Wind Power Myths Debunked - Utility Variable Generation ...

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Wind Power Myths Debunked - Utility Variable Generation ...

Wind Energy and the Power System:An Interactive FAQJanuary 28, 2010Moderator: Michael GogginManager of Transmission Policy, AWEAPresenter: Dr. Michael Milligan,Principal Analyst in the Transmissionand Grid Integration Group, NREL


Wind Energy and the PowerSystem: Wind Power MythsDebunked, from IEEE Powerand Energy Magazine, Nov/Dec2010Webinar Jan 2010Michael MilliganLead AuthorNational Renewable Energy LaboratoryGolden, Colorado USANREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC


National Renewable Energy LaboratoryInnovation for Our Energy Future


Authors•Michael Milligan, NREL•Kevin Porter, ExeterAssociates•Edgar DeMeo, RenewableEnergy Consulting Services•Paul Denholm, NREL•Hannele Holttinen, VTTTechnical Research Center,Finland and chair of IEATask 25: Large-ScaleIntegration•Brendan Kirby, Consultant,NREL•Nicholas Miller, GE Energy•Andrew Mills, LawrenceBerkeley Laboratory•Mark O’Malley, UniversityCollege, Dublin, Ireland•Matthew Schuerger, EnergySystems Consulting•Lennart Soder, RoyalInstitute of Technology,Stockholm,SwedenNational Renewable Energy LaboratoryInnovation for Our Energy Future


Thanks to Organizations Sponsoring this Webinar• National Renewable Energy Laboratory• IEEE Wind Power Coordinating Committee• Utility Wind Integration Group (www.uwig.org)• American Wind Energy Association (special thanksfor managing the logistics)National Renewable Energy LaboratoryInnovation for Our Energy Future


Large-Scale Wind Integration Studies• Sponsored by US DOE, managed by NREL• Eastern Wind Integration and Transmission Study,released Jan 20, 2010• Western Wind and Solar Integration Study, to bereleased in Mar 2010• Evidence from these studies is not included in thearticle or webinar, but supports the conclusionshereinNational Renewable Energy LaboratoryInnovation for Our Energy Future


Power System Basics• Portfolio of different type ofgenerators are managed sothat the sum of all output =load at each moment• Base-load generators run atconstant output• Intermediate/cycling unitspick up daily load swings• Peaking units are seldomrun but provide peakcapacity when neededSystem Load (MW)seconds to minutesRegulationTime (hour of day)0 4 8 12 16 20 24tens of minutes to hoursLoadFollowingDaysUnitCommitmentdaySchedulingNational Renewable Energy LaboratoryInnovation for Our Energy Future


National Renewable Energy LaboratoryInnovation for Our Energy Future


Power System Basics (cont)• Extra generation – reserves – available in caseof generator or transmission outage:Contingency reserves• Some generators can change output and areused to manage variability in load (demand)• The demand for power is not known withcertainty so may influence the level of reservesfor managing this uncertainty• Wind increases the level of variability anduncertainty that the power system operatormust manageNational Renewable Energy LaboratoryInnovation for Our Energy Future


Load-less-wind = net load16x10 3141210MW864LoadNet LoadWind2012001220124012601280Hours130013201340National Renewable Energy LaboratoryInnovation for Our Energy Future


Wind Power Myths Debunked1) Can grid operators deal with thecontinually changing output of windgeneration?2) Does wind have capacity credit?3) Does the wind stop blowingeverywhere at the same time?4) To what extent can wind power bepredicted?5) Isn’t it very expensive to integratewind?National Renewable Energy LaboratoryInnovation for Our Energy Future


Wind Power Myths Debunked6) Doesn’t wind power need new transmission,and won’t that make wind expensive?7) Does wind power need back-up generation?Isn’t more fossil fuel burned with wind thanwithout, due to back-up requirements?8) Does wind need storage?9) Isn’t all the existing flexibility already usedup?10) Is wind power is as good as coal or nucleareven though the capacity factor of wind poweris so much less?11) Is there a limit to how much wind can beaccommodated by the grid?National Renewable Energy LaboratoryInnovation for Our Energy Future


Where did the questions come from?• International experience with windintegration• Common questionsNational Renewable Energy LaboratoryInnovation for Our Energy Future


Where do the Answers Come From?• Extensive analysis– Power system simulations that mimic real-timeoperations– Statistical analysis of wind and load data– Experience operating power systems with wind• International Energy Agency Task 25 Report:Design and operation of power systems withlarge amounts of wind power State of the artreport.– http://www.vtt.fi/inf/pdf/tiedotteet/2009/T2493.pdf• Utility Wind Integration Group www.uwig.org• NREL Systems Integration– http://www.nrel.gov/wind/systemsintegration/– http://www.nrel.gov/publicationsNational Renewable Energy LaboratoryInnovation for Our Energy Future


1) Can grid operators deal with the continuallychanging output of wind generation?West Denmark January 10-16, 20054,0003,5003,000LoadNet load2,500MW2,0001,5001,00050001 25 49 73 97 121 145hourNational Renewable Energy LaboratoryInnovation for Our Energy Future


1) Can grid operators deal with the continuallychanging output of wind generation?West Denmark January 10-16, 2005400035003000WindLoad2500MW20001500100050001 25 49 73 97 121 145hourNational Renewable Energy LaboratoryInnovation for Our Energy Future


1) Can grid operators deal with the continuallychanging output of wind generation?45.00%40.38%40.00%35.00%)(% 30.00%ntiotrae 25.00%nePrew 20.00%oPdin15.00%W7th May8th May9th May10th May10.00%5.00%0.00%HourNational Renewable Energy LaboratoryInnovation for Our Energy Future


1) Can grid operators deal with the continuallychanging output of wind generation?Output Normalized to Mean1.61.41.21.00.80.61.61.41.21.00.80.61.61.41.21.00.80.615 Turbines Stdev = 1.21, Stdev/Mean = .184200 Turbines Stdev = 14.89, Stdev/Mean = .126215 Turbines Stdev = 15.63, Stdev/Mean = .125051015Seconds202530x10 3(Approximately 8 hours)National Renewable Energy LaboratoryInnovation for Our Energy Future


2) Does wind have capacity credit?Loss of Load Expectation (days/year)0.120.110.100.090.080.070.06Original Reliability CurveReliability Curve after Adding New GenerationTarget Reliability LevelEach generator added to the systemhelps increase the load that can besupplied at all reliability levelsG iG i+1G i+2Added GeneratorsG n-2CombinedResourcesWithWind8.08.59.09.5Load (GW)10.010.5National Renewable Energy LaboratoryInnovation for Our Energy Future


2) Does wind have capacity credit?Wind is primarily anenergy resource,but can make asmall contributionto planningreservesDepends on timingof wind energyvs. loadcharacteristicsRange in the U.S.approximately5%-40% of ratedcapacityPeak Period MethodsISO New EnglandOctober-MayISO New EnglandJune-SeptemberPNMJulyIdaho PowerJulyNY ISODecember -FebruaryNY ISOJune - AugustPJMJune - AugustCPUCMay -September12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PMNational Renewable Energy LaboratoryInnovation for Our Energy Future


3) How often does the wind stop blowingeverywhere at the same time?www.osei.noaa.govNational Renewable Energy LaboratoryInnovation for Our Energy Future


4) To what extent can wind power be predicted?• Easier to predict wind for short time steps• Errors ~5-7% MAE based on rated wind capacity• More difficult day-ahead• Errors ~20% MAE• Relative forecast errors are reduced for largegeographic footprints (energy & meteo)National Renewable Energy LaboratoryInnovation for Our Energy Future


5) Isn’t it very expensive to integrate wind?DateStudyWindCapacityPenetration(%)RegulationCost($/MWh)LoadFollowingCost($/MWh)UnitCommitmentCost($/MWh)GasSupplyCost($/MWh)Tot Oper.CostImpact($/MWh)May ‘03Xcel-UWIG3.500.411.44na1.85Sep ‘04Xcel-MNDOC150.23na4.37na4.60June ‘06CA RPS40.45*tracenana0.45Feb ‘07GE/Pier/CAIAP200-0.69tracena***na0-0.69***June ‘03We Energies41.120.090.69na1.90June ‘03We Energies291.020.151.75na2.922005PacifiCorp2001.63.0na4.60April ‘06Xcel-PSCo100.20na2.261.263.72April ‘06Xcel-PSCo150.20na3.321.454.97Dec ‘06MN 20%31**4.41**Jul ‘07APS14.80.372.651.06na4.08* 3-year average; total is non-market cost** highest integration cost of 3 years; 30.7% capacity penetration corresponding to 25% energy penetration;24.7% capacity penetration at 20% energy penetration*** found $4.37/MWh reduction in UC cost when wind forecasting is used in UC decisionNational Renewable Energy LaboratoryInnovation for Our Energy Future


5) Isn’t it very expensive to integrate wind?• Primary cost comes from additional operatingreserve and impacts on non-wind generationoperations• Additional reserve is not constant throughout theyear: it depends on what the wind and load aredoing• Wind’s variability combines with the variability ofload• Small balancing areas will normally find it moredifficult and costly to integrate wind than largerbalancing areas• Sub-hourly energy markets can help managevariabilityNational Renewable Energy LaboratoryInnovation for Our Energy Future


6) Doesn’t wind power need new transmission, andwon’t that make wind expensive?• Transmission is needed formost new generationsources• Joint Coordinated SystemPlan found benefit/cost ratioof 1.7/1 for transmission thatwould support a 20% windenergy penetration.Transmission was 2% of thewholesale energy cost.• Consumers often will benefitby lower energy costs• Transmission build-out canreduce the need for newgenerationNational Renewable Energy LaboratoryInnovation for Our Energy Future


7) Does wind power need back-up generation? Isn’t morefossil fuel burned with wind than without, due to back-uprequirements?• Total load must be met by acombination of generation• Individual generators are notbacked up: but reserves areprovided on a system basis• Wind will displacegeneration, freeing up thatgeneration to providereserves (if economic)• Generators that changedispatch as a result of windmay have reducedefficiency, but total fuel burnand emissions will decreaseSystem Load (MW)seconds to minutesRegulationTime (hour of day)0 4 8 12 16 20 24tens of minutes to hoursLoadFollowingDaysUnitCommitmentdaySchedulingNational Renewable Energy LaboratoryInnovation for Our Energy Future


8) Does wind need storage?• Storage is always useful, butmay not be economic• Detailed simulation of powersystem operation find no needfor storage up to 30%penetration• Experience with more than31,000 MW of installed windin the US shows no need forstorage• However: storage is verybeneficial with and withoutwind• Depends on cost-benefitLarge-scale studies (EWITS andWWSIS) do not find a need forstorage at wind penetrations upto 30% of all electricity, althoughstorage does have valueNational Renewable Energy LaboratoryInnovation for Our Energy Future


8) Does wind need storage?National Renewable Energy LaboratoryValue of storage with current resource mix.Innovation for Our Energy Future


National Renewable Energy LaboratoryValue of storage with new flexible resource mix.Innovation for Our Energy Future


9) Isn’t all the existing flexibility already used up?Load requires a lot of flexibility from generators10x10 3 8Load (MW)64205200National Renewable Energy Laboratory53005400Hour of Year55005600Innovation for Our Energy Future


9) Isn’t all the existing flexibility already used up?Analysis of 3 different balancing areas showed that all 3have excess load-following capability inherent in theconventional thermal generation mixNational Renewable Energy LaboratoryInnovation for Our Energy Future


9) Isn’t all the existing flexibility already used up?• Additional sources of flexibility may be needed athigh penetration rates• newer types of generation: CTs, reciprocating engines• Institutional flexibility• Fast energy markets• Sub-hourly scheduling protocols with neighboring balancingareas• Demand response• Plug-hybrid vehicles in the futureNational Renewable Energy LaboratoryInnovation for Our Energy Future


9) Isn’t all the existing flexibility already used up?• Impact of Inter-BA Wind With Slow Schedule Response• Extra installed capacity is required in the host BA, increasing costs for all• Larger imbalances and costs will be incurred• Scheduling inefficiencies restrict units that can respond• Solution: fast scheduling (~5 minutes) between balancing areasWind Generation (MW)8006004002000One Week200Forecast Error (MW)0-200-40047.447.647.8Wind Energy30-minute forecast error10-minutex10 3 forecast error2-hour persistence forecast error48.048.2-600790079207940796079808000802080408060National Renewable Energy LaboratoryInnovation for Our Energy Future


10) Is wind power is as good as coal or nuclear eventhough the capacity factor of wind power is so much less?908070Wind project sample includesprojects built from 1998-20082008 $/MWh6050403020100Nationwide W holes ale Power Price Range (for a flat bloc k of power)Cumulative Capacity-Weighted Average W ind Power Pric e (+/- 1 s tandard deviation)2003 2004 2005 2006 2007 200849 project s 62 projec ts 80 projec ts 98 projec ts 117 projects 145 project s2,268 MW 3,069 MW 4,083 MW 5, 165 MW 7, 654 MW 9,873 MWAverage Cumulative Wind and Wholesale Power Prices Over Time. Source: Wiser, Ryanand Mark Bolinger. Annual Report on U.S. Wind Energy Markets: 2008. U.S. Departmentof Energy, http://www1.eere.energy.gov/windandhydro/pdfs/46026.pdf.National Renewable Energy LaboratoryInnovation for Our Energy Future


10) Is wind power is as good as coal or nuclear eventhough the capacity factor of wind power is so much less?System Load (MW)Time (hour of day)0 4 8 12 16 20 24seconds to minutesRegulationtens of minutes to hoursLoadFollowingdaySchedulingDaysUnitCommitmentMidwest ISO Plant Capacity Factor by Fuel Type(June 2005–May 2006)National Renewable Energy LaboratoryInnovation for Our Energy Future


11) Is there a limit to how much wind can beaccommodated by the grid?• Studies done so far in the U.S. have not identified aphysical limit, up to 30% energy penetration• However, changes in standard operational andplanning techniques may need to change• Larger electrical footprints for system balancing• Sub-hourly dispatch within balancing areas• Sub-hourly scheduling between balancing areas• More flexible generating technology• Fast ramp• Low turndown• Quick startup• Responsive load• Incorporation of wind forecasts into standard operationsNational Renewable Energy LaboratoryInnovation for Our Energy Future


16x10 3Steeper rampsLower turn-down141210MW864LoadNet LoadWind2012001220124012601280Hours130013201340National Renewable Energy LaboratoryInnovation for Our Energy Future


West Denmark January 10-16, 2005MW4000350030002500200015001000WindLoad45.00%40.00%35.00%)(% 30.00%ntiotrae 25.00%nePrew 20.00%oPdin15.00%W10.00%40.38%7th May8th May9th May10th May5005.00%01 25 49 73 97 121 145hour0.00%HourNational Renewable Energy LaboratoryInnovation for Our Energy Future


Summary• Wind energy adds additional variability anduncertainty to power systems operations• New methods for planning and operating the systemmay be needed to achieve higher penetration rates• Much analysis is ongoing to address operational andplanning issuesNational Renewable Energy LaboratoryInnovation for Our Energy Future


Questions?National Renewable Energy LaboratoryInnovation for Our Energy Future


Thank You!Please submit your questions onthe toolbar on your screen.Note: The presentation will bemade available after the webinar.

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