Thermodynamic Influence Analysis of Available Fuels and Reforming Methods on SOFC System Efficiency

In this paper the results of a thermodynamically exact calculation method for determining SOFC (solid oxide fuel cell) system efficiencies depending on reforming method and fuel are presented. Several fuels (diesel, gasoline, liquefied petroleum gas, ethanol, methane and biogas) are studied. The aim is to identify combinations of fuels and reforming methods with the potential for high efficiencies. The influence of the S/C (steam/carbon) ratio and reformer air ratio λRef on achievable efficiency is examined, explaining the superiority of steam reforming. Only with biogas partial oxidation can achieve comparable values to steam reforming due to its specific composition containing CO2 making biogas an ideal fuel for SOFCs. Also a close look is taken at the demand of heat flux to or from the reforming step in order to reveal potential necessities of a complex heat management.