Hydrogen storage in an underground hydrosystem: physicochemical behaviour, monitoring and environmental impact

Underground H2 storage (UHS) is a promising technology to conserve electricity produced in excess by intermittent renewable energy sources as wind or solar. Given the explosiveness of the mixture of H2 and O2, environmental monitoring of H2 leaks to the soil surface is a major issue. The originality of this project is to study H2 leakages from a storage, their environmental impact and the site safety. Such an approach will be carried out in a unique pilot natural site (underground cavities in Saint-Emilion, SW France), which will be used as the model of formations above a H2 storage. These cavities give access to an aquifer and the unsaturated (or vadose) zone and make it possible to experimentally and numerically model the migration and transformations of H2 from storage facility to the surface. We will analyse scenarios of H2 leakage initiation and develop monitoring and prevention methods. The project is supported by three major French energy companies involved in underground H2 storage, TotalEnergies, Storengy and Térèga.