The Impacts of High V2G Participation in a 100% Renewable Åland Energy System

19 Pages·2017·3.31 MB·English

energies
Article
The Impacts of High V2G Participation in a 100%
Renewable Åland Energy System
MichaelChild1,* ID,AlexanderNordling2andChristianBreyer1 ID
1 SchoolofEnergySystems,LappeenrantaUniversityofTechnology,53850Lappeenranta,Finland;
Christian.Breyer@lut.fi
2 FacultyofScienceandEngineering,ÅboAkademi,20500Turku,Finland;alnordli@abo.fi
* Correspondence:Michael.Child@lut.fi;Tel.:[phone]
(cid:1)(cid:2)(cid:3)(cid:1)(cid:4)(cid:5)(cid:6)(cid:7)(cid:8)(cid:1)
(cid:1)(cid:2)(cid:3)(cid:4)(cid:5)(cid:6)(cid:7)
Received:27July2018;Accepted:22August2018;Published:23August2018
Abstract: A 100% renewable energy (RE) scenario featuring high participation in vehicle-to-grid
(V2G) services was developed for the Åland islands for 2030 using the EnergyPLAN modelling
tool. Hourlydatawasanalysedtodeterminetherolesofvariousenergystoragesolutions,notably
V2G connections that extended into electric boat batteries. Two weeks of interest (max/min RE)
generationwerestudiedindetailtodeterminetherolesofenergystoragesolutions. Participationin
V2GconnectionsfacilitatedhighsharesofvariableREonadailyandweeklybasis. InaSustainable
Mobilityscenario,highparticipationinV2G(2750MWh )resultedinlessgasstorage(1200MWh ),
e th
electrolyser capacity (6.1 MW ), methanation capacity (3.9 MWh ), and offshore wind power
e gas
capacity(55MW )thanotherscenariosthatfeaturedlowerV2Gparticipation. Consequently,total
e
annualisedcostswerelower(225M€/a). TheinfluenceofV2Gconnectionsonseasonalstorageisan
interestingresultforarelativelycold,northerngeographicarea. Akeypointisthatstoredelectricity
neednotonlybeconsideredasstorageforfutureusebythegrid,butV2Gbatteriescanprovidea
bufferbetweengenerationofintermittentREanditsend-use. DirectconsumptionofintermittentRE
furtherreducestheneedforstorageandgenerationcapacities.
Keywords: energy system modelling; storage solutions; 100% renewable energy; Åland;
vehicle-to-grid;power-to-gas
1. Introduction
Driven by efforts to eliminate dependency on imported fossil fuels and increase overall
sustainability,islandnationsandregionsofarchipelagomayencounterhighersharesofrenewable
energyintheirenergysystemsmuchfasterthantheircontinentalcounterparts. Indoingso,these
regionswillbethefirsttodetermineoptimallevelsofvariousenergystoragesolutionsneededas
highersharesofintermittentrenewableenergy(RE)resourcesareassimilated[1]. Furthermore,island
groupsrepresentinterestingcasestudiesoftransitionsastheirenergysystemsarerelativelycompact,
homogeneous,andlesscomplex. Forthesereasons,suchregionsmayofferpotentialblueprintsor
test-bedsforenergysystemtransitionstowardsustainabilitythatwillhappenonawiderscaleinthe
future[2].
InordertoencourageatransitionawayfromfossilfuelsandtowardsustainabilityontheAegean
ArchipelagoIslands,Kadellisetal.[3]suggestthatislandenergysystemsbasedonREandappropriate
EnergyStorageSolutions(ESS)canaidinachievingbothenvironmentalgoalsandresultinfinancial
advantages. Further,Hlusiaketal.[4]highlighthowutilisingthestoragepotentialofbatteryelectric
vehicles(BEV)cancontributetoislandgridstabilitywhilenotimposingsignificantrestrictionson
electric vehicle range. The potential coupling of RE generation and electrified mobility, therefore,
seemspromising.
Energies2018,11,2206;doi:10.3390/en11092206 www.mdpi.com/journal/energies
Energies2018,11,2206 2of19
Overthepasttwodecades,therehasbeenconsiderableresearchinterestintheideathatelectrified
vehicles could offer benefits to both the transport and power sectors when a sector coupling is
achieved [5,6]. In essence, the concept of vehicle-to-grid (V2G) involves the bidirectional flow of
electricitybetweenpowergridsandvariousformsoftransportinamannerthatismutuallybeneficial.
It includes the idea that electrified forms of transport will have batteries that can offer flexibility
to energy systems, thereby improving efficiency and profitability of power grids, enabling higher
sharesofrenewableenergy,reducinggreenhousegas(GHG)emissionsforthetransportsector,and
offeringpotentialincomeforvehicleowners[6]. Thisflexibilitywillcomeintheformofso-called
smart charging or enabling vehicles to charge when electricity is abundant or when demands are
otherwiselowandfromdischargingbatteriesbacktothegridattimeswhendemandexceedssupply.
Thisflexibilitybecomesmorerelevantinenergysystemsthatfeaturehighsharesofvariablerenewable
energy,suchassolarphotovoltaics(PV)andwindturbines. Zhangetal.[7]showhowsmartcharging
ofBEVscanpositivelyaffectpowersystemsthroughvalley-fillingandpeakshavingofloadprofiles.
Further,severalstudieshavedemonstratedhowbroaderuseofelectricvehiclescanbeaneffective
meansofmanagingvariablerenewableenergyresources[8,9]. Further,smartchargingneednotplace
unnecessaryburdensonpowersystemsifproperlymanaged[10,11],andthelifetimesoflithium-ion
vehiclebatteriescouldbeextendedthroughoptimalV2Gstrategies[12].
TheÅlandIslandsareanarchipelagosituatedintheGulfofBothniaoftheBalticSeabetween
Finland and Sweden. Åland is composed of 6757 islands, 60 of which are populated by 28,916
inhabitants[13]. ÅlandisanautonomousregionofFinlandyetalsohasstrongtrade,cultural,and
linguistictieswithSweden. Currently, theGovernmentofÅlandaimstoidentifyactionsthatcan
betakentoachievesustainablegrowthgoalsby2051[14]. Thesegoalsaredefinedbysustainability
principlesoutlinedwithinaFrameworkforStrategicSustainableDevelopment[15]. Inturn,theÅland
SmartEnergyPlatformhasemergedasagroupdedicatedtoenvisioninganddemonstratinghowa
fullysustainableenergysystemcouldbedevelopedfortheregion,onethatenablesthedeliveryof
reliable,costcompetitive,andqualityenergyservicestoenduserswhicharefreeoffossilfuels[16].
Previous work for the whole of Finland suggested that a combination of 100% RE and an
appropriate mix of energy storage solutions (ESS) could provide the basis of a sustainable and
affordable energy system for the entire country by 2050 [17]. In addition, Child and Breyer [18]
showedhowstoragetechnologiescouldplaysupporthighsharesofsolarPVandwindpowerathigh
northernlatitudes. However,asthegeographyandenergysystemofÅlandrepresentuniquecontexts
withintheFinnishsystem,amorespecificandlocalanalysiswasrequired. Inaddition,followingthe
ideathatenergysystemtransitiontowardshighsharesofrenewablescouldbeachievedonislands
andregionsofarchipelagosoonerthancontinents,anacceleratedtimeframeforÅlandwasneeded
forinvestigation. Thetransitiontowardsasustainableislandenergysystemwillrequireavarietyof
complementaryenergygenerationandstoragesolutions. Pastresearch[19]indicatesthatelectricity
storagewillberequiredafter50%ofelectricityisgeneratedfromvariableRE,andthatseasonalstorage
willberequiredafterthatlevelexceeds80%[20,21]. Currently,avarietyofflexibilitymeasuresare
availablewhichsupporthighlevelsofvariableRE[22].
For these reasons, several sustainable energy scenarios were investigated for Åland [23].
In total, six scenarios were developed and compared to a Business as Usual scenario for the year
2030. The Sustainable Mobility—High Electrification (2030 SM El) scenario emerged as a highly
cost-competitiveoptionforÅland. Thisscenariofeaturedahighlyelectrifiedtransportsector,which
includedbothlandandwater-basedformsofmobility. Costsavingswereobservedashighcapacities
of BEV battery storage and V2G connections resulted in lower requirements of seasonal storage,
syntheticfuelproduction,andoffshorewindinstalledcapacity. Asreportedin[23],theeffectofhigh
V2Gparticipationresultinginlessneedforaformofseasonalstorage,inthiscasePower-to-Gas(PtG),
hasneverbeforebeenreported,andrepresentsanoveltythatmeritsfurtherinvestigation. Another
noveltyofthescenarioisthatitextendedV2Gparticipationbeyondautomobilesandfeaturedthe
use of batteries of electrified watercraft. The significance of such batteries is that they often stay
Energies2018,11,2206 3of19
unusedfortransportpurposesduringmuchofthewinterseason,offeringasourceofflexibilitynot
previouslyconsidered.
ThepurposeofthiscurrentstudyistoexplaintherolesofESSinmoredetailintheÅlandcontext.
Includedinthisanalysisaregasstorage,PtGtechnologies,ThermalEnergyStorage(TES),stationary
batteries, andV2Gconnections. Severalkeyquestionswillbeansweredtoaidindeterminingthe
significanceofESSinthisfutureenergysystem.
• TowhatextentarewindandsolarPVpoweruseddirectly?
• Howmuchdostoragetechnologiescontributetoannualenergydemand?
• WhatistheamountofstoredenergyarisingfromV2Gconnections?
• WhatistheamountofstoredenergyarisingfromTES?
• Whatistheamountofstoredenergyarisingfromgasstorage?
2. MaterialsandMethods
TheEnergyPLANtoolisanadvancedenergysystemanalysiscomputermodel[24], andwas
employedtosimulatea100%REscenariowithahighlyelectrifiedmobilitysectorforÅlandin2030.
The chosen scenario was one of nine developed in the study by Child et al. [23], and was chosen
becauseitwasthemostcostcompetitiveofthescenariosstudied. Afulldescriptionofthetoolused,
scenarioparameters,andthemaininputstoEnergyPLANforthe2030SMElscenariocanbefound
in[23]aswellasinitsdetailedsupplementarymaterials. Asummarytableofmaininputsisprovided
inTable1. Inaddition,anannualenergyflowdiagramisprovidedinFigure1.
The EnergyPLAN modelling tool was designed at Aalborg University in 1999 and has seen
continued development since that time. Version 12.4 was used for this study and was the most
recent version available at the moment the study began. The model has been formally described
as a simulation model, which compares options or scenarios that can differ between key input
parameters, such as costs, emission factors, energy generation technologies, storage options, and
manyothers[25]. Themodelhastypicallybeenusedtosimulatenationalenergysystemsbutcanalso
beusedforsmallerregions.Simulationmodelsdifferinnaturetooptimisationmodels,whichgenerally
establishanoptimalstrategybasedpurelyonquantitativeanalysesaccordingtoonecriteria. Instead,
simulationmodelsallowseveralcriteriatobecomparedthroughthecreationofuniquescenarios[25].
The strengths and weaknesses of scenarios can then be compared and discussed. A comparative
discussionandoverviewofthemanymodellingtoolsavailablecanbefoundin[26].
As stated above, this current study examines one scenario in greater detail to determine the
roles ofvarious formsofESS, andtoelaborate onthe findingin[23]that V2Gparticipationcould
notonlyaidinenablinghighersharesofREbutcouldprecludetheneedforotherformsofstorage,
most notably seasonal energy storage. The 2030 SM El scenario under analysis featured a special
focus on the mobility sector, whereby electrification of passenger vehicles was assumed to reach
100%. Inaddition,anextra350MWh ofV2Gbatterycapacitywasaddedtorepresentacapacityof
e
marinetransportbatteries. Thisvaluewasdeemedsufficienttorepresentthemorethan7000marine
watercraft,fromrecreationalboatstolargeRorovesselsandferries,thatarefoundinÅland[13]and
thelevelofelectrificationthatmightbepossible. However,completeelectrificationoftransportwas
notassumed. Forthisreason,31GWhofbiodieseland9GWhofsyntheticdieselwereproducedto
satisfytheremainingtransportdemand. Inthisscenario,itwasalsoassumedthatV2Gandflexible
chargingparticipationwouldbelimitedto75%ofvehicles,withtheremainderofelectricvehicles
beingchargedduringtheeveninghours.
Energies2018,11,2206 4of19
Energies 2018, 11, x 4 of 19

Figure 1. Simplified annual energy flows (in GWh) for the 2030 SM El scenario. Data source: [23].
Figure1.Simplifiedannualenergyflows(inGWh)forthe2030SMElscenario.Datasource:[23].
From the EnergyPLAN outputs, data was collected and processed to show the workings of the
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Table 1. Main input parameters for the 2030 SM El scenario.
Parameter Unit Value
RE generation capacity
Wind onshore MWe 70
Wind offshore MWe 55
Solar PV—Rooftop MWe 28
Solar PV—Ground mounted MWe 55
Thermal plant capacity
Condensing PP MWe 10
CHP MWe 20
Energies2018,11,2206 5of19
Table1.Maininputparametersforthe2030SMElscenario.
Parameter Unit Value
REgenerationcapacity
Windonshore MWe 70
Windoffshore MWe 55
SolarPV—Rooftop MWe 28
SolarPV—Groundmounted MWe 55
Thermalplantcapacity
CondensingPP MWe 10
CHP MWe 20
DHBoilers MWth 15.3
DHHeatpumps MWe 5
Storagecapacities
Heatstorage MWhth 1100
V2Gelectricstorage MWhe 2750
Methanestorage MWhth 1200
PtGcapacities
Electrolysis MWe 6.1
Methanation MWhgas 3.9
Annualelectricitydemand GWhe 451.54
Annualdistrictheatingdemand GWhth 135
Annualindividualheatingtotal GWhth 240.05
Biomass GWhth 50.05
Heatpump GWhth 150
Electricity GWhth 40
Annualfuelfortransport Mkm 415
Biodiesel GWhth 30.73
Syntheticdiesel GWhth 9.27
Electricity(Dumpcharge) GWhe 17.8
Electricity(Smartcharge) GWhe 51.2
Toexploreabroadercontext,severalthehourlyprofileswereexaminedforthedurationofyear.
Theseincludedannualelectricitysupplyandconsumptionbycategoryaswellasthestateofchargeof
electric,DH,andgasstorage. Hourlyend-userdemanddataforÅlandwerebasedonrealvaluesfrom
2014obtainedfromKraftnätÅland,theÅlandtransmissionsystemoperator. Adistrictheatdemand
andwindenergygenerationprofileswereprovidedbyalocalenergycompany(MariehamnsEnergi).
Eachprofilewasbasedonrealdatafrom2014. SolarPVproductiondatawasderivedfrom2005data
originatingfrom[27,28],assuitable,realproductiondatawasnotavailablefor2014. Alloriginaldata
isavailablein[23].
TocalculatethevariouscontributionsofESSoptionsemployedinthisstudy,totalenergydemand
was calculated based on electric and thermal energy end-user consumption, which represent to
EnergyPLANinputs. Intotal,797GWhofenergywasconsumedfortheyear,representedby422GWh
ofelectrictyand375GWhofheat. AnumberofannualandhourlyoutputsfromEnergyPLANwere
available,includingdischargevaluesfromV2G,stationarybattery,andthermalenergystorage. Atthe
sametime,valuesfortheannualelectricityandheatthatcamefromstoredgaswerecalculatedusing
theequationslistedin[18].
The direct usage of solar PV and wind energy was calculated as the sum of the categories of
supply(onshorewind+offshorewind+solarPV)dividedbythesumofelectricitysupplyfromall
sources. TocalculatetheamountofwindandsolarPVpowerthatwasconsumeddirectly,thisratio
wasmultipliedbytheleveloftotalelectricity. Theratiowasalsomultipliedbythesumofpowergoing
toelectricitystorage(V2Gbatteries+stationarybatteries+PtGelectrolysers)tocalculatetheamount
ofwindandsolarbeingtransferredtostorage. TheshareofdirectlyconsumedsolarPVandwind
energyistheratioofsolarPVandwindenergywhichwasdirectlyconsumedtotheconsumptionof
totalelectricitybyallsources. Thesecalculationsweremadeforallhoursandthenaddedtodetermine
annualtotals. Furthercompilation,tabulationandanalysisoftheresultswereperformed.
Energies2018,11,2206 6of19
3. Results
Annual results are shown in Figures 2–6 for electricity supply, electricity demand, electricity
storage,thermalstorageandgridgasstorageintheenergysystem. Calculationresultsareshownin
Figure7andTable2. HourlyresultsarecompiledforthetwostudyperiodsinFigures8–13forthe
electricity,districtheatingandgascomponentsoftheenergyscenario.
ElectricityconsumptionandsupplyareshowninFigures2and3. GenerationfromsolarPVis
moreconcentratedduringthelatespringtoearlyautumnmonthsandisseentobevariableatanhourly
resolution. Windenergy, especiallyoffshorewind, islessvariable, andshowsmoreconcentration
during the period of late autumn to early spring. This represents a somewhat natural seasonal
complementofthetworesources,whichreducesthevariabilityofREinmoregeneralterms. Atthe
sametime,CombinedHeatandPower(CHP)plantsareavailabletomaintainthebalancebetween
supplyandconsumption. ThebalancingofferedbyV2Gandflexibledemandsalsocontributesto
systemstabilitythroughpeakshavingandvalley-fillingduringtimesofextremehighsandlows. Some
curtailmentofwindandsolarisnecessarywhengenerationfromREishighest,butthisislimitedto
lessthan3.5%oftotalgeneration.
Figures4–6demonstratethenatureofdifferenttypesofstorage. Ingeneral,storageofgasand
thermal energy appears to follow a typical pattern of charging during the period of late spring to
autumnasexcesselectricitypredominantlyfromsolarPVisconvertedtootherenergycarriersthatcan
beutilisedduringthecoldermonthsoftheyearwhendemandsforenergyarehigher. Inaddition,itis
seenthatelectricvehiclebatteriesgenerallyshowdailyandmulti-daycharginganddischargingcycles.
However,thereisalongerperiodduringthewintermonths(roughlyhours400–1200,corresponding
tolateJanuarytomid-February)whentheuseofbatteriesissignificant,andtheyareamajorsource
ofpowerinthesystem. Atthesametime,thermalandgasstoragelevelsareatannuallowlevels,
suggestingthatthelargecapacityofV2Gbatteriesalsohavearoleasastoragetechnologythatcan
contributetobalancingoveralongertimeperiod. Thisisalsosupportedbytheobservationin[23]
thatloweroverallcapacitiesofPtGtechnologieswereneededcomparedtootherscenarios. Discharge
ofV2Gbatteriestotals78GWhandrepresents17%ofannualelectricitygeneration.
Table2.Summaryofcalculationsrelatedtostoragedischargeandconsumption.
Parameter Unit Value
Consumptionofelectricity GWhe 452
Consumptionofheat GWhth 375
Consumptionoftotalenergy GWh 827
DischargefromV2G GWhe 78
Electricityfromstoredgas GWhe 0
Heatfromstoredgas GWhth 0
DHstoragedischarge GWhth 7
DirectconsumptionofSolarPVandwind GWhe 273
as%oftotalsolarPVandwindproduction 67%
as%oftotalelectricityproduction 53%
as%offinalelectricityconsumption 60%
SolarPVandwindtoelectricstorage GWhe 115
as%oftotalsolarPVandwindproduction 29%
SolarPVandwindtocurtailment GWhe 20
as%oftotalsolarPVandwindproduction 4%
Totalstoragedischarge GWh 85
as%oftotalconsumption 10%
Electricitystoragedischarge GWhe 78
as%ofelectricityconsumption 17%
V2Gdischarge GWhe 78
as%ofallelectricitystoragedischarge 100%
Thermalstoragedischarge GWhth 7
as%ofheatconsumption 2%
Gasstoragedischarge GWhgas 4
as%ofgridgasconsumption 31%
Energies2018,11,2206 7of19
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Energies 2018, 11, x 7 of 19
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150
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Consumption Flexible demand DH heat pumps PtG Methane
Consumption Flexible demand DH heat pumps PtG Methane
Home heat pumps Home electric heating V2G Curtailment or export
Home heat pumps Home electric heating V2G Curtailment or export

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200
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Electricity supply
150
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Onshore wind Offshore wind Solar PV CHP Power plants V2G Import
Onshore wind Offshore wind Solar PV CHP Power plants V2G Import

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also seasonally complemented by wind power to a lesser extent.
alsoseasonallycomplementedbywindpowertoalesserextent.
Energies2018,11,2206 8of19
Energies 2018, 11, x 8 of 19
Energies 2018, 11, x 8 of 19
Electricity storage
3000
Electricity storage
3000
2500
2500
2000
h
W 2000
h1500
MW1500
M1000
1000
500
500
0
0 18529630741852963074185296307418529630741852963
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1357913468024689135791346802467913579124680246
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V2G Batteries

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pFrigouvirde i4n.g H floeuxirblyil ietlye cotnri ac dstaoirlyag aen lde vmeulsl t(iM-dWayh lee)v feolr. Hthieg hy ecaarp. aMciatixeism ouf mV 2sGto rleadg et oc arepdaucicteyd i sn 2ee7d50 f oMr Wsehase.o Vna2lG g absa tstteorriaegs eh. ad a significant role in the energy system,
providingflexibilityonadailyandmulti-daylevel.HighcapacitiesofV2Gledtoreducedneedforseasonalgasstorage.
providing flexibility on a daily and multi-day level. High capacities of V2G led to reduced need for seasonal gas storage.
1100
Thermal energy storage
11010000
Thermal energy storage
1900000
890000
780000
h
W 670000
h
MW 560000
450000
M
340000
230000
120000
1000
0 18529630741852963074185296307418529630741852963
8764321987543109865421087653219875432098654210
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876431211191817252423212029383635343241404847465553525159586765646362707978767584828180
1357913468024689135St7or9age1 c3apa4ci6ty 802467913579124680246
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Storage capacity

Figure 5. Hourly thermal storage levels (MWhth) for the year. Maximum storage capacity is 1100 MWhth. Thermal storage has a strong coupling with heat pump use
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in the district heating system, thereby allowing excess electricity to be stored as heat in long-term storage.
inthedistrictheatingsystem,therebyallowingexcesselectricitytobestoredasheatinlong-termstorage.
Energies2018,11,2206 9of19
Energies 2018, 11, x 9 of 19
Energies 2018, 11, x 9 of 19
Gas storage
1200
Gas storage
1200
1000
1000
800
h 800
W
h 600
W
M 600
M 400
400
200
200
0
0
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1357913468024689135791346802467913579124680246
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Storage capacity
Storage capacity

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highergenerationofwindpower.GasstoragebecomeslowerduringthesummermonthswhensolarPVgenerationisatitsmaximum.
higher generation of wind power. Gas storage becomes lower during the summer months when solar PV generation is at its maximum.
100
100
80
80
60
60
%
% 40
40
20
20
0
0
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Hourly share of solar PV, onshore wind and offshore wind used directly

Figure 7. Amount of solar PV, onshore wind and offshore wind that is directly consumed (%). Values are in the range of 0–85% with a mean of 73%. As a result of
Figure 7. Amount of solar PV, onshore wind and offshore wind that is directly consumed (%). Values are in the range of 0–85% with a mean of 73%. As a result of
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high direct utilization of RE and extensive use of V2G storage, there was noticeably less need for gas and thermal storage.
directutilizationofREandextensiveuseofV2Gstorage,therewasnoticeablylessneedforgasandthermalstorage.
Energies2018,11,2206 10of19
Energies 2018, 11, x 10 of 19
200
Electricity supply: March 26-April 1
150
W
100
M
50
0
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Onshore wind Offshore wind Solar PV CHP Power plants V2G Import

200
Electricity consumption: March 26-April 1
150
W
100
M
50
0
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Consumption Flexible demand DH heat pumps PtG Methane
Home heat pumps Home electric heating V2G Curtailment or export

Electricity storage: March 26-April 1
2500
2000
h 1500
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M
1000
500
0
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V2G Batteries

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