ERCOT PUBLIC 5/20/ RTP Inputs and Assumptions-Updated April 22, 2014

ERCOT PUBLIC 5/20/ Outline  Initial 2014 RTP case overview  Generation summary  Weather year selection for wind and load in economic analysis  Hydro dispatch in economic analysis  Updates to the RTP scope  Next steps

ERCOT PUBLIC 5/20/ Initial 2014 RTP case overview  The initial 2014 RTP summer peak cases for years 2015, 2017, 2019 and 2020 were created per the RTP scope  “Higher-of” load was used in the summer peak case  Generation was added and retired per the planning guide and RTP scope

ERCOT PUBLIC 5/20/ NCP Load-Generation Balance Summary Year Load* + LossGeneration**MarginImbalance * Load on this table is the NCP load using higher-of the SSWG or 90 th percentile forecast ** This includes generation available as per planning guide section 6.9, with wind and solar dispatched as per the RTP scope with no adjustments to address the imbalance

ERCOT PUBLIC 5/20/ Generator addition/retirement summary Site NameCountyCODFuel MW For Grid Sufficient Financial Security Received Panda Temple PowerBellAug-14GAS717Yes J.T. Deely 1 & 2BexarN/ACOAL845N/A (Retired in 2018)Yes No Stephens Ranch Wind Energy Phase 1 BordenOct-14WIND201Yes Mesquite CreekBordenJan-15WIND249Yes Longhorn Energy CenterBriscoeDec-14WIND361Yes Cameron County WindCameronJun-15WIND165Yes Panhandle WindCarsonJul-14WIND218Yes Conway WindfarmCarsonDec-14WIND600Yes Hereford WindCastroSep-14WIND200Yes Wake Wind Energy Floyd and Crosby Apr-15WIND299Yes CPV Rattlesnake Den Ph 1 GlasscockMay-15WIND201Yes Miami Wind 1 ProjectGrayJul-14WIND289Yes Panda Sherman PowerGraysonAug-14GAS720Yes Deer Park Energy CenterHarrisJul-14GAS190Yes Rentech ProjectHarrisAug-14GAS15Yes Keechi Wind 138 kV Joplin JackDec-14WIND102Yes Sendero Wind Energy Project Jim HoggFeb-15WIND78Yes Baffin (Penascal Wind Farm 3) KenedyDec-14WIND202Yes OCI Alamo 4KinneyAug-14SOLAR38Yes

ERCOT PUBLIC 5/20/ Generator addition/retirement summary Site NameCountyCODFuelMW For Grid Sufficient Financial Security Received Green PasturesKnoxFeb-15WIND300Yes Ferguson Replacement Project LlanoJul-14GAS570Yes Goldthwaite Wind Energy MillsApr-14WIND149Yes Spinning Spur Wind Two OldhamJun-14WIND161Yes Spinning Spur Wind Three OldhamDec-14WIND194Yes Barilla SolarPecosNov-14SOLAR30Yes Route66 WindRandallDec-14WIND150Yes Los Vientos IIIStarrDec-14WIND200Yes Panda Temple Power II BellAug-15GAS717YesNoYes Briscoe Wind FarmBriscoeDec-15WIND300YesNoYes Panhandle Wind 2 (Phase 2) CarsonNov-15WIND182YesNoYes Antelope Station*HaleJun-16GAS359YesNo Patriot (Petronilla) Wind NuecesAug-15WIND178YesNoYes Midway Farms WindSan PatricioOct-15WIND161YesNoYes *359 MWs of antelope station has financial commitment, but ERCOT is working to understand the configuration and availability for ERCOT reliability cases.

ERCOT PUBLIC 5/20/ Generators not added to the cases Site NameCountyCODFuelMW For Grid Sufficient Financial Security Received Windthorst 2ArcherDec-14WIND65No Stephens Ranch Wind Energy Phase bBordenApr-15WIND177No Freeport LNG PreTreatment FacilityBrazoriaJun-17GAS11No Jumbo Road WindCastroApr-15WIND300No South Clay WindfarmClayDec-14WIND200No Logans Gap Wind IComancheMay-15WIND200No Moore Wind 1CrosbyAug-14WIND149No Goldsmith Peaking FacilityEctorJun-15GAS408No Texas Clean Energy ProjectEctorJun-18COAL240No South Plains Wind IFloydJul-15WIND200No South Plains IIFloydDec-15WIND300No PHR PeakersGalvestonApr-15GAS390No CPV Rattlesnake Den Ph 2GlasscockMay-16WIND150No Miami Wind 1 ProjectGrayAug-15WIND111No Pampa Wind ProjectGrayMar-17WIND500No Antelope Station CT1HaleJul-16GAS197No Antelope Station CT2HaleJul-16GAS197No Friendswood Energy GenerationHarrisSep-15GAS316No Pondera King Power ProjectHarrisJun-17GAS1629No Gunsight MountainHowardAug-15WIND120No Cobisa-GreenvilleHuntDec-16GAS1792No Forney Power Plant UpgradeKaufmanAug-14GAS34No White Camp SolarKentOct-14SOLAR100No FGE Texas 1MitchellJun-16GAS799No Mariah WindParmerOct-14WIND232No Mariah WindParmerDec-15WIND200No Mariah WindParmerDec-16WIND168No Comanche Run WindSwisherDec-16WIND500No Mustang Solar ProjectTravisDec-15SOLAR30No

ERCOT PUBLIC 5/20/ Study regions in 2014 RTP  2014 RTP cases will have four study areas North and North Central Coast and East South and South Central West and Far West  Each study region will have its load at the “higher- of” SSWG or ERCOT 90 th percentile load levels

ERCOT PUBLIC 5/20/ Study regions in 2014 RTP Year 2015 RTP load (80512 MW)2017 RTP load (83171 MW) Study regionsN, NCW, FWS, SCE, CN, NCW, FWS, SCE, C Wind output outside of study region (MW) Mothball generation on (MW) Outside scaling %* 95% 97% 96 % 92%94% 93% 92% Study region load (MW) Year 2019 RTP load (85963 MW)2020 RTP load (87219 MW) Study regionsN, NCW, F WS, SCE, CN, NCW, FWS, SCE, C Wind output outside of study region (MW) Mothball generation on (MW) Outside scaling %* 85% 89% 87% 86%84%88% 85% 84% Study region load (MW) Wind output outside study region increased up to the 25 th percentile output * Outside load will be scaled from the “higher-of” load levels

ERCOT PUBLIC 5/20/ Load and wind profile analysis  Economic analysis uses 8760 profile for load (by weather zone) and wind (by plant site)  Normalized load and wind patterns tend to smooth out peaks and valleys experienced in real-time conditions and don’t necessarily correlate well to each other  ERCOT plans to use a representative “weather year” for load and wind profiles in the economic analysis based on an analysis of historical weather year data

ERCOT PUBLIC 5/20/ Weather year selection for economic analysis  ERCOT 50 th percentile forecast is derived from twelve years worth of historic weather and load data  ERCOT planning obtained twelve load forecasts for 2017 (sample year) using weather data from as the only variable  Load forecast for 2008 weather year was ignored because of the impacts of hurricane Gustav  Annual energy and peak load levels for each of the twelve sample forecasts were compared to the official forecast

ERCOT PUBLIC 5/20/ Annual energy comparison

ERCOT PUBLIC 5/20/ Annual peak comparison

ERCOT PUBLIC 5/20/ Weather year selection for economic analysis  Based on the correlation analysis the 2006 weather year is the most correlated to the 2014 official 50 th percentile forecast with respect to both the peak and monthly energy  AWS Truepower wind profiles from 2006 will be used in 2014 economic analysis

ERCOT PUBLIC 5/20/ Hydro dispatch in economic analysis  Hydro dispatch from 2003 through 2013 was analyzed  Data shows that most hydro units have some output, even in 2011  ERCOT plans to use a 8760 profile for each hydro unit  The 8760 profile will be created based on historical dispatch for the representative weather year  ERCOTs representative weather year analysis identified 2006 to be the representative year

ERCOT PUBLIC 5/20/ Updates to RTP scope  Solar plant dispatch in reliability analysis has been changed to 70% from a previous 50%. This was done based on a percentile/confidence analysis using Solar curves data (similar to what was done for wind)  The horse hollow plant will still be connected to Kendall and not to West Texas.

ERCOT PUBLIC 5/20/ Next steps Case conditioning Initial start cases, contingency list and list of overloads ready N-1 SCOPF analysis G-1 screening followed by G-1+N-1 analysis X-1 screening followed by X-1+N-1 analysis Reliability analysis complete with all reliability issues resolved Economic case preparation Economic analysis Prepare the final RTP report

ERCOT PUBLIC 5/20/ Update 1: Annual Wind Energy comparison There was a request to compare annual wind energy across the years. As seen below the year selected for 2014 RTP economic analysis (2006) is an acceptable representative wind year.

ERCOT PUBLIC 5/20/ Update 2: Wind dispatch inside and outside the study region Dispatch for wind units as percentage of the generator capacity Wind Zone Inside the study region Outside the study region Coast12.28%20.24% North0.93% 3.08% Panhandle2.80%7.88% South6.60% 12.98% West2.38%6.82% There was a request to see the percentage wind output used in the RTP cases inside and outside the study region.

ERCOT PUBLIC 5/20/ Update 3: Hydro dispatch There was a request to compare Hydro dispatch for the selected year 2006 to the recent drought years. As seen below, the dispatch for 2006 is a reasonable representation of hydro dispatch in an average weather year.

ERCOT PUBLIC 5/20/ Update 4: Demand in April in 2006 There was a request to compare monthly energy forecast using 2006 weather year to the official. This was based on the recollection that, the month of April 2006 had seen higher than expected energy demands. Here is a comparison of the 2006 monthly energy to the official forecast for As seen below, 2006 is a good representative year, even with April energy using the 2006 weather is slightly higher.