Syngas Production By Coelectrolysis of CO2/H2O: The Basis for a Renewable Energy Cycle

Electrolysis was carried out at 700-800 degrees C using solid oxide electrochemical cells with H2O-CO2-H-2 mixtures at the Ni-YSZ cathode and air at the LSCF-GDC anode. (YSZ = 8 mol %, Y2O3-stabilized ZrO2, GDC = Ce0.9Gd0.1O1.95, and LSCF = La0.6Sr0.4C0.2Fe0.8O3). The cell electrolysis performance decreased only slightly for H2O-CO2 mixtures compared to H2O electrolysis and was much better than for pure CO2 electrolysis. Mass spectrometer measurements showed increasing consumption of H2O and CO2 and production of H-2 and CO with increasing electrolysis current density. Electrolyzers operated on 25% H-2, 25% CO2, and 50% H2O at 800 degrees C and 1.3 V yielded a syngas production rate of similar to 7 sccm/cm(2). The use of electrolytically produced syngas for producing renewable liquid fuels is discussed; an energy-storage cycle based on such liquid fuels is CO2-neutral, similar to hydrogen, and has the potential to be more efficient and easier to implement.