Generation Repowering & Potential GHG Savings August 8, 2007 Sacramento CA

The Fleet Serving California is Aged Source: “California’s Electricity Generation and Transmission Interconnection Needs Under Alternative Scenarios” Electric Power Group LLC Consultant Report to California Energy Commission, 2003. www.electricpowergroup.com

The Relationship of Age to Efficiency is Not Straightforward Source: CEC, “Resource, Reliability and Environmental Concerns of Aging Power Plant Operations and Retirement,” 2004, Pub. 100-04-005D

GHG Performance has been Deemphasized in California Studies to Date CEC studies emphasize criteria pollutants and water-use effects. Primary findings discuss possible emissions increases in identified air basins, as a result of improved power plant performance, and hence greater usage, following a repower. GHG emissions from any given repowered facility are likely to be unconstrained, given current technology, and hence may increase as a result of repowering. Dispatch order and plant operational profile may change in a given grid location following repowering, meaning that GHG performance must be considered on both a plant-by-plant basis and in interaction with other grid resources.

Key Policy Considerations at this Juncture Given the interactivity of influences in the GHG and repowering context, a useful frame of reference may be the total control regime. One policy approach may be to consider the aging fossil fleet as a regulated sub-sector, and emphasize net GHG savings that result from repowering. All else equal, including no diminution of gains in local environmental performance. In advance of this effort, the CEC could undertake an update of its environmental assessments with explicit emphasis on the potential for GHG savings as a result of repowering. Existing analysis does not appear sufficient to justify a course of action in regards to potential GHG savings. Future analysis should consider the potential of repowering with deployment of carbon capture and sequestration technologies.

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