Exergy and economic comparison between kW-scale hybrid and stand-alone solid oxide fuel cell systems

Abstract

Although hybrid solid oxide fuel cell (SOFC) microturbine systems generate power more efficiently than stand-alone SOFC systems, hybrid systems remain in the demonstration phase. The present study compares a hybrid system's exergetic and economic performance with that of a stand-alone system. Both systems meet a university building's kW-scale power demand.The hybrid system operates at 66% exergetic efficiency, and the stand-alone system operates at 59% exergetic efficiency. Increasing the fuel cell's operating voltage increases the systems' exergetic efficiencies, and varying the fuel cell's temperature, pressure, and fuel utilization influences the systems' exergetic performances, though to a lesser extent. The present study calculates the systems' life cycle costs. We find that the systems' life cycle costs depend significantly on the systems' operation. During baseline operation,