2014 RTP Inputs and Assumptions April 22, 2014

1. 2014 RTP Inputs and Assumptions April 22, 2014

2. 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

3. 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

4. NCP Load-Generation Balance Summary

5. Generator addition/retirement summary

6. Generator addition/retirement summary *359 MWs of antelope station has financial commitment, but ERCOT is working to understand the configuration and availability for ERCOT reliability cases.

7. Generators not added to the cases

8. 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 90th percentile load levels

9. Study regions in 2014 RTP + Wind output outside study region increased up to the 25th percentile output* Outside load will be scaled from the “higher-of” load levels

10. 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

11. Weather year selection for economic analysis • ERCOT 50th 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 2002-2013 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

12. Annual energy comparison

13. Annual peak comparison

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

15. 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

16. 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.

17. Next steps