Hydrogen internal combustion engine, a path to the energy transition

Hydrogen is seen as one of the solutions for contributing to the reduction of greenhouse gas emissions, and to the transition to a low-carbon economy, including in the passenger and freight transport sector. In France, this sector alone is responsible for almost a third of CO ₂ emissions . Hydrogen's key advantage is its zero-emission potential when used, whether in a fuel cell or in an internal combustion engine (also known as a hydrogen combustion engine).

The strengths of the hydrogen combustion engine for mobility are numerous: mass and volume density of energy storage compared with battery-powered electric solutions; autonomy; rapid energy recharging; and robustness in relation to ambient conditions. The sectors of application concerned are those where autonomy and logistical constraints are greatest: so-called heavy transport; construction and agricultural vehicles and machinery; service vehicles; motor sport.

Hydrogen-powered internal combustion engines are increasingly being incorporated into the roadmaps of players in the field. However, this solution is not without its challenges. Firstly, for hydrogen to be considered as one of the solutions contributing to the reduction of greenhouse gas emissions, it must itself be derived from a decarbonized process, which is one of the major challenges facing the industry. Secondly, the relevance of the combustion engine as a technical solution lies in its maturity. It is based on a tried-and-tested approach, with controlled costs. However, the adaptation of existing motorization technologies to hydrogen fuel still requires further investigation.

After setting the context for low-carbon mobility and the hydrogen industry, this article focuses on the use of hydrogen in an internal combustion engine, the physicochemical properties to be taken into account and their impact on existing technologies, and, finally, a few examples of applications currently under development.