Underground hydrogen storage: A UK perspective

Hydrogen is anticipated to play a key role in global decarbonization and within the UK's pathway to achieving net zero targets. However, as the production of hydrogen expands in line with government strategies a key concern is where this hydrogen will be stored for later use. This study assesses the different large-scale storage options in geological structures available to the UK and addresses the surrounding uncertainties moving towards establishing a hydrogen economy. Currently, salt caverns look to be the most favourable option, considering their proven experience in the storage of hydrogen, especially high purity hydrogen, natural sealing properties, low cushion gas requirement and high charge and discharge rates. However, their geographical availability within the UK can act as a major constraint. Additionally, a substantial increase in the number of new caverns will be necessary to meet the UK's storage demand. Salt caverns have greater applicability as a good short-term storage solution, however, storage in porous media, such as depleted hydrocarbon reservoirs and saline aquifers, can be seen as a long-term and strategic solution to meet energy demand and achieve energy security. Porous media storage solutions are estimated to have capacities which far exceed projected storage demand. Depleted fields have generally been well explored prior to hydrocarbon extraction. Although many saline aquifers are available offshore UK, geological characterizations are still required to identify the right candidates for hydrogen storage. Currently, the advantages of depleted gas reservoirs over saline aquifers make them the favoured option after salt caverns.