能源存储：跟踪技术将电力行业转型

Energystorage:Trackingthetechnologiesthatwilltransformthepowersector

Contents

Executivesummary 3

Introduction 4

Acrossthevaluechain 5

Energystorageeconomics–Aviewthroughtoday’slens 7

Storagecosts 7

Storagebenefits 8

Benefit/costratios 9

Bulkenergyandancillaryservices 9

Transmission&distribution,renewableintegration 11

Consumers 11

Technologicalinnovations–Alookintowhatthefuturemightbring 13

Disruptivetechnologies 14

Regulatoryconsiderations–Aneedforreform 16

Implications-Acalltoactionforstakeholders 17

AppendixA:Characteristicsofenergystoragetechnologies 19

AppendixB:Abstractandacronyms 20

Abstract 20

Listofacronyms 21

Energystorage:Trackingthetechnologiesthatwilltransformthepowersector

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Executivesummary

Theworld’spopulationisexpectedtogrowbytwobillionpeopleby2050andglobalenergydemandisexpected

toroughlydoubleduringthesameperiod.1Concurrently,thepowersectorisonthebrinkofamajortransformationasmorestakeholderslookintothepossibilityofmovingawayfromtraditionalfossil-energy-basedcentralizedpowersystemstowardsthepotentialofrenewable-energy-baseddistributedgeneration.However,thepenetration

ofrenewabletechnologieshasbeenhamperedbytheircosts-whichareimproving-andtheirintermittencyandvariability,whichreducesavailabilityandinducesgridinstability.Therefore,theutilityindustryshouldconsiderovercomingthesechallengesifrenewablesaretoaccountformorethanjustanegligibleportionoftheglobalenergyportfolio.

Atpresent,theemergingconsensus2isthatenergystorageisthepivotaltechnologythatwillreshapetheenergysectorbyenablingwidespreadadoptionandgrid-integrationofsolarandwindrenewables.Inthesamewaythattransmissionlinesaffectwhereelectricityis

consumed,energystorageinfluenceswhenitisconsumed.Thus,commercialandresidentialconsumersareprovidedtheflexibilitytobecomepowergeneratorsandtoselectthepricepointatwhichtheywillconsumeelectricity,

andutilitiesandthegridgaintheagilitytoaccommodateproducersandconsumerswithdisparatetemporalbehaviors.Regulatorsarebeginningtorecognizethevalueofstorageandarecreatingpoliciesthatfurtherimprovethebusinesscaseforadoption.

Recentadvancementsinmaterialsandmanufacturinghaveimprovedtheeconomicsofstorage.Traditionalstoragetechnologiessuchaspumpedhydroandcompressed

airhavelimitedapplicabilityandarelosingmarketsharetoemergingbatterytechnologies,manyofwhichareleveragingexperienceinthetransportationandconsumer

electronicssectorstocompeteinthepowersector.Inadditiontothevarioustechnologiesthataregainingcommercialtraction,therearenumerousdisruptivetechnologiesunderdevelopmentthatofferthepotentialofstep-changeimprovementsinperformanceorcost.Themultitudeofcurrentandemergingstorageoptionscanmakeitdifficulttodecidewhichtechnologytoadoptandwhen.Toassistdecisionmakers,thispaperoffersapreliminaryfeasibilityassessmentthatevaluatesthebusinesscaseandbenefit/costratioofstoragetechnologieswithincertaincustomerclasses.

Theimpactofenergystorageisfar-reaching,asnotonlydoesitaddresstheissuesthathavelimitedrenewableenergy’spenetration,itfundamentallyaltersthelongstandingrelationshipbetweenutilitiesandtheircustomers.Thedisruptivepotentialofstorageisunlikeotherenergytechnologiesinthatitpervasivelyextendsacrossthevaluechaininawaythatstakeholderswillimpactandbeimpactedbyitsadoption.Toremainacasualobserveristoriskdisruption,asevennon-powercompanies(e.g.,Tesla,Daimler)areenteringthemarket.Ifthedecisionistoadopt,thereisaneedtotranslatethetechnicalparametersofstorageintofinancialimplicationstounderstandthebottom-lineimpact.Ifthedecision

istonotadopt,thereisstillaneedtorespecttheinterdependenciesoftheecosystemandevaluatepotentialimpactstothebusinessandoperatingmodel.Eitherway,thepotentialofstoragerequiresthatstakeholdersdeveloprobuststrategiesthatdecreasetheriskandincrease

theopportunity.

1 “2014EnergyandClimateOutlook,”MIT,2014.

2 AtarecentU.S.DOE“townhall”meeting(February9,2015),U.S.SecretaryofEnergyErnestMonizwasaskedtonamea“BlueSky”technologythathasthepotentialtorevolutionizetheenergysector.Hisresponse:“DistributedEnergyStorage.”Similarly,arecentsurveyofelectricutilitiesrevealedthatenergystorageisthetopemergingtechnologythatwarrantsinvestment.(2015StateoftheElectricityUtilitySurveyResults)

Introduction

Effectiveuseoftheworld’senergyresourcesdependsonhavingtheflexibilitytoselectivelyprovideenergyatchoicetimes,whichisthefundamentalconceptbehindenergystoragetechnologies(Table1)--theconversionofenergyfromonestatetoanother(i.e.,kinetictopotentialorviceversa)sothatitcanbeharnessedatalaterdateorusedinanalternativemanner.3Thetemporalflexibilityofferedbystoragecanhelpthepowersectoraccommodateperiodsofsupply/demandmismatch(frombrieffluctuationstoextendedoutages)andtherebyimprovethereliabilityofthegrid,thequalityof

itselectricity,andtheprofitabilityofinfrastructureinvestments.4Fromasocietalperspective,storagecanaddresstheemergingenergydemandofruralareas,empowerconsumerstomanagetheirenergyconsumption,andstrengthenthevaluepropositionofrenewableenergyinstallations.

Thepotentialbenefitsofenergystoragehavecaughttheattentionofmanystakeholdersinthepowersector,leadingtosignificantgrowth.Installationsassociatedwithgridandancillaryservicesareprojectedtogrowbyroughly40xoverthenext10years(538.4MWin2014to20,800MWin20245)duetodriverssuchasrenewableintegration,energydemand,assetretirements,andtechnologicalinnovation.Energystorageamongendusers(commercialandresidential)isexpectedtoseeevengreatergrowthof70x(172MWin2014to12,147MWin2024)due,inlargepart,tosmartgridtechnology.6Therangeofstoragetechnologiesthatwillfueltheseexponentialgrowthratesspansthestatesofenergyandtheprinciplesofphysics.

Table1.Energystoragetechnologies7

Kineticenergy

Potentialenergy

Thermaltechnologies

Electricaltechnologies

Mechanicaltechnologies

Electrochemicaltechnologies

Chemicaltechnologies

Hotwater

Supercapacitors

Flywheels

Pumpedhydro

Lithiumion

Hydrogen

Moltensalt

Superconductingmagneticenergy

Compressedairenergy

Leadacid

Syntheticnaturalgas

Phasechangematerial

Redoxflow

Sodiumsulfur

3 “Energycannotbecreatedordestroyedbutcanbeconvertedfromoneformtoanother.”TheLawofConservationofEnergy.

4 “ElectricalEnergyStorage,”InternationalElectrotechnicalCommissionWhitePaper,2011.

5 “EnergyStoragefortheGrid&AncillaryServices,”Navigant,2014.

6 “Community,Residential,andCommercialEnergyStorage,”NavigantResearch2015.

7 “ElectricityStorageFactBook,”SBCEnergyInstitute,September2013.

Acrossthevaluechain

Thestabilityofthepowergriddependsonvariousactorsworkinginconcerttomaintainabalancebetweenelectricitysupplyanddemand.Traditionally,electricityassetsarecategorizedbasedontheirfunction;i.e.,generation,transmission,ordistribution.Storagesystemsdifferinthattheyhavetheabilitytobalancesupplyanddemandacrossthesegmentsthatcomprisethevaluechain.Thenewcontrolpointsofferedbystoragesystemsenableoperatorstoselectivelyrespondtofluctuationsingridinputsandoutputs.Suchfunctionalityisessentialtorealizingthevisionof“smartcities”whereproducersandconsumersareequallyinformedandequippedtorespondtomarketdynamicsinrealtime.However,manyelectricalgridswerenotoriginallydesignedtoaccommodateassetsthatcanbothgenerateandconsumeelectricity.Theimplicationsoftwo-waypowerflowandtheroleofenergystoragewithinamodernelectricityecosystemhavebeenstudiedbymanyinstitutions.PotentialapplicationsandappropriatestoragetechnologieswithineachsegmentofthevaluechainareillustratedinFigure1.

Figure1.Energystorageacrossthepowersector8

8 “EnergyStoragefortheElectricityGrid:BenefitsandMarketPotentialAssessmentGuide:AStudyfortheDOEEnergyStorageSystemsProgram,”SANDIA,December2010.

Thedisparitiesbetweenelectricitysupplyanddemandcanspantimescalesfrommillisecondstomonths.Asingletechnology,however,isincapableofoperatingacrossallpotentialtimescales.Sometechnologiesprovidepowerquicklywhileotherscandeliveritoveranextendedperiod.Whiletheneedforstoragespansthevaluechainandincludesmultipletimescales,manygrid-relatedapplicationsclusternearthemulti-hourdischargerequirement.Inaddition,thevaluableapplicationsalsotendtorequiretechnologiesthathavemulti-hourdischargedurations,asshowninFigure2.

Figure2.Energystorageapplicationsandcorrespondingvalueforvariousdischargedurations9

$70

Potentialvalueofstorageapplicationsfordischargedurationcategories

($Billion)

ApplicationCategories

ElectricEnergyTime-Shift

ElectricSupplyCapacity

BulkEnergy

Area ElectricSupplyRegulation ReserveCapacity

VoltageSupport

AncillaryServices

TransmissionSupport

ElectricServiceReliability

ElectricServicePowerQuality

LoadFollowing

T&DUpgradeDeferralTransmissionCongestionRelief

TOUEnergyCostManagement

DemandChargeManagement

RenewableEnergyTime-shiftRenewablesCapacityFirming

WindIntegration

Transmission&Distribution

Consumers

RenewablesIntegration

SubstationOnsitePower

$60

$50

$40

$30

$20

$10

$0

1second

1minute

1hour

2hours

3hours

4hours

5hours

6hours

7hours

8hours

9hours

10+hours

Whilethedischargedurationofatechnologyisimportantandoftengovernswhetheritshouldbeconsideredforaparticularapplication,therearenumerousotherchemicalandphysicalcharacteristicsthatcontributetothefinalselectiondecision,suchas:powerrating,storageduration,cycling,self-discharge,energydensity,powerdensity,efficiency,responsetime(AppendixA).Whiletheseattributesmaydeterminewhichstoragetechnologymaybepreferredforacertainapplication,thefundamentalfactorthatdeterminesthefeasibilityofimplementationiswhetherthebenefitsofferedbyatechnologyexceeditscost.Abusinesscaseforstorageadoptionemergesonlywhentheeconomicsarefavorableenoughtosignifyapotentialreturnoninvestment.

9 Eyer,Jim;GarthCorey“EnergyStoragefortheElectricityGrid:BenefitsandMarketPotentialAssessmentGuide–AStudyfortheDOEEnergyStorageSystemsProgram,”SandiaNationalLaboratories,February2010.

Energystorageeconomics–Aviewthroughtoday’slens

Whenevaluatingthecostsandbenefitsofenergystorageforasingleapplication,storagetechnologiesareoftenprohibitivelyexpensivecomparedtothealternatives.Forexample,whenoffsettingtheintermittencyofrenewableenergysuchassolarandwind,energystorageisoftencomparedtocombustionturbines,whichcanalsoflattenthepowergenerationprofileofrenewableenergysystems.Currently,PHSandCAES,bothheavilycapital-intensive,arethetwotechnologiesthatarecompetitivewithcombustionturbineswhentheoperationalparametersassociatedwithrenewableintegrationareconsidered.10Otherapplicationshavesimilarcompetitivelandscapeswherestoragetechnologiesmustunseatincumbenttechnologies.Tojustifyadoption,eitherthecostsofenergystoragetechnologiesneedreducedthroughscaleandtechnologicalinnovationorthebenefitsneedincreasedthroughstackingofservices.

Storagecosts

Whetheranenergystoragetechnologyisaviableoptionforaparticularapplicationdependsonitscostperunitofpowerorenergy.Energystoragetechnologiestypicallyexcelatprovidingeitherpowerorenergy,butnotboth.Thecostsassociatedwiththeprovisionofpowerorenergyarenotnecessarilypositivelycorrelatedand,infact,flywheelsandCAES

aretwoexamplesinwhichthecostofenergyandpowerarenegativelycorrelated.11Figure3showshowthecostperunitofenergyandpowervariesforeachofthestoragetechnologiesinquestion.

WhileFigure3representscurrenttechnologycostranges,companiesareactivelyengaginginR&Dtoreducethecostofimplementingstoragesystems.Thepaceatwhichadvancementsaremadeandcostsreducedvariesfrom

technologytotechnology.14Asonemightexpect,someofthemorematuretechnologieshavecostcurvesthatdonotdeclineassignificantlyasothers.Forexample,PHSisalreadymatureandwillexperiencesmallcostdecreasesbasedonmoreefficientpowerstationequipmentandbetterconstructiontechniques.Conversely,thecostofhydrogenstoragesystemscoulddeclinerapidlyastechnologicaladvancementsinbothproductionandelectrificationareachieved.BatterytechnologiesareprojectedtoexperiencesimilarcostreductionsexceptinthecaseofNaSandafewoftheRedoxFlowbatteries,whichmayexperiencemorerapidcostreductions.

Figure3.Theoreticalcapitalcostofenergystoragetechnologies12,13

Power

Energy

5,5

4,4

3,3

2,2

1,1

0

2,2

4,4 6,6

8,8 11

SMES

Supercapacitor

PHSCAES

Flywheels

NaS

PbAcidLi-ion

FlowBatteries

Hydrogen

thousand€/kw

thousand$/kw

5 4 3 2

thousand€/kwh

thousand$/kwh

1 0 2 4 6 8 10

10“ElectricityEnergyStorageTechnologyOptions–AWhitePaperPrimeronApplications,Costs,andBenefits,”EPRI,December2010.

11“ElectricStorageFactbook,”SBCEnergyInstitute,September2013.

12EPRI,December2010;“EconomicAnalysisofLarge-ScaleHydrogenStorageforRenewableUtilityApplications,”SANDIA,SchoenungS.,August2011.

13Exchangerateasof2ndApril2015,1$=1,1€Thisconversionrateisusedthroughoutthepaper.

14Thecostprojectionsforthestoragetechnologiesusedduringtheanalysisarebasedonbusinesscasesconductedbyvariousresearchinstitutions,vendorinputsandexpertinterviews.SupercapacitorsandSMESwereapproximatedbyalearningcurveapproachwhichstatesthateverydoublingoftheirunitscomesalongwithacertaincostreduction.(footnote:thereductiondependsontheassumedlearningrateandwasretrievedfromIRENA,April2014,“ElectricityStorage–TechnologyBrief”).

Storagebenefits

Thepotentialbenefitsofferedbystoragetechnologiesaremonetizedbyorganizationsthroughincreasedrevenuesorreducedcosts–bothbudgetedcapitalandoperatingexpenses.Inaddition,storageoffersotherlessquantifiablebenefits,suchasintegratingrenewableenergyandreducinggreenhousegasemissions.15Whilethese“societalbenefits”16areimportant,itisdifficulttorationalizeaninvestmentbasedsolelyonexternalities.

Instead,implementationofenergystoragetechnologiesdependsontheextenttowhichatechnologycanprovideavaluableserviceatacostthatisattractivecomparedtothealternatives.Storagetechnologiesdifferfromothersystemsacrossthegridinthattheycanefficientlyprovidemultipleservices,therebyimprovingtheireconomicviability.Whilethebenefit/costratioforasingleapplicationmaynotbefavorable,anamalgamationofapplicationsprovidesmultiplerevenuestreamsforthesameinvestment.Theeffectivenessofthisconceptof“stackingservices”dependsontheextenttowhichsynergiesexistamongtheapplicationsbeingstacked(Figure4).

Thesiloednatureofthepowersectorpresentsachallengetostackingservices.Thatis,thecurrentregulatoryenvironmentdoesnotcreateameansforeachbeneficiarytocompensatethetechnology.TheDirectoroftheEnergyStorageAssociation,MattRoberts,suggeststhat“ifthevaluethatenergystorageoffersacrossthevaluechainissummeditexceedsthecostofthestoragesystem,

yetmarketsthatallowasystemownertocaptureallthevaluestreamsascompensationarestillevolving.”18Asaresult,servicesaretypicallystackedwithineachcustomersegment.

Figure4.Complementaryenergystorageapplications17

Bulk Ancillary T&D Consumers RenewableEnergyServices Integration

WindGenerationGridIntegration

RenewablesCapacityFirming

RenewablesEnergyTimeshift

ElectricServicePowerQuality

ElectricServiceReliability

DemandChargeManagement

Time-of-UseEnergyCostManagement

T&DUpgradeDeferral

TransmissionCongestionRelief

VoltageSupport1

ElectricSupplyReserveCapacity

AreaRegulation

ElectricSupplyCapacity

ElectricEnergyTimeshift

ElectricEnergyTimeshiftElectricSupplyCapacityAreaRegulation

ElectricSupplyReserveCapacityVoltageSupport

TransmissionCongestionReliefT&DUpgradeDeferral

Time-of-UseEnergyCostManagement

DemandChargeManagementElectricServiceReliabilityElectricServicePowerQualityRenewablesEnergyTimeshiftRenewablesCapacityFirming

WindGenerationGridIntegration

EnergyStorageApplications

Key

ExcellentSynergies

GoodSynergies

FairSynergies

PoorSynergies

Incompatible

BulkEnergy

EnergyStorageApplications

AncillaryServices

T&D

Consumers

RenewableIntegration

15“DecisionAdoptingEnergyStorageProcurementFrameworkandDesignProgram”OrderinstitutingRulemakingPursuanttoAssemblyBill2514toConsidertheAdoptionofProcurementtargetsforViableandCost-EffectiveEnergyStorageSystems,PublicUtilitiesCommissionoftheStateofCalifornia,October21,2013.

16“EnergyStoragefortheElectricityGrid:BenefitsandMarketPotentialAssessmentGuide,”Sandia,February2012.

17Eyer,Jim;GarthCorey“EnergyStoragefortheElectricityGrid:BenefitsandMarketPotentialAssessmentGuide–AStudyfortheDOEEnergyStorageSystemsProgram,”SandiaNationalLaboratories,February2010.

18DeloitteInterviewwithMattRoberts,Director,EnergyStorageAssociation.

Benefit/costratios

Becausethecostsandbenefitsofenergystorageareincontinualflux,potentialusersareoftenunawareofwhichtechnologiestoconsiderduringadoptiondecisions.Inprinciple,technologiesthatshouldbeonacustomer’sradararethosewhosebenefitsexceedtheircosts.Thisistheinitialsteptodeterminethetechnologiesthatarefeasiblebeforedown-selectingatechnologythatisoptimal.ThechartsinFigures5,6,719assistindeterminingthefeasibilityofstoragetechnologiesbydepictingwhenspecifictechnologiesarelikelytowarrantconsiderationwithinacertaincustomerclass.Inotherwords,thechartsillustratehowthepotentialsuiteofstoragesolutionsmightevolveoverthenext15yearsforspecificcustomers.Thechartsprovideageneralindicationoftheyearinwhichastoragetechnologybecomesfeasiblecomparedtoitspeersandshouldattracttheattentionofcustomers.Inaddition,asatechnologygravitatestowardthecenteroftheradarcharts,itoffersagreaterbenefitrelativetoitscostcomparedtothetechnologiesattheperipheryofthecircle,buttheultimateselectionwilldependonwhetheratechnologyalignstotheadoptioncriteria,whichvariesamongcustomerclasses.

19KeyinformationrelatedtoFigures5,6,7:

Thecurvesrepresentaveragevalues,whichisimportantbecausetherangesassociatedwithbothcostandbenefitvarywildlydependingoninnovationandmarketforces.

Thegraphsindicatetheyearinwhichatechnologywithanaveragecostissuitableforanapplicationwithanaveragevalue.Companieswithlow-costtechnologiesormarketswithhighvalueapplicationscanshifttheresults.

Regulatoryfactorssuchasgovernmentincentivesintheformofrebatesartificiallychangethebenefit/costratioofatechnology,therebyaffectingtheresultsinthecharts.

Theanalysisconsidersthefeasibilityoftechnologieswithincertaincustomerclasses,andinthiswayimposesbordersbetweensegments.Thebordersareconsistentwiththesiloednatureoftheglobalpowersector,yetprogressiveregulatorychangesareenablingstoragetechnologiestodeliverbenefitsacrossthevaluechain,whichimproveseconomicsandimpactsthecharts.

Thescalesofeachcustomerclassdiffer,whichmakesitdifficulttomakecomparisons.Forexample,a“High”benefit/costratioisnotequivalentacrossallclasses.Thescalewithineachclassisrelativetothetechnologiesandapplicationsassociatedwiththatclass.

Certaintechnologiesareindevelopmentalphasesandarenotimmediatelyreadyforcommercialization.Suchtechnologiesappearontheradarsduringthetimeframeinwhichcommercialuseisanticipated.

Eachgraphconsidersthevalueandcostofenergy-andpower-basedapplications.Thelinecapturedwithineachradarchartrepresentsthegreateroftheopportunitiespresentedbyenergyandpower.

Sources

“ElectricityEnergyStorageTechnologyOptions,”awhitepaperprimeronApplications,Costs,andBenefits,ElectricPowerResearchInstitute,December2010.

Eyer,Jim;GarthCorey“EnergyStoragefortheElectricityGrid:BenefitsandMarketPotentialAssessmentGuide–AStudyfortheDOEEnergyStorageSystemsProgram,”SandiaNationalLaboratories,February2010.

“GridEnergyStorage,”U.S.DepartmentofEnergy,December2013.

Bulkenergyandancillaryservices

Figure5.Energystorageradarchartsforbulkenergyandancillaryservices

Bulkenergy Ancillaryservices

Bulkenergy

Bulkenergystorageinvolvesshiftingtheenergyproductionofcurrentgeneratorssuchthatutilitiescan“buylow”and“sellhigh”withindailyorseasonalmarkets.Inaddition,bulkenergystoragesystemscanstave-offtheneedforthegenerationcapacityofferedbypeakingplants.20Currently,PHSandCAESarethefeasibleoptionsforbulkenergystorage;however,bothdependontheavailabilityofsuitabletopologyorgeology,whichisoftenlimited.Inaddition,financialchallengesemergewhenrationalizingthelargecapitalexpendituresthatarerequiredtoscalePHSandCAESsystemstomaximizeefficiency,especiallyinthecaseofCAESplants,whichlackoperationaldatatomitigatetheriskofa40yearinvestment,eventhoughtheyseemtobethemostviabletechnology,asreflectedinFigure5.21ConventionalbatteriessuchasNaSandPb-Acidemergeasviableoptionsthatarelikelybetter-suitedforsmall-ormedium-sizeapplicationsduetotheirscalingandlifecyclelimitations.SimilartechnicalconstraintsoccurforLi-ionsystems,whichhavemuchhigherefficienciesandpowerdensities,andarepushedbytheautomotivesectortobecomecost-effective,makingthem

muchmoreappealingthanotherconventionalbatterytypes.Flowbatteriesmayemergeandevensupplantexistingtechnologiesastheyachievecommercialdeployment.Sincebulkstoragerequiresrelativelylargeamountsofenergywithfrequentdischargesthroughouttheyear,replacementandO&Mcostsaresignificantfactors.Amongtheviabletechnologies,however,therearetrade-offsbetweenreplacementandO&Mcostsbecausemechanicalsystemsoftenrequiremoremaintenanceduringtheirlifetime,whileelectrochemicalsystemsaremoreexpensivetoreplace.Finally,hydrogenstoragewouldbewell-suitedforbulkapplicationsinthefuture,asthehydrogencouldpotentiallybeusedinconventionalgas-fueledpowerplants.Currently,however,thisopportunityisconstrainedbythetradeoffbetweeninfrastructuremodificationsrequiredtoaccommodatehighblendingpercentagesofhydrogen.22

20Inadditiontostorageandcombustionturbines,capacityresourcesincludedemandresponse,energyefficiency,anddistributedgeneration.

21InterviewwithDirkUweSauer,Professor,ISEARWTHAachen,ElectrochemicalConversionandStorage.

22Hydrogencouldbeusedinacurrentnaturalgasinfrastructuregivencertainmixing(blending)percentagesaremet.Ifthethresholdsarenotrespectedcostlyinfrastructuremodificationshavetobeimplemented.Methanationcouldoverridethisissuebuthasevenhighertotalcostasadditionalconversionstepsarerequired.

Ancillaryservices

Energystoragetechnologiesareuniquelysuitedtoprovideancillaryservices,whicharecurrentlybeingperformedbygeneratorsthatarenotdesignedforthispurpose.Moreover,theprovisionofancillaryservicesimpairstheprimaryfunctionoftraditionalpowergenerationassetsbyrequiringthattheyoperateatsuboptimallevelsinordertorespondtochangesinthegrid.Energystorage,ontheotherhand,offersresponsivetechnologiesthatcanaccommodatetheneedforfrequentbutrelativelyshortdischarges.Currently,batterytechnologiessuchasLi-ionandPb-acidarethemosteconomicallyviablestorageoptions,withflywheelsonthecuspoffeasibility.23(Flywheelsprovideanadvantageinboththeirextendedlifetimeandminimalmaintenancecosts.)SupercapacitorsandSMESarecurrentlyimmaturebutofferthepotentialforextremelyhighefficienciesandlonglifetimesuponachievingcommercialization.

Transmission&distributionandrenewableintegration

Figure6.Energystorageradarchartsfortransmission&distributionandrenewableintegration

Transmission&distribution Renewableintegration

Transmission&distribution

Energystoragecanimprovethestabilityandperformanceoftransmissionassetsaswellasdefertheneedforadditionalinfrastructurebyalleviatingtrafficcongestionalongtransmissionlinesduringpeaktimes.ConventionalbatterytechnologiesarecurrentlybeingusedwithintheT&DspacewithresearchersatSandiaNationalLaboratoriesestimatingthat“100,000batterystoragesystems(areinstalled)atutilitysubstationsintheU.S.”24Inaddition,above-groundCAESappearstobeaviableoptionforT&Dapplicationsininstanceswherespaceislessofanissue.WithintheT&Dsegmenttherearealsoapplicationsthatrequiresub-secondresponses(e.g.,transmissionsupport)thatwillmakeSMESandsupercapacitorsdesirabletechnologies.Goingforward,flowbatterieswillpresentanintriguingoptionbasedonthepotentialbenefit/costratiooncetheyachievecommercialmaturity.

Renewableintegration

Storagetechnologiesareessentialforrenewableenergysystemstorealizetheirfullpotential.Renewablepowerisoftenproducedatinopportunetimes,resultinginanundesirablepriceorpossiblecurtailment.Storagecanimprovetheeconomicsofrenewablesystems,yettheappropriatestoragetechno