There are three types of hydrogen engines:
The internal combustion hydrogen engine, also called an explosion engine, converts the chemical energy of the explosive reaction between dihydrogen and dioxygen into mechanical energy:
2 H2 + O2 = H2O + energy
The recovered mechanical energy activates a piston according to the same principle used for a petrol or diesel explosion engine. However, the specific qualities of hydrogen require that a few modifications be made in consideration of its gaseous state, its tendency to self-ignite, its quicker speed of combustion and its corrosive effect.
The efficiency of this engine is between 30 and 40%.
A classic internal combustion engine for a vehicle. © DR