Underground hydrogen storage is essential to meet the world’s growing energy needs, particularly in the context of the energy transition and the rise of hydrogen as an energy carrier. By 2030, Europe aims to integrate hydrogen up to a quarter of its annual primary energy consumption in France. To achieve this goal, the European Union has set out an ambitious plan to produce 10 million tonnes of hydrogen using electrolysers with a total capacity of 40 gigawatts (GW), as well as to import 10 million tonnes of renewable hydrogen.

To store such quantities of hydrogen, underground storage solutions are envisaged, including saline cavities, porous reservoirs and coated mined cavities. Saline cavities, which consist of storing hydrogen in cavities created by dissolution of a geological layer of salt, are considered a preferred option due to their low cost and flexibility. These cavities, present in various parts of the world, can store large quantities of hydrogen under pressure.

Porous reservoirs, meanwhile, consist of rock formations with natural voids. They have been used since 1915 for natural gas storage and can be adapted for hydrogen storage. However, challenges related to hydrogen migration in porous rock need to be taken into account.

Coated mined cavities are another promising option for underground hydrogen storage. These cavities consist of galleries dug into hard rocks, coated with a waterproof membrane to isolate hydrogen. This technique requires in-depth studies and technical developments to ensure the tightness and safety of storage.

 

As regards hydrogen transport, several methods are envisaged, including transport in ships specially designed for liquefied hydrogen at very low temperatures (-253°C). However, further research and development is needed to optimize containment systems and reduce liquefaction costs.

Overall, underground hydrogen storage is a key element of the energy future, ensuring stable supplies and meeting growing demand for clean energy. Continued investment in research and development is essential to overcome the technical and economic challenges associated with these underground storage technologies.