Selection Criteria for Underground Hydrogen Storage

The selection criterion for future underground hydrogen storage may initially be based upon the storage capacity combined with the proximity to the hydrogen transport network. This market driven approach neglects other information which may strongly influence the economics of such storage. Several risks such as legacy or abandoned wells, cap rock quality or microbial activity might alter the development of the underground storage. The Analytical Hierarchy Process was applied to identify the most suitable storage opportunity between salt caverns and porous media traps (covering depleted fields, existing underground gas storages and aquifers). Seven criteria were used in the analysis: the lithology of the seal, its estimated minimum thickness and lithology, the existing faults and number of abandoned wells, the lithology of the storage and its readiness level (estimated time to market), and the microbial risk. Following this analysis, when suitable salt deposits are available in a country, salt caverns are likely to be the most suitable setting for underground hydrogen storage. Porous media storages such as depleted gas fields or conversion of existing natural gas storages may also be suitable opportunities for underground hydrogen storage.