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MichaelMilligan,Ph.D.(Consultant)NationalWindTechnologyCenterNationalRenewableEnergyLaboratoryGolden,ColoradoUSA10FAQ’s(FrequentlyAskedQuestions)AboutWindEnergy…andAnswersKansasStateLegislatureFebruary7,200810FAQ’saboutWind1)HowmuchwindiscurrentlyinstalledintheUS?2)Whatarethebenefitsofwindenergytothepowersystem?3)Howcanwind’svariabilitybeincorporatedintopowersystemoperations4)Doeswindplantoutputstart/stopsuddenly?5)Canwindbepredicted?10FAQ’saboutWind6)Canthepowersystembereliablyoperatedwithwindenergy?7)Doeswindneedbackuporstorage?8)Istherealimittohowmuchwindcanbeaccommodatedonthegrid?9)Canwindpowerplantsbecontrolled?10)Canwindenergymakeeffectiveuseoftransmissionlines?11)BonusQuestion:Howcanmorewindbeaccommodatedonthegrid?1)HowmuchwindiscurrentlyinstalledintheUS?1)HowmuchwindiscurrentlyinstalledintheUS?Colorado/Xcel:Approx20%windpenetration(windcapacity/systempeak)Iowa:Approx16%windpenetration(windcapacity/systempeak)MWInstalledEnd2006Installed2007End2007TotalEU-12419263675TotalEU-1547,6518,29155,860TotalEU-2748,0698,55456,5351b)HowmuchwindiscurrentlyinstalledinEurope?2)Whatarethebenefitsofwindenergytothepowersystem?•Windenergydisplaces–Fuel–Emissions;carbon•Windprovidesahedgeagainstrisingfuelprices(naturalgas,coal)•WindisanenergysourcewithlimitedcapacitycontributionÆothergenerationisalsorequired•Windcanbecost-competitivewithotherformsofgenerationandmayreduceelectricitycost3)Howcanwind’svariabilitybeincorporatedintopowersystemoperations•Electricload(withoutwind)variesconsiderably•Powersystemoperatingpracticesarebuiltaroundmeetingthevariableloadwithdispatchablegeneratorsthatcanchangetheiroutputlevel•Windaddsmorevariabilitytothesystem•Existingoperatingpracticecanbeused/expandeduponwithwind14x10312108Load(MW)60x103402005-minutePeriods10005000-500-10005-minutechanges6,600Hoursof5-minuteElectricLoad4)Canwindpowerstartandstopsuddenly?•Largewindfarmshavemanyindividualwindturbines•Theturbinesarespreadovermanymilesanddonotexperiencethesamewindatthesametime•TXeventFeb24,2007:dropof1,500MWover2hoursissimilartobehaviorofloadTotalWIND050010001500200025002/24/079:002/24/079:282/24/079:572/24/0710:262/24/0710:552/24/0711:242/24/0711:522/24/0712:212/24/0712:50TotalWIND2Hours)Canwindbepredicted?•Windforecastsarederivedfromweatherpredictionmodels•Windforecastaccuracyisimproving•SeveralwindforecastingfirmsinU.S.Courtesy:WindLogics,Inc.St.Paul,MN6)Canthepowersystembereliablyoperatedwithwindenergy?•Yes–additionalflexiblegeneration(operatingreserves)maybenecessaryathigherwindpenetrations•Thisadditionaloperatingreservehasamodestcost,typicallyabout10%ofthecostofthewindenergyitself•Graphshowsthislevelofoperatingreserve(blue)isarelativelysmall,varyingfractionofwindgeneration7)Doeswindneedbackuporstorage?•Increasedoperatingreservesmaybenecessary,butnotdedicatedbackup•Althoughnewstoragehasvalue,itmaynotbecosteffective•Thereistypicallyalreadystorageonthesystem–Naturalgasinthepipelineorstoragefacility–Controllablehydro•ArecentstudybyXcelEnergyinColoradofound–existingpumpedstorageprovided$1.30/MWhoffsettowindintegrationcost–EnlargingexistinggasstoragefacilitywaseconomicatlargewindpenetrationWindPenetration10%15%$/MWHGasImpactNoStorageBenefits$2.17$2.52$/MWHGasImpactWithStorageBenefits$1.26$1.458)Istherealimittohowmuchwindcanbeaccommodatedonthegrid?•CurrentstudiesintheU.S.haveanalyzedupto25%ofallelectricenergyfromwind•Basedonworkdonesofar,thequestionisnotwhetherwindcanbeaccomodatedathighpenetrations,thequestionishowandatwhatcostofintegration8)Istherealimittohowmuchwindcanbeaccommodatedonthegrid?•RecentInternationalEnergyAgencyReport:Designandoperationofpowersystemswithlargeamountsofwindpower)Istherealimittohowmuchwindcanbeaccommodatedonthegrid?LennartSöder,KTH,Sweden,presentedatUWIG,Oct23-25,2006Denmarkhasaccesstolargeexportmarkets9)Canwindpowerplantsbecontrolled?•Newlow-voltageride-through(LVRT)gridcodesintheU.S.willhelpwindturbinescontributetogridreliability•Windturbinescanbecontrolledbutnottotheextentthatconventionalgenerationcanbecontrolled–Rampratelimits–Up-regulation(operatebelowpotentialsothatwindoutputcanbeincreasedifneeded)–Curtailment,ifnecessaryandeconomic,atlow-load/high-windconditions10)Canwindenergymakeeffectiveuseoftransmissionlines?•Conditional-firmtransmissiontariff(recentFERCruling)•Winddoesnotneedtransmissionallofthetime•Mosttransmissionpathshavesomeopencapacitymostofthetime•Addingwindcanresultinmoreefficientusageofexistingtransmission11Bonus)Howcanmorewindbeaccommodatedonthegrid?•Utilitybalancingareascancombineorcooperate–largeelectricitymarkets(example:Denmark/Europe)11Bonus)Howcanmorewindbeaccommodatedonthegrid?•Utilitybalancingareascancombineorcooperate–largeelectricitymarkets•Example:Ramping,orchangingoutputofgeneratorsthatcanbeeliminatedwithlargerbalancingareas-1000-50005001000Ramp(MW/hr)53045298529252865280HourofYear(oneday)-400-2000200400-400-2000200400ExcessRampingandRampPenalty(MW/hr)Operatingseparatebalancingareascausesextrarampingco