Fuel flexibility of solid oxide fuel cells

One of the major advantages of SOFCs is their high fuel flexibility. Next to natural gas and hydrogen, which are today's most common fuels for SOFC-systems and cell-/stack-testing respectively, various other fuels are applicable as well. In the literature, a number of promising results show that available fuels as propane, butane, ammonia, gasoline, diesel etc. can be applied. Here, the performance of an anode supported cell operated in specialized single cell test benches with different gaseous and liquid fuels and reformates thereof is presented. Fuels as ammonia, dissolved urea (AddBlue(TM)), methane/steam and ethanol/water mixtures can directly be fed to the cell, whereas propane and diesel require external reforming. It is shown that in case of a stable fuel supply the cell performance with such fuels is similar to that of appropriate mixtures of H-2, N-2, CO, CO2, and steam, if the impact of endothermic reforming or decomposition reactions is considered. Even though a stable fuel cell operation with such fuels is possible in a single cell test bench, it should be pointed out that an appropriate fuel processing will be mandatory on the system level.