Molecular hydrogenH2 (which is practically non-existent in nature, but whose combustion energy is 3 times greater than that of a liter of petrol) is seen as a possible energy carrier, particularly for the development of renewable energies that do not emitCO2. But we still need to know how to produce, transport and store it properly. This lecture attempts to answer this question by giving a panoramic view of production/transportation and storage processes in terms of principle and technological maturity, in order to better highlight the associated difficulties and challenges.
Hydrogen is produced from abundant hydrogen sources on earth, such as fossil fuels, biomass and water: 40% from natural gas, 30% from oil, 18% from coal and 4% from water electrolysis. It should be noted that the production ofH2 from fossil fuels via steam-reforming or partial oxidation processes, although leading to yields of 60-70%, is associated with massiveCO2 emissions. The same applies to thermochemical conversion of biomass forH2 production. On the other hand, for identical yields, the production ofH2 from water is less polluting, on one condition: that the primary electricity used is clean (i.e. from nuclear power plants, not thermal power plants). Nevertheless, it is obtainingH2 fromH2Ovia photoelectrolysis or photosynthesis, or even artificial photosynthesis, that is the most attractive in terms of sustainable development. However, in this case, yields are still too low, which justifies the intensity of current research in these fields.
