2023年香港氢能经济研究及报告（英文版）-香港生产力促进局

HongKongHydrogenEconomyStudyandReport

MarketStudyontheUseofHydrogeninGreenTransportationinHongKong

September2023

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A.ExecutiveSummary

InthelatestPolicyAddress,theGovernmentiscommittedtoreducingcarbonemissions,includingexploringdifferenttypesofzero-carbonenergyanddecarbonisationtechnologies,tostrivetowardcarbonneutrality.Hydrogenisoneofthepotentialsourcesofenergycarrierwhichhasversatilitytosubstitutefossilfuelinvariousutilizationscenarios.TheCleanAirPlanforHongKong2035(releasedinJune2021)clearlyidentifiessixmajorareasforfurtheraction,whichincludegreentransport,liveableenvironment,comprehensivereduction,cleanenergy,scientificmanagement,andregionalcollaboration.

Hydrogencantypicallyplayaroleincontributingtoaresilient,sustainableenergyfutureintwomajordirections:(1)current/traditionalpracticeofhydrogenusage,dominantlypresentinindustrialactivities(e.g.refinery,steelproduction,fertilizermanufacturingetc.),canusehydrogenproducedfromgreeneralternativemethods;(2)hydrogenreceivesinterestinnewandemergingapplicationsmainlyinelectricitygeneration,heatingsourceandtransportation(i.e.fuelcellvehicleFCV).InHongKong’scontext,hydrogenusageinthe(2)findsitsultimaterelevance.Hydrogencanbedirectlyusedinitspureformstoredindifferentphysicalstates(includinguncompressedgas,compressedgas,liquefiedhydrogenandsolid-statehydrogenasmetalhydride).Alternatively,hydrogencanbeconvertedtohydrogen-basedfuelssuchasammonia,methaneorliquidalcoholfuels.Withthesemultiplefacetsofhydrogen,thereispotentialtoconnectdifferentpartsoftheenergysystemwithhydrogen-derivedfuels.

Disregardingtherawsourcesofhydrogen,HongKonghasanobviousadvantageoverothercitiesintheworldinthatthehydrogenmixturedistributionnetworkisreadilyavailablethroughoutHongKong.ThesignificantportionofhydrogenintheutilitygasmixturewithitsextensivenetworkaccessibilityisrenderingHongKongconvenientinextractingpurehydrogenforitsdedicatedusageatthedesirablesites.Theexistinginfrastructurescapableofhandlinghydrogen-blendedmixturealsoofferthepotentialofcosteffectivenessinfurtherdevelopingtheapplicationofpurehydrogenfortransportationpurpose.Promotinghydrogen-fuelledvehicles,inadditiontobattery-poweredelectriccounterparts,inHongKongwillhelptodecarbonisethetransportationsector.Bothmodesofgreentransport(hydrogenandbattery-powered)havecomplementaryrolesinsatisfyingvehicleswithdifferentenergydemands.EnactmentofpoliciesandregulationsonhydrogenutilizationwouldbethenextmajoreffortinfacilitatingtherealadoptionofhydrogeninHongKong.

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B.MarketAnalysisontheUseofHydrogeninHongKongHongKong’sPotentials

Thereleaseofthe“CleanAirPlanforHongKong2035”inJune2021islikelytomarka

turningpointformanysectors.AsHongKonglookstocreateamoresustainablesocietywithhealthylivingthroughlow-carbontransformation,itwillbecomeincreasinglyfocusedonlow-carbonenergy,includinghydrogen.WithinthesixmajorareascoveredintheCleanAirPlanforHongKong2035,thereareatleastthreemajorareasthatcanseethepotentialrapidgrowthofhydrogen,includingtheareasforgreentransport,comprehensiveemissionsreductionandcleanenergy.

Hydrogenhasbeenusedinawiderangeofapplicationsformanydecades.Itisanimportantreagentinoilrefining,steelmaking,fertilizerproduction,andmanufacturingofplastics,fabricsanddyes.ThesetraditionalusagesofhydrogenarerelativelydistanttothecontextofHongKongbecauseoftheirtrivialpresenceinthoseindustries.However,asatoolinrealizingdecarbonisation,hydrogenmayhavearoletoplayintransportationandpowergeneration,andalsoasameansofenergystorage.ItremainsrelativelyinfancyinHongKongbuttherearepromisingsignsofbuildingmomentumforthedeploymentofhydrogeninthebelowareas.

Greentransportation.AselaboratedintheCleanAirPlanforHongKong2035,greentransportationhasbeenidentifiedasamajorareaandhydrogendeploymenthasthereforeseenthepotentialroomalbeitstillinitsinitialphases.InAsia-Pacific,abroadrangeofcommitmentsacrossthegovernmentandprivatesectorstosupporttheintroductionofhydrogeninthetransportationsectorisobservedasthissectorisamajoremissionscontributor.Whilebatteryelectricvehiclesarethecurrentpreferredoptionforsmallvehiclestravellingthroughshorterdistances,hydrogenhasbeenconsideredamoresuitablecandidateforheavyvehicletransportationowingtoitsmuchlargerenergydensityascomparedwithbattery.Thismayrepresentasub-sectorwithingreentransportationtofacilitatepreferentialgrowthofhydrogenfuel-cellvehicles(FCV)forheavydutytransportationsuchasbuses,domestictrailersandcross-bordertrucksforlogisticservices.Japan,ChinaandSouthKoreahaveexpressedobjectivesandtargetstoincreasetheusageofhydrogenFCVs.AccordingtoJapan’sBasicHydrogenStrategy,theyhavesetatotalnumberof200,000FCVsby2025and800,000FCVsby2030.Thenumbersareinclusiveofvehiclesofallcategories.Japanisconstructing320hydrogenstationsby2025.Hence,therewouldbemorereferencesof

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deployedhydrogenstationsfromJapanthatcouldbeofvaluabletoHongKong’spathwaytowardshydrogen.ToenablegreentransportationbyhydrogeninHongKong,hydrogengasstationmustbethefoundationforthepromotionofhydrogenFCVs.StrategicallocationfortheinitialinstallationofhydrogenstationismostlikelytobeoutskirtofHongKongtoavoidpopulatedarea.Theconstructionofahydrogengasstationontheoutskirtsmayalsobeapreferredoptionforheavydutyvehicleoperatorsowingtothenatureoftheirroutinerouteoperation.Besidesroadtransportation,thereisalsopotentialforitsuseasamarinefuelinHongKong’scontext.Domesticferriesandintermediate-distanceferriescouldbethepotentialusersofhydrogenbecausetheelectrificationofferriesbybatterytechnologiesappearstobeinadequate.TheInternationalMaritimeOrganization’snewbunkerfuelregulationshavesetthelimitsofSulphurcontentofmarinefuelsto0.5%from1January2020.Althoughthishasnodirecttranslationintotheuseofhydrogen,thereareafewcommitmentsannouncedbythemarineprivatesectortoexploretheuseofhydrogenasfuelfortheinternational/inter-continentalshippingindustries.Asoneofthebusiestportsintheworld,HongKongmaybeimpactedbythelatestrapidadoptionofgreentechnologies.

Powerandheatingsector.HongKongiscurrentlyunderwaytoreplacecoalwithnaturalgasinpowergeneration.Ithasseenagreatandcontinuingreductionofgreenhousegasemissionsfromthepowerutilitiescompanies(i.e.CLP,HKElectricandTowngas).TheconstructionoftheoffshorenaturalgasterminalisanotherimportantmilestoneforHongKonginachievingthefurtherreplacementofcoalbynaturalgasinthepowergenerationsector.Inordertoachievenetzeroemissionafterobsoletingcoal-firing,naturalgascouldalsobegraduallyandeventuallyreplaced(toacertainextent)byhydrogen.HydrogeninjectionintotheexistingpipelineisalreadypartofthenationalhydrogenstrategyforafewcountriesincludingtheUK,Australia,JapanandSouthKorea.HongKong-basedcompanyhasbeeninvolvedintheseinitiativesandcouldbeanimportantcontributorinadoptingthestrategyinHongKong.Initialplansaretheblendingofhydrogeninalowmixturepercentagewithnaturalgasforinjectiontoavoidmajormodificationstopipelinenetworks.Higherconcentrationsmayrequirenetworkmodificationssuchasthereplacementofsteelwithcompositepipesorthereplacementofcompressors.Otherthanpipelinesfortransportinghydrogen,thereisalsothedevelopmentofmoreadvancedgasturbinescapableofacceptingfuelblendswhichmaycontain50%ormorehydrogen.Majorturbinemanufacturersaredevelopinggasturbinesthatcouldrunon100%hydrogen.Althoughthereisalongwaybeforehydrogenmightfullyreplacenaturalgasforelectricitygeneration,andthepredictedtimelineforsuchtransitionhasuncertainfactors,itisaverysignificantstepawayfromfossilfuelstowardsalow(orzero)carboneconomy.

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Incontrast,utilitygasmixtureinHongKonghasseentheadoptionofhighcontenthydrogen(upto51%ofthemixture)fordecades.TheextensiveaccessibilityofutilitygaspipelinethroughoutentireHongKongisanobviousadvantageinfurtherextendingitsusage,includingextractingpurehydrogenforhydrogenfuelstations.Notethatthehydrogenintheexistingutilitygasisnotproducedfromthecleansourceatthecurrentstage.

Short-termenergystorage.Hydrogencancouplewithrenewableenergy(solarandwind)toaddressthedrawbacksofrelianceonrenewableenergy.Energygeneratedbywindorsolarpowerplantscanbestoredandtransportedfromregionswithhigherproduction(e.g.offshoreforwindfarm,ruralareaforsolarPVfarm)toareaswithhigherdemand.Otherwise,itcanbesimplystoredduringlow-consumptionperiodsuntilthereisapeakinenergydemand.Certainly,theproductionofhydrogenandsubsequentlyre-conversiontoelectricitywillcarryanadditionalcostandinvolvesenergylosses.However,thecontinuingfallingcostofrenewableenergycanstillenhancetheviabilityofhydrogenasthestoragemediuminalongterm,seasonalandtransportablemanner.Thismaynotbethemostidealsituationinlongtermbutitisimportantintheearlydaysfordevelopingtheutilizationofhydrogen.HongKonghasanumberoflarge-scaledeploymentsofwindfarmsandfloatingphotovoltaic(PV)systems.Theuseofelectricityfromtheserenewablefacilitiesmayfindanopportunityinthemediumofhydrogenbecausethedirectusageofelectricityfromwindfarms/floatingPVgenerationsitesmaynotbeconvenientlyfeasibleinthenearterm.

RecentdevelopmentinHongKong

HongKongismakingeffortstokeepupwithotherOECDcountriesinhydrogen-relateddevelopmentandinitiativeisbeginningtobeputinplace(forexample,themuchanticipatedGreenTechnologyFundGTF).HongKongGovernmenthassetuptheGTFin2021toprovidebetterandmorefocusedfundingsupportforresearchanddevelopment(R&D)projectswhichcanhelpHongKongdecarboniseandenhanceenvironmentalprotectionasHongKongstrivestowardsitsgoalofcarbonneutralitybefore2050.TheGTFisconsideringallcategoriesofgreentechnologies.However,thefundingoutcomehassuggestedthevisionoftheHongKongGovernmentinpro-actively

exploringthesuitablewayoftheCity’sownhydrogendevelopmentalplan.Outofthe14approved

projectsoutofover190applicationsinthefirstroundoffunding,fourprojectscentredonhydrogentechnologieshavebeenapprovedatmultimillionHongKongdollarscale.

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Thefourhydrogen-focusedprojectsledbyHongKonglocaluniversitiescoverthescopeofgreenhydrogenproduction,hydrogenstorage,andhydrogenapplications.Inthespaceofgreenhydrogenproduction,twoprojectsusingnewphotocatalytictechnologyandmembrane-lesselectrolysershavebeenselectedforfurtherdevelopment.Bothprojectsaimtoutilisewaterasthehydrogensource.Anotherprojectwasapprovedtodevelopsolid-statehydrogenstorageasapotentialwayintacklingthestorageissueofhydrogen,whilealong-lifehydrogenfuelcellprojectsecuredanotherslotinthefirstroundoftheGTFcall.

HongKong’sClimateActionPlan2050releasedinOctober2021hasincludedgreenhydrogenenergyinitsmedium-termdecarbonisationtargets.Itisalsomentionedthattheuncertaintyofthetechnologywilldependonitsmaturity,reliabilityandcost-effectivenessforlarge-scaleapplications.Besidetheadoptionofelectricvehicles(generallyreferredtobatteries-poweredelectricvehicle),manyautomobileplayersaredevelopinghydrogen-powervehicles(suchasheavy-dutytype)andHongKongiscollaboratingwithfranchisedbuscompaniesinthenextthreeyears(2022-2024)totestouthydrogenfuelcellelectricbusesandheavyvehicles.GuangdongProvincehasestablishedhydrogenproductionfacilitiesthatmightprovidehydrogensupplytoHongKong.Hence,feasibilitystudiesonhydrogen-fuelledtransportandconstructionofhydrogen-fillingfacilitiesareorsoonwillbeunderway.FollowingthereleaseoftheCleanAirPlan,theGovernmenthassetupanInterdepartmentalWorkingGroupontheapplicationofhydrogenenergyinHongKong.CityUniversityofHongKong(SchoolofEnergyandEnvironment)hasbeenworkingwiththeWorkingGroupinthisinitiativeanddeliveredatrainingmoduletotheinterdepartmentalpersonnelonhydrogenproductiontechnologies.

BesidetheGovernment’sinitiatives,HongKongutilitiescompanieshavelaunchedhydrogen-focuseddevelopmentplans.CLPhaskick-startedcollaborationwithGEtojointlydevelopadecarbonisationroadmapforCLP’sgas-firedpowergenerationfacilitiesinHongKong.CLPandGEexplorethefeasibilityofburningavariableblendofnaturalgasandhydrogenuptoapossible100%hydrogen,toreducecarbonemissionsattheBlackPointpowerplant.HongKongandChinaGas(Towngas)isdevelopingthecapacitytoproducezero-carbonhydrogenaspartofitslong-termdecarbonisationplan.Towngashasbeenconductingpilotprogrammesonhydrogenutilisationandequipmentinstallationsforthepastyears.

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HongKong’slimitation

Despitethepromisingaspectsofhydrogen,therearemajorchallengesforwidespreaduseinworldwide,includinginHongKong.Ingeneral,hydrogenisusedatlargescaleinmanyindustries(e.g.steelmaking,oilrefining,fertilizerproducingetc.).Decarbonizingindustrialsectorsthroughgreenhydrogenisanindispensablestrategyinmanyindustrializednationsasthecarbonemissionfromtheindustrialsectorissignificant.TheutilizationofhydrogeninindustriesinHongKongisbasicallyrare.Instead,aselaboratedearlier,hydrogenfindspotentialinnewapplicationssuchasgreentransportationandcleanenergy.BelowaresomeofthechallengesencounteredinHongKongandhowtheymightbeovercome.

Greenhydrogenisexpensive.Asofnow,theproductioncostofblueorgreenhydrogenremainsmuchhigherthanthatoffossilfuels.Currently,thecostofproductionofgreenhydrogenisestimatedtobeUSD$2.50-6.80perkgH2whilebluehydrogenisestimatedtobeUSD$1.40-2.40perkgH2.Forgreenhydrogentobecomecommerciallycompetitive,ithasbeensaidthattheproductioncostneedstobeloweredtoorlowerthanUSD$2perkgH2.ThereareprojectionstoseethepriceofgreenhydrogenfallbelowUSD$2perkgbeforetheendofthisdecade.Themaindriversforloweringthegreenhydrogenproductioncostarethefallingcostofrenewableelectricity(especiallylarge-scalesolarPV)andthepriceofelectrolysisfacilities(benefitsofscale-upmanufacturing).Thetrendisexpectedtocontinue.ThecostofCCSwillneedtobereducedanditsefficiencyneedstobeimproved.Onecriticalfactoroftenoverlookedorignoredistheaccesstoawatersourceforelectrolysis.Thecurrentelectrolysertechnologies,aselaboratedintheabovesections,arerelyingoneitheralkalinewaterorclean(deionized-grade)waterforoperation.Whilethewaterresourcemaynotbeanimmediateproblem,theprovisionoftreatedcleanwaterfortheoperationofelectrolysismightposealong-termchallenge,especiallywhenitisproducedatamegawattscale.

Thoughgreenhydrogenisexpensive,thereareexamplesofincreasinggovernmentsupportfortheuptakeandusageofhydrogen.Governmentsupportisintheformof(1)financialsubsidiesandinvestmenttomakehydrogenmoreeconomical,and(2)carbontaxesoremissionstradingschemestoincreasethecostoffossilfuels.China,Japan,andSouthKoreahavealreadyimplementedemissionstradingschemesindifferentforms.Thisiscritical,especiallyduringtheinitialdeploymentphasesofnewgreentechnologies,includinghydrogen.Hydrogensubsidyschemesmaybecoordinatedwithotherenvironmentalincentiveschemes.

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Transportationofhydrogen.Ifhydrogenisnotproducedlocally,thetransportationofhydrogencancompriseasignificantcomponentofthefinalcostofhydrogen.Forshorterdistances(forexample,fromGreaterBayAreatoHongKong),hydrogenmightbetransferredbygroundtransportorupgradedpipelines.Forlongdistancetransportation(e.g.fromAustraliaorChiletoHongKong),themostrealisticoptionatthemomentwouldbeliquefiedhydrogen.Ammoniaasthehydrogen-carrierhasalsobeenseriouslyconsideredanoptionbyJapanandAustralia.Thereareenergylossesincurredduringtheconversionofhydrogen-nitrogenintoammoniaattheexportersite;therearealsoenergylossesduringthere-conversionofammoniabacktohydrogen.However,itmaystilloffercostbenefitswhencomparedwiththepriceassociatedwithliquefyinghydrogenatextremelylowtemperatureforultra-longdistancetransportation(suchasfromAustraliatoJapan).InHongKong,itmightbeidealtoproducehydrogenon-siteatoutskirtfacilitiesthroughwaterelectrolysis.Transportationneedscouldberemovedifthegenerationsitesaretheutilizationpoint.TransportationthroughpipelinesfromGBAmightbeanotheroptionpriortoconsideringofinter-continentaltransportationofhydrogenthroughshipment.ThevariationinstandardsadoptedintheGBAandHongKongshouldbesorted.

Lackingofdistributioninfrastructure.WidespreaddeploymentofpurehydrogenwithinHongKongwillrequireextensiveinvestmentinthedistributioninfrastructure.Ingeneral,existingpipelineinfrastructurewillneedtoberetrofittedtoaccepttheinjectionofmoreconcentratedorpurehydrogen.Morecritically,forthepromotionofgreentransportationthroughhydrogenFCV,thereisnorefuellinginfrastructureinHongKong.Tostartwith,FCVscostconsiderablymorethancarswithcombustionengines.Withouttheprovisionofeasilyaccessiblehydrogenrefuellingstations,itisunlikelythattherewillbeanuptakeordemandforhydrogenFCVs.Thedilemmaencounteredisthatpartiesmaynotinvestininfrastructureunlessthereisademand,butdemandwillnotmaterializewithouttheinfrastructure.Thedrivetowardshydrogeninfrastructureinvestmentmayseearoleforthegovernmenttoprovidefinancialandpolicysupport.

Theneedsforclearandcomprehensiveregulatoryframework.Operational,environmental,safety,andtechnicalstandardsneedtobeimplementedinordertoensureconsistentstandardsforutilization,transportation,andstorageofhydrogen.InHongKong’scontext,ifhydrogenissourcedfromMainlandChina,thecross-bordertransportationofhydrogenisstillinitsinfancy.Clearregulationspertainingtotransportationcan,inturn,promotethegrowthanddevelopmentofhydrogenprojects.Thereareexamplesofcountriesthathaverolledoutinitiallawsonhydrogenusageand

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domesticsafetystandards.Forexample,SouthKoreahaspassedtheHydrogenEconomyPromotionandHydrogenSafetyManagementLaw.However,substantialfurtherworkisstillinprogresstodevelopdetailedrulesandregulations.Internationalandcross-borderregulationsofhydrogentradeandtransportationarealsointheearlystages.

C.AnalysisoftheSupplyChainofHydrogen

C1.HydrogenProductionGreenHydrogenTrend

Althoughgreenhydrogenhasbeenvigorouslydiscussedandconsensuallyagreedasoneoftheeffectivesolutionsinaddressingdecarbonisationstrategyworldwide,99%ofthe~70millionmetrictonnes(Mt)isstillproducedfromthesteamreformingofnaturalgas(71%)andthegasificationof

coalandoil(27%),asshownin

Figure1.

Theproductionofthis70Mtofhydrogenwasaccompanied

bythereleaseof830MtofCO2.Itisclearthattheuseofhydrogenproducedfromcarbonintensivesourceshaslittlerelevancetodecarbonisation.ThishydrogeniscategorizedasgreyhydrogeninwhichtheCO2emissionisunsustainablyhighrelativetoitsusage.Greyhydrogenisthedominantandtraditionalsourceusedinrefineries,ammoniaandmethanolproduction.Ammoniaistheimportantrawmaterialforfertilizerproductionwhichsupportstheagriculturalactivities(e.g.foodcrops)whilemethanolisusedinplasticproductionandfueladditive.

Figure1Hydrogenproductionmethodsusedin2018.Source:IEATheFutureofHydrogen.

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Thescenarioisexpectedtochangeinwhichlow-carbonhydrogenwillbethedominantsourceofhydrogenwhilegreyhydrogenwillbecompletelyphasedoutby2050,mainlydrivenbythefallingpriceofgreenhydrogenenabledbytechnology.Figure2showsthattheprojected500-800Mtofhydrogenproducedin2050willcomprisegreen(85%)andblue(15%)hydrogen.Bluehydrogenisessentiallyanupgradedversionofgreyhydrogenequippedwithcarboncaptureandstorage(CCS)technology.Bluehydrogenisconsideredanintermediatestagebeforethefulltransitionfromgreytogreeninhydrogenproduction.Ideally,existinggreyhydrogenproductionfacilitiescanberetrofittedwithCCSandbecomeanoptionfortheexistinghydrogenstakeholderstoachievelowergreenhousegas(GHG)emissions.Thisallowsforthepromotionofhydrogenmarketgrowth.Inprinciple,atheoretical85-95%ofcarbonemissionsfromtraditionalgreyhydrogencanbecapturedbytheinstallationofCCS.Existingindustrieslikeammoniaplantsandsteelproductioncouldusebluehydrogenasaninitialsolutionbeforethematurationofgreenhydrogentechnologies.

Figure2Multiple-foldincreaseincleanhydrogenproductionby2050.Source:ETC(2021)MakingtheHydrogenEconomyPossible.

However,fiercedebatescontinuetotakeplaceonthefeasibilityoftheCCSapproach(bluehydrogen).AsCCSisgenerallyregardedasanintermediatestageorshort-termsolution,bluehydrogenencountersafewmajorchallengesincludingthedoubtscastonitsbestcaptureefficienciestoreach85-95%.Theremaining5-15%oftheCO2willstillbeemittedandthescaleisstillmassive.Furthermore,thesehighcaptureefficiencieshaveyettobeachieved.Moreover,additionalcosts

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associatedwithretrofittingexistingfacilitiestoincludeCO2transport,storageandmonitoringalso

faceacceptanceissues.Thestoredcarbonwouldneedlongtermmonitoringmechanismwhiletheriskofleakagescontinuestobealiability.

Asreportedbymanyinternationalsurveys,greenhydrogenisproducedfromwaterelectrolysispoweredbyrenewableenergy/electricity.Commonlyadoptedscenariointhosemajorreports(suchasIEA,ETC,ARENA,IRENA)includestheuseofsolarphotovoltaicandwindturbinetodrivevarioustypesofelectrolysersthatsplitwaterintohydrogenandoxygen.Thehydrogenproductioncostprojectionismainlybasedontheabove-mentionedtechnologies.Othernon-electrolysisrenewable-basedsolutionsdoexistandhavebeendiscussedwidelybutnotamainstreampractisewhenitcomestocostprojection.Theseoptionsincludebiomasspyrolysis,thermochemicalwatersplitting,photocatalysisandanaerobicdigestionofbiomass.Greenhydrogenistherefore,inmanycases,solelyreferringtorenewable-poweredwaterelectrolysis.Renewableenergy,withparticularinterestinsolarphotovoltaictechnology,showsdecreasingcostsaccompaniedwithimprovementinefficiency,whichbringspossibilitiestolowcostgreenhydrogen.Thepresenceofmatureelectrolyser(alkalineelectrolysers)andemergingnewtypeofelectrolyser(polymerelectrolytemembrane(PEM)electrolysers)areanotherfactorinstrengtheningtheimpressionofgreenhydrogenbeingderivedfromrenewable-poweredelectrolysisofwater.Hence,inthisstudytheevaluationofgreenhydrogeniscloselyassociatedwiththistechnology.

HydrogenGeneration

Hydrogenproductioncanbegroupedintothreeprimarypathways,namely

(a)Thermochemicalpathway(b)Electrochemicalpathway(c)Emergingpathway

Existingortraditionaldedicatedhydrogenproductionmethodsaremostlyfromthecategoryofthermochemicalapproach.Itis,however,unfairtoperceivethermochemicalpathwayastheuncleanhydrogenproductionmethod.Theexistingthermochemicalapproachisacarbonintensiveprocessonlybecauseoftheuseoffossilfuelasthehydrogensource.

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Thermochemicalapproach

Thethermochemicalmethodisaprocessinvolvingtheuseofheattointeractwithprecursors.Theuseoffossilfuelasthehydrogensourcedominatesthethermochemicalapproach.Hydrocarbons,coal,naturalgasandthebiomassarecommoncarbon-basedfuelsreferredintheabove.Inthefirststageofthermochemicalapproach,syngasmadeofhydrogenandCO/CO2mixturesareproduced.Thesyngasissubsequentlysubjectedtothemature“water-gasshiftreaction”toconcentratetheamountofCO2andhydrogen.Conventionally,CO2isproducedastheby-productwithoutbeingpairedwithCCS.

Figure3

showsthematureandtraditionalthermochemicalhydrogenproductiontechnologies.Steammethanereforming(SMR)isthemostwidelyusedmethodforhydrogenproductionfollowedbythecoalgasification.ThepercentageofSMRandcoalgasificationvariedfromcountrytocountrybutpersistentlybothofthemarethemostusedmaturetechnologies.Hydrogenproducedfromtheseapproachesrequiresfurtherpurificationsuchaspressureswingadsorption(PSA)andgasseparationmembrane.TowngasinHongKongisadoptingPSAintheirproduction.Withcurrentpurificationmethods,hydrogenpuritylevelsof99.9999%canbeobtained.

Process

Description

Dis/Advantages

SteamMethane

Reforming(SMR)

Lighthydrocarbons,suchasnaturalgasorbiomethane(upgradedbiogas),aremixedwithsteaminthepresenceofacatalystathightemperature(~750oC)andmoderatepressuretoproducesyngas.SMRonitsownusesapproximately4.5LofwaterperkgH2.

+Establishedtechnology

−Requirespurif