Modeling of indirect carbon fuel cell systems with steam and dry gasification

•An equilibrium gasifier model is coupled to a detailed 1-D MEA model.•Cell performance is greatly enhanced by sending H2O to the gasifier instead of CO2.•Thermal coupling between the gasifier and fuel cell significantly raises efficiency.•State-of-the-art efficiency is predicted for an indirect carbon fuel cell system.

An indirect carbon fuel cell (ICFC) system that couples coal gasification to a solid oxide fuel cell (SOFC) is a promising candidate for high efficiency stationary power. This study couples an equilibrium gasifier model to a detailed 1D MEA model to study the theoretical performance of an ICFC system run on steam or carbon dioxide. Results show that the fuel cell in the ICFC system is capable of power densities greater than 1.0 W cm−2 with H2O recycle, and power densities ranging from 0.2 to 0.4 W cm−2 with CO2 recycle. This result indicates that the ICFC system performs better with steam than with CO2 gasification as a result of the faster electro-oxidation kinetics of H2 relative to CO. The ICFC system is then shown to reach higher current densities and efficiencies than a thermally decoupled gasifier + fuel cell (G + FC) system because it does not include combustion losses associated with autothermal gasification. 55–60% efficiency is predicted for the ICFC system coupled to a bottoming cycle, making this technology competitive with other state-of-the-art stationary power candidates.