2009 State of the Market Report
Figure 46: Day-Ahead Scheduling vs. Real-Time Wind Generation 2008 – 2009
3,500 3,000 2,500 2,000 1,500 1,000
Day-Ahead Wind Real-Time Wind Difference
The figure shows the continued rapid growth of wind generation and seasonality of wind – output is generally higher during shoulder months. Wind generation was under-scheduled in the day-ahead market for most of the year. This creates price convergence issues in western areas and can lead to uncertainty regarding the need to commit resources for reliability. It can also cause real-time RSG costs that are not currently allocated to wind suppliers because wind capacity is an intermittent resource. Efficient RSG cost allocation is essential to the effective integration of wind generation, but allocations must remain incentive-compatible with energy markets and should be assessed on a cost-causation basis. The Midwest ISO filed with the Commission to remove this exemption on December 7, 2009, and will take effect along with the implementation of the Dispatchable Intermittent resource type on June 1, 2011.
Wind capacity factors, measured as actual output as a percentage of maximum output, vary substantially across the footprint by region, hour, season, and temperature. They have been higher in the western portion of the footprint where the resource potential is greater. Wind