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

Abstract

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 + 2 H₂) 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.