Events

Abstract:
Wind power is being added to the grid at a rapid pace, offsetting fossil fuel generation and reducing emissions.  To accommodate the variability of wind, dispatchable generation must offer increased flexibility including more partial load operation and shut downs (collectively termed "cycling").  Coal plants were not designed to provide this level of flexibility and operating them in such a manner may increase emissions and reduce the environmental benefits of wind power.  Because attributional life cycle assessments (LCA) of wind power do not capture these impacts of grid integration, this study employs a consequential LCA approach.  Using a comprehensive dispatch model and a wind development optimization model, this study quantifies the emissions from coal unit cycling caused by wind variability, including the impacts from partial load operation, number of unit starts, ancillary service requirements, increased forced outage rates, and heat rate degradation.  The findings show that emissions from increased coal cycling can be four times as large as the attributional emissions associated with wind turbine materials, manufacturing, maintenance, and end-of-life management.  This underscores the importance of consequential LCA methods when examining changes in the power sector.