Underground storages, reservoirs and deep drilling In the context of both the energy transition and the fight against climate change, the underground environment offers numerous opportunities for storage, whether in natural reservoirs (hydrocarbon deposits, deep aquifers) or in structures specifically built for storage (salt cavities, mine cavities). Today these structures are mainly used to store gas, hydrocarbons or waste . However, in the future, they could fulfil society’s strategic needs, especially for storing renewable energy (such as compressed air or hydrogen), heat or CO2. Managing potential risks is clearly a determining factor among the conditions for developing these industrial solutions in an acceptable way. For many years, Ineris has been involved in issues of industrial safety for the underground storage (gas, hydrocarbons, waste, energy, CO2) through its numerous research projects, its support program for the French Ministry of the Environment and the expert consultation it provides to industry. The Institute relies on its background of expertise in deep underground accidental risk to make recommendations for risk assessment and safety measurement in the context of reservoirs, shafts and surface installations related to underground storage sites. The Institute is involved throughout the lifecycle of underground storage sites, from conception and development to operation and decommissioning. It uses its multidisciplinary skills and expertise to support industrial operators and public decision-makers in completing authorization applications at each of these steps. In particular, Ineris has developed a unique expertise in the decommissioning of commercial underground sites, mines and storage areas, with priority given to helping operators and public authorities make these sites safe for the very long term. Finally, the Institute is deeply committed in the field of deep drilling safety, whether applied to hydrocarbon exploration or exploitation (onshore and offshore), deep geothermal energy or any other use of the underground that involves drilling (solution salt mining, coal gas, new mines, etc.).