Underground hydrogen storage: Characteristics and prospects

In this study underground hydrogen storage in various storage types (aquifers, depleted deposits of natural gas and oil, salt caverns) is examined. A road map for the implementation of underground hydrogen storage is presented. Underground hydrogen storage does not significantly differ from natural gas storage. Nevertheless, it is not yet an available and technically feasible manner of storing energy and it will not prove to be one in the near future. The lower cost of hydrogen production through electrolysis will be the decisive factor for the implementation of this method of energy storage on an industrial scale. Numerous problems and challenges in this field are presented. The fact that specific properties of gaseous hydrogen will have to be handled adequately to provide tightness during underground storage, transport and withdrawal has been noted. The choice of geological structures for underground hydrogen storage should be based on a detailed geological analysis, taking geological and engineering criteria into account. Any possibility of hydrogen escape beyond the limits of an underground storage facility should result in the rejection of the hazardous location. The factors related to the surface installations should be considered only after the selection based on geological criteria has been conducted. Geological, technological, economic, legal and social obstacles have to be overcome before the underground hydrogen storage is implemented on a full scale. As a result of the complexity of the issue coupled with the lack of experience in this kind of operations a prolonged period of studies can be expected. Any future implementations will have to be preceded by extensive studies aimed at a better understanding of the processes of hydrogen interaction with ambient rocks and the installations. Plans to reduce all the hazards involved should be prepared. These activities should proceed in well-defined time frames.