Performance evaluation and optimization of a solid oxide fuel cell system combined with solid oxide electrolysis cell

As solid oxide fuel cell (SOFC) systems fueled with natural gas and biogas are applied widely, the capture and utilization of CO₂ in SOFC exhaust gas are important issues. This paper proposes a new SOFC system combined with a solid oxide electrolysis cell (SOEC) stack, which absorbs renewable electrical power such as solar power and wind power to convert CO₂ in SOFC exhaust gas into fuel by electrolysis reactions, and the SOFC-SOEC system model is built for in-depth steady state analysis and multi-objective performance optimization. After that, the performance of the SOFC-SOEC system is evaluated by comparing with a typical external steam-reforming SOFC system. The results show that the SOFC-SOEC system acquires significant advantages in high system efficiency, long time sustainable power supply and low CO₂ emission.