Modeling of direct carbon-assisted Solid Oxide Electrolysis Cell (SOEC) for syngas production at two different electrodes

Abstract

Syngas can be produced from H2O/CO2 co-electrolysis using an SOEC. However, H2 and CO are both produced in the cathode and the electricity consumption is large. In this paper, direct carbon-assisted SOEC for H2O electrolysis (DC-SOFEC) is proposed for cogenerating electricity power and syngas with easy control of H2/CO ratio. A 2D numerical model is developed to study the effects of operating and design parameters on the DC-SOFEC performance. The model is validated with experimental data for direct carbon solid oxide fuel cell. One important finding is that the carbon assisting is effective in lowering the equilibrium potential of SOEC, thus greatly reduces the electrical power consumption for H2O electrolysis. The DC-SOFEC can generate electrical power, CO and H2 simultaneously at a low current density and sufficiently high temperature. Compared with conventional SOEC for H2O/CO2 co-electrolysis, DC-SOFEC is advantageous as CO and H2 are produced in the anode and cathode, respectively. This enables easy control of H2/CO ratio, which is helpful for subsequent processes to synthesize other chemicals or fuels from syngas. Besides, DC-SOFEC can actually produce electricity rather than consuming it. The model can be used for subsequent design optimization of SOFEC for effective energy storage and conversion.