Co-electrolysis SOEC and internal reforming SOFC for achieving a carbon-neutral society

Abstract

Solid oxide electrolysis cells (SOECs) can produce carbon monoxide (CO) from carbon dioxide (CO2) in addition to hydrogen (H2) from steam using renewable energy sources such as solar and wind power. Methanol (MeOH) and dimethyl ether (DME) are industrially synthesized from syngas (H2 + CO mixture) with an H2/CO ratio of 2. Solid oxide fuel cells (SOFCs) can generate power using MeOH and DME in addition to H2. To achieve a carbon-neutral society, H2O/CO2 co-electrolysis SOECs and internal reforming SOFCs using MeOH and DME were investigated using the same negatrode-supported microtubular cells. As a result of quantitative analysis of the gas composition, the H2/CO ratios of the product gases were identical to the H2O/CO2 ratios of the input gases during the co-electrolysis. The gas diffusion resistance increased with decreasing H2O/CO2 ratios for co-electrolysis SOECs, and increased with time during co-electrolysis at H2O/CO2 = 2 and internal reforming of MeOH and DME. H2O/CO2 co-electrolysis SOECs and internal reforming SOFCs using MeOH and DME were successfully operated for 100 h.