fuel cells – understand the hazards, control the risks · pdf filefuel cells understand...

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Health and Safety Executive

Fuel cells Understandthehazards,controltherisks

This is a free-to-download, web-friendly version of HSG243 (First edition, published 2004). This version has been adapted for online use from HSE’s current printed version.

Youcanbuythebookatwww.hsebooks.co.ukandmostgoodbookshops.

ISBN 978 0 7176 2766 0Price £8.50

Thisbookprovidesanintroductiontothehazardsassociatedwithfuelcellsandthefuelsthattheyuse.Itgivessimple,straightforwardtechnicaladvicetomakedesignersandusersmoreawareofthehazardsandthetechniquesavailabletocontroltherisksfromthisrapidlydevelopingtechnology.Italsoprovidesguidancetoenableeveryoneworkingon‘hydrogeneconomy’projectstobemoreawareoftheirresponsibilitytoprotectpeople,andshouldhelptopreventanincidentthatcouldjeopardisetheacceptanceofthesenewtechnologies.

HSE Books

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© Crown copyright 2004

Firstpublished2004

ISBN9780717627660

Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmittedinanyformorbyanymeans(electronic,mechanical,photocopying,recordingorotherwise)withoutthepriorwrittenpermissionofthecopyrightowner.

Applicationsforreproductionshouldbemadeinwritingto:TheOfficeofPublicSectorInformation,InformationPolicyTeam,Kew,Richmond,SurreyTW94DUore-mail:[email protected]

ThisguidanceisissuedbytheHealthandSafetyExecutive.Followingtheguidanceisnotcompulsoryandyouarefreetotakeotheraction.Butifyoudofollowtheguidanceyouwillnormallybedoingenoughtocomplywiththelaw.Healthandsafetyinspectorsseektosecurecompliancewiththelawandmayrefertothisguidanceasillustratinggoodpractice.

Fuelcells:Understandthehazards,controltherisks Page3of32


ContentsIntroduction 4How fuel cells work 5Typesoffuelcell 5Hazards associated with fuel cell installations 8Fireandexplosionhazards 8Electricalhazards 12Controlling the risk from fire and explosion 13Avoidingflammablemixtures 13Avoidingignitionsources 18

Controlling the risk from exposure to harmful chemicals 21

General safety considerations 22Manualhandling 22Training 22Emergencyprocedures 22Legal requirements 23Generallegislation 23Legislationdealingwiththefireandexplosionhazardsoffuelcells 23Legislationdealingwiththeinstallationandmaintenanceoffuelcells 24Appendix 1: Fuel cell types and electrochemistry 26

Appendix 2: Minimum separation distances 27

Glossary 28

References 30

Further information 32



Introduction1 Sincethestartofthenewmillennium,interestandactivityinhydrogenandfuelcelltechnologyhasbeenacceleratingrapidly.Thoughtheinventionofthefuelcellcanbetracedbacktoworkcarriedoutin1839byWilliamGrove,itwastheworkdonebyNASAthatreallyestablisheditspotential.

2 Theuseoffuelcellstoprovidethein-flightelectricalpowerfortheApollospacecraftinthe1960sinitiatedglobalindustrialresearchanddevelopmentprogrammes.Fuelcelltechnologyhasnowreachedapointwherethesedevicescanbeconsideredviableoptionsformanyapplications,includingcombinedheatandpowersources,back-uppowersupplies,remotelocationelectricityprovisionetc.

3 Thepotentialforpollution-freetransportthroughtheuseoffuelcellshasexcitedpeopleformanyyears.Itnowseemslikelythatfuelcell-poweredbusesand,ultimately,carswillbeafeatureofurbantransportintheforeseeablefuture.

4 Thepurposeofthisguidanceistoprovideanintroductiontothehazardsassociatedwithfuelcellsandthefuelsthattheyuse.Itgivessimple,straightforwardadvicetohelpdesignersandusersbecomemoreawareofthehazardsandunderstandhowtherisksfromthisrapidlydevelopingtechnologycanbeminimised.Everyoneworkingon‘hydrogeneconomy’projectsshouldbeawareoftheirresponsibilitytoprotectpeopleandpreventanincidentthatcouldjeopardisetheacceptanceofthesenewtechnologies.



How fuel cells work5 Afuelcellisadeviceforharnessingtheenergyliberatedwhenhydrogen,orahydrogen-richfuel,reactswithoxygentoproducewater.Normally,whenhydrogenandoxygenreact,aflameandheatenergyareproduced.Inafuelcellaflameisnotproduced;thereactionproducesonlyelectricityandheat.

Hydrogen+oxygen fuelcell

water+electricity+heat Hydrogen+oxygen

combustion water+heat

6 Insomewaysafuelcellissimilartoabattery.Bothareelectrochemicaldevicesinwhichanelectriccurrentisproducedfromchemicalreactionsthattakeplaceattheelectrodes.Abattery,however,storeselectricityandneedsregularrechargingorreplacement,whileafuelcellcontinuesproducingelectricityaslongasitissuppliedwithfuel.

7 Asinglefuelcellconsistsofanelectrolytesandwichedbetweentwothinporouselectrodes-theanodeandthecathode.Theanodeofthecellisusuallycoatedwithaspecialcatalystwhichsplitseachhydrogenmoleculeintotwoprotons(H+ions)andtwonegativelychargedelectrons.Theelectronsleavetheanodeandprovidetheelectricalcurrentintheexternalcircuittowhichthefuelcellisconnected.Oxygen,usuallyfromair,isfedtothecathodeofthecellwhereitreactswithprotonsandtheelectronsreturningfromtheexternalcircuit,toproducewater.

Types of fuel cell

8 Althoughthereactionbetweenhydrogenandoxygenisthebasisofalmostallfuelcells,themannerinwhichthisreactionisharnessedvariesconsiderably.Thewaythecellworksisheavilydependentuponthenatureoftheelectrolyte.Thecharacteristicsandhalf-cellreactionsofthemostcommontypesoffuelcellaresummarisedinAppendix1.

9 Fuelcellscanbelooselygroupedintothosewithacidicelectrolytes,thosewheretheelectrolyteisalkaline,andthosethatoperateathightemperatures.

Acidic electrolyte fuel cells: PEMFCs and PAFCs 10Successfulexamplesofacidicelectrolytefuelcellsaretheprotonexchangemembraneorpolymerelectrolytemembrane(PEM)andthephosphoricacid(PAFC)fuelcell.Inbothofthesecellstheprotonsproducedattheanodemovethroughtheelectrolytetothecathodewherewaterisproducedfromtheirreactionwithoxygenandthereturningelectrons.

11TheelectrolyteinthePEMcellisaspecialfluorocarbonpolymerthatisimpervioustohydrogengasandelectronsbutwillreadilyallowthepassageofprotonsfromtheanodetothecathode.InthePAFCtheelectrolyteisathinfilmofphosphoricacidheldinafluorocarbon-bondedmatrix.TheelectrodesofbothPEMandPAFCunitsareusuallymadefromporouscarbonimpregnatedwithplatinum.Inbothofthesedevicestheelectrolyteisnothickerthanafewsheetsofpaper,allowingalargenumberofcellstobearrangedinseriestoproduceacellstack.

g

g



12PEMandPAFCdevicesarecompactandcangeneratequitealotofpowerfromarelativelysmallunit.PEMcellsarecurrentlybeingusedinlargetransportvehiclessuchasbusesandtractionunits.PAFCunitsareoftenassembledintoverylargestacksandagreatmanyPAFCassemblieswithelectricalpoweroutputsinexcessof200kWareinusearoundtheworldforstationarypowergeneration.Thehightoleranceoftheseunitstoimpuritiessuchascarbonmonoxideandcarbondioxideenablesthemtoberunonhydrogengeneratedfromnaturalgasorotherhydrocarbonsusingareformer.

Alkaline electrolyte fuel cells: AFCs13Thesecellsoftenuseanaqueoussolutionofpotassiumhydroxideastheelectrolyteandoperateatquitehightemperatures,100–250ºC.Thisallowsthemtousenon-preciousmetalcatalystsattheelectrodes.However,thesepotentialadvantagesareoffsetbytheneedforveryhigh-purityhydrogenfeed.Traceamountsofcarbondioxidereactwiththeelectrolyteandcauseirreparabledamagetothecell.



14AFCsdifferconsiderablyinthewayinwhichtheygenerateelectricity.Oxygen,fromairsuppliedtothecell,reactswithwateratthecathodeofthecell,producinghydroxideions.Thesemovetowardstheanodewheretheircatalysedreactionwithhydrogenproduceswaterandliberateselectronsintotheexternalcircuit.Consequently,inthesecellswaterisproducedattheanoderatherthanthecathode,asisthecasewithotherfuelcells.

High-temperature fuel cells: MCFCs and SOFCs15Moltencarbonatefuelcells(MCFCs)operateattemperaturesaround650ºCanduseamoltenmetalcarbonatesuspendedinaporousceramicmatrixfortheelectrolyte.Atthecathode,oxygenandcarbondioxideareconvertedtocarbonateions,whichthenmovethroughtheelectrolytetotheanodeandreactwithhydrogentoproducecarbondioxideandwater.

16Thehighoperatingtemperatureofthesecellsenableslessexpensivecatalyststobeusedandtheydonotrequireaseparatereformer.Suitablehydrocarbonfuelscanbefeddirectlyintothecellwhereinternalreformingtohydrogentakesplace.Moltencarbonatefuelcellsarenotdamagedbythepresenceofcarbondioxideinthefeedgases,allowingawiderangeoffuelstobeused.

17Solidoxidefuelcells(SOFCs)useahard,non-porousceramicmaterialastheelectrolyte.Theveryhighoperatingtemperature,around1000ºC,enablesthesecellstocarryoutinternalreformingofsuitablehydrocarbonfuelsandtheuseoflessexpensivecatalysts.SOFCshavequitegoodresistancetopoisoningbysulphurorcarbonmonoxide,enablingawiderangeoffuelstobeused.



Hazards associated with fuel cell installations18Thissectiondiscussesthehazardsofthesubstancesandtechnologyassociatedwithfuelcells.Everyoneinvolvedinthedesign,installation,useandmaintenanceoffuelcellsshouldhaveanappropriateunderstandingofthesehazards.Withoutthisknowledgeitisnotpossibletocarryoutasuitableriskassessment.

19Inmanysituationsthemajorhazardsassociatedwithafuelcellinstallationmaybeputintothefollowingcategories:

n dangeroussubstances:1

– fireandexplosion;– harmfuleffectsofexposure;

n electricshock;n generalsafetyhazards,forexamplemanualhandling.

20Thisguidanceconcentratesoncontrollingtheriskfromfireandexplosion,particularlywhenhydrogenisthefuel.Generalguidancedescribinghowriskintheworkplacefromtheothersignificanthazardsshouldbecontrolledisalreadyavailable.2

Fire and explosion hazards

Fuels21Allthefuelssuitableforuseincellsreadilycatchfireandsopresentasignificantfireandexplosionhazard.Materialssuchasthesearecalled‘dangeroussubstances’undertheDangerousSubstancesandExplosiveAtmospheresRegulations2002(DSEAR).1TheseRegulationsintroducenewdutieswhichincludeavoidingsourcesofignitionandthereleaseofdangeroussubstancesintotheworkplace.



22DSEARalsoreinforcesthegeneralrequirementforemployersundertheManagementofHealthandSafetyatWorkRegulations1999toidentifythesignificanthazardspresentintheworkplaceandtocarryoutasuitableandsufficientassessmentoftheriskfromthosehazards.2Appropriatemeasuresmustthenbetakentoreducethoseriskstoanacceptablelevelthatisas low as is reasonably practicable.

23Allfuels,suchashydrogen,petrol,methane,LPGetc,willcatchfireandmayproduceanexplosion.Beforeanexplosioncanoccur,aflammablemixtureofthefuelandairmustformandasourceofignitionmustbepresenttoigniteit.

24Petrolandmethanearefuelsroutinelyusedbymillionsofpeopleeveryday.Mostusersareawareofthepropertiesofthesefuelsandwhatneedstobedonetohandlethemsafely.Thepropertiesofhydrogenareoftennotwidelyappreciatedandthiscanresultintherisknotbeingproperlycontrolled.

25Thehazardsofhydrogenarediscussedinsomedetailbelow,followedbyabriefsummaryoftheimportantdifferentoradditionalhazardsofotherfuels.Someofthewaysinwhichsourcesofignition,theotherrequirementforanexplosion,maybeavoidedarediscussedlater(seeparagraphs82–90).

Hazardous properties of hydrogen and its storage26Hydrogenhassomeunusualproperties.Ifthesearenotappreciatedandappropriatemeasuresnottaken,thenthelikelihoodofhydrogenescapingandafireorexplosionoccurringmaybegreaterthanwithmanyotherfuels.Someoftheimportantpropertiesofhydrogenthatmaycontributetowardsthisare:

n verywideflammabilityrange;n verylowignitionenergy;n possibilityofdetonation;n lowviscosity;n highdiffusivity;n verymuchlighterthanair;n causestheembrittlementofsomemetals;n condensationofoxygen-richliquidaironcryogenicstoragesystems.

27Hydrogenisagasthatcatchesfireveryeasily.Itburnswithaflamethatisalmostinvisibleandreadilyformsanexplosivemixturewithair.Therangeofhydrogen/airconcentrationsthatwillexplodeisextremelywide,muchwiderthanalmostanyotherfuel.Mixturescontainingfromaslittleas4%v/vhydrogen,whichisthelowerexplosionlimit(LEL),uptoasmuchas75%v/v,theupperexplosionlimit(UEL),willreadilyigniteandexplode.3

28Ifaflammablemixtureofhydrogenandairisallowedtoform,thelikelihoodofanexplosionoccurringisveryhigh.Thisisbecausetheenergynecessarytoinitiateahydrogen/airexplosionisverysmall.Theignitionenergyfora2:1hydrogen/oxygenmixtureisonlyabout0.02mJ.Thisislessthanonetenththatofothercommonfuelssuchasmethane,LPGorpetrol.Evenverysmallsparks,suchasthoseproducedbywearingcertaintypesofclothing,arecapableofignitinghydrogen/airmixturesandcausinganexplosion.4

29Asignificantdifferencebetweenhydrogenandothercommonflammablefuelsisthatforthebulk(18–69%v/vhydrogen)ofitsflammablerangethereisapossibilitythatahydrogen/airmixtureinaconfinedandheavilycongestedsituationmaydetonate.4,5

30Detonationscausemuchmoredamageandarefarmoredangerousthanordinaryexplosions(deflagrations).Consequently,theriskfromdetonationshould



alwaysbeconsideredintheriskassessmentofsystemshandlingorstoringhydrogen.

31Hydrogengashasaverylowviscosityandsoitisverydifficulttopreventhydrogensystemsfromdevelopingleaks.Pipeworkthatwas‘leak-tight’whenpressure-testedwithnitrogenwilloftenbefoundtoleakprofuselywhenusedonhydrogenduty.Thispropertyincreasesthelikelihoodofaflammablemixtureforming.

32Hydrogenisverymuchlighterthanair,muchmoresothannaturalgas(methane),andisalsoverydiffusive.Whenitescapesitmovesupwardsveryrapidly.Ifaleakoccursinanopenorwell-ventilatedareaitsdiffusivityandbuoyancywillhelptoreducethelikelihoodofaflammablemixtureforminginthevicinityoftheleak.

33However,whenleaksoccurwithinpoorlyventilatedorenclosedareas,theconcentrationofhydrogeninthehigherregionsmayrapidlyreachdangerouslevels.Ifunprotectedelectricalequipmentorothersourcesofignitionarepresent,theriskfromexplosionwillbeconsiderable.

34Almostallhydrogeniscurrentlystoredinhigh-pressurecylinders.Thecryogenicstorageofliquidhydrogenforfuelcellusemay,however,becomemorewidespreadinthefuture.Thehazardsfromtheverylowstoragetemperaturesusedforliquidhydrogen,around-250ºC,includeseverecold-burnsandthecondensationofoxygen-enrichedliquidaironunprotectedpipework.

35Liquidhydrogenboilsat-253ºCatatmosphericpressureandsohydrogenleakingfromcryogenicstoragewillbeverycoldandmaybeheavierthanair.Asaresult,leakinggaswilloftensinkinitially,formingaflammableatmosphereatlowlevel,beforewarmingup,becomingbuoyantandrising.Thisisinmarkedcontrasttoaleakofcompressedhydrogenwheretheaccumulationofaflammableconcentrationofhydrogenisalwaysathighlevel.

36Researchanddevelopmentworkonthestorageofhydrogeninmetalhydrideshasbeeninprogressformanyyears.Therearetwomaintypesofhydridestoragesystem.‘Traditionalhydrides’usethereversibleabsorptionofhydrogenintothemolecularlatticeoftransitionmetals.6Thefinelydividedmetaliscontainedinsideapressurevesselandisoftenaflammableorpyrophoricsolid.

37‘Complexhydrides’storehydrogenthroughreversiblereactionsinvolvingsodiumaluminiumhydrideandsimilarmaterials.7Thesematerialsareflammablesolidsthatalsoreactvigorouslywithwatertoproducehydrogenandacorrosiveaqueoussolution.

38Thepressureofhydrogeninthesetypesofstoragesystemdependsonstoragetemperatureandthestateofcharge/discharge,butmayoftenbeinexcessof10barg.

The hazards of fuels other than hydrogen39Manycellsusehydrogenproducedfromhydrocarbonfuelsusingreformer-typetechnologylocatednearthefuelcellstack.Somehigh-temperaturefuelcellsareabletorunonsuitablehydrocarbonfuelswithoutaseparatereformer.

40Thereactionsthattakeplacewithinthereformer,orwithinhigh-temperaturefuelcells,convertthehydrocarbonfuelintohydrogenforuseinthecellandcarbondioxide,whichisvented.Useappropriatemeasures,suchascontainmentandventilation,toensurethatthecarbondioxideeffluentstreamfromlargercellsiseffectivelydischargedanddoesnotproduceanasphyxiationrisk.



41Naturalgas(methane)islighterthanairandwilltendtodiffuseupwards,thoughmuchmoreslowlythanhydrogen.Theexplosionlimitsfornaturalgas(5–15%v/v)arealsomuchnarrowerthanthoseforhydrogen.8Considerthecharacteristicsofbothfuelsfullywhendesigningandoperatingdualfuelsystems.Thepipeworkandequipmentusedtosupplynaturalgastothefuelcellshouldbesuitableandbedesignedtoanappropriatestandard.9

42LPGvapourisconsiderablyheavierthanair,especiallywhencold,forexamplewhentakendirectlyfromaliquidstoragevessel.Intheeventofaleak,LPGvapourwillusuallypercolatedownwardsandmayaccumulateonthefloororinlow-lyingsumps,rapidlyproducingaflammableatmosphere.Mixturescontaining2–10%v/vLPGinairwillreadilyigniteandexplode.10ThesignificantdifferencesinthebuoyancyanddispersioncharacteristicsofthetwofuelsshouldbecarefullyconsideredinsystemswhereLPGandhydrogenmaybothbepresent.ThepipeworkandequipmentusedtostoreandsupplyLPGtothefuelcellshouldbesuitableandbedesignedtoanappropriatestandard.9

43Methanolcanbeuseddirectlybysometypesoffuelcell.Thisfuelhassomehazardsthatdemandparticularattention.Inadditiontobeingahighlyflammableliquid,methanolisalsotoxicbyinhalation,ingestionand,notably,byskinabsorption.11Appropriateprecautionssuchascontainmentandventilationshouldbetakentopreventspillagesandtheaccumulationofhazardousmethanol/airmixtureswheneveritisused.

44Ignitionsourcesshouldbeavoidedthroughthemeasuresdescribedlater(seeparagraphs82–90)wherethereisthepotentialforflammablemethanol/airmixturestoform.12,13MoredetailedadviceontheseissuesiscontainedinSafe use and handling of flammable liquids.14

Sources of ignition45Aflammablefuel/airmixturewillnotexplodeunlessitisexposedtoasufficientlypowerfulignitionsource.Commonsourcesofignitioninclude:

n nakedflamesandsparksfromwelding,burningorgrinding;n electrostaticsparksfrompoorlyearthedornon-conductivepipework;n electricalsparksfrommotors,switches,relaysormobilephones;n sparksfrommechanicalimpacts;n hotsurfaces,forexamplebearings.

46FurtherguidanceonsourcesofignitionmaybefoundinSafe use and handling of flammable liquids.14



Electrical hazards

47Electricshockcanbealife-threateninghazardandmustnotbeoverlookedinthedesign,operationandmaintenanceofthefuelcellanditsassociatedequipment.15

48Electricalhazardsusuallyarisefromtwodistinctareaswithinfuelcellinstallations-thenormal240or415voltmainsa.c.supplyintotheareaandthed.c.electricaloutputofthefuelcellstack.Withlargerunitstheremaybeathirdarea-thea.c.outputofaninverterconnectedtothefuelcell.

49Thevoltageandcurrentproducedbyeachelementinthestackisusuallyquitesmall;however,thetotaloutputfromthestackmaybeoftheorderof200–400voltsandlargeelectricalcurrentsareoftenavailable.Theelectricaloutputfromquitemodestfuelcellscanbelifethreatening.

50Largefuelcellstacksmayalsoprovidelargecurrentsaswellaslethalvoltages.Ifametalobjectisinadvertentlyplacedacrosstheoutputbusbarsofsuchacellthena‘shortcircuit’willbeproducedandalargeelectricalcurrentwillflowthroughtheobject.Thisislikelytogethotveryquicklyandmayproduceashowerofsparks.

51Theelectricalequipmentassociatedwiththefuelcellshouldbedesignedandinstalledtoanappropriatestandard,andsuitablearrangementsshouldbeinplacetoensurethatonlycompetentpersonnelareabletogainaccesstotheequipment.



Controlling the risk from fire and explosion52Considerthefollowingapproacheswhendevelopingthestrategytominimisetheriskfromfireandexplosion:

n investigatethereplacementofhydrogenwithalesshazardousfuel;n avoidtheformationofflammablemixtures;n avoidsourcesofignition;n usesuppression,containmentormitigationoftheexplosion.

53Inmanysituationsavoidingflammableatmospheresandsourcesofignitionwillbethemostusefulapproach.

Avoiding flammable mixtures

54Thelikelihoodofaflammableatmospherebeingproducedmaybereducedusingthefollowingtechniques:

n containment;n segregation;n separation;n ventilation.

Containment55Measurestopreventthereleaseofdangeroussubstancesshouldbegiventhehighestpriority.Ifyoucanpreventarelease,aflammableatmospherecannotformandtheriskfromexplosioniseliminated.

56Minimisethelikelihoodofaleakoccurringbyusinghigh-qualityengineering.Payparticularattentiontothedesign,operationandmaintenanceofthehydrogen-handlingequipment.Inthiswaythelikelihoodandsizeofanypotentialleakcanbeminimised,leadingtoagreatlyreducedriskfromexplosion.5Byconsideringtheguidancebelowyouwillbefollowinggoodpractice:

n ensurethatthestorageequipment,pipeworkandconnectionsconformto anapprovedstandardforhydrogenequipment;3

n ensurethatmaintenanceworkiseffectivelycontrolledandisonlycarriedout byauthorisedcompetentpeople;

n minimisethefrequencywithwhichconnectionsaremadeandbroken;n useappropriaterefillablestationarystorageratherthanregularlyreplacing

largenumbersofseparatelyconnectedcylinders;n usetheminimumlengthandsizeofpipeworkthatisappropriate;n minimisethenumberofjointsbyusingcontinuouslengthsofpipework

whereverpracticable;n usefusionjointing(weldingorbrazing)orflanged/threadedconnectorsto

joinpipework;n ensurethatthesystemisleak-testedbeforeuseinamannerappropriatefor

hydrogensystems;3

n carryoutappropriateinspectionsofthesystematsuitableregularintervals andrecordtheresults;

n reviewtheoperationandmaintenancehistoryatsuitableintervals.



57Whenhigh-pressurestorageisuseditshouldbedesignedandbuilttoanappropriatedesigncodeorstandardandlocatedinasecureopen-aircompound.3

Themeasuresusedtopreventunauthorisedaccess,vandalismandimpactfromvehiclesshouldbeappropriatetothelocation.

58Indoorstorageofcompressedhydrogenisnotrecommended.Itmaybepermissibleinsingle-storey,purpose-designedbuildings,providedappropriatesafetymeasures,suchaseffectiveventilation,fire-resistantconstructionandexplosionreliefaretakenandtheriskshavebeenreducedaslowasisreasonablypracticable.3Inmostsituations,however,indoorstorageshouldusuallybeconsideredinappropriateifanoutdoorlocationispracticable.

59 Cryogenichydrogenstorageinstallationsshouldbeconstructedtoanappropriatecodeandlocatedinasuitableopen-airpositionandnotwithinanoccupiedbuilding.16Low-temperaturestorageinstallationsshouldincorporatesuitablemeasurestopreventoxygen-richliquidair,apowerfuloxidisingagent,fromcondensingonuninsulatedsurfacesexposedtoliquidhydrogentemperatures.16Toavoidtheriskfromfire,potentiallyflammablematerials,includingasphaltandtarmac,shouldnotbepresentbeneathpipeworkwherecondensationmayoccur.

60Useonlyappropriatepipeworkandfittingsforthesupplyofhydrogen.3,17Cupro-nickelandstainlesssteelarepreferredmaterialsforhigh-pressurepipeworkwhereascoppercanbeusedforlowerpressures.Allpipeworkjointsshouldbebrazedorwelded.Flangedorscrewedjointsareacceptablebutavoidusingthemifpossible.

61Compressionjointsaregenerallynotrecommendedforuseonhydrogensystemsasitisdifficulttoachieveandmaintaintheseina‘leak-free’condition.Wheretheiruseisconsideredessential,suchasonsmall-borepipework,theyshouldbesuitableforthedutyandusedinstrictaccordancewiththemanufacturer’sinstructions.

Segregation and separation62Arrangingthecomponentpartsofaninstallationinanappropriatewaycansignificantlyreducethelikelihoodofanexplosion.Theriskfromexplosionwillusuallybemuchlowerwhenthehydrogen-handlingequipmentiswellseparatedfromelectricalequipmentorotherignitionsources.

63Alwaystakeintoaccountthetendencyofhydrogentomigraterapidlyupwards.Itsbuoyancyshouldbefullyconsideredandusedtoreducetheriskfromfireandexplosionwhendesigningorarrangingthecomponentsofafuelcellorinstallation.Thiscanbedonethroughthefollowingmeasures:

n segregateandphysicallyseparateequipmentforhandlinghydrogenfrom foreseeablesourcesofignition;

n separatethehydrogenstorageareafromthefuelcellandthefuelcellfrom equipmentusingitselectricaloutput;

n locateanypotentialsourcesofignitionwellbelowanyequipmentfromwhichhydrogenmayleak;



n avoidlocatingpotentialsourcesofignition,suchasnon-flameproofelectricallightfittings,immediatelybelowhorizontalbulkheadsorimperviousceilingsunderwhichhydrogenmayaccumulate;

n ensurethatanyarea,enclosureorhousingetc,intowhichhydrogenmayleak,isdesignedtopreventthegasbecomingtrappedandisequippedwitheffectivehigh-andlow-levelventilation;

n donotlocatesystemsusingorstoringhydrogenbeneathunprotectedelectricalequipmentorhigh-voltagepowerlines;3

n usegas-tightcompartmentsorbulkheadsandventilationtoreducethelikelihoodofleakinghydrogenreachingpotentialsourcesofignition.

Separation distances64Recommendedseparationdistancesaretheminimumdistancesconsiderednecessarytomitigatetheeffectsoflikelyforeseeableeventsandpreventaminorincidentescalatingintoamajorone.18Theyareusedtoseparatedifferenthazards,suchashigh-pressurehydrogenstoragefromanignitionsource,orahazardfromvulnerableobjectsorpeople.

65Therecommendeddistancesareintendedtogivepeopleandequipmentasuitabledegreeofprotectionfromaforeseeableeventontheinstallation,suchasahydrogenleakandsubsequentjetfire.Theseparationthattheyprovideshouldensurethattherisktopeoplefromheatradiationorfromflameimpingementontootherflammablematerialsislow.Separationdistancesarealsocalculatedtogiveprotectiontotheinstallationfromoff-siteeventssuchasimpactfromvehiclesormachinery,releasesofflammablematerials,uncontrolledignitionsourcesortheradianteffectsofoff-sitefiresetc.

66Theuseofestablishedseparationdistancesaroundequipmenthandlingorstoringhydrogenorotherdangeroussubstanceshastraditionallybeenconsidered

4 8

4

8



afundamentalrequirementforthedesignofasafeinstallation.Youshouldmeasurethehorizontalseparationdistancesrequiredfromthosepointsinthesystemwhere,inthecourseofoperation,anescapeofhydrogenmayoccur.Consultthemostrecentversionofanappropriatecodeforadditionalinformationontheappropriateuseofseparationdistances.

67IncircumstanceswhereitisnotpracticabletousetheminimumseparationdistancessummarisedinAppendix2,anacceptablesituationmaybeachievedthroughtheuseofsuitablefire-resistantbarriersorotherriskreductiontechniques.3

68Theremaybesituationswheretherecommendeddistancesareconsideredinappropriate,forexamplewhentheoperatingpressureofthesystemislow.Wheretherecommendedseparationdistancesarenotemployed,theonusisonthedutyholdertodemonstratethroughasuitableassessmentthattheriskisacceptableandhasbeenreducedaslowasisreasonablypracticable.

Ventilation69Ventilationisaveryeffectivewayofloweringtheriskfromexplosion.Whentheconcentrationoffuelinafuel/airmixtureisreducedbelowthelowerexplosionlimit(LEL)anexplosioncannotoccur.

70DSEAR1requiresemployerstoprovideadequateventilationtoensurethatanyforeseeablereleaseofadangeroussubstancedoesnotaccumulatetoaconcentrationthataffectsthesafetyofpeople.Usethefollowingprinciplestoensurethateffectiveventilationisprovided:

n locatehydrogenstorage/handlingequipmentoutside;n estimatethemaximumforeseeableleakrate;n provideadequatehighandlowventilation;n bewareoflowceilings,canopies,coversandroofs;n ensurethedilutionairisdrawnfromasafeplace;n ensureventsandpurgesdischargetoasafeplace;n usecomputationalfluiddynamics(CFD)forcomplexventilationrequirements.

71Thosepartsofthefuelcellinstallationthathandlehydrogenorotherdangeroussubstancesshouldbelocatedintheopenair.Wherethisisnotdone,theonusisonthedutyholdertojustifythatitwasnotreasonablypracticabletouseanoutdoorlocationandthattheriskfromtheequipmentinthechosenlocationisacceptable.

72Whenusinganoutdoorlocationforhydrogenstorageitisstillessentialtoensurethatefficientdilutionofanyleakagewilltakeplace.Followtheguidelinesbelowwhendesigningoutdoorstorageandsupplysystemstoensurethatthelikelihoodofaflammableatmosphereaccumulatingisminimised:

n avoidtheuseoflow,imperviousroofs,canopiesorbulkheads;n avoidlocationsbeloweavesorotheroverhangingstructures;n useasuitable,non-combustiblesecurityfenceratherthanawall;n ensureadequatehigh-andlow-levelventilationapertureswhereawallaround

thestoragesystemisunavoidable.



73Wheneverhydrogenisusedorstoredinanenclosedorpartiallyenclosedarea,effectiveventilationmustbeusedtopreventtheformationofanexplosiveatmosphere.Thesizeofanyforeseeableleakintotheareashouldbeestimatedandusedasabasisforcalculatingtheventilationrequirements.Theseshouldbesufficienttoensurethattheconcentrationofhydrogeninsideanyoccupiedareaisnormallymaintainedbelow10%LELwithoccasionaltemporaryincreasesupto25%LEL.Insideanunoccupiedenclosure,fuelcellhousingorcompartment,theventilationshouldensurethattheconcentrationcannotexceed1.0%v/v(25%LEL).

74Insituationswhereeffectivemonitoringofthehydrogenconcentrationisprovidedandinterlockedintoasuitableshutdownsystemitmaybeacceptabletooperatecabinetsandhousingatupto2%v/vhydrogen.Consultrelevantguidancetoensurethatthealarm/shutdownarrangementsaresuitablefortheinstallation.19

75Useappropriatemechanicalmeanswhenevernaturalventilationcannotprovidethenecessarydilution.Inthesesituationsasuitablemonitoringandshutdownsystemshouldensurethatthesupplyofhydrogentotheareaissafelyisolatedintheeventofafailureoftheventilationequipmentorwhenabuild-upofhydrogenisdetected.

76Thedesignofanymechanicalventilationsystemmustnotinvolvethelocationofthefanmotorwithinapotentiallyexplosiveairstream.Positionventilationfans

4

8

4

8



neartheairinletandusethemtoforcecleanairthroughtheenclosure.Donotsitethemneartheoutletorusethemtodrawpotentiallycontaminatedairthroughthesystem.

77Thecooling/air-supplyfanorcompressorpresentinmanyfuelcellmodulesmaysometimesbesuitabletoprovideeffectiveventilation.Wherethisapproachisused,theairmustbedrawnfromasafeplaceandthedirectionoftheforcedairflowshouldbecompatiblewiththeexpectedmovementofanyhydrogenreleaseasaresultofbuoyancy,thermaleffectsetc.

78Thetendencyforhydrogentorisefromleaksandaccumulateagainstimperviousceilingsandhigh-levelbulkheadshasbeenidentifiedpreviouslyasasignificanthazard.Thelocationandtypeofelectricalequipmentusedinareaswherehydrogenmaybepresentandthedesignofventilationarrangementsshouldrecognisethishazardandbeappropriate.

79Internalpartitionsandbulkheadsmaybeusedeffectivelytoseparateignitionsourcesfrompotentialsitesofhydrogenleakage.Differentialpressurisationofseparatecompartmentsmaybeusedtopreventtheingressofhydrogenintoareascontainingsourcesofignition.Wherethistechniqueisused,thepressurisationairshouldbedrawnfromanddischargedtoasafeplace.Installanappropriatealarm/shutdownsystemtodetectandrespondtoanylossofventilationordifferentialpressure.

80Thedilutionairflowandthenumberandlocationofflammableatmospheredetectorsshouldbeappropriateincomplexsystemsorcongestedlocations.Anappropriatemodellingtechniqueshouldbeusedinthesesituationstoensurethatpocketsofflammablemixturewillnotaccumulateandremainundetected.

81Insituationswhereotherfuelssuchasmethane,LPGetcarepresent,inadditiontohydrogen,takeintoaccounttheirdifferentdensitiesanddiffusivitiestoensurethattheventilationarrangementsprovidedareappropriate.

Avoiding ignition sources

82Aflammablemixturewillnotexplodeifasourceofignitionisabsent.Althoughitisextremelydifficulttoeliminateallsourcesofignition,avoidingignitionsourcesshouldbeanimportantpartofyouroverallriskreductionstrategy.Itmustbeusedinallareaswhereapotentiallyexplosiveatmospheremaybepresent.Thefollowingtechniquesshouldbeincludedinyourapproachtoavoidingignitionsources:

n carryoutahazardousareaassessment;n identifythenatureandextentofhazardouszones;n usesuitablesignstodenotetheboundariesofhazardouszones;n locateelectricalequipmentinnon-hazardousareas;n useappropriatelyclassifiedequipmentinhazardousareas;n usecontinuitybonding,earthingandanti-staticclothingtoavoidstatic;n controlhotwork,vehicles,smokingandtheuseofmobilephones;n providelightningprotectionwhereappropriate.

83Whenplanningafuelcellprojectitisimportanttoconsiderwhetheritwillintroducenewfireandexplosionhazardsintoanareawherepreviouslythesewereabsentorwhethertheproposedlocationisalreadyahazardousarea.Inotherwords,doestheneedtocontrolignitionsourcesresultfromthepossibilityofahydrogenleakfromthenewfuelcellinstallationordoesthefuelcellrepresenttheintroductionofapotentialsourceofignitionintoanexistinghazardousarea?



84Whereapotentiallyexplosiveatmospheremaybepresentintheworkplace,DSEAR1requiresemployerstoassessandidentifythoseareasinwhichignitionsourcesneedtobecontrolled.TheareaswhereexplosiveatmospherescouldbeformedmustbeidentifiedanddesignatedashazardouszonesaccordingtotheprinciplesofHazardousAreaClassification.12,13

85Theresultsfromtheclassificationexerciseshouldbeusedtoensurethattheappropriatecategoryofequipmentisusedinthefuelcellinstallationandthatonlysuitableequipmentispresentinthevicinityofthenewinstallation.

86Forsituationswherehydrogenand/orotherflammablegasesorliquidsmaybepresent,thefollowingclassificationsshouldbeusedwhereappropriate:

n Zone0:Anareainwhichanexplosiveatmosphereispresentcontinuouslyorforlongperiods.Onlycategory1equipmentshouldbeusedintheseareas;

n Zone1:Anareawhereanexplosiveatmosphereislikelytooccurduringnormaloperation.Onlycategory1or2equipmentshouldbeusedintheseareas;

n Zone2:Anareawhereanexplosiveatmosphereisnotlikelytooccurduringnormaloperationand,ifitdoesoccur,islikelytodosoinfrequentlyandwillonlylastforashortperiod.Onlycategory1,2or3equipmentshouldbeusedintheseareas.

87Electricalequipmentappropriateforuseinthedifferentareasoftheworkplaceshouldbedeterminedoncethehazardousareashavebeenidentifiedandclassified.12,13Whenselectingelectricalequipmentforuseinhazardousareas,specifythetemperatureclassandtheapparatusgroupappropriateforthetypeofflammableatmospherelikelytobepresent.

88Youshouldusetheresultsofthehazardousareaclassificationexercisetoensurethatsuitablecontrolsareplacedonallotherforeseeableignitionsources.Theseshouldincludehotwork,smoking,vehicles,mechanicalequipment,mobilephonesandworkclothing.

89Itisimportantnottooverlookthefuelcellitselfwhenensuringthatonlysuitableequipmentispresentinhazardousareas.Whendesigningandconstructingthefuelcellyoushouldconsiderthefollowingpoints:

n ensurethatanyfuelcelllikelytobeusedwhereapotentiallyexplosiveatmospheremaybepresent,ieahazardousarea,complieswiththeATEX(ECDirective94/9/EC)RegulationsandBSEN60079;20,12

n ensurethattheelectricalcomponents,connectors,materialsetcemployedaresuitablefortheirintendeduseandenvironment;

n locatetheelectrical/electroniccomponentsofthefuelcellbelowanyforeseeablesourcesofhydrogenleakage;

n usesuitablegas-tightbarrierstoseparateelectrical/electronicequipmentfromareaswherehydrogenmaybepresent;

n useappropriateventilationtopreventtheformationofpotentiallyexplosivemixtures;

n theuseofexplosion-resistantequipmentorexplosionreliefmaybeappropriateincertainsituations;

n usetheguidanceavailableinrecognisedstandardssuchasIEC62282toavoidbasicdesignflaws.21

90Staticelectricitysparkshaveoftenbeenthesourceofignitioninexplosionsofflammablehydrogen/airmixtures.Effectivearrangementsshouldbeinplacetopreventthebuild-upofstaticchargesthatmayleadtoanincendivedischarge.Considersuitablemeasurestoreducetheriskfromstaticelectricity.Thesemayinclude:



n ensuringthatallpipeworkisconductiveandhaseffectiveelectricalcontinuity,especiallyacrossmechanicaljointssuchasflanges;

n ensuringthatallpipeworkandequipmentiseffectivelyearthed;n carryingoutanddocumentingappropriateearthing/continuitychecks;n wearingantistaticclothingandfootwearinhazardousareas;n providingappropriateprotectionagainsttheriskfromlightningwhendesigning

outdoorfuelcellorhydrogenstoragefacilities.3



Controlling the risk from exposure to harmful chemicals91Assessallthechemicalsassociatedwiththefuelcelltoidentifyifanyofthemposearisktohealth.Somefuelcellsmaycontainharmful,corrosiveorirritantchemicalsintheirelectrolytes.However,thesechemicalsaregenerallyinaclosedsystemandposenothreattohealthfromexposureduringnormaluse.Noadditionstoorreplacementoftheelectrolytearenormallyanticipated.Theremaybesomeriskofexposuretothesesubstancesifthefuelcellbecomesdamagedorduringdisposal.Havesuitableproceduresinplacetosafeguardpersonnelfromtheharmfuleffectsofspecificchemicalsandfromthepotentialforsuchanexposure.

92Methanol/airmixturesarehazardoustohealthaswellasbeingpotentiallyexplosive.Consequently,youshoulddoasuitableandsufficientassessmentoftherisktohealthundertheControlofSubstancesHazardoustoHealthRegulations(COSHH)andidentifythestepsthatneedtobetakentopreventoradequatelycontrolexposure.22Tousemethanolsafelytheserisksmustbetakenintoaccountandsuitablecontrolmeasuresincorporatedintoequipmentandprocedures.

93Theconcentrationofmethanolinairconsideredtobeharmfultohealth(TWA200ppm)isverymuchlowerthanonewhichisflammable(LEL6%v/v).11Consequently,forlargeenclosureswhichpeoplemayenter,theventilationarrangementsetcshouldbeappropriatetoensurethataharmful(tohealth)atmospheredoesnotaccumulate.Thesearrangementsshouldeasilyensurethattheriskofexplosioniseliminated.



General safety considerations94Itisimportantnottoforgetthebasicaspectsofasafesystemofworkwhendesigningandoperatinginahigh-technologyenvironment.Manualhandling,trainingandemergencyproceduresarethreeaspectsofsafetymanagementthatshouldnotbeoverlooked.

Manual handling

95Thoroughlyassesstherisksarisingfrommanual-handlingoperationsassociatedwiththeuseandmaintenanceofthefuelcell.Inparticular,thechoiceoflocationandthemodeoffuelstorage(forexamplecylinders,refillablestaticstorageetc),easeofaccessandtheequipmentprovidedcanhaveasignificantimpactontheoverallriskfromtheinstallation.

Training

96Everyonewhomaybeaffectedbythehazardsassociatedwiththefuelcellinstallationshouldhavebeentrainedtoanappropriatelevel.Theoperationandmaintenanceofthefuelcellinstallationshouldbecoveredbyestablisheddocumentedprocedures.

Emergency procedures

97Documentedproceduresshouldbeestablishedtocoverallforeseeableemergencysituations.Appropriatetrainingontherequiredresponsetoemergencysituationsshouldthenbegiven.Duringtheplanningstageofafuelcellprojectitisgoodpracticetoinformthefirebrigadethathydrogenwillshortlybestoredatthelocation.

98Itislikelythatastheuseoffuelcelltechnologyaccelerates,manyapplicationswillinvolveinstallingequipmentintoexistingworkplaceenvironmentsratherthanintonewpurpose-designedareas.Thesafe‘retro-fitting’offuelcellsintoareaswithlittlepriorexperienceofhydrogen,especiallydomesticenvironments,willraiseamultitudeofnewissues.Manyoftheseissuesmaynothavebeenexaminedpreviouslyastheywerenotconsideredrelevantorwereoflittlesignificanceintheindustrialenvironmentsinwhichhydrogenhashistoricallybeenused.

99Thesenewhydrogenusage/storagesituationswilloftenpresentsignificanttechnicalandengineeringchallengestodutyholders.Oneofthemostsignificantofthesewillbetheverylargedemandforthetechnicalskillsnecessarytoensurethatappropriateriskassessmentsarecarriedout.Itisparticularlyimportantthatpressuretofindsolutionstotechnicalorcommercialproblemsdoesnotresultin‘tunnelvision’wheresafetyisconcerned.

100Themostimportantaspectofdesigningandoperatingafuelcellinstallationistoensurethat:

n the important hazards have been identified and appropriate measures taken so that the risk presented by the fuel cell installation is acceptable and has been reduced as low as is reasonably practicable.



Legal requirements101Therearetwoareasofhealthandsafetylegislationrelevanttofuelcellinstallations:

n thoseidentifyinggeneralduties;n thoseregulatingparticularfeaturesortechnicalaspects.

General legislation

102EmployersarerequiredundertheHealthandSafetyatWorketcAct1974tosecurethehealth,safetyandwelfareofpeopleatworkandtoprotectthosenotatworkfromriskstotheirhealthandsafetyarisingfromworkactivities.

103TheManagementofHealthandSafetyatWorkRegulations1999,oftenreferredtosimplyasthe‘ManagementRegulations’,requireallemployersandself-employedpeopletoassesstheriskstoworkersandotherssothattheycandecidewhatmeasuresneedtobetakentofulfiltheirstatutoryduty.2

104ThegeneralprinciplesofanappropriateriskassessmentareidentifiedinBSEN1050:1997Safety of machinery. Principles of risk assessment23andintheManagementRegulations.Intheriskassessmentprocessemployersshouldidentifythepotentialhazardsanddeterminetheirsignificance.Theyshouldthentakeappropriateprecautionarymeasurestoreducetheriskfromthehazardstoanacceptablelevelthatisaslowasisreasonablypracticable.

105TheProvisionandUseofWorkEquipmentRegulations1998(PUWER98)willapplytofuelcellsinmostworksituationsandimposedutiestoensurethattheequipmentprovidedissuitableandappropriate.24

Legislation dealing with the fire and explosion hazards of fuel cells

106Employersandotherdutyholdersshouldensurethatthedesign,installation,operationandmaintenanceoffuelcellinstallationscomplieswiththerequirementsoftheDangerousSubstancesandExplosiveAtmospheresRegulations2002(DSEAR).1

107DSEARisasetofregulationsconcernedwiththeprotectionofpeopleagainsttherisksfromfireandexplosionarisingfromtheuseorstorageofdangeroussubstancesintheworkplace.Dangeroussubstancesincludeallthoseflammablematerialslikelytobeusedasfuelsforcells,forexamplehydrogen,methanol,naturalgasandLPG.UnderDSEARtherisksfromfireandexplosionarisingfromtheuseofdangeroussubstancesmustbeassessedinanappropriatemanner.

108AriskassessmentunderDSEARshouldincludeacarefulidentificationandexaminationofthedangeroussubstancespresentorlikelytobepresentintheworkplace.Itshouldconsiderwhichactivitiesinvolvedangeroussubstances,andhowtheseactivitiesmightgowrongandproduceafireorexplosionthatcouldharmemployeesorthepublic.ThepurposeofDSEARistohelpdeterminewhatneedstobedonetoeliminateorreducethesafetyrisksarisingfromtheuseofdangeroussubstancesinthefuelcellsystem.Theoverallriskassessmentshouldtakeaccountofthehazardsofthedangeroussubstancesusedandanyotherhazardsassociatedwiththeoperationofthefuelcell,forexample:



n thelikelihoodofhazardousexplosiveatmospheresoccurring;n allpotentialignitionsources;n allforeseeablefactors,includingaccidentaldamageandvandalism;n controlofanynon-routineoperations;n maintenanceandrepairactivities;n manual-handlingissues;n humanfactorsandtrainingrequirements.

109Wherefiveormorepeopleareemployed,thefindingsoftheriskassessmentmustberecordedandreviewedatasuitablefrequencyorwhensignificantchangesoccurintheworkplace.

Legislation dealing with the installation and maintenance of fuel cells

110Fuelcellsoperatingonhydrogen,methane,ethaneorLPGmaybeclassifiedasgasappliancesundertheGasSafety(InstallationandUse)Regulations1998(GSIURegulations).9,25TheseRegulationsdealwiththesafeinstallation,maintenanceanduseofgassystems,includinggasfittingsandappliances,mainlyindomesticandcommercialsituations.Inmostsituationstheprincipalfunctionofthefuelcellwillbetheproductionofelectricityandnotheat.Whereelectricityistheprimaryoutput,irrespectiveofhowtheelectricalenergyisused,thefuelcellappliancewillnotbecoveredbytheGasApplianceDirective90/396/EEC(GAD).

111Regulation3oftheGSIURegulationsrequiresanyonecarryingoutworkonagasfittingorstoragevesseltobecompetenttodoso.Self-employedpeopleandemployersofpeoplecarryingoutworkongasfittingsandappliancesindomesticsituationsandnon-industrialpremisesarerequiredtobelongtoaclassofpersonsapprovedbytheHealthandSafetyExecutive.Currently,thismeansthatonlymembersoftheCouncilforRegisteredGasInstallers(CORGI)maycarryouttheworkinthesesituations.

112TheGSIURegulationsapplytofuelcellsusingmethane,ethaneorLPGindomesticandcommercialsituations.TheRegulationsalsocoverfuelcellsoperatingonhydrogenthatarelocatedindomesticpremises,butdonotapplytohydrogencellsinnon-domesticpremisessuchascommercialbuildings,warehouses,officesorfactories.

113Unlessthepremisesareusedfordomestic,sleepingoraccommodationpurposesorarehiredoutaspartofabusiness,theGSIURegulationsdonotapplytofuelcellswhentheyarelocatedinfactories,farms,constructionsites,mines/quarries,shipsorvehicles.25InthesesituationsDSEARwillnormallyapply.

114Insummary:

n whereafuelcelloperatesonhydrogeninadomesticsituationallinstallationorrepairworkmustbecarriedoutbya(CORGI)registeredinstallerwhoiscompetentintheworkbeingdone;

n whereafuelcelloperatesonmethane,ethaneorLPGinadomesticsituationorincommercialpremisesallinstallationorrepairworkmustbecarriedoutbya(CORGI)registeredinstallerwhoiscompetentintheworkbeingdone;

n whenafuelcellislocatedinafactoryallinstallationorrepairworkmustbecarriedoutbyapersoncompetenttocarryoutthatwork.TheydonotnecessarilyneedtoberegisteredwithCORGI.



115TheenforcingauthorityfortheGSIURegulationsisHSEortherelevantlocalauthorityasdeterminedintheparticularcircumstancesbytheHealthandSafety(EnforcingAuthority)Regulations1998.26

116Ingeneral,DSEARandtheGSIURegulationsdonotcoverfuelcellslocatedonvehiclesoperatingonpublicroads.InmostinstancestheVehicleandOperatorServicesAgency(DfT)willbetheleadregulatorinthesesituations.



Appendix 1: Fuel cell types and electrochemistry

Fuel cell type Electrolyte Operating

temperature

(ºC)

Electrode reactions

PEM:Protonexchange

membrane

Polymerelectrolyte

membrane

Perfluorosulphonicacidpolymer 60–100 Anode:2H2->4H++4e-

Cathode:O2+4H++4e-->2H2O

DMFC:Directmethanolfuel

cell

Perfluorosulphonicacidpolymer 60–100 Anode:2CH3OH+2H2O->2CO2+12H++12e-

Cathode:12H++3O2+12e-->6H2O

PAFC:Phosphoricacidfuel

cell

Liquidphosphoricacidsoakedina

matrix

175–100 Anode:2H2->4H++4e-

Cathode:O2+4H++4e-->2H2O

AFC:Alkalinefuelcell Aqueouspotassiumhydroxide

soakedinamatrix

90–100 Anode:2H2+4OH-->4H2O+4e

-

Cathode:O2+2H2O+4e-->4OH-

MCFC:Moltencarbonate

fuelcell

Moltenlithiumandsodium/

potassiumcarbonatesinamatrix

600–1000 Anode:2H2+2CO32-->2H2O+4e

-+2CO2

Cathode:O2+CO2+4e-->2CO32-

SOFC:Solidoxidefuelcell Solidzirconiumoxidewithtraceof

Yttria

600–1000 Anode:2H2+2O2-->2H2O+4e

-

Cathode:O2+4e-->2O2-



Appendix 2: MINIMUM SEPARATION DISTANCES

Type of exposure Distance from hydrogen

source (m)

1 Openflame,ignitionsourceincludinguncertifiedelectrical

equipment

5

2 siteboundary,orareaswherepeoplecongregate,such

ascarparks

8

3 Building,woodframeconstruction 8

4 Wallopeningsinofficesorworkshops(installations

shouldnotbedirectlybelowopenings)

5

5 BulkflammableliquidsorLPGaboveground 8

6 BulkflammableliquidsorLPGunderground 5

7 Flammablegascylinderstorageotherthanhydrogen 5

8 Oxygencylinderstorage 5

9 Liquidoxygenstorage 8

10 Liquidnitrogenorargonstorage 5

11 Storedcombustiblematerial,egtimber 8

12 Aircompressorandventilatorintakes(installationsshould

notbedirectlybelowsuchintakes)

8

13 Activityotherthanthatdirectlyrelatedtothehydrogen

installation

5



GlossaryAnode:Theelectrodeatwhichtheoxidationreactionofthecelloccurs.Thiselectrodeacceptselectronsfromsubstancesinthecell.Catalyst:Asubstancethatspeedsupachemicalreactionbutisnotconsumedinthereaction.

Cathode:Theelectrodeatwhichthereductionreactionofthecelloccurs.Thiselectrodedonateselectronstosubstancesinthecell.

CFD:Computationalfluiddynamics.Theuseofcomputermodellingtosimulateandpredictthemovementandconcentrationgradientsofgasesandliquids.

Cogeneration:Thesimultaneousproductionofelectricityandheatfromapowersource.

Dangerous substance:Asubstanceormaterialwhich,becauseofitspropertiesorthewayinwhichitisused,couldcauseharmtopeople.

DSEAR:TheDangerousSubstancesandExplosiveAtmospheresRegulations2002.

Direct methanol fuel cell (DMFC):Afuelcellinwhichmethanolisoxidiseddirectlyattheanodewithoutpriorreformingtohydrogen.

Distributed generation:Small-scalepowergenerationequipmentthatprovideselectricalpoweratormuchclosertothecustomer’ssitethancentrallylocatedlarge-scalepowerstations.

Electrode:Asolidelectricalconductorthroughwhichelectricityentersorleavesthecell.

Electrolyte:Anon-metallicconductorinwhichthecurrentiscarriedbythemovementofions.

External reforming:Productionofhydrogenfromahydrocarbonorotherhydrogen-richfuelbeforeentryintothefuelcell.

Fluorocarbon:Chemicalcompoundcomposedalmostentirelyoftheelementscarbonandfluorine.

Fuel:Substanceusedtogenerateheatorelectricalpowerthroughachemicalreactionsuchascombustionorelectrochemistry.

Fuel cell:Anelectrochemicaldevicethatcontinuouslyconvertsthechemicalenergyofafuelandanoxidisingagentintoelectricalenergy.Thefuelandoxidantarestoredoutsidethecellandaretransferredtothecellastheyareconsumed.

Hazardous area/place:Aplaceinwhichanexplosiveatmospheremayoccurinsuchquantities/frequenciesastorequirespecialprecautionstoprotectthehealthandsafetyoftheworkersconcerned.

Hydrocarbon:Achemicalcompoundconsistingofonlytheelementscarbonandhydrogen,forexamplemethane,propane,butaneetc.



Incendive:Havingsufficientenergytoigniteaflammablemixture.

Ignition source:Asourceofenergy,suchasasparkorhotsurface,thatislikelytocauseaflammablemixturetocatchfire.

Ion:Anelectricallychargedatomormolecule.

Matrix:Thesupportingmaterialintowhichtheactivematerialsareembedded.

Membrane:Theseparatinglayerincertaintypesoffuelcell(PEMandDMFC)thatactsasanelectrolyteaswellasabarrierfilmsegregatingthegasesintheanodeandcathodecompartments.

Oxidation:Thelossofelectronsfromasubstance.Inafuelcellthisisthereactionthatgeneratestheelectriccurrent.

Reformer:Acatalyticdeviceinwhichhydrocarbonfuelsareconvertedintohydrogen-richfuelgasessuitableforuseinafuelcell.

Unprotected electrical equipment:Electricalequipmentwhich,becauseofitsdesignormanufacture,isnotsuitableforuseinapotentiallyexplosiveatmosphere.

Ventilation:Thesupplyofsufficientcleanairtoensurethatreleasesofdangeroussubstancesdonotaccumulatetoaconcentrationthataffectspeople’shealthandsafety.



References1 Dangerous substances and explosive atmospheres. Dangerous Substances and Explosive Atmospheres Regulations 2002. Approved Code of Practice and guidanceL138HSEBooks2003ISBN07176220272 Management of health and safety at work. Management of Health and Safety at Work Regulations 1999. Approved Code of Practice and guidanceL21 (Secondedition)HSEBooks2000ISBN07176248893 Gaseous hydrogen stationsIGCDoc15/96EuropeanIndustrialGases Association4 Safety standard for hydrogen and hydrogen systemsNSS1740.161997 NationalAeronauticsandSpaceAdministration5 Basic considerations for the safety of hydrogen systemsISO/DPAS15916 20016 Agreement on production and storage of hydrogen. Task 12: Metal hydrides and carbon for hydrogen storage: Final task report InternationalEnergyAgency7 DKSlatteryandMDHamton‘Complexhydridesforhydrogenstorage’ Proceedings of 2002 hydrogen programme reviewUSDoE8 Essential gas safety(Thirdedition)2003CORGITel:087051681119 Safety in the installation and use of gas systems and appliances. Gas Safety (Installation and Use) Regulations 1998. Approved Code of Practice and guidanceL56(Secondedition)HSEBooks1998ISBN071761635510Bulk LPG storage at fixed installationsCodeofpractice1LiquefiedPetroleum GasAssociation11Lewis,RJSax’s dangerous properties of industrial materials(Tenthedition) JWileyandSons2000ISBN047135407412BSEN60079-10:2003Electrical apparatus for explosive gas atmospheres. Classification of hazardous areasandPD60079-14:2000A guide to the application of BS EN 60079-14BritishStandardsInstitution

13Area classification code for installations handling flammable fluids. Model code of safe practice in the petroleum industryPart15InstituteofPetroleum ISBN0852932235

14Safe use and handling of flammable liquidsHSG140HSEBooks1996 ISBN0717609677

15Electricity at work: Safe working practicesHSG85(Secondedition)2003 HSEBooksISBN071762164216Safety in storage, handling and distribution of liquid hydrogenDoc06/02/E EuropeanIndustrialGasesAssociation17Industrial gas cylinder manifolds and distribution pipework/pipelines (excluding acetylene)CodeofPracticeCP4BritishCompressedGasesAssociation



18Determination of safety distancesIGCDoc75/01/E/revEuropeanIndustrial GasesAssociation19BSEN50073:1999Guidelines for selection, installation, use and maintenance of apparatus for the detection and measurement of combustible gases or oxygenBritishStandardsInstitution20The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996SI1996/192TheStationeryOffice 1996ISBN011053999021Fuel cell technologies. Part 2: Fuel cell modulesDraftIEC62282-222COSHH essentials: Easy steps to control chemicals - Control of Substances Hazardous to Health Regulations HSG193(Secondedition)HSEBooks2003 ISBN071762737323BSEN1050:1997Safety of machinery. Principles for risk assessment BritishStandardsInstitution24Safe use of work equipment. Provision and Use of Workplace Equipment Regulations 1998. Approved Code of Practice and guidance1998L221998 HSEBooksISBN071761626625The Gas Safety (Installation and Use) RegulationsSI1998/2451 TheStationeryOffice1998ISBN011079655126The Health and Safety (Enforcing Authority) Regulations 1998SI1998/494 TheStationeryOfficeISBN0110656423

Whileeveryefforthasbeenmadetoensuretheaccuracyofthereferenceslistedinthispublication,theirfutureavailabilitycannotbeguaranteed.

Further informationForinformationabouthealthandsafetyringHSE’sInfolineTel:08453450055Fax:08454089566Textphone:08454089577e-mail:[email protected],CaerphillyBusinessPark,CaerphillyCF833GG.

HSEpricedandfreepublicationscanbeviewedonlineororderedfromwww.hse.gov.ukorcontactHSEBooks,POBox1999,Sudbury,SuffolkCO102WATel:01787881165Fax:01787313995.HSEpricedpublicationsarealsoavailablefrombookshops.

BritishStandardscanbeobtainedinPDForhardcopyformatsfromtheBSIonlineshop:www.bsigroup.com/ShoporbycontactingBSICustomerServicesforhardcopiesonlyTel:02089969001e-mail:[email protected].

TheStationeryOfficepublicationsareavailablefromTheStationeryOffice,POBox29,NorwichNR31GNTel:08706005522Fax:08706005533e-mail:[email protected]:www.tso.co.uk(Theyarealsoavailablefrombookshops.)StatutoryInstrumentscanbeviewedfreeofchargeatwww.opsi.gov.uk.

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