Development of a Highly Efficient SOFC Module Using Two-stage Stacks and a Fuel Regeneration Process

Abstract

A solid oxide fuel cell (SOFC) module using two-stage stacks and a fuel regeneration process between them was developed in this study for the first time, to the best of the authors' knowledge. Upon configuring the first-stage and second-stage stacks and a steam reformer between them in the SOFC module, a gross output power of DC 2.27 kW was generated with gross power generation efficiency of DC 69.2% (lower heating value (LHV)), at a total fuel utilization rate of 86.3%. This technology enables operation at a very high total fuel utilization rate even while operating the stacks at a moderate fuel utilization rate (below 70%). Considering an auxiliary device loss (6%) and inverter loss (5%), the net power generation efficiency is estimated to be AC 61.8% (LHV); hence, the module is considered to exhibit a high power generation efficiency. Further increases in the power generation efficiency could be realized in the future by removing the CO2 from the anode off-gas during the fuel regeneration process and/or operating the stacks at higher temperatures by decreasing heat leakage from the module.