2009 Scenario Reliability Assessment - NERC

Scenario Reliability Self-AssessmentsThe operational and reliability impacts of this penetration of wind are significant, requiringimproved wind forecasting, increased levels of ancillary services and potentially, new types ofAncillary Services, These changes in ancillary services requirements may lead to changes in theinstalled generation fleet, including the incorporation of different technologies, such as storagesolutions and coordinated demand management. While a detailed study of the impact of theScenario 2 level of wind generation on ancillary services and grid reliability was completed as apart of the CREZ analysis, such a study has not yet been accomplished for the 25 GW levelevaluated in this Scenario Case. Changes to the current installed fleet of generating units(retirements and additions) would also likely occur at the Scenario Case level of installed windgeneration, but the current assessment does not address these economic decisions.DemandThe weather, economic assumptions, demand forecast, and demand response values used in theScenario Case is the same as in the 2008 Long-Term Reliability Assessment Reference Case.GenerationIn order to meet the requirements, the Scenario Case assumes that a total of 24,859 MW of windgeneration capacity is online by 2018, which is an additional 14,261 MW of wind generationcapacity added to the Reference Case.As in the Reference Case, only the Effective Load-Carrying Capability (ELCC) of 8.7 percent ofthe wind generation nameplate capacity is included in the Existing-Certain amount used formargin calculations. The remaining existing wind capacity amount is included as Existing-Othergeneration. Consequently, the expected on-peak capacity of these resources range from a currentvalue of 708 MW to 919 MW by 2013 and to 2,163 by 2018.Figure ERCOT-3 reflects the fuel mix for generation in the Region. In the Scenario Case, windenergy represents 18 percent of the total energy generated in 2018, which is a significant increaseover the 5 percent of 2008 load produced by renewable generation in 2008.Figure ERCOT-3: 2008 and 2018 Fuel Mix for Energy Generation2009 Scenario Reliability Assessment Page 25