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.
The previously obtained experience in gas storage, including hydrogen storage in salt caverns in the US and the UK, show that underground hydrogen storage is a technically feasible way to store energy in areas with an adequate geological structure.
Geological, engineering, economic, legal and social issues have to be overcome before the full-scale underground hydrogen storage will be implemented, similarly as is the case with the underground storage of carbon dioxide, following a roadmap that can design this process. For Europe, and for Italy, this roadmap can be considered the Green Deal, published in 2020, that see hydrogen storage as a potential resource to integrate energy production for renewables sources.
The choice of locations for the underground hydrogen storage is an important aspect to define, and, as in the case of the other underground activities, this evaluation phase, characterized by low TRL, is a field
where universities can give a substantial contribution to the advancing of knowledge.
At present, an inventory of hydrogen storage locations for Italy does not exists; on the other side, we think that it is an important tool as support for decision decision-makers and public authorities. The possibility to work on the definition of ranking criteria for our territory is in fact a strong contribution of to the approaching of the problem. We aim to start this evaluation, to develop estimation methods for the potential capacity of underground hydrogen storage; using numerical simulation in the last part of the project we also would like to work on the elaboration of prediction methods regarding how stored hydrogen will behave in the underground storage facility.
In this framework is placed this proposal, with the aims to be a first step for the full understanding of the processes of hydrogen storage in the Italian peninsula. Moreover, the participants are proposing an investigation that never has been applied to Italian territory before and that can assume a very important value in the future. The analysis performed during this project will increase the knowledge of the studied sites and will create specific methods and standardized approaches for site selection and capacity evaluation for hydrogen. These procedures will also allow us to characterize the Italian territory using up-to-date European and Italian criteria and allow further international collaborations for our research community that can be applied to the study and assessment of hydrogen storage feasibility and capacity evaluation. This can collocate the research group in an international contest where the acquired knowledge can be proposed and used to obtain collaboration and further possibility of financial support at a European scale. At the same time, collaboration can be possible in this field of study with industries that are interested in this kind of results, having the need to select adequate locations and that can provide detailed geological information based on geophysical surveys, boreholes, and modelling.