Comparison of carbon formation boundary in different modes of solid oxide fuel cells fueled by methane

For comparison purpose, SOFCs with the hydrogen-conducting electrolyte were also investigated. According to the study, they were observed to be impractical for use, regarding to the tendency of carbon formation. Higher values of the H2O/CH4 ratio are required for the hydrogen-conducting electrolyte, which is mainly due to the difference in location of water formed by the electrochemical reaction at the electrodes. In addition, with this type of electrolyte, the required H2O/CH4 ratio is independent on the SOFC operation modes. From the study, DIR-SOFC with the oxygen-conducting electrolyte seems to be the promising choice for operation.