact. Whilst they are obviously a movein the correct conceptual direction as far as small hydro-power developers areconcerned, it remains to be seen whether or not the practical upshot will satisfyall parties concerned. There are already signs that the new tariffs may not go farenough to satisfy autoproducers.

With regard to engineering standards, the logic behind such standards isirrefutable, the main complaint being that the standard was perhaps too high orover-engineered. It may be hoped that the publication and widespreaddissemination of the standards, together with their revision, will encourage thedevelopment of simple low-cost, mass-produced equipment, ‘type approved’, tomeet them. Such developments will benefit autoproducers of all types, and gosome way to assisting the development of small hydro-power schemes.

5.5.3Grants and aids

In order to exploit the U.K.’s small hydro-power potential, a large number ofindividuals (potential developers) will have to be convinced of its worth and thengo on to take the decisions necessary to carry the project through. The disparitiesbetween the cost, benefit and economic assessment criteria used by differingindividuals and bodies in assessing any one scheme have been noted above.

One of the ways in which the national Government or the EuropeanCommunity (EEC) can encourage development along these lines is through thefunding of grants or other forms of aid. Unfortunately, small hydro-power hasfound itself rather uncomfortably between two extremes when it comes toattracting such aid. In many ways it is considered a ‘mature’ technology, whichmeans that it receives very little in the way of research funding. It also often failsto pass the ‘novelty’ criterion when it comes to demonstration projects.Furthermore, being capital-intensive, it often fails to pass the stringent economiccriteria demanded of development and demonstration projects, which are often


expressed as payback periods and thus fail to get to grips with the longevity ofhydro-power installations.

5.5.4Design and engineering

One of the fundamental conflicts of small hydro-power is that by definition (theindividual resources being small) very little money is available in any onescheme for design and engineering. Nevertheless, as is emphasised in the Sectionof this Report that deals with costs, each scheme is different and in a perfectworld demands full attention to the optimum selection of all the various criteria.

The solution may be the application of the appropriate technology in eachparticular case. Two points arise from this. First, how does the small hydro-power developer obtain advice on the ‘appropriate’ technology for his particularproject? For those unable or unwilling to do their own research options are byand large restricted to the established engineering consultancies, or possibly auniversity-based consultancy service of the type recently set up at Salford. Asyet the volume of work on small schemes does not appear to be sufficient tosupport specialised services appropriate to the smallest of schemes, althoughthere are moves in this general direction.

The second point is that the ultimate success of any programme of smallhydro-power development must depend upon the availability of standard mass-produced packaged equipment of low cost and high reliability with a minimumof operating and interfacing requirements. To some extent the development ofsuch equipment depends upon the presence of a vigorous market, and hence thefamiliar ‘chicken and egg’ syndrome may occur. Encouragement may be drawnfrom the moves in this direction in the field of small schemes for combined heatand power (CHP) (somewhat accelerated by the Energy Act 1983) together withthe undoubted market potential in the less developed countries of the world.Areas of particular note are the gathering momentum of micro-electronics in thefields of protection and control, which could simultaneously lower costs andraise efficiency, and the recent use of low-cost pumps in reverse as highly cost-effective hydro turbines.

Bibliography

1. Small Scale Hydro-Electric Power. ETSU, Harwell, November 1982.2. Vernon, K.R. Potential for Small Scale and Other Hydro developments. ESRC

Paper, March 1981.3. Scott, M.M. Small Scale Hydro Power in the British Isles. Imperial College of

Science and Technology MSC Report, September 1982.4. Birkett, D.G. Review of Potential Hydro-Electric development in the Scottish

Highlands. Electronics and Power Vol. 25, No. 5, May 1979.


5. Head, C.R. The Real Costs of Mini Hydro in Developing Countries. Modern PowerSystems, February 1983.

6. Francis, E.E. An Appraisal of Low Head and Run-of-River Water Power inEngland and Wales. Department of Energy, November 1978.

7. Banks D. Imaginary Hydro-Electric Schemes, Paper presented to West of Scotlandsection of the Institution of Civil Engineers.

8. Electricity in Scotland: Report of the Committee on Generation and Distribution inScotland. HMSO, Cmnd 1859, London, November 1962 (the ‘Mackenzie Report’).

9. Manser, W.A.P. Hydro Electricity in Scotland. Federation of Civil EngineeringContractors Study, 1984.

10. Garcke. Manual of Electrical Undertaking. Vol. 44 (1946–47 edition).11. Crichton, C. Thirty years’ experience of private hydro-electric generation. Energy

for Rural or Island Communities, Pergamon Press, Oxford, 1981.12. Agnew, P.W. Appropriate Control Systems for Water Turbines. Ibid. 13. Johnson, F.G. Hydro power in the UK—past performance and potential for future

developments. IEE Hydro Power Colloquium, May 1984.14. Prescott, W. Mini hydro plant—the packaged concept. Ibid.15. Williams, D. Turbine selection. Ibid.16. Grant, A. A pump as a small turbine. Ibid.17. The Nationalised Industries. White Paper. Cmd. 7131, HMSO, London, 1978.18. Proof of Evidence to the Sizewell Inquiry, Central Electricity Generating Board,

London, 1984.



Section 6Conclusions and recommendations

J.V.Corney

Sir Alexander Gibb & Partners,

Earley, Reading

and

H.W.Baker

James Williamson & Partners,

GlasgowConclusions and Recommendations

6.1

The Potential

The working group considers that small-scale hydro-power is a valuablerenewable source of power which is still unexploited and that the potential ofsmall-scale hydro-power which could be economically developed at the presenttime as a useful addition to the energy resources of the United Kingdom amountsto somewhere between 500 and 1000 GWh/year (broadly between 200×103 and300×103 t coal equivalent).

6.2Obstacles

The main obstacles which may have inhibited development in the past areconsidered to be:

(a) The cost of electricity from the National Grid has been, until recent years,low enough to make small-scale hydro-electric development appear unattractive,particularly by comparison with the convenience of an easily available and reliablepublic source of supply.

(b) Electricity authorities have shown little interest in small-scaledevelopments.

(c) Incentives for water authorities to explore and develop hydro-electricpotential have been limited.

(d) Prior to 1983, no positive action had resulted from Governmentdiscussions with the electricity supply industry and water authorities aimed at

improving the situation (e.g. tariff arrangements) that had been brought out inGovernment-commissioned studies.

(e) Owners had often not appreciated that they had an economic exploitablepotential. There was no organised system of making owners and potentialdevelopers aware of their resource.

(f) Financial backers have shown little interest in longer payback periods, eventhough these were demonstrably attractive in the longer term.

(g) The grants system operated by the Government and by the EuropeanEconomic Community is designed to assist innovative development but does notapply to conventional small-scale hydro-power development,

(h) The obstacles to a developer in the shape of complicated statutoryrequirements, especially in England and Wales, are formidable, and theadministration of legislation is difficult to interpret.

(i) The cost of overcoming possible objections, whether or not they are valid,may make a development unviable.

(j) It has been widely held that suitable plant and equipment were not readilyavailable and that control equipment in particular was complex and expensive.The advent of micro-electronics for control and protection has an immenseimpact which has not yet been fully exploited.

6.3Recommendations

The working group was invited to make suggestions for further study or action,with the eventual objective of helping to overcome the main obstacles andstimulate new schemes. In so doing, the group draws attention to the Energy Act1983 and emphasises its significance as a substantial step forward in removingobstacles to development; it considers that the full benefit of this Act has not yetbeen fully appreciated. It is perhaps too soon to gauge its effect.

In making the following suggestions the group is conscious that, in someinstances, it has not specifically identified a source of funding or partiesresponsible for action. In some cases it is believed that the Government would bethe appropriate party. It is hoped that publication of this Watt Committee Reportwill stimulate further discussion and that from such interest will emerge positiveaction which will result in development of a substantial proportion of thisuntapped resource.

(a) The basic facts of the Energy Act 1983 should be publicised by electricityauthorities, drawing attention to the possibility of collaboration with privatedevelopers.

(b) In order to simplify and clarify the rather confusing interface whichcontinues to exist between Water Authorities and potential hydro-powerdevelopers, the Department of the Environment should consider issuing aStatutory Instrument or similar guideline, as appropriate, to achieve somemeasure of standardisation and consistency. It is hoped that this might result in

CONCLUSIONS AND RECOMMENDATIONS 79

either the abolition of the charge for abstraction for small hydro-electricdevelopments (as in Scotland) or the introduction of a standard set fee, coveringthe necessary administration.

(c) Reconsideration should be given by the Government to funding promotionand construction of pilot small-scale hydro-power developments with the objectof identifying obstacles and recommending action to ease or remove suchobstacles.

(d) In any appraisal of economics, the funding agencies (public or private)should be encouraged to use more realistic return periods of ‘pay-back’,especially where the proportion of civil construction is high (say ten to fifteenyears).

(e) Government and European Economic Community should considerremoving some of the restraints on grants to make them more accessible toconventional small-scale hydro-power development. The availability of such aidshould be more widely advertised and the procedures for applications simplified.

(f) Government should commission assessments of undeveloped potential inthe U.K. where this has not already been done. This should include a schedule ofthe location of and current situation regarding former installations, say in excessof 50 kW potential. Such assessments, along with earlier studies, should lead to asituation where beneficial development is identified and possible developers aremade aware of the potential.

(g) Methods of dealing with objections should include means of obviatingcosts and delays; this is especially important where objections are suspected ofbeing frivolous or spurious.

(h) Manufacturers should be encouraged to standardise on and mass-producemechanical, electrical and control equipment—a process which may help exportsas well as development in the U.K.

80 CONCLUSIONS AND RECOMMENDATIONS

Appendix 1Sixteenth Consultative Council Meeting of

the Watt Committee on EnergySmall-Scale Hydro-Power

On 5th June 1984 the Watt Committee on Energy held the sixteenth in the seriesof its Consultative Council meetings. The theme was ‘Small-Scale Hydro-Power’, and the meeting was held at the City Conference Centre of the Instituteof Marine Engineers, London. Those present were the secretaries and appointedrepresentatives of the member institutions of the Watt Committee and others withprofessional interests in the subject of the meeting.

Papers (listed below) were presented informally by members of the WattCommittee working group on Small-Scale Hydro-Power, and there were severalperiods of discussion. The contents of the papers form part of the present WattCommittee Report. As published here, the papers have been expanded andrevised to present additional information for which there was insufficient time atthe meeting and to take account of questions that arose in discussion (includingsubsequent written contributions).

Programme of MeetingSession 1 Chairman: J.V.Corney (Institution of Civil Engineers)Official Opening by Dr J.H.Chesters OBE FEng FRS (Chairman, Watt

Committee on Energy)J.V.Corney: IntroductionProfessor E.M.Wilson (Institution of Civil Engineers): The potential for small-

scale hydro-power in the United KingdomJ.Taylor (Institution of Electrical Engineers): Mechanical and electrical plant

and equipment for small-scale hydro-powerN.A.Armstrong (Institution of Electrical Engineers and Institution of

Mechanical Engineers): Civil engineering aspectsDiscussionSession 2 Chairman: H.W.Baker (Institution of Civil Engineers)E.C.Reed (Institution of Water Engineers and Scientists),D.J.Hinton (Institution of Civil Engineers) and A.T.Chenhall (Institution of

Electrical Engineers): Institutional barriers to small-scale hydro-powerdevelopment

DiscussionSession 3 Chairman: Professor E.M.Wilson

A.T.Chenhall: Economics of small public and private schemesDiscussionJ.V.Corney: Concluding remarksContributors to discussionW.R.Abram, South West WaterP.W.Agnew, University of GlasgowJ.H.Amos, Institution of Electrical EngineersJ.M.Bain, Institution of Mechanical EngineersD.J.Banks, Institution of Civil EngineersDr W.O.Binns, Chartered Institute of ForestersCommander G.C.Chapman, National Association of Water Power UsersJ.A.Crabtree, National Association of Water Power UsersDr P.J.Fenwick, Department of EnergyDr M.Flood, International Solar Energy Society—U.K. SectionO.M.Goring, Water Power EngineeringR.Holland, Institution of Electrical EngineersDr P.O.McGovern, Scottish Development Department Planning ServicesDr J.C.McVeigh, Institution of Production EngineersDr M.Mansell, Institution of Civil EngineersP.Mason, Institution of Structural EngineersW.A.Patterson, Institution of Civil EngineersI.F.Seager, Institution of Electrical EngineersT.E.Truslove, Institution of Mechanical EngineersDr M.L.Wright, Water Power Engineering

82 APPENDICES

Appendix 2Government grants and funding available

by P.J.Fenwick

Department of Energy, London

There are currently a number of schemes, funded both by the United KingdomGovernment and the European Economic Community, which may be applicablefor either the development or installation of small-scale hydro-power projects.The names and addresses given here were correct in February 1985.

A.2.1EEC Support for Demonstration Projects

The European Commission will again be inviting applications in 1985 for thefunding of the demonstration of hydro-electric schemes with outputs of up to 3MW. The criteria for funding of up to 49% of the total cost are that the schemesshould generally be of low head and be of a decidedly innovative character.General enquiries relating to the scheme may be made to:

Dr G.PrestonDepartment of Energy,Thames House South,Millbank,London SW1P 4QJ.Telephone 01–211 5461.

A.2.2Energy Efficiency Survey Grants: Department of Energy

The Energy Efficiency Office at the Department of Energy has recently includedthe category ‘Use Renewable Energy Source’ as a recommendation which mightbe made under the grant-aided Energy Efficiency Survey Scheme. The purpose ofthe survey is to identify opportunities for potentially cost-effective improvementto energy efficiency, and the scheme offers a grant of 50% towards the cost of asurvey carried out by an independent consultant. If, therefore, at a particular site,small-scale hydro-power were to offer one of the better opportunities for cost-effective improvement, this would appear in the ranking of the recommendationsmade by the consultant. Further details of the scheme may be obtained from:

Energy Efficiency Office,

Department of Energy,Room 1697, Thames House South,Millbank,London SW1P 4QJ.Telephone 01–211 7074.

A.2.3Support for Innovation: Department of Trade & Industry

This scheme provides general support to manufacturing organisation towards thecosts of the research, design, development and launch of technically innovativeproducts. Grants of up to 25% of the total costs are currently available. In thefield of small-scale hydro-power, those proposals leading to the development ofinnovative equipment suitable for export markets would be particularlyappropriate. Further information may be obtained from:

Research & Technology Policy Division,Department of Trade & Industry,24 Bressenden Place,London SW1E 5DT.Telephone 01–213 5839.

A.2.4Research and Development Funding: Department of

Energy

The Department of Energy provides research and development funding for arange of energy projects, including the renewable energy sources such as small-scale hydro-power. The Department’s primary objective is to investigatepotentially significant new and renewable forms of energy and assess whatcontribution they might make to U.K. energy supplies in the longer term.Support for the development of selected promising ideas, techniques orequipment is assessed in terms of its contribution towards achieving theDepartment’s primary objectives. Further details may be obtained from:

Mr W.Macpherson,Department of Energy,Thames House South,Millbank,London SW1P 4QJ.Telephone 01–211 6580.

84 APPENDICES

A.2.5Regional Development Grants: Department of Trade &

Industry

The installation of a small-scale hydro-power scheme may in specificcircumstances qualify for support under the general criteria of the regionaldevelopment grants. These grants are primarily designed to encourage investmentin new capital assets for manufacturing activities located in specificallydesignated geographical areas. Grants of up to 22% are available towards thecapital expenditure incurred in providing new buildings, works, machinery onplant for use on qualifying premises. Further information may be obtained from:

Regional Policy and Development Grants Division,Department of Trade & Industry,Room 429, Kingsgate House,66–74 Victoria Street,London SW1E 6SJ.Telephone 01–212 6712.

APPENDICES 85

Appendix 3Use of water for milling or power

generation: circumstances in which a licenceis required

Memorandum by the Department of the Environment andWelsh Office

NOTE. In supplying a copy of this Memorandum, which was prepared in August1974, the Department of the Environment draws attention to changes in thecircumstances, especially the level of charges, that may have occurred since.

1. Following representations made to the Parliamentary Commissioner forAdministration regarding charges for abstraction of water for the purpose offlowing over waterwheels or turbines in order to generate power or operatemachinery, it was found that there were to some extent differing views amongthe former river authorities as to the licenseability of such uses. Added to this wasthe fact that, in some areas, use of water for power generation was eitherminimal or it had little effect on resources and had therefore been exempted fromcharge, while in other areas such uses had considerable effect on the resources ofparticular areas. This led to variations in charges to perhaps a greater degree thanwas normal in the case of other uses which every river authority consideredlicenseable and appropriate for charge.

2. In consequence, the Commissioner suggested that it might help to reduceinconsistency if the Secretary of State gave his views on the subject oflicenseability, although he recognised that such advice would have no force inlaw. As the Water Resources Act stands at present, there is no provision for theSecretary of State to determine whether the taking of water in any set ofcircumstances is a licenseable abstraction under the Act. Moreover, because ofthe many different physical circumstances governing the use of water for powergeneration, it is impossible to cover every instance, but the following covers themore usual situations.

3. Where water for power generation is concerned, that part of the operationwhere water is actually flowing over turbines is of itself unlikely to constitute anabstraction so that the point to be resolved is, normally, whether a licenseableabstraction is taking place in order to get water to the point where it will flowover the turbines or wheels. Then, if abstraction is taking place within themeaning of section 135 of the Act, the abstractor requires to obtain from theappropriate water authority a licence authorising that abstraction. He is thenliable to whatever is the appropriate charge under the authority’s currentcharging scheme. Set out below are views on some fairly basic types ofcircumstances, although it is recognised that there may be many variations.

4. Under section 23(1) of the Water Resources Act 1963 no one may abstractwater from a source of supply except in pursuance of a licence. (There are certainminor exceptions such as abstraction of water for the domestic purposes of anindividual household). The definition of ‘abstraction’ in section 135(1) of theWater Resources Act 1963 is as follows:-

‘“abstraction”, in relation to water contained in any source of supply in a riverauthority area, means the doing of anything whereby any of that water isremoved from that source of supply and either—

(a) ceases (either permanently or temporarily) to be comprised in the waterresources of that area, or

Figure A.1 Scheme involving no abstraction.

APPENDICES 87

(b) is transferred to another source of supply in that area, and “abstract” shallbe construed accordingly’.

‘Source of supply’ is also a term of art (section 2 and section 135(1),especially the definitions of ‘inland water’ and ‘watercourse’), but in addition torivers and streams it includes passages through which water flows, subject onlyto limited exceptions which are virtually certain to be immaterial in the presentcontext.

5. The use of water to drive wheels or turbines seems unlikely of itself toconstitute an abstraction at that point of the operation. (Where there is some fallof water on to a wheel, the time during which the water is not in a ‘source ofsupply’ is so short it is thought that the maxim de minimis would normally

Figure A.2 Scheme involving abstraction.

88 APPENDICES

apply). Where a sluice-gate is in a stream and it is operated to allow water to flowdirectly onwards to turn a turbine or waterwheel sited in that stream, theoperation of the sluice gate merely allows water to flow on within the samesource of supply and therefore water is not being removed from a source ofsupply nor is it transferred from one source to another, so no abstraction is takingplace within the meaning of the Act.

6. A licenseable abstraction for the purposes of power generation thereforeusually arises from diversion of water, e.g. the removal of water from a stream to

Figure A.3 Abstraction from primary leat to secondary leat at sluice.

APPENDICES 89

the mill leat (a different source of supply) where the turbines or mill wheel areplaced, and then only if there is a sluice gate or other form of regulator to whichsomething is ‘done’ (turned, raised, etc.) in order to ‘remove’ water from thestream, the original source of supply, and transfer it to the other source of supply(the mill leat). The most usual form is the weir on the main stream whichimpounds the flow to get a head of water, which is then released into the leat by

Figure A.4 Abstraction from river but not from leat: abstraction is considered tooccur at A but not at B.

90 APPENDICES

means of a sluice gate at or near the junction of the stream and the leat. In certaincases, this sluice gate may be positioned farther down the leat itself instead of ator near the stream, but it may have the same effect. When the sluice gate is shut,water is ponded back as far as the entrance to the leat and forms a barrier whichprevents more water flowing from the main stream into the leat. When the sluicegate is opened, the effect is to ‘remove’ water from the stream by allowing it toflow into the leat.

7. A series of sketches is attached showing various circumstances andindicating whether or not the Department considers abstraction is taking place.

Figure A.5 Abstraction through pipeline.

APPENDICES 91

Figure A.6 Arrangement with separate channels for turbine and overflow belowsluice: no abstraction.

92 APPENDICES

Appendix 4National Association of Water Power Users:

Paper for the Watt Committee

Note This paper was presented at a meeting of the Watt Committee workinggroup on 2 December 1983.

A.4.1Aim

This paper aims to present to the Watt Committee’s Working Group on Small-Scale Hydro-Power the views of the National Association of Water Power Users(NAWPU), and of some members of its Council, in answer to the questionsposed in the Working Group’s Terms of Reference, and in correspondence.

A.4.2Background

The NAWPU was formed in 1975 principally to ease, for water power users, theconstraints caused by the Water Resources Act 1963, and the various ElectricityActs; the former leading Water Authorities to charge for so-called ‘abstraction’,and the latter restricting the activities of private generators of electricity inrelation to the nationalised electricity supply industry.

The Association’s aims include promotion of water power use, and steps are atpresent being taken to improve the service to members in this direction.

The Association welcomes the opportunity to assist the Working Group andlooks forward to seeing its report in due course.

A.4.3Questions

The questions to be answered are, we believe:(1) What is the potential for further small-scale hydro-power development in

the United Kingdom?(2) What factors inhibit such development?(3) What plant is available in the U.K.?(4) What is the export potential?

A.4.4.Definition

‘Small-scale’ is obviously relative. We wish to draw no hard and fast upperlimit, but to suggest that perhaps the 10-MW level (see Energy Act 1983, Section2) below which private generators do not need to inform their Area Board mightbe appropriate.

While a lower limit is perhaps unnecessary, it is worth remarking that thelowest energy levels we have found in use which either are, or could be, hydro-powered, are in the order of 200 Wh per day for domestic lighting: a hydraulicram is comparable. As insulation levels of houses improve— and conversionefficiency of e.g. lighting appliances—so demand is falling.

A.4.5Potential for Further Small-Scale Hydro-Power

Development in U.K.

NAWPU membership has been something over 200 for most of its eight years oflife, with around 350 people or firms being members at one time or another.Many more eligible users and interested people have enquired. Currently, amajority of members are either water power users or have projects in mind orhand and it is likely that they are a representative sample. Nevertheless, theNAWPU membership is a small proportion only of water power users.

One report1 put the number of working water-power sites in England in thepeak period of the 1800s at over 20000; another has identified over 600 usablesites of over 25kW in Wales.2 Francis in 1978 put the usage at 370.3 So ifEngland and Wales have say 21000 sites, perhaps 900 are in use. In the U.K. as awhole there may be around 1000 in use, with the potential to develop another20000 at least.

This number can possibly be increased, since its basis is the relatively lownumber of sites associated with water-wheels. Use of longer pipelines, higherhead and turbines and modern dam-building, on the one hand, and low-headturbines, on the other, will widen the scope for finding sites, though this will beoffset to some extent where various factors, e.g. depletion of river flows by(genuine) abstraction, have rendered old sites unusable. As a matter ofobservation, virtually all usable water-wheel sites have been exploited at sometime or other.

Francis estimated the potential energy available from the usable sites that heidentified at 0.7M tons of coal equivalent per year—say 1.4×109kWh/year or160000kW continuously. If this were to be generated by 21000 units, the averagepower output would be 7.6kW—which sounds reasonable.

Not only is this energy important nationally, it can make a very useful andeconomic contribution to many businesses and individuals.

94 APPENDICES

A.4.6Factors Inhibiting Development

Water resources The Water Resources Act 1963 took no account of the use ofwater for energy production, and the definitions of ‘abstraction’ (Section 135(1))and ‘source’ (Section 2(1)) are such that Water Authorities regard any deviceother than an undershot wheel placed in a river as ‘abstracting’. This has not, asfar as we know, been challenged in the Courts. From this the Water Authoritieshave insisted that commercial users be licensed and charged both a fee for thelicence (Section 57) and a charge based on the quantity of water used (Section 58(2)).

After much work by the Association and others, the Energy Conservation Act1981, Section 16, added a paragraph to Section 60(2) of the 1963 Act tellingWater Authorities to ‘have regard to…the need to conserve sources of energy(other than water) and the consequent desirability of preventing the charges inquestion from inhibiting the use of water as a source of energy’. This was afterMinisters had agreed that for energy use a licence fee to cover the administrativecost was all that was justified.

Regrettably Parliament—or the Departments—did not see fit to amend orrepeal Section 58(2) and the Welsh Water Authority (for one at least) continuesto attempt to exploit that section. Indeed, in addition, they seem intent oncharging not only on a basis of quantity but also for the length of leat or pipe; thegreater the distance over which the water is ‘abstracted’ from the main stream,the more you pay.

At the same time, Water Authorities are inviting users to submit financialaccounts to show the extent to which an ‘abstraction’ charge would render ascheme unprofitable: presumably with a view to setting the charge at such a levelthat the scheme is sufficiently profitable for the owner to go ahead—or not shutdown an existing plant.

This really can only be described as waterway robbery. The merit of water-power is that the fuel is not only from a self-refilling source, but it is ‘free’ in thesense that the delivery system is very largely provided naturally. Some placeseven have to spend money to prevent a surplus of fuel causing damage. To levy acharge for water so that a user is just kept from using a fossil-fuel source isindefensible—but this is what is proposed.

There is an element of iteration here. If the price of Electricity Board energy isused as a comparator in the assessment of a private plant’s fee, and that price isalready higher than it might otherwise be because the CEGB is paying an‘abstraction’ charge then…!

Again, this has not yet been fully put to the test in negotiation or the Court, orby appeal to the Minister.

The CEGB, be it noted, is not a member of NAWPU.Electricity generation The Energy Act 1983 permits private generators of

electricity to buy and sell from and to the Boards and to use the Boards’ lines to

APPENDICES 95

supply private consumers. SWEB have recently published their tariffs. Whilethese set out the various charges they no more than mention the metering andother arrangements which have been used in the past (by some Area Boards) todiscourage private generation, whatever the prime mover.

It is perhaps too soon to assess the effect of the 1983 Act; but it is worthpointing out that the potential total of small-scale hydro-electricity power isaround 160MW made up of many small units, and this should be seen in relationto the CEGB’s total capacity and output. It is also worth noting that the CEGB’sown small hydro-power plants in Devon (a total of 3.34MW at three sites) areshut down at night, presumably because the cost of watch-keepers at night,together with the abstraction charges, renders them uneconomic in relation to thecoal- and nuclear-fired base generators.

Costs It seems that many potential users are advised by their accountants toseek a 2–3–4-year payback period for a hydro-power plant. It is the accountantswho need to be convinced of the merits, in the long term, of investment in hydro-power where the payback period is of the order of 10 years and the life 50 to 100years. One question for the accountants to answer is, ‘What capital sum must beinvested to be sure that the net interest (after tax and inflation) will pay theelectricity bill for ever?’

Even so, there is a belief among some small hydro-power engineers that thereis a tendency to over-design, and where a system designer is new to the subjectthis is understandable. As a designer gains experience, he can simplify; this canlead to considerable cost reduction.

The NAWPU list of ‘Experts’ includes, besides those who manufacture or sellequipment, a number of consultants. Perhaps it is revealing that none of themclaims to specialise in, e.g., surveys of water resources or design or installationof complete systems. Generally, people with a stream or river or derelict millhave difficulty in finding anyone who admits to having the knowledge, skill andtime to survey, design and install a scheme and to quote for or estimate the cost.Where schemes are started they seem, in general, to take longer to complete thanthe customer thinks necessary. As often as not, the customer himself undertakessome of the installation and civil engineering work.

To date, the industry has not ‘taken off, or rather, recovered the situation ofthe late 1700s, when the collective knowledge and experience of water powerwas held partly by millwrights and partly by users (millers, farmers,industrialists) and was considerable and widely available.

Generally, there are probably enough chartered and other engineers eitheralready on the NAWPU list or lurking in the background to meet a biggerdemand than exists at present: very few are over-worked. As long as demand isconstrained for any of the other reasons, an apparent shortage of qualified,experienced people who are prepared to build schemes cheaply (with a provenrecord of success) further restricts demand.

96 APPENDICES

One of the few bonus points is that at many disused sites much of the surveyhas already been done and the civil engineering assets would be readilyrestorable.

A.4.7Plant Available in U.K.

Of manufacturers or agents (including those who are members of NAWPU),* thebreakdown is:

Turbines, 8Water-wheels, 1Electronic load controllers, 5Generators, 4

This list is certainly not exhaustive. Of the makers of electrical generators, allmake brushless machines for outputs from 3kW upwards, and there are morefirms who make larger machines. A wide range of machines is available fromstock and on the second-hand market.

There is also a handful of firms and individuals who restore old hydro-powerplant and machinery. Restoration for museum use with sales, e.g. of stone-ground organically grown flour, does seem to be a growth activity.

We suggest that the manufacturers should be asked to give details of theirproducts and where they may be seen in manufacture and in operation.

A.4.8Export Potential

NAWPU is in no position to assess the export potential of small hydro-powerplant. What we would say is that the world is a much smaller place with a bettereducated population than it was 150 years ago, when the U.K. could find a readymarket for its manufactures and expertise overseas. Today the capability of somepeople in virtually every country to engage in ‘state of the art’ small-scale hydro-power development, manufacture and installation is as good as that in the U.K.,and the capacity—on account of lower wages and less rigorous engineering andsafety standards—is frequently greater. As often as not, we can learn from them.Our ability to exploit any export potential will depend on the same factors asaffect potential at home, and also on our ability to produce better products morecheaply, to time and within budget. Possibly systems expertise has a greaterexport potential than straight manufacture.

* See Table 2.4, page 20.

APPENDICES 97

One body which has concerned itself with aid to developing countries (and aidto our own exports) is the Intermediate Technology Development Group.

References

1. Weisbach, J. A Manual of the Mechanics of Engineering &c. Translated by A.Jaydu Bois, Vol. 2, John Wiley & Sons, New York, 1880.

2. Hydro-power potential in Wales. A Report for the Department of Energy, byProfessor E.M.Wilson, Salford University, Oct 1980.

3. Francis, E.E. An Appraisal of the low head and run-of-river water power inEngland and Wales. Dept of Energy, 1978.

98 APPENDICES

Appendix 5Abbreviations Used in this Report

Abbreviations used in this Report, and certain other abbreviations that are likelyto be encountered, are listed here. The units and other abbreviations used vary, insome instances, according to common practice, although the units of the SystèmeInternationale (S.I.) are usually preferred. Conversion factors and approximateequivalents for certain quantities that occur frequently are also given, but itshould be remembered that approximate equivalents are not suitable for accuratecalculations, for which accurate equivalents must be used.

Organisations

CEC Commission of the European Communities

CEGB Central Electricity Generating Board

CERL Central Electricity Research Laboratory (CEGB)

EEC European Economic Community (‘the Community’, whosepower is exercised by the Commission of the EuropeanCommunities—‘the European Commission’—under the policydirection of the Council of Ministers subject to the powers ofthe European Parliament)

ESRC Electricity Supply Research Council

IEC International Electrotechnical Commission

NAWPU National Association of Water Power Users

NCB National Coal Board

NIES Northern Ireland Electricity Service

NSHEB North of Scotland Hydro-Electric Board

OECD Organisation for Economic Co-operation and Development

SSEB South of Scotland Electricity Board

WMO World Meteorological Organisation

UN United Nations

UNEP United Nations Environmental Programme

UNECE United Nations Economic Commission for Europe

Units

Lengthm metre (1 m=1000 mm=1.094 yard=3.28 ft)mm millimetre (1 mm=0.03937 inch)km kilometre (1 km=1000 m=0.621 mile)Areaha hectare (1 ha=10000 m2=2.47 acre)Volume/capacity1 litre=(1 l=10−3 m3=1.759 pint=0.220 gallon (Imp.))Mass (weight)g gram (1 g=1000 mg=0.0353 oz)kg kilogram (1 kg=1000 g=2.205 lb)t tonne (1 t=1000 kg=0.9842 ton)

PowerW watt (1 W=1 J/sec=1 VA=9.478×10−4 Btu/sec)kW kilowatt (1 kW=1000 W=1.341 horsepower)MW megawatt (1 MW=1000 kW=106 W)EnergykWh kilowatt hour (1 kWh=3600 kJ=3.412 Btu)MWd megawatt day (1 MWd=24000 kWh)GWy gigawatt year (1 GWy=365000 MWd)J joule (1 J=1 Nm=0.0009478 Btu)MJ megajoule (1 MJ=106 J=9.478×10−6 therms)GJ gigajoule/1 GJ=103 MJ=109 J=9.478×105 Btu=9.478 therms)EJ exajoule (1 EJ=1018 J=1 Q=1015 Btu (quadrillion Btu))Btu British thermal unitElectric currentA ampereV voltkV kilovolt (1 kV=1000 V)MV megavolt (1 MV=1000 kV=106 V)ForceN newton (1 N=1 kg m/sec2)Pressureatm atmosphere (1 atm=101325 N/m2

=4.7 lbf/in2

=1013.2 millibar)

Approximate equivalents

1 tonne of coal equivalent (1 t.c.e.) =26 GJ=0.6 t.o.e. (tonnes of oil equivalent)

100 APPENDIX

=7250 kWh electrical energy (totalenergy)=675 m3 of natural gas

106 t of coal =25.5×1012 Btu

Other

CBR cost-benefit ratio

CHP combined heat and power

FDC flow duration curve

IRR internal rate of return

LRMC long-run marginal cost

MWSO megawatts sent out (i.e. net of station auxiliary power)

NEC net effective cost

NPV net present value

pmf probable maximum flood

PP payback period

TDR test discount rate

THE WATT COMMITTEE ON ENERGY 101

TERMS OF REFERENCE

The Watt Committee on Energy, being a Committee representing professionalpeople interested in energy topics through their various institutions, has thefollowing terms of reference: —

1. To make the maximum practical use of the skills and knowledge available inthe member institutions to assist in the solution of both present and futureenergy problems, concentrating on the U.K. aspects of winning, conversion,transmission and utilisation of energy and recognising also overseasimplications.

2. To contribute by all possible means to the formulation of national energypolicies.

3. To prepare statements from time to time on the energy situation forpublication as an official view of The Watt Committee on Energy in thejournals of all the participating institutions. These statements would alsoform the basis for representation to the general public, commerce, industryand local and central government.

4. To identify those areas in the field of energy in which co-operation betweenthe various professional institutions could be really useful. To tackleparticular problems as they arise and publish the results of investigationscarried out if suitable. There would also, wherever possible, be a follow-up.

5. To review existing research into energy problems and recommend, incollaboration with others, areas needing further investigation, research anddevelopment.

6. To co-ordinate future conferences, courses and the like being organised bythe participating institutions both to avoid overlapping and to maximise co-operation and impact on the general public.

GENERAL OBJECTIVE

The objective is to promote and assist research and development and otherscientific or technological work concerning all aspects of energy and todisseminate knowledge generally concerning energy for the benefit of the publicat large.


Dr E.G.Masdin, Institution of Chemical EngineersDr J.R.Milford, Royal Meteorological SocietyW.B.Pascall, Royal Institute of British ArchitectsW.Ridley, Society of Business EconomistsDr P.A.A.Scott, Royal Society of ChemistryA.Silverleaf, Royal Institution of Naval ArchitectsProfessor A.J.Smith, Geological Society of LondonProfessor J.Swithenbank, Institute of EnergyE.L.Walker, Institute of Purchasing and SupplyN.G.Worley, British Nuclear Energy SocietyJ.G.Mordue, SecretaryNote:A part of the executive rotates on an annual basis at 30th April each year. The

following institutions were members of the executive for the years shown:

1983/84British Association for the Advancement ofScience

Dr J.G.Collingwood

Hotel Catering and Institutional ManagementAssociation

M.J.Moore

Institute of Chartered Foresters J.N.R.JeffersInstitution of Agricultural Engineers J.C.WeeksInstitution of Electronic and Radio Engineers R.F.C.ButlerInstitution of Water Engineers and Scientists C.Cash1984/85Geological Society of London Professor A.J.SmithInstitute of Purchasing and Supply E.L.WalkerInstitute of Metals Professor W.O.AlexanderInternational Solar Energy Society (U.K. Section) R.F.C.ButlerRoyal Institution of Naval Architects A.SilverleafRoyal Meteorological Society Dr J.R.Milford

THE WATT COMMITTEE ON ENERGY 103

EXECUTIVE COMMITTEE as at March 1985: ChairmanDr J.H.Chesters, O.B.E., F.Eng., F.R.S. Deputy Chairman Dr

G.K.C.Pardoe

E.A.Alcock, Institute of Cost and Management Accountants (Hon. Treasurer)Professor W.O.Alexander, Institute of MetalsJ.W.Rogers, Institution of Civil EngineersH.Brown, Institution of Plant EngineersR.F.C.Butler, International Solar Energy Society (U.K. Section)Professor I.C.Cheeseman, Chartered Institute of TransportJ.Boddy, Institute of PetroleumProfessor A.W.Crook, Institution of Mechanical EngineersR.S.Hackett, Institution of Gas EngineersDr A.F.Jackson, Institution of Electrical Engineers

small-scale hydro-power: papers presented at the sixteenth consultative council meeting of the watt...

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