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2009 State of the Market Report

Market Performance


Wind Generation

Wind generation and capacity have grown rapidly in the Midwest ISO market since its inception. Wind resources now make up 5.1 percent of installed capacity (approximately 7.5 GW) and 2.9 percent of generation, producing up to 6,000 MWh. This growth trend is expected to continue due to the prevalence of abundant wind capability in the western areas of the footprint, favorable existing federal and state mandates, and various subsidies and tax incentives. In addition, future federal carbon and energy policies will likely further encourage wind generation.

Wind generation promises substantial environmental benefits. As intermittent resources, however, wind generators present particular operational, forecasting, and scheduling challenges that most conventional resources do not. These challenges are amplified as wind’s portion of total generation increases. Intermittent resources are by definition prone to changes in output that can result in system reliability and congestion management problems.

In the day-ahead market, intermittent resources can submit offers (accompanied by generation forecasts) and can be committed as capacity resources under Module E of the Tariff at a 20 percent capacity factor.16 In real time, however, they cannot schedule offers, be committed, follow setpoint instructions, or be dispatched by the real-time market. As a result, the market generally does not coordinate the production of intermittent resources. Instead, the Midwest ISO relies on rule-based methods in the commitment and scheduling algorithms to relax lower priority requirements and utilizes manual dispatch when necessary to ensure reliability.

Figure 46 shows the day-ahead commitment and real-time output of wind resources in 2008 and 2009.


This capacity factor was reduced to 8 percent for Planning Year 2010-2011.

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