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

Electrolysis was carried out at 700−800 °C using solid oxide electrochemical cells with H2O−CO2−H2 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 = La0.6Sr0.4Co0.2Fe0.8O3). 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 H2 and CO with increasing electrolysis current density. Electrolyzers operated on 25% H2, 25% CO2, and 50% H2O at 800 °C and 1.3 V yielded a syngas production rate of ∼7 sccm/cm2. 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.