Hydrogen is often presented as a key energy vector for the energy transition, in particular for decarbonizing sectors that are difficult to electrify. There are various types of hydrogen, including green hydrogen and low-carbon hydrogen, which differ in terms of how they are produced and their environmental impact. Today approximately 116 Mtonnes of hydrogen are produced per year in the world of which only 1% comes from green hydrogen.
Low carbon hydrogen (or low-carbon hydrogen) includes several production technologies that reduce CO2 emissions compared to gray hydrogen (produced from fossil gas without capturing CO2). He emits at least 70% fewer GHGs than fossil fuels over its entire life cycle, which is less than 3.38 kgCo2e/kgH2 (compared to 11 kgCo2e/kg/H2 for “gray” hydrogen)). The methane steam reforming is used to produce low-carbon hydrogen, combined with carbon capture and storage (CCS) technologies, with global production ofabout 0.6 Mton in 2021. It can also be obtained by electrolysis using electricity from low-emission sources such as nuclear power. It has several advantages: more competitive costs compared to gray hydrogen in the immediate future, a continuous production that makes it less dependent on the fluctuations of renewable energies and ease of implementation in industry through the use of existing infrastructures. However, it also has limitations, including the risk of methane leaks, requires appropriate infrastructure for its transport and storage, and remains dependent on fossil fuels (shown in the table below), making it a transitional solution - until 2030-2035 - but not completely decarbonized.
Different types of hydrogen and their characteristics (Zenon, May 2023)
Green hydrogen is produced by electrolysis of water using electricity exclusively from renewable sources (solar, wind, hydroelectricity). This method generates fewgreenhouse gas emissions (GHG) provided that the electricity used is decarbonized. Among its advantages, it offers zero direct emissions, a major asset for the ecological transition. It also allows energy independence from fossil fuels by valorizing renewable resources and by aligning with global climate goals. However, its cost remains high due to electrolysis technologies that are still expensive and because of the variability of renewable energies. In addition, its production requires a considerable quantity of renewable energy, whose availability remains limited; this is why Europe is calling for green hydrogen production projects to be linked to new renewable capacities, in order not to divert current resources that could be exploited in other areas.
In general, green hydrogen is an attractive long-term solution for decarbonization, but low-carbon hydrogen can play a transitory role - while waiting for costs and infrastructure to change - by gradually reducing emissions from the hydrogen sector, but the objective remains to develop green hydrogen on a large scale. To achieve this, several levers are essential:
- reduce the costs of electrolysers and improve their effectiveness ;
- invest in renewable energies, diversify the energy mix, develop storage, strengthen networks and modulate demand to ensure a stable supply;
- put in place incentive policies, such as subsidies and carbon taxes, in order to make green hydrogen more competitive.
The strategy to be adopted must be adapted to the economic, technological and regulatory contexts of each region.
The update of the National Hydrogen Strategy (SNH II) reinforces France's ambition to become a leader in carbon-free hydrogen, with a goal of 8 GW of electrolysis installed by 2035. It supports the industrialization of key equipment and the development of industrial uses such as refining or chemistry. More than 150 projects have already been financed since 2020, creating 8,000 jobs and structuring industrial hubs in Fos-sur-Mer, Le Havre and the Chemical Valley. However, the creation of a green hydrogen sector remains uncertain, as evidenced by the failure of the Belfort Mega-Factory in McPhy which has just initiated a judicial conciliation procedure and launched a call for tenders for a possible sale of assets before the end of June 2025.