Modeling of Direct Carbon-Assisted Solid Oxide Electrolysis Cell (SOEC) for Syngas Production at Two Different Electrodes

Syngas can be produced from H 2 O/CO 2 co-electrolysis using an SOEC. However, H 2 and CO are both produced in the cathode and the electricity consumption is large. In this paper, direct carbon-assisted SOEC for H 2 O electrolysis (DC-SOFEC) is proposed for cogenerating electricity power and syngas with easy control of H 2 /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 H 2 O electrolysis. The DC-SOFEC can generate electrical power, CO and H 2 simultaneously at a low current density and sufficiently high temperature. Compared with conventional SOEC for H 2 O/CO 2 co-electrolysis, DC-SOFEC is advantageous as CO and H 2 are produced in the anode and cathode, respectively. This enables easy control of H 2 /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.