Hydrogen internal combustion engine vehicle

A hydrogen internal combustion engine vehicle (HICEV) is a type of hydrogen vehicle using an internal combustion engine (ICE) that burns hydrogen fuel. Hydrogen internal combustion engine vehicles are different from hydrogen fuel cell vehicles (which utilize hydrogen electrochemically rather than through oxidative combustion). Instead, the hydrogen internal combustion engine is simply a modified version of the traditional gasoline-powered internal combustion engine. The absence of carbon in the fuel means that no CO₂ is produced, which eliminates the main greenhouse gas emission of a conventional petroleum engine.

Pure hydrogen contains no carbon. Therefore, no carbon-based pollutants, such as carbon monoxide (CO), carbon dioxide (CO₂), or hydrocarbons (HC), occur in engine exhaust. However, hydrogen combustion occurs in an atmosphere containing nitrogen and oxygen, which can produce oxides of nitrogen (NO_x). In this respect, the combustion process is much like other high temperature combustion fuels, such as kerosene, gasoline, diesel, and natural gas. Therefore, hydrogen combustion engines are not considered zero emission.