Over the last decade, there has been a growing interest in the large-scale use of hydrogen in the
transportation and renewable energy sectors. Underground geologic storage of hydrogen gas could offer substantial energy storage cost reductions as well as buffer capacity to meet possible interruption in energy supply or changing of the seasonal demands. Generally, underground hydrogen storage does not significantly differ from natural gas storage or CO2 geological storage and much of the gained know-how can be transferred from these technologies. Geologic storage site options include salt caverns, depleted oil and/or gas reservoirs, aquifers, and hard rock caverns. Nevertheless, it is not yet an available and technically feasible way of storing energy and it requires more detailed and extensive studies. One of the main aspects is that gaseous hydrogen must be handled adequately to provide tightness during underground storage, transport and withdrawal so that mixing gaseous species can be potentially considered to reduce risks and improve safety. The choice of geological structures for underground hydrogen storage should be based on a detailed geological analysis, taking geological and engineering criteria into account.
The factors related to the surface installations should also be considered, once the selection based on geological criteria has been conducted. Geological, technological, economic, legal and social obstacles need to be addressed before the underground hydrogen storage is implemented on a full scale. In this proposal, the potential of the Italian territory to hydrogen geological storage will be assessed using a regional approach, as already tackled for other gasses storage (methane and CO2), to improve our knowledge on different aspect of gas storage processes and to provide information to decision decision-makers.
