Improvements of a Molten Carbonate Fuel Cell Power Plant via Exergy Analysis

Abstract

A proposed molten carbonate fuel cell power plant design, intended for commercial production by the end of the 1990s and developed under the auspices of the U.S. Department of Energy, the Gas Research Institute, and Energy Research Corporation, has been analyzed with exergy and pinch analysis. The commercial production units, targeted for dispersed power generation markets, are based on an existing demonstration molten carbonate fuel cell power plant design which was demonstrated from 1996–1997. Exergy analysis of the commercial plant design shows the overall, second-law system efficiency to be 53 percent. The principal inefficiency, 17 percent of the total, lies in the catalytic combustor. Another major inefficiency is the stack loss, 14 percent. Heat transfer accounts for approximately 6 percent of the loss. System reconfigurations, incorporating a steam cycle with reheat (System I) and a gas turbine cycle (System II), both with revised heat exchanger networks, for significant improvement are proposed and evaluated. The second-law system efficiency is raised to 66 percent in System I and to 70 percent for System II.