Ammonia consists of 17.6wt% hydrogen, showing that ammonia is an indirect hydrogen storage compound. Ammonia‟s energy density is 4.32 kWh/liter, which is similar to methanol (CH3OH), and approximately double that of liquid hydrogen.
Points out that liquefying hydrogen is more difficult when compared to ammonia, since ammonia liquefies at −33.15°C and at atmospheric pressure: Hydrogen has to be liquefied by chilling to temperatures lower than −253°C.
Ammonia is easily stored in bulk as a liquid at modest pressures (10-15 bar) or refrigerated to -33°C. This makes it an ideal chemical store for renewable energy. There is an existing distribution network, in which ammonia is stored in large refrigerated tanks and transported around the world by pipes, road tankers and ships.
Ammonia can be burnt in an engine or used in a fuel cell to produce electricity. The maritime industry is likely to be an early adopter, replacing the use of fuel oil in marine engines.