Replacing jet fuel with ammonia: The future of aviation

Ammonia engines have powered the jet fighter X15 in the 50s. It is light, with a high energy content and well known. The Liquid O2 and NH3 powered engines reached Mach6.

Ammonia combustion-- 4NH3 + 3O2 -> 2N2 + 6H2O (nitrogen and water only combustion products)

Reaction engines have announced in August 2020 in a UK study that is ground-breaking regards ammonia fuel for a sustainable aviation propulsion system

The downside of ammonia for jet fuel is its limited ignition range and flame stability, which is solved by burning with liquid oxygen. This was deemed to be beyond the scope of applicability for general aviation purpose until new technology has allowed NH3 flame stability