Hydrogen: one atom, several sources, many uses
Hydrogen, discovered by Cavendish in 1766, is a chemical element occurring naturally but which can also be extracted from primary resources. Hydrogen is already put to many uses. The key challenge in terms of the energy transition is succeeding in the “clean” capture of hydrogen.
Sources of hydrogen
The main primary resources used to produce hydrogen are water and hydrocarbons (coal, oil and gas). Each water molecule is created through the combination of one oxygen atom and two hydrogen atoms, giving H2O. Hydrocarbons meanwhile are created from a combination of carbon and hydrogen atoms. This is the case for methane or natural gas, the formula of which is CH4, one of the most simple hydrocarbon combinations.
Hydrogen also exists in a natural state. The first natural hydrogen sources were discovered at the bottom of the ocean in the 1970s. Other sources have since been found on land. But the profitable production of hydrogen is still a distant prospect. Further progress still needs to be made on our knowledge of the origin of the formation of naturally occurring hydrogen and on research into production techniques.
Regarding environmental protection, the main use of hydrogen is the elimination of sulphur, a natural component of oil, in order to produce cleaner fuels.
Combined with a fuel cell, hydrogen is also a remarkable source of clean energy as it can be used to produce electricity on board electric vehicles as well as in areas not connected to the power grid and in sensitive sites.
Hydrogen played a key role from the very beginnings of the space industry as a rocket fuel. It is the fuel with the highest energy concentration, containing three times more energy per kilo than petrol. This is of crucial importance given that a rocket launcher needs to be as light as possible.
Contribution to the energy transition
Hydrogen could fulfil two key objectives in the energy transition. First of all, it reduces carbon in the transport sector (though the solution is environmentally favourable only if the hydrogen is produced using carbon-free sources, see the article “Hydrogen, a sound choice for the energy transition”). Second, it offsets variability in the production of some renewable energies, as hydrogen can be stored.
But the production of “green hydrogen” has yet to become a reality. A full 95% of today’s hydrogen is produced using fossil fuels. The situation requires a transformation in energy systems and the technical and economical paradigm.
- Sources : Air Liquide, Engie, IFP Energies nouvelles
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