7. Solid Oxide Fuel Cells

The Solid Oxide Fuel Cell (SOFC) is an all solid type of high-temperature fuel cell that can directly convert any mixture of hydrogen, carbon monoxide and methane into electricity. The electrical efficiency of SOFC systems can reach very high values up to and above 60%, which makes the SOFC interesting for stationary power generation at all scales from below 1 kW_el up to several MW_el, but also for on-board electricity generation on vehicles in the range of 25 W_el to several 100 kW_el. An overview is given here of the great variety in materials and configurations that can be exploited by SOFC designers depending on the application requirements. SOFC systems display high efficiency thanks to the possibility to recycle the high quality heat into chemical (fuel) energy heat, but this involves careful engineering; also tolerance to fuel contaminants is generally higher than with other fuel cells though corrosive species need to be eliminated from the fuel stream in any case. The level of quality of cell components available is high, but further effort has to be mustered to further strengthen the SOFC for long-term operation and transient conditions.