1. April 13, 2007 Regional Planning Group Meeting Wind Impact/Integration Analysis Warren Lasher Regional Planning

2. Regional Planning Group Meeting April 13, 2007 2 Wind Capacity ERCOT currently has ~2,981 MW of wind capacity online There are ~1,605 MW additional wind capacity that will be on-line by summer 2008 (executed interconnection agreements; sum = 4,586 MW) More wind units are expected to become operational before the end of 2008 4,586 MW is ~7.1% of 2008 peak demand forecast for ERCOT (64,318 MW)

3. Regional Planning Group Meeting April 13, 2007 3 History ERCOT released an RFQ on May 23, 2006 ERCOT evaluated the responses, and worked with bidders to develop a final scope of work ERCOT released an RFP to a short-list of qualified bidders on January 22, 2007 ERCOT has selected GE Energy to conduct the study

4. Regional Planning Group Meeting April 13, 2007 4 Other Regions Similar studies have been conducted in several regions: –NY ISO –Minnesota –Wisconsin (WE Energies) –Ontario –Alberta –California –Bonneville PA –PacifiCorp –Germany

5. Regional Planning Group Meeting April 13, 2007 5 Study Goals Identify changes to the methodology for assessing the level of required ancillary services (regulation, responsive, balancing, replacement and non-spinning reserves) Assess the amount of each ancillary service required for three specific wind scenarios Identify changes to current procedures or new procedures for operations with impending severe weather conditions

6. Regional Planning Group Meeting April 13, 2007 6 Study Methodology 1)Quantitative analysis of the hourly sum of wind generation and load (net load) 1)Analysis of net load variability at different time-frames 2)Analysis of correlation of load and wind generation during periods of specific interest 3)Correlation between variability of net load and load magnitude 4)Correlation between net load variability and seasons or time of day 2)Analysis of the predictability of net load 3)Evaluation of Ancillary Service Needs and Costs

7. Regional Planning Group Meeting April 13, 2007 7 Extreme Weather Events

8. Regional Planning Group Meeting April 13, 2007 8 Study Deliverables Statistical analysis of the variability of wind resources and system load Analysis of the accuracy of day-ahead wind and load forecasts and the impact on unit commitment Analysis of the adequacy of ramp-rates of generation units expected to be on-line during different seasons for the three scenarios Evaluation of specific changes required to the current ERCOT methodology for determining the adequate levels of regulation, non-spin, and balancing energy service Evaluation of the adequacy of the currently procured level of responsive reserves (2,300 MW) with respect to changes in wind generation output (not unit contingencies) Evaluation of the additional system costs of maintaining adequate ancillary services for the selected scenarios A detailed report documenting the methodology and results of this study

9. Regional Planning Group Meeting April 13, 2007 9 Wind Levels Project scope includes evaluation of three wind scenarios Wind levels and locations have not yet been determined The relationship between ancillary service requirements and increasing wind capacity is likely to be non-linear Operations may need one scenario to evaluate likely wind levels in spring 2008 (~5,000 MW) Suggestions for reasonable scenarios would be appreciated

10. Regional Planning Group Meeting April 13, 2007 10 Project Schedule GE Energy will complete its analysis on or before October 31, 2007 ERCOT System Planning will communicate the interim and final results of this study to RPG, ROS, and WMS

11. Regional Planning Group Meeting April 13, 2007 11 Summary This study will evaluate: –the impact of increasing levels of wind capacity on ancillary services requirements –the correlations between wind output and load –the correlation of the accuracy wind and load forecasts –the impacts of extreme weather events –the costs of increased ancillary services as a result of increased wind capacity in ERCOT

12. Questions or Comments?