Examination of a high-efficiency solid oxide fuel cell system that reuses exhaust gas

Enhancing the power generation efficiency, which is the main advantage of solid oxide fuel cells (SOFCs), can have valuable benefits to introduce SOFC systems into business and industrial markets of Japan, where power demands are higher than thermal demands. In this study, we examined a high-efficiency SOFC system with an off-gas regenerating technique. A two-stage SOFC stack configuration was employed. For off-gas regeneration, we used a CO2 absorber and a H2O condenser. A total of 92.0% of the fuel was successfully used with an electrical efficiency of 77.8% (DC, LHV). However, there existed the heat loss from the fuel cell system due to the thermal insulation performance. To compensate the heat loss, additional electric heaters were used to keep temperatures high, therefore heat sustainability remained an issue.