Internal combustion hydrogen engine

There are three types of hydrogen engines:

• reaction engine;
• internal combustion engine;
• combined fuel cell and combustion engine.

Principle of the internal combustion hydrogen engine

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.

In addition, adjustments are necessary in order to limit the nitrogen oxide emissions (NOx) caused by the oxidation of atmospheric nitrogen.

The efficiency of this engine is between 30 and 40%.

Currently, vehicles sold or designed with this type of engine are flex-fuel or hybrid, to compensate for the shortcomings in hydrogen distribution and autonomy.