Is steam addition necessary for the landfill gas fueled solid oxide fuel cells?

Landfill gas in Hong Kong – a mixture of about 50% (by volume) CH4 and 50% CO2 – can be utilized for power generation in a solid oxide fuel cell (SOFC). Conventional way of utilizing CH4 in a SOFC is by adding H2O to CH4 to initiate methane steam reforming (MSR) and water gas shift reaction (WGSR). As the methane carbon dioxide reforming (MCDR: CH4 + CO2 ↔ 2CO + 2H2) is feasible in the SOFC anode, it is unknown whether H2O is needed or not for landfill gas fueled SOFC. In this study, a numerical model is developed to investigate the characteristics of SOFC running on landfill gas. Parametric simulations show that H2O addition may decrease the performance of short SOFC at typical operating conditions as H2O dilute the fuel concentration. However, it is interesting to find that H2O addition is needed at reduced operating temperature, lower operating potential, or in SOFC with longer gas channel, mainly due to less temperature reduction in the downstream and easier oxidation of H2 than CO. This preliminary study could help identify strategies for converting landfill gas into electrical power in Hong Kong.