Paper: Heat Rate Improvements and Limitations Based on EPA’s Block Strategies

Case studies on heat rate improvement audits conducted for two NRECA plants


In June 2014, the EPA published the “Carbon Pollution Emission Guidelines for Existing Stationary Sources.” The proposed rule does not set emissions standards for individual sources, but provides guidelines for states to follow in developing plans to address greenhouse gas emissions from existing sources in and beyond the power sector.  To establish the state-specific rate-based CO2 emission goals, EPA proposed potential CO2 emission reductions associated with various “building blocks” that affect the power generating industry, including reducing CO2 emissions (i.e., lb CO2/MW-net) at individual affected electric generating units through heat rate improvements (HRIs) via EPA’s Block 1 strategy.

The purpose of this paper is to conduct a review of potential HRIs that can be applied to existing coal-fired EGUs and to identify potential limitations in applying these technologies.  The purpose is demonstrated by conducting HRI audits on two power plants within The National Rural Electric Cooperative Association (NRECA). Because of the diverse nature of utilities and units that comprise NRECA, and because of the highly site-specific applicability and performance of HRI technologies, the scope of this paper includes a discussion of major limitations in applying each technology, or a combination thereof, to operating units. A brief discussion of the potential for HRI technologies to degrade in performance over time is included. Additionally, an analysis of how load cycling impacts heat rates in operating units was conducted to determine how EPA’s Block 2 (increased dispatch to NGCC units) will affect coal units.  Finally, HRI case studies were conducted to explore previous and potential future heat rate improvements from two stations within the NRECA fleet, for a total of five units.

Emily J. Kunkel, Rajendra Gaikwad, William A. Rosenquist – Sargent & Lundy
Michael J. Casper, Rae E. Cronmiller – National Rural Electric Cooperative Association

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