In the future energy system with a high share of renewable sources, the role of hydrogen will be essential to deal with the fluctuations in the electricity produc-tion. Hydrogen is understood as a system capable of storing energy for a later use in a controlled way. In this way, surplus electricity coming from renewable energies is used for generating hydrogen by the electrolysis process. Once pro-duced, hydrogen is stored in one of the different underground storage structures to be used when needed. In this context, the aim of this research is to provide a preliminary evaluation about the potential for underground hydrogen storage in the country of Spain, considering the usual geological formations of these sys-tems (deep aquifers, salt caverns and depleted hydrocarbon fields). The analysis of each alternative has allowed highlighting that Spain presents potential loca-tions where future hydrogen storage could be feasible. Regarding salt caverns, this country has high onshore storage capacities, with a total of located 24 cav-erns. Furthermore, the Spanish potential of hydrogen storage in aquifers is also relevant especially in Tertiary sedimentary basins as the Ebro, Duero and Gua-dalquivir basins. The storage potential in depleted oil and gas fields is however reduced due to the limited hydrocarbon activity of the country.
