Testing of Solid Oxide Fuel Cells Using Ammonia for Carbonless Aviation Applications

Ammonia powered solid oxide fuel cells could prove as a potential option for carbon free power and propulsion systems in aviation. Ammonia works as a hydrogen carrier and is cracked at solid oxide fuel cell operating temperatures which splits it into hydrogen and nitrogen. Testing of tubular solid oxide fuel cells fueled by ammonia was done at multiple operating pressures and temperatures and compared to hydrogen as well as simulated ammonia. These tests were performed as constant stoichiometry polarization curves which were normalized based on a baseline hydrogen polarization curve ran at the beginning of each test. Testing showed that ammonia performed slightly worse than simulated ammonia and pure hydrogen, but the peak powers were within 4-6% of each other. Results also showed that pressure and temperature had a much larger effect on the peak power than the fuel choice between ammonia and hydrogen. Mass spectrometer data showed how ammonia decomposition changed with temperature and proved that the ammonia was not being fully cracked before reaching the fuel cell. These results prove that ammonia could be a very suitable replacement for hydrogen in terms of solid oxide fuel cell power systems for aviation.