電動(dòng)、混合動(dòng)力和氫燃料車輛的技術(shù)-由可再生能源轉(zhuǎn)換的電力-畢業(yè)論文外文翻譯

英文資料與翻譯Technologiesforelectric,hybridandhydrogenvehicles:ElectricityfromrenewableenergysourcesintransportAbstractThearticleanalysesandcompareselectricityandhydrogenastransportationfuels.Theanalysisincludesaspectssuchastheenergyutilizationfromgridtowheels,vehiclerange(linkedtothephysicalpropertiesoftheonboardstorage),costs,anddurability(particularlyofbatteries).Thearticleconcludesthatitisnotpossibletoidentifyoneoptionasthebestchoicegiventhewiderangeofaspectstoconsiderandthesubstantialuncertainties.Thereisnoclearcutprioritybetweenthemainoptionseelectric,hybridorhydrogen/fuelcelldriveeorwithinthese.Ontheotherhand,theanalysisalsoidentifiesoptionsthatareclearlynotadvantageousintermsofenergyefficiency,e.g.hydrogenininternalcombustionenginesorliquidhydrogen.1.IntroductionUsually,akeyinstrumentinstrategiestopromotesustainabletransportistheintroductionofalternativefuels.Frequently,theprincipalobjectiveofintroducingadifferentenergycarrieristoutiliseitforintroducingrenewableenergysourcesintothetransportsectorand/orimprovingenergysecuritybyreducingthedependenceonoil.Inthiscontext,themainoptionsasregardsenergycarriersforrenewableenergysourcesareelectricity,hydrogen,bio-fuelsandbiogas.Regardlessoftheirrespectivestrengthsandweaknesses,asenergycarriersinthetransportsector,electricityandhydrogenhaveincommonthestrengthsofhavinghighflexibilitywithrespecttoprimaryenergysourcesandthepossibilityofselectingbetweenseveralrenewableenergysources.Incontrast,liquidbio-fuelsandbiogas,whicharefrequentlyseenasmoreimmediatelyapplicablealternativefueloptionsintheshortterm,areinpractice(withacceptableconversionefficiencies)confinedtoaquitelimitedresourcebaseofbiomass.Sincetheseenergycarrierscanrelativelyeasilybegeneratedfromfossilfuels,thelimitedresourcebaseposesarealisticrisk,forinstanceincasethedemandforbio-fuels/biogasoutstripstheproductioncapacity.Thechoicebetweenhydrogenandelectricityasfuels,andbetweentheirdifferentpaths,isacomplexevaluationofvariousaspects,alsoinvolvingassumptionsonthelong-termdevelopmentoftechnologieswithverydifferentdevelopmenttrends,asseentoday.Theevaluationisfurthercomplicatedbythefactthattheelectricity/hydrogenformspartoftheelectricitysupplysystemandcanonlyfullybeanalysedinthiscontext.Thisarticleillustratessomeoftheproblemsinthiscontext,highlightingissuesofparticularimportance:energyefficiency,range,costs,anddurability,amongothers.Itconcentratesonthevehicleandthegenerationoffuels,anddoesnotincludesystemsanalysisoftheelectricitysystem.Insteadthearticleintendstoraisevehicle/fuel-relatedissuesthataresignificantforsuchananalysis.Anoverallconclusionisthatitisnotpossibletomakesimplerecommendationsonthechoicebetweenelectric,hybridandhydrogenvehiclesepartlybecauseofthedifficultiesinassessingthedifferentdimensions,andpartlybecauseconsiderablevariationsexistbetweenthedifferentpathswithinthemainoptions.2.OverviewoffuelcycleofelectricityandhydrogenElectricitymaybeusedeitherdirectlyasfuelinbatteryelectricvehiclesorplug-inhybrid-electricvehicles,orbeconvertedintohydrogenandappliedininternalcombustionengine-basedvehiclesorinfuelcellvehicles.Acommonfeature,exceptfortheinternalcombustionenginevehicle,isthattheycanbeperceivedasvariationsofelectricdrive,inwhichtheelectricityiseithersuppliedfromthegridviaabattery(orsimilarelectricstoragetechnologies)orgeneratedonboardeitherinaninternalcombustionengine(theplug-inhybrid)orinafuelcell.Ifelectricityisusedasfuelinbattery-electricvehicles(BEV),thisistypicallysuppliedfromthepublicgrid,storedonboardthevehicle(typicallyinbatteries)andusedinelectricmotordrives.Inprinciple,therechargingcanbeachievedthoughexistingsockets,andinthiscasetheinfrastructureisveryinexpensive.Thisis,however,asolutionwhichimposesmanyrestrictionsontheplaceandspeedoftherecharging.Hence,inpractice,morerequirementsandcostswillbelinkedtothisoption,particularlyiffastrechargeisrequiredandiftheelectricityconsumptionneedstobemonitored.Thisisusuallyaveryenergyefficientoption.Hybrid-electricvehicles(HEV)arecharacterisedbyhavingbothelectricmotorsandinternalcombustionenginesinitsdrivesystem(Graham,2001;Duvall,2002;Gage,2003;LipmanandDelucchi,2003;Boschert,2006).Theplug-inhybridelectricvehicle(PHEV)isahybridwhichcanberechargedfromthegrid.ItcanbeperceivedasaBEVsupplementedwithaninternalcombustionengine-baseddrive.Infact,thePHEVcategorycontainsawiderangeofdifferentoptions,definedbyfactorssuchas:impactsofdifferenthydrogenoptions,butnormallyeventhemostefficienthydrogenpathwayshavegreaterlossesthantheleastefficientoptionbasedonelectricityasfuel.Ontheotherhand,thevehiclerangeisusuallyconsiderablehigherforhydrogenthanforBEVsandthiswillinallprobabilitycontinuetobethecaseinthefuture.Thisislinkedtothecostsandphysicalpropertiesandthetwostoragemediumsasdescribedindetailbelow(Amos,1998;Kalhammeretal.,2007).Arangeofdifferentoptionscanbeidentifiedwithregardtoonboardhydrogenstorage.Storageintheformofliquidhydrogen(LH2)canachieverangesinthesameorderasconventionalvehicles,butthisoptionhasextremelypoorenergyefficiencyandotherweaknessesinaddition.Fromanenergyefficiencyviewpoint,themostattractivesolutionsatpresentareprobablycompressedgastanks(CH2storage)andmetalhydridestorages,butthelatterofthesestillrequiresconsiderabledevelopmentinordertoreduceweightandcosts.Infrastructurerequirementsandcostsconstituteamajordrawbackinconjunctionwithhydrogen.Inthisrespect,hydrogenundoubtedlyinvolvesthegreatestnumberofobstaclesofallalternativefuels.Thisweaknessincombinationwiththecurrentlyshorterrangesinconnectionwithhydrogenvehicleshaveresultedintheexplorationofoptionsinwhichliquidfuels(gasoline,diesel,methanoletc.)areconvertedintohydrogenonboardthevehicle.Thissolutioninvolvesconsiderableenergylossesandinaddition,manytechnicalproblemsaswellasproblemsofreducingthevolume.Hydrogencanbegeneratedthroughotherpathsthanviaelectricity,notably(inarenewableenergycontext)byconversionofbiomassthroughgasificationorotherprocesses(Padro′andPutsche,1999;S?rensenetal.,2001;Ogdenetal.,2004).Itmayalsobeproducedfromvariousfossilfuels,particularlynaturalgasorcoal.Fromasustainabilitypointofview,however,thereislittlepointinshiftingtohydrogenifthisisbasedonfossilfuels,eveninthelongterm.HydrogenproducedbyelectrolysisbasedonelectricityfromthepresentDanishorEuropeanelectricgridandusedasvehiclefuelgenerallyhasmuchhigherenergyconsumptionandCO2emissionsthanthepresentfuelsusedforthesameapplications.Thenon-grid-connectedHEVisgenerallynotusedinordertoshiftfuelbutonlytoimprovetheenergyefficiencyofthevehicle.Inprinciple,itcanuseanyliquidorgaseousfuel,includinghydrogen,bio-fuels,biogasandothers.Seenfromtoday’spointofview,thisisnotaverylikelyoption.However,thismaychangeinthelongertermifandwhenthehybriddrivetraintypeisdevelopedintoastate-of-the-arttechnology,particularlyifthefuelcelltechnologyisnotsuccessfulinthelongtermoronlyachievesalimitedapplication.Thishybridtypeisfrequentlyseenasacompetitortothefuelcellandasaveryefficientdrivesysteminthelongterm(Edwardsetal.,2007).Whileitwillprobablynotreachthesameenergyefficiencylevelsasfuelcelldrivesystems,itwillnotneedabreakwiththepresentautomobiletechnologies,fuelsandinfrastructure.Itislikelytoremainalower-costoptioncomparedtofuelcellsunlessthelatterexperiencesalarge-scalebreakthrough.3.Keydilemmasandtrade-offsThechoicebetweendifferenttechnologiesandenergycarriersandrecommendationsinthisconnectionisverycomplicatedandassociatedwithgreatuncertainty,formanyreasons.Boththepotentialsolutionsandtheconsiderationstobetakenintoaccountarewide-rangingandheterogeneousincharacter,furthercomplicatedbytheuncertaintiesinconjunctionwiththefuturedevelopmentoftechnologiesnotyetonthemarket.Moreover,thetechnologiesinquestiongenerallyhavedevelopmentalandmarket-relatedhurdlestobesurmountedforwidespreadapplication.Theprincipalconsiderationsintheassessmentofalternativefuelsincludethefollowing(Kemptonetal.,2001;Kalhammeretal.,2007):directandindirectenergyandenvironmentalimpacts(includingimpactsthroughenergyandtransportsystems);vehiclerangebetweenrefueling;weightandvolumeofonboardenergystorage,fuelcellsandthedrivesystemingeneral;costsofpurchaseandoperationofvehicleandfuels;durabilityofkeycomponents,particularlythosewithhighcosts(notablybatteryandfuelcell);demandstoinfrastructureforfuelsandtechnicalbackup;needforabreakwiththepresentdevelopmentoftechnologiesandfuels;flexibility,notleastwithrespecttoenergyresources.Inthecontextofthisarticle,comparingdifferentapplicationsofelectricityinvehicles,itisappropriatetolimitthecomparisontothespecificelectricityconsumptionperkmoffthegridebeitfordirectsupplyofthevehicleorthroughconversionintohydrogen.Theenergyefficiencyisstillacrucialindicatorevenwithrenewableenergyreplacingfossilfuels.Renewableenergyisnotlikelytobecomeanunlimitedandunproblematicsourcewithoutnegativeimpactsintheformofcosts,landrequirements,environmentalandvisualimpactsetc.Onthisbackground,keytrade-offscanbeoutlinedtoillustratetheevaluationandchoiceofdifferenttechnologies.Onecrucialtrade-offisbetweenenergyefficiency/CO2emissions(asrepresentedbythespecificelectricityconsumption)ontheonehandandvehiclerangeontheother.Anotherisbetweencostsontheonesideandeitherrangeorenergyefficiency．ontheother.Afurtherkeytrade-offisbetweenflexibilitytowardsenergyresourcesandperspectivesofcoveringasubstantialshareofthetransportsectorenergydemand(inprinciple100%)ontheonesideandtherequirementstoandcostsofinfrastructureontheother,andinthatconnection,theneedforabreakwiththedevelopment.Inrelationtothelatter,thereisthevitalchicken-and-eggproblem,inparticularwithregardtohydrogenandfuelcells,asthemarketforvehiclesandtherefuellinginfrastructurearedependantoneachother.4.ComparisonoftheenergyefficiencyofelectricityandhydrogenSincethearticlecomparesdifferentutilisationsofelectricityasfuelinvehicles,aconvenientenergychainappliedtomeasuretheenergyefficiencyrunsbetweentheelectricitysupplyoffthegridandthedrivingwheelsofthevehicle.Forelectricityusedinelectricvehicles,themainlossesinvolvedareconversionlossesintheelectricmotor,lossesinthebatteryandrecharginglosses.Thefollowingassumptionshavebeenused(HorstmannandJ?rgensen,1997;Kalhammeretal.,2000;GainesandCuenca,2000;DelucchiandLipman,2001;Kemptonetal.,2001;Delucchi,2003;LipmanandDelucchi,2003;Duvall,2004;Horstmann,2005;Kalhammeretal.,2007):conversionefficiencyelectricmotors:80e85%forpresentmotorsand90e92%orevenhigherinfutureadvancedelectricvehicles;efficiencyofbatteries:70e85%(dependingonthebatterytypeandnotonlyonthedevelopmentstageandhencenotnecessarilydeveloping);rechargingefficiency:efficienciesintheorderof95%;regenerationofbrakinglosses,assumingabout70e75%ofbrakinglossestoberecoveredandresultinginimprovementsofthetotalaveragevehicleenergyefficiencyby15e20%.Inadditiontothegainsinconjunctionwiththeelectricmotorassuch,electricdrivesystems,includingtheonesbasedonfuelcells,canbemadesimplerandmoreefficientbyleavingoutthetransmissionentirelyandtherebyreducinglossesandweight.Moreover,idlinglossesareeliminatedandalsotheyarebettersuitedforpartload.ThedevelopmentincontrolandpowerelectronicshasenabledtheapplicationoflighterACmotors.TheenergyefficiencyofhydrogenusedinvehiclesbasedoneitherfuelcellorICEdrivetrainsistheproductofthefollowingmainfactors(Padro′andPutsche,1999;Kemptonetal.,2001;Ogdenetal.,2001;S?rensenetal.,2001;Delucchi,2003;Koljonenetal.,2004;Ogdenetal.,2004;Crawley,2007;Edwardsetal.,2007;Kalhammeretal.,2007):inFCvehicleseaverageconversionefficiencyoffuelcellsandelectricmotors:between37%and55%;ininternalcombustionenginevehicleseaverageconversionefficiencyoftheICE,includingidlinglossesandtransmissionlosses:15e18%;efficiencyofonboardenergystorage,includingboil-offlossesetc.:93e100%(dependsheavilyonstoragetypeanddrivingpatterns);refuellingefficiency:95e100%;hydrogengenerationbyelectrolysis:75%inpresentalkalinetechnologiesandupto92%infutureadvancedpolymerelectrolysis;liquefactionofhydrogenforthealternativesbasedonliquidhydrogen:70e72%;inFCvehicleseregenerationofbrakinglosses,improvingthevehicleefficiencybybetween0%(atpresent)and15%(inthelongerterm).Fig.1showsthecalculatedspecificelectricityconsumptionperkmoffgridforanaverageDanishpassengercarbeingabattery-electricvehicle(BEV)andavarietyofhydrogenbasedoptions(internalcombustionengine/fuelcell,LH2/CH2),respectively,bothpresentstate-of-the-artandadvancedtechnologies.Hydrogenisassumedtobegeneratedbyelectrolysis.Itcanbeseenthatallhydrogenoptionshaveahigherspecificelectricityconsumptionthanbothofthebatteryelectricvehicleoptions.Attheverybest,thehydrogensolutions(fuelcellandCH2)areaboutathirdpoorerintermsofenergyefficiencythanthepresentbattery-electricvehicle;andatworst,uptoaboutafactor10poorer(ICE/LH2).Fig.2showsthecalculatedCO2emissionsfortheelectricityconsumptionfiguresinFig.1,assumingthatitiscoveredbyaverageelectricityintheDanishelectricitysupplysystemasof2004(DanishEnergyAuthority,2007a).TheestimatedCO2emissionsarealsoshownassumingthathydrogenisgeneratedthroughsteam-reformingofnaturalgas(Ogdenetal.,2001).Finally,thecalculatedCO2emissions(includingupstreamemissions)ofanaverageDanishpassengercarareshown(RoadSafetyandTransportAgency,2007;Edwardsetal.,2007).Thegraphsillustratethepointthattherationaleofhydrogenistoserveasenergy-carrierforrenewableenergy.Butbasedonnaturalgasreforming,thebesthydrogenoptionscangivesubstantialCO2reductionscomparedtothepresentconventionalvehicle(uptoafactor2e3).Andbattery-electricvehicleswillhaveconsiderablelowerCO2emissionsevenbasedonthepresentelectricitysystem.Thisprovidesaconservativeassessmentofbothelectricandhydrogenvehicles,partlybecausetheelectricitysupplysystemisplannedtobeimprovedconsiderablyoverthecomingyears(DanishEnergyAuthority,2007b)andpartlybecauseitignoresthebenefitsachievedbyusingelectricandhydrogenvehiclesasflexibleelectricitydemand(NielsenandJ?rgensen,1997;S?rensenetal.,2001;LundandMu¨nster,2006a,b).Afurtherperspectivecouldbetheutilisationofelectricorhydrogenvehiclesnotonlypassivelyasflexibleloadsonthedemandsidebutalsoactivelyasdecentralisedpowergenerationunits,e.g.(Kemptonetal.,2001;Gage,2003;KemptonandTomie′,2005a,b).5.ThevehiclerangeissueAlthoughtherangeofvehiclesisnotnormallygivenmuchattentioninthecaseofconventionalautomobiles,itcanbeaseriousobstacleforcertaintypesofalternativefuelssuchaselectricityinBEVsorhydrogen.Therangeisdeterminedthroughthejointimpactof:storageweight/volume;specificenergyperweight/volumeofthestorage;thespecificfuelconsumptionperkmofthevehicle.Hence,improvedenergyefficiencyisacrucialwaytoincreasevehiclerange(throughreductionsoflossesand/orbyloweringofdemands).Greaterweight/volumeisameansforincreasingrange,butthisatthesametimeincreasesthespecificelectricityconsumption.Thedifferenthydrogenstorageoptionshaveenergydensitiesinrelationtobothvolumeandweightthatare5e10timeshigherormorethansimilarbatteries.Eventhoughtheconversionofelectricityhasahigherefficiencythanforhydrogen,thisinnowaycompensatesforthedifferentenergydensities.Fig.3illustratestheproblembyshowingcalculatedweightsofthebatteryandhydrogenstorage(compressedhydrogen)forapassengercar.Fourdifferentbatterytechnologiesareincludedbasedonthefollowingprojectionassumptionsfor‘‘highvolumeproductionruns’’(100,000unitsormore)fromstudiescarriedoutbyUniversityofCaliforniaDavis,InstituteofTransportationStudies(DelucchiandLipman,2001):lead/acid(Pb/acid)eenergydensity(aselectricity)30e35Wh/kg,specificcost70e75DKr/kg(equivalentto2e2,25DKr/Wh),lifetime770cycles;nickel/metalhydrideofsecondgeneration(NiMH2G)eenergydensity60e75Wh/kg,specificcost240e300DKr/kg(equivalentto3,25e5DKr/Wh),lifetime670cycles;nickel/metalhydrideoffourthgenerations(NiMH4G)eenergydensity85e110Wh/kg,specificcost240e330DKr/kg(equivalentto2,25e3,00DKr/Wh),lifetime1330cycles;lithium/ion(Li/ion)eenergydensity120e150Wh/kg,specificcost280e400DKr/kg(equivalentto2e3,25DKr/Wh),lifetime1100cycles.TheNiMH2Gbatteryisthecurrentstate-of-the-artfortractionpurposeswithsomedevelopmenttowardsNiMH4G.Thelattercanbeperceivedasanimprovedbatteryatroughlythesamecostsperkg.ThePb/abatteryistheformerstate-of-the-artfortraction,illustratingthedevelopmentovertherecentcouplesofdecades.Inadditiontothebatteries,twohydrogenonboardstorageoptionsareincluded(Ogdenetal.,2001;Edwardsetal.,2007):300baraluminiumtank(presentstate-of-the-art)eenergydensity(ashydrogen)1100Wh/kg,specificcost100DKr/kg(0,09kr/Wh);600barcompositeeenergydensity(ashydrogen)2200Wh/kg,specificcost160DKr/kg(0,09kr/Wh).Itshouldbenotedthattheanalysesarebasedontheoreticalcalculationsnotpracticalresultsandalsothatitdoesnotshowthefullpicturesincetheweightofthefuelcellwilloffsetsomeofthedifference.Inpractice,itwouldnotbepossibletoprovidevehicleswithbatteriesorhydrogenstorageswhichareequivalenttothis,e.g.correspondtohalfofthevehicleweight.Nevertheless,thegraphillustratesthedifferencebetweenbatteriesandhydrogen.WiththeNiMHbatterytechnologyshown,itisnotpossibleinpracticetoextendtherangebeyondapproximately150kmbasedon2Gtechnologyand200e250kmbasedon4Gbatteries.EvenwiththeadvancedLi/ionbattery,itwillnotinthiscalculationberealistictoextendtherangemuchbeyond300e350km.Forhydrogen,ontheotherhand,itwillbepracticablypossible,thoughnotunproblematic,toachieverangesintheorderof600kmevenwiththepresenttechnology;andwithadvancedtypes(highercompressionandlightermaterial),itmaybepossibletoachievethiswithonlyminorproblems.6.Vehiclecostsebatteries,fuelcellsThekeycostcomponentsforelectric/hybridandhydrogenfuelcellvehiclesarethebatteryfortheformerandthefuelcellforthelatter.Thereareotherimportantfactors,includingtheelectricmotor,electrolysis,andonboardstorageofhydrogen.Controlandpowerelectronicsplayasignificantindirectroleforcostsbyallowingmoreappropriatetechnologiestobeapplied.Forsomeoftheseelements,considerableprogresshastakenplace,particularlyforcontrolandpowerelectronics,allowingnewelectricmotorstobeutilised,whichcanbeofsignificanceforelectricpropulsioningeneral,i.e.bothforelectricvehiclesandhydrogen/fuelcellvehicles.Forbothfuelcellsandbatteries,thelifetimeofthecomponentcanhaveseriousimpactsonthelifecyclecostsofthevehicle,intheformofaneedtosubstitutehigh-costcomponentsduetoashortlifetime.Inparticular,thishasbeen,andstillis,acrucialproblemforbatteries,anddurabilityisakeydevelopmentissueforadvancedbatterytypes,suchaslithiumbatteries.Forbatteries,acertainimprovementoftheperformancehastakenplaceoverthelastcoupleofdecadesbutthemaindevelopmentisthatnewebetterbutalsomoreexpensiveebatterytypeshavebecomestate-of-the-art,namelyNiMHbatteriesinsteadoflead/acid,withNiCdbatteriesastheintermediarystepinEurope(LipmanandSperling,1996;Kalhammeretal.,2000;Duvall,2004;Kalhammeretal.,2007).Inaddition,though,adevelopmentoftheNiMHbatteryhasalsobeenseen.Fig.4showscalculatedcostsofthesamebatterytypesandhydrogenonboardstoragesasshowninFig.3(DelucchiandLipman,2001;Ogdenetal.,2001;Edwardsetal.,2007).Here,thesamepictureisseenasinthecaseofweight:comparedtohydrogen,batterieshavemuchhighercosts(intheorderofafactor10e20ormore)whilebeinglimitedtoconsiderablyshorterranges,particularlyforthepresentbatteries.Althoughtheoperationalcostsofelectricvehicleswillalsobelowerthanthoseofhydrogenvehicles,asshownbyFig.1,thisinnowaycompensatesforthemuchhighervehiclecosts,atleastnotintheshortterm.Electricbatteriesareutilisedforarangeofdifferent,andmuchmoresignificant,applicationsbesidestheuseastractionbatteriesfor:electrictools,portablecomputers,cellphones,camerasandmanyothers.Fortheseapplications,thereisaconsiderablepressuretoreducecostsandimprovethedurability,andthisisfrequentlypresumedtocontributetoreducingthecostsoftractionbatteries.However,thepresentspecificcostsofbatteriesfortheseapplicationseintermsofcostsperenergyunitcapacityeisaroundafactor5e10higherthanthatoftractionbatteries,1evenwhencomparingtothepresentmuchtoohighcostseandevenmoresocomparingtofuturecosttargets.Tractionbatteriesareseveralordersofmagnitudelargerthantheseotherapplications,whichwillleadtosubstantiallylowerspecificcosts,everythingelsebeingequal.Ontheotherhand,theywillbemanufacturedinmuchsmallerseries,whichwillinfluencethecostsintheoppositedirection.Thelifetimeofbatteriesisusuallygivenintermsofchargingcycles(forthebatterytypesrelevantinelectricvehicles).Hence,reducingtheelectricityconsumptionperkmisameansofimprovingthelifetimeofbatteries,inadditiontoincreasingtherange.Fig.5illustratesthecalculatedlifetimesofselectedbatterytypesforanaverageDanishautomobileinaveragedrivingpatterns,basedondatafrom(DelucchiandLipman,2001).Theaverageannualdrivingfrequencyisnaturallyakeyfactorconvertingthelifetimesofbatteriesincyclesintoyears.Itisassumedtobe20,300km/a,equivalenttotheaverageoftheDanishautomobilestock.Furthermore,thelifetimeofthebatteryisinverselylinkedtothesizeoftheelectricityconsumptionperkmofthevehicle,andhencethebatterylifetimemaycanbeincreasedbymeansofimprovedfueleconomy,inadditiontoitspositiveimpactontherange.Sincegreaterrangeofthevehicleisequaltomorekilometersdrivenpercycle,thiswillresultinalongerlifetime(butalsoamorecostlyone),everythingelsebeingequal.Itcanbeseenthatthecalculatedlifetimesoflead/acidbatteriesandthepresentgenerationofNiMHbatteriesareconsiderablyshorterthanthelifetimeofthevehicle(forrealisticbatterysizes),whileLi/ionbatteriesmaypotentiallyachievethesamelifetimeorlongerthanthatofthevehicle.Today’sbatteriesforotherapplicationsewhetherLi/ionorNiMHearealongwayfromreapingthispotentialwithlifetimesintheorderof200e300cycles,whichwouldbeequivalenttoabout2e3yearsfortractionapplications.Indeed,durabilityisconsideredakeydevelopmentissueforlithiumbatteriesfortractionapplicationsbesidescostreduction(GainesandCuenca,2000;Kalhammeretal.,2000;Duvall,2004).Forhydrogenvehicles,thecrucialcostissueislinkedtothefuelcelltechnology.ThePEMfuelcellhasexperienceddramaticdevelopmentoverthelastcoupleofdecades,particularlywithaviewtotransportationapplications(Padro′andPutsche,1999;Ogdenetal.,2004).Thisappliestothepropertiesingeneraleweight,volume,operationetc.eandtocostsinparticular.Other,albeitmorelimited,costissuesofsignificanceforhydrogenpropulsionareonboardhydrogenstorageandhydrogenproduction(electrolysis).Inadditiontovehiclecosts,thecostsofinfrastructuremaybeacrucialitem,particularlyduringthetransferperiod.Refuellinginfrastructureinparticularrepresentaprobleminrelationtohydrogen.7.ComparisonofhydrogenandelectricvehiclesFig.6showsthecharacteristicsofdifferentelectricityandhydrogentechnologieswithrespecttospecificelectricityconsumption(kWhelectricityperkm)andrange(km).Electricalpropulsionbasedontoday’stechnologicallevel(‘‘PresentEV’’)resultsinaveryefficientfuelcyclebutalsoalimitedrange.Advancedelectricaltechnology(‘‘AdvancedEV’’)mayleadtoaconsiderablygreaterrangeand,atthesametime,probablyanevenbetterfuelcycleefficiency,potentiallycreatingvehiclesthatcanbeusedformostpurposes.Ontheotherhand,theremaystillbeaneedforvehicleswithlongerrangesehence,providingapotentialroleforhydrogen.Hydrogeninternalcombustionenginevehiclescouldincreaserangesconsiderably,butattheexpenseofthefuelcycleefficiency.Inparticular,liquidhydrogenappliedininternalcombustionengines(‘‘LH2,ICE’’)hasverypoorenergyefficiencycharacteristicsbutalsoascopeforverylongranges,whereasonboardstorageinmetalhydridesorascompressedgas(‘‘C