2023储能电站分析

StationaryBatteryEnergyStorageSystemsAnalysis

Afocusonintradayshifting

March2023

Contents

Preface 3

Anoteontheanalysis 3

Summary 4

Recommendations 4

Definitions 5

Context 6

ExamplesofBESSprojectsandinstallations 7

Technologiesandmanufacturers 8

Lithiumionbatteries 8

Redoxflowbatteries(RFB) 8

Moltensaltbatteries 9

Othermetalbatteries 9

Non-metalbatteries 9

Commercialisationconsiderations 10

Analysis 13

Technicalcomparison 13

Commercialcomparison 17

Environmentalcomparison 19

Safetycomparison 21

Conclusionandrecommendations 22

Appendix 23

References 25

Preface

Thepurposeofthisdocumentistoprovideatechnicalandcommercialcomparisonofvariousbatteryenergystoragesystem(BESS)chemistrieswhicharecurrentlyavailableonthemarketsuitableforintradayshifting.

WhensuchaBESSiscombinedwithanintermittentrenewableenergysystemwithnoinherentstorage(wind,solar,run-of-the-riverhydro),throughouttheday,theresultinghybridsystemcandivertanyexcessenergyproducedattimesoflowdemandtostorage.TheBESScansubsequentlysupplythegridattimesofhighdemand,whilstalsominimisingtheuseoffossilfuelswhenattemptingtomatchpeakdemandandovercomenetworkconstraints.

Anoteontheanalysis

TheanalysispresentedinthisdocumentwasconductedinternallybyAraAkeinQ42022,andassuch,onlyshowsasnapshotoftheBESSmarketintime.DuetothesignificantgrowthandinnovationoccurringintheBESSmarket,dependinguponwhenthisdocumentispickedupbythereader,theresultsthroughoutregardingthechemistriespresentedmaybeoutofdate.

3

Summary

RenewableenergyisNewZealand’slargestsourceofelectricitygeneration(82%)andprovidesapproximately41%ofNewZealand’sprimaryenergysupply.1Of

theinstalledrenewableelectricitycapacity,20%isassociatedwithintermittentrenewableenergysystems(IRES)withlittletonocapacityforenergystorage.2

ThereispotentialtoovercomethisissuebycombiningIRESwithstationaryenergystoragesystems(i.e.batteries).Withthiskindofhybridsystem,throughintradayshifting,anyexcessenergyproducedbytheplantattimesoflowdemandmaybestoredtosubsequentlysupplythegridattimesofhighdemand,whilstalsominimisingtheuseoffossilfuelswhenattemptingtomatchpeakdemandandovercomenetworkconstraints.

AraAkehasidentifiedanumberofpotentialIRESpowerplantswithinNewZealandtodemonstratesuchahybridsystem.Lithiumiontechnologydominatesthebattery

marketacrossmostsectors,3includingrenewableenergystorage,butitisofinteresttoAraAketounderstandthetechnicalandcommercialcharacteristicsofallthevariousbatterysolutionsavailableonthemarket,aswellasthesafetyandenvironmentalimpactsofthesetechnologies.

Recommendations

Ofthemorethan10containerisedBESSstudied,nickel-hydrogen(NiH2)isastandoutchemistryforstorageof12hoursorlesswhenconsideringallaspectsduetoauseablelifetimeof30yearsand30,000charge/dischargecycles.

Onafootprintbasis,nickel-hydrogeniscompetitiveintermsofuseableannualenergyoutputwithhigherenergydensitylithiumionandmoltensaltbatterychemistries.Onalifetimebasis,nickel-hydrogenhasamongthehighestenergyoutputofalltechnologiesstudied,beatingallmanufacturers,buttwolithiumionofferings(CATLandTesla).

Nickel-hydrogenisdesignedforuptothreecharge/dischargecyclesperday,yetisalsocapableofdischargeratesvaryingbetween2and12hours.Competitorshavesimilarcharge/dischargerates,butareonlydesignedforamaximumofonetotwocyclesperdaybeforesignificantlyimpactingbatterylifetime.

Fromacostperspective,nickel-hydrogenisthebestvaluefor12hoursorlessofstoragewhencomparingthelevelisedcostofstorage(LCOS)ofthetechnologies,ameasureofthetotalcostofanenergystoragesystemagainsttheenergydischargedoverthebattery’slifetime.

Theestimatedenvironmentalimpactofthebatteryiscomparabletoanumberofcompetitors,butsignificantlylowerthanlithiumion.

Thenickel-hydrogentechnologyhaspassedallrelevantbatterysafetystandards,includingtheUL9540Atestforthermalrunaway.Manynewbatterytechnologieshavepassedthistest,however,fewlithiumionmanufacturershavewithonlyasinglecontainerisedlithiumionbatterymanufacturerintheUL9540Adatabase(EVLO).

Themanufacturer,EnerVenue,hasbeenbackedbymultibilliondollarengineeringcompany,Schlumberger(marketedasSLB),whowillsupportlarge-scaledeploymentofnickel-hydrogenbatterytechnologyacrossselectedglobalmarkets.Currentproductionvolumeis60MWh/year,howeverplannedfacilitiessoontobeunderconstructionwillresultinexceeding2GWh/yearbytheendof2024.

Anotherbatterytechnologywhichcouldbeofinterestiscalcium-antimony(CaSb),givenitshighenergyoutputandlowLCOSsimilartonickel-hydrogen.

Noenvironmentaldataforthistechnologywasavailable,butallthingsconsidered,itcouldbeaninterestingtechnologyforsimilarapplications.

4

Definitions

Electricalcurrent(A)

Theflow(andamount)ofelectricityinanelectricalcircuit,measuredinamperes.1Aisequaltoanelectricalflowrateof6.241509074×10¹⁸electronspersecond.

Electricalresistance(Ω)

Theoppositiontoflowofelectricalcurrentinacircuit,measuredinOhms.

Voltage(V)

Theelectromotivedrivingforceinanelectricalcircuit,measuredinVolts.Voltageistheproductofcurrentandresistance.

Electricalpower(W)

Therateelectricalenergyistransferredbyanelectricalcircuit,measuredinwatts.Poweristheproductofvoltageandcurrent.

Battery

Adevicecontaininganelectriccelloraseriesofelectriccellsstoringenergythatcanbeconvertedintoelectricalpower.

Ratedpoweroutput(kW)

Thetheoreticalmaximumamountofinstantaneouspower,measuredinkilowatts,whichcanflowintooroutofabattery.

Ratedbatterycapacityorenergyoutput(kWh)

Atheoreticalmeasureofbatterypowerdeliveredoveragiventimeperiodi.e.1kWhisequivalentto1kWofconstantpowerovertheperiodof1hour.1kWhisalsoequivalentto3.6megajoules(MJ).

Roundtripefficiency(%)

Thepercentageofenergyusedtochargethebattery(i.e.putintostorage)whichcanthenbelaterretrieved.Thisisessentiallyameasureoftheenergylostduringagivencharge-dischargecycle.

Useablebatterycapacity(kWh)

Theactualbatterypowerdeliveredoveragiventimeperiod,onceaccountingforroundtripefficiency.

C-rating(hours-1)

Thecharge/dischargerateisameasureofhowmuchtimeisrequiredtofullychargeordischargeabattery.NotethattheC-ratingofabatteryimpactspoweroutpute.g.a120kWhbatterywithaC/2ratingwillprovide60kWofpowerover2hours.AC/12equivalentwouldprovide10kWover12hours.

Batterycycle

StationaryBatteryEnergyStorageSystemsAnalysisMarch2023

Theprocessofchargingabatteryanddischargingitasrequired.Asinglechargeanddischargeisequivalentto1cycle.

Lifetimedegradation(%/lifetime)

Aprocesswhichpermanentlyreducestheamountofenergyabatterycanstore,ortheamountofpoweritcandeliver.Usuallypresentedonapercycleorperyearbasis.

Batterylifetime(yearsorcycles)

Batterylifetimeisequivalenttothenumberofcyclesbeforethebatterywilleithernolongerholdchargeorperformanceissignificantlyreduced.Thislifetimemayalsobeconvertedtoyears.

5

Context

RenewableenergyisNewZealand’slargestsourceofelectricitygeneration(82%)andprovidesapproximately41%ofNewZealand’sprimaryenergysupply.1

Ofthe7682MWofrenewableelectricitycapacityinstalledinNewZealandbytheendof2021,1703MWaregeneratedbyintermittentrenewableenergysystems(IRES).2Suchsystemsinclude:

Run-of-theriverhydropower(586MW),3whereelectricityisgeneratedfromwaterflowinginariverorstream(asopposedtoconventionalhydrowhichgeneratespowerfromthegravitationalpotentialenergyofdammedwater)†;

Wind(913MW),whereturbinesgenerateelectricityfromthewind’skineticenergy;and

Solar(205MW),wherephotovoltaic(PV)cellsconvertsunlightintoelectricalenergy.

Thekeydifferencebetweentheabovesystemsandconventionalhydropowerandgeothermalplantsisthattheyhavelittletonocapacityforenergystorageandaresubjecttoambientconditionssuchasseasonalriverflow,windspeed/directionandsolarradiation.Thismakestheseplants’electricitysupplyirregularwiththeinabilitytoco-ordinateelectricaloutputwithconsumerdemand.

StationaryBatteryEnergyStorageSystemsAnalysisMarch2023

ThereispotentialtoovercomethisissuebycombiningIRESwithstationaryenergystoragesystems(i.e.batteries).Withthiskindofhybridsystem,throughintradayshifting,anyexcessenergyproducedbythepowerplantattimesoflowdemandmaybestoredtosubsequentlysupplythegridattimesofhighdemand.Havingaccesstothisstoredrenewableenergywillminimisetheuseoffossilfuelswhenmeetingpeakdemandandalsohasthepotentialtoprovidemoreeffectiveembeddedgeneration,tomatchpeakloadandnetworkconstraints.

AraAkehasidentifiedanumberofpotentialIRESpowerplantswithinNewZealandtodemonstratesuchahybridsystemtosupportintradaygenerationshiftingandlinescompanyconstraintmanagement.Lithiumiontechnologydominatesthebattery

marketacrossmostsectors4,includingrenewableenergystorage,butitisofinteresttoAraAketounderstandthetechnicalandcommercialcharacteristicsofallthevariousbatterysolutionsavailableonthemarket,aswellasthesafetyandenvironmentalimpactsofthesetechnologies.

†ThereisanargumentthatanumberofNewZealand’slargeconventionalhydroelectricplantsareessentiallyrun-of-the-riverbecauseoftheirlimitedstorage,howeveradistinctionismadethatiftheriverisimpoundedtocreateareservoirofsignificantsizethentheplantistechnicallynotrun-of-the-river.5

6

ExamplesofBESSprojectsandinstallations

Bytheendof2021,theinstalledcapacityofgrid-scaleBESSaroundtheworldexceeded16GWandglobalinvestmentsapproached$10billionUSD6.Somerecentexamplesofbothdomesticandinternationalrenewableenergybatterystoragehybridprojectsinclude:

InMarch2022,WELNetworksandInfratecannouncedthattheyhadenteredintomajorcontractsforthesupplyandbuildofNewZealand’sfirstrenewableenergyBESShybrid7.Alongwiththeproposedbatteryfacility,consistingofa35MWlithiumionunitfromSAFT,anewsolarfarmisbeingexploredtoreducethecostofrenewablepowerforconsumers.ConstructionbeganinAugust2022and,oncecommissioned,thefacilitywillstoreenoughenergytomeetthedailydemandsofover2,000homesandwillbecapableofprovidingfastreservessupportfortheNorthIslandgrid.

AESChilesubmittedanEnvironmentalImpactAssessmentinlateFebruary2023foran$800MUSDhybridparkintheAntofagastaregion.Theprojectwillinvolvetheconstructionofa140MWwindfarm,252MWofsolaranda623.5MW,3,100MWhlithiumionBESS8.ThisproposedBESShybridfollowsonfromthe2019installationofa10MW,50MWhlithiumionenergystoragesystematits178MWhrun-of-the-riverhydropowerfacilityattheCordilleraComplexnearSantiago,Chile.Priortothis2019

installation,AESChile(thenAESGener)conductedananalysisonarangeofstorageoptions,finallychoosinglithiumionbatteriesbecausethetechnologyisscalingexponentiallyandwasmostfavourableintheirassessmentwhenconsideringfactorsincludingcost,safety,energydensity,charginganddischargingrates,andoveralllifecycle.9

InJanuary2023,RWE,aGermanenergyprovider,commissioned117MW,128MWhoflithiumionbatteriesacrosstwooftheirrun-of-the-riverplants.10Thesystems

atGersteinwerkinWerneandEmslandstationinLingenhaveenergycapacitiesof79MWhand49MWhrespectively.Throughtheseinstallations,RWEcanmake

additionalelectricitycapacityavailabletothegridandalsobalancetheflowofenergyfromthepowerstations,helpingtokeepthefrequencyofthepowergridstable.

NewZealandgentailer,MeridianEnergy,announcedinDecember2022thatconstructionoftheRuakākāBESSatMarsdenPointwillbegininQ12023.11Uponcompletionandcommissioning(expectedH22024),the100MW,200MWhSAFTlithiumionunitwillbehybridisedwithanew130MWsolarPVplanttoreducecosts.12

PortlandGeneralElectriccommissionedtheUnitedStates’firstfacilitytoco-locatewindandsolargeneration,coupledwithbatterystorage,inSeptember2022.13TheWheatridgeRenewableEnergyFacilityhasa300MWwindfarm,a120MWsolarfarmanda120MWhlithiumionBESS.Atmaximumoutput,thefacilitylocatednearLexington,Oregonproducesmorethanhalfofthepowerthatwasgeneratedby

Oregon’slastcoalplant(demolishedthesamemonththisfacilitybecameoperational)orenoughemissions-freeenergytopowerabout100,000homes.14

Theexampleslistedherereflectthatlithiumionbatterystoragecurrentlyexhibitsacleardominanceintherechargeablebatterymarket,accountingformorethan90%ofallBESSdeploymentsinboth2020and2021.6Thisdominancehoweverislikelyduetoavarietyoffactors,suchasmanufacturingcapability,asmanynewertechnologiescapableofcompetingwithlithiumiononatechnicalandcommercialleveldonotyethavethemanufacturingcapacitytosupplylargeMW-scaleenergystoragesystems.

7

Technologiesandmanufacturers

Ananalysishasbeenconductedonstationary,longdurationbatterysolutionssuitableforapplicationtointermittentrenewableenergysystems.

Atypical20ftcontainerisedBESSproducinggreaterthan100kWhofenergy,over12hoursorless,hasbeenusedasabaselineforthisanalysis,soonlyperceivedcompetitorstosuchaproducthavebeenincluded.

Thebatterysolutionsandmanufacturerswhichhavebeenidentifiedaredetailedinthesubsequentsection.Althoughidentifiedhere,somecompaniesassociatedwiththetechnologiesofinterestdonotprovidesufficientinformationtoallowforanykindofanalyticalcomparisonbetweenproductsandthereforehavenotbeenincludedintheanalysis.

Lithiumionbatteries

Lithiumionbatteriesutilisesolidelectrodesoftypicallycarbonandmetaloxidewithaliquidorganicelectrolytecontainingadissolvedmetalsalt.Metalionstravelbetween

Redoxflowbatteries(RFB)

InRFBs,redox(reductionandoxidation)reactionswithinelectrochemicalcellsenablesenergytobestoredinaflowingliquidelectrolytesolutionduringbatterychargeanddischarge.Batterypowerisdependentuponthesizeoftheelectrochemicalstack,whereasbatteryenergydependsuponthevolumeofelectrolyte.Thisseparation

ofpowerandenergyisakeydistinctionandadvantageofRFBswhencomparedtootherelectrochemicalstoragesystemsassystemvulnerabilitytouncontrolledenergyreleaseislimitedbysystemarchitecturetoafewpercentofthetotalenergystored.22

Vanadium(VRFB)

CellCube23

InvintyEnergySystems24

RongkePower25

VRBEnergy26

electrodesviaaporousmembrane,generatinganelectricalcurrent.15Thetwomostcommonchemistriesarelithiumironphosphate(LFP)andnickelmanganesecolbolt(NMC).ManufacturersaremovingmoretowardstheformerasdespiteNMCtypicallyhavingahigherenergydensity,LFPischeapertoproduce,hasalongerlifecycleandislesssusceptibletothermalrunaway.

Lithiumion

CATL16

CorvusEnergy17

Eaton18

Zinc-Bromide(ZnBr2

Redflow27

Zinc-Air

Zinc828

Ironflow(IFB)

ESS29

Organic(non-metal)

flow)

EVLO19

SAFT20

Tesla21

CERQ(formerlyJenaBatteries)30

8

Moltensaltbatteries

Thesebatteriesoperatewellinexcessof1000Candtheanodeandcathodearetypicallyliquidseparatedbyasaltelectrolyteorceramicmembranecapableofconductingmetalionstogenerateanelectricalcurrent.

Calcium-Antimony(CaSb)

Ambri31

Sodium-Nickel-Chloride(NaNiCl2)

FZSoNick32

SodiumSulphur(NaS)

NGKInsulators33

Othermetalbatteries

Nickel-Hydrogen(NiH2)

Nickelhydroxideandnickelalloyelectrodesinthepresenceofanalkalineelectrolytecreateanelectricalcharge,producingandconsuminghydrogengasonchargeanddischarge.

SLB(partneredwithEnerVenue)34,35

Zinc-Bromide(ZnBr2non-flow)

Typicallyaredoxflowbatterychemistry,oxidationreductionchemistryoccursbetweenzincandbromideelectrodesviaeitherasolidgeloraqueouselectrolyteallowingzincionstoflowthroughamembrane,subsequentlygeneratingcurrent.

EOSEnergyEnterprises36

Gelion37

Lead(Pb)

Interestingly,nolead-basedbatterieshavebeenidentifiedinthisparticularspace,likelyduetothechemistry’slowenergydensity,shortlifetimeand,asaresult,highpricewhencomparedtolithium-ion,thedominantchemistryintoday’sbatterymarket.

Non-metalbatteries

Conductivepolymer

Solidcarbon-graphenehybridelectrodescombinedwithaliquidelectrolyteandapermeableseparatingmembraneenableionstotravelbetweentheanodeandcathode,creatingelectricalcurrent.

PolyJoule38

9

Commercialisationconsiderations

TheprevioussectiondetailsasubsetoftheplayersinthestationaryBESSmarket,howeveranimportantdiscussionpointbeyondthechemistryishowfarthroughthecommercialisationjourneyareeachofthesechemistriesand/orcompanies.

Table1detailsanumberofkeycommercialisationmetricswhichhavebeenidentifiedacrossthemanufacturerslistedintheprevioussection.Thesemetricsincludeyearfounded,installedbatteryvolume(inMWh),numberofemployees,revenue(in$MUSD,ifany),annualproductionvolumeandtotalagreedprojectpipeline(bothinMWh).

SomeimportantthingstonoteisthatanumberofthesecompanieshavebusinessinterestsoutsideofstationaryBESS,sothenumberspresentedmaynotnecessarilybeadirectresultoftheiractivitiesrelatedtoBESS.Also,althoughtheremay

beasignificantdifferenceinsomevaluespresentedwhencomparedtoothermanufacturers,thisdoesnotnecessarilymeanthattheyareatdifferentstagesofcommercialisation,itmaysimplyreflectothermarketindicatorssuchasmarketshare(i.e.twoBESScompanieswith200and2000employeesmaybesimilarlycommercialisedwithinthemarket.Athirdcompanywith20employeesislikelysignificantlylesscommercialised).Nevertheless,themetricspresentedprovidereasonableproxiestoindicateacompany’sstageofcommercialisation.

Similarlytotheprevioussection,althoughidentified,somecompaniesassociatedwiththetechnologiesofinterestdonotprovidesufficientcommercialinformationinthepublicdomaintoallowforanykindofanalyticalcomparisonbetweenproductsandthereforehavenotbeenincluded.Inthemajorityofcases,eachcompanypresenteddoesnotdetaileachandeverymetricofinterestinthepublicdomain,howevertheydoprovideenoughtomakeaneducatedcomparison.

Estimatesofcommercialisationstagemaybemappedagainstthe11-pointtechnologyreadinesslevel(TRL)scalepresentedbytheInternationalEnergyAgency

(seeFigure1).39

Figure1:TechnologyReadinessLevel(IEA)

10

TherangewhichisrelevanttothemanufacturersincludedisestimatedtobeTRL7toTRL11,pre-commercialdemonstrationtomatureinmarket:

TRL11:Matureinmarket(verylargeproductvolumesmanufactured,deliveredanddemonstratedinfieldi.e.>1GWh,revenuelikely>$50MUSD)

CATL

CorvusEnergy

NGKInsulators

RongkePower

SAFT

Tesla

TRL10:Earlyadoptioninmarket(largeproductvolumesmanufactured,deliveredanddemonstratedinfieldi.e.100MWh-1GWh,revenuelikely$10M-$50MUSD)

CellCube

EOSEnergyEnterprises

FZSoNick(acquiredbyHitachiChemical-$5.8BUSDrevenuein2021)

TRL9:Commercialoperation(significantproductvolumesmanufactured,deliveredanddemonstratedinfieldi.e.10MWh-100MWh,revenuelikely$1M-$10MUSD)

InvintyEnergySystems

VRBEnergy

TRL8:Commercialdemonstration(smallproductvolumesunderdemonstrationwithsignificantgrowthinmanufacturingi.e.1MWh-10MWh,revenuelikely$100K-$1MUSD)

Ambri

EnerVenue(globallybrandedasSLB-$28.1BUSDrevenuein2022)

ESS

Redflow

TRL7:Pre-commercialdemonstration(onlysmallproductvolumesmanufactured,deliveredanddemonstratedinfield,minimalorpre-revenue)

Gelion

PolyJoule

Zinc8

SometakeawaysfromthisTRLmappinginclude:

Oldertechnologies,withfewerrecentdevelopments,suchaslithiumion,vanadiumflowandmoltensodiumbatteriesarehigheruptheTRLscale.

Ofthenewertechnologies,EOSEnergyEnterprises(non-flowzinc-bromide)appearstohaveasignificantcommercialadvantageoveritscompetitors,generatingover

$10MUSDinrevenuein2022withatleasta1.8GWhprojectpipeline.

CompanieslowerontheTRLscale(TRL7-8)willhaveasignificantnumberofcommercialisationbarriers(forexample,manufacturingandsupplychain)tocrossbeforegainingearlyadoptioninthemarket.Thiswillbesignificantlymore

challengingforindependentcompanieswhencomparedto,forexample,EnerVenue(nickel-hydrogen),whohavebackingfromglobal,multibilliondollarengineeringcompany,Schlumberger(nowmarketedasSLB).

11

Table1:Commercialmetricsofbatterymanufacturers

Chemistry

Manufacturer

Founded

Dispatchedvolume

Employees

Revenue*

Productionvolume

Pipelinevolume

Year

MWh

#

$MUSD/year

MWh/year

MWh

14,36440

(Additional140,000peryearunderconstruction)

-

61

(2020)41

>1,000

-

780

(58MforBESS)42

170,000

(Totalplannedproduction

-

81,462

40,000(Megapackonly)

-

Approx.

CATL

2011

-

33,000

CorvusEnergy

2009

400

192

SAFT

1918

-

>4,000

Tesla

2003

>17,000

128,000

170,000

Lithiumion

by2025)

(10,000non-automotive)43

CellCube

2008

42.9

61

4.09(2019)44

-

-

InvintyEnergySystems

2020

28.0

171

3.245

-

66.3

Vanadium RongkePower

2008

992

-

-

300

-

VRBEnergy

2007

>30

65

-

-

>500

EOSEnergyStorage

2008

640

250

18.4

800

>1,800

Gelion

2015

Pilotscale#

50

0.4346

2

-

Zinc-based Redflow

2005

>2

62

1.1247

80

-

by2024)48

by2024)

FZSoNick49

2011

400

130

32.2(2019)50

100

-

NGKInsulators51

1919

4,100

20,100

4041

1,000

-

Zinc8 2011 Pilotscale 44 0(Goaltogenerate

1(Ambitionof60MWh -

Sodium-based

Ironflow ESS 2011 - 183 0.8752 750 >12,00053

endof2023)

Calcium-Antimony Ambri 2010 Commercialpilot# 122 - 200(200,000cellsby

2024;31,000by2027)

Nickel-Hydrogen EnerVenue(SLB) 2020 Commercialpilot 110 - 60(2,200plannedby

>1,20054

>5,00055

Organic PolyJoule 2011 Pilotscale 11 - >1(10000cells) <1

* RevenuedatahasbeengainedfromGoogleFinanceQ32021toQ32022,unlessspecifiedotherwise.Unknowndatanotavailableinthepublicdomainhasbeenindicatedwithadash.

# Pilotscalereferstoinstallationslessthan1MWh.Commercialpilotreferstoinstallationsbetween1–2MWh. 12

Analysis

Thedatapresentedinthissectioniseitherpubliclyavailableorhasbeengainedthroughdirectconsultationwiththemanufacturer.Forthosetechnologieswithmultipleplayers(i.e.lithiumionandvanadiumflow),batterydatahasbeenaggregatedandaveragevaluesarepresented.Theraw,non-aggregateddataisprovidedintablesintheAppendix.

Technicalcomparison

Effectiveenergydensity

Theenergydensityofbatteriesistypicallypresentedinwatt-hourspergram(Wh/gorkWh/kg).Thisprovidesareasonablecomparisonwhentheuseableenergyoutputandweightofthebatteryisknown,however,inthecaseofcontainerisedenergystoragesystems,thereissignificantvoidagewithinthecontainerforthepurposeofmaintenance,airflowetc.Thismeansthatonlyaneffectiveenergydensitycanbedeterminedusingtheuseableenergyoutputandtheweightofthecontainerisedsystem.

Thisapproachisalsochallengingassomemanufacturersdonotprovidetheweightofthecontainerisedsystem,however,allprovidetheareafootprintofthesystemforagivenenergyoutput,enablinganeffectiveenergydensityofkWh/m2tobepresentedinFigure2.Notethatanadvantageofcontainerisedsystemsisthattheymaybestacked,however,forthepurposeofthiscomparison,thefootprintdensityhasonlybeenpresentedforasystemwithasinglecontainer.

Lithiumionhasthehighestaverageenergydensityofthetechnologiescomparedatapproximately145kWh/m2.Thisobservationisnotsurprisingaslithiumionisknownforhavingaparticularlyhighenergydensitywhencomparedtootherrenewablebatterytechnologies.56Thisisthenfollowedbymolten-saltbatteries(calcium-antimony,sodium-nickel-chloride,sodium-sulphur),whicharealsoknownforhighenergydensities,57atapproximately80kWh/m2.Zinc-brominetechnology,inbothflowandnon-flowbatteryconfigurations,hasaneffectiveenergydensityof30kWh/m2.Thisdensityissimilartonickel-hydrogen(25kWh/m2),butmuchhigherthanotherflowchemistries(Vanadium,10kWh/m2;Iron,15kWh/m2).Duetoitsearlystageofdevelopment,theconductivepolymerbatteryhasalowenergydensityof15kWh/m2,similartoverylargeredoxflowsystems.

Figure2:Effectiveenergydensityofbatterytechnologies

150

Effectiveenergydensity(kWh/m2)

100

50

0

13

Batterycycling

Thelifetimeofabatteryismeasuredbythetotalnumberofcharge/dischargecyclesabatterycanachievebefore:

Thebatterycannolongerholdacharge;or

Significantenergycapacitydegradationhasoccurred.

Ofthebatterytechnologiesinvestigated(seeFigure3),nickel-hydrogeniscapableofachievingatleast30,000cyclesinitslifetime.Thisisfollowedbyvanadiumandironredoxflowbatterieswithlifetimesofapproximately20,000cycles.Allother

technologieshaveatheoreticallifetimelessthan12,000cycles,withthemajoritylessthan7,000cycles.

Forthisresearch,itisofparticularinteresttounderstandwhichbatterytechnologyissuitableformultiplecyclesonagivenday.Somebatterymanufacturersstatethattheirtechnologyiscapableofanunlimitednumberofdailycyclesdespitestatingaverylonglifetimeinyears(whichdoesnotalignwiththetheoreticalcyclelifetime).Asaresult,somebatterytechnologiescapableofmultiplecyclingperdayareonlyabletodosobysignificantlydecreasingtheyearsofuseablebatterylife.

Toconductafaircomparison,theannualcyclesofagiventechnologyhasbeendeterminedbydividingthetheoreticalcyclelifeofthebatterybythedesignlifeti