5. Environmental and energy aspects

5.1 Hydrogen production and distribution

Hydrogen can be produced by steam reforming of hydrogen-rich fuels. This process is highly energy-efficient, up to 90% (losses being mainly thermal). However, the CO ₂ emitted during this transformation is greater than the direct combustion of these fuels. Water electrolysis is the process which, if the electricity used is decarbonized, makes it possible to obtain green hydrogen. Electrolysis efficiency can reach 85% for large-scale PEM (Proton Exchange Membrane) technology.

Hydrogen transport and distribution require storage in compressed or liquid form. Compression losses are of the order of 10 to 20% in energy for pressures between 300 and 700 bar. For hydrogen liquefaction,...