Does the United Kingdom have sufficient geological storage capacity to support a hydrogen economy? Estimating the salt cavern storage potential of bedded halite formations

Hydrogen can be used to enable decarbonisation of challenging applications such as provision of heat, and as a fuel for heavy transport. The UK has set out a strategy for developing a new low carbon hydrogen sector by 2030. Underground storage will be a key component of any regional or national hydrogen network because of the variability of both supply and demand across different end-use applications. For storage of pure hydrogen, salt caverns currently remain the only commercially proven subsurface storage technology implemented at scale. A new network of hydrogen storage caverns will therefore be required to service a low carbon hydrogen network. To facilitate planning for such systems, this study presents a modelling approach used to evaluate the UK's theoretical hydrogen storage capacity in new salt caverns in bedded rock salt. The findings suggest an upper bound potential for hydrogen storage exceeding 64 million tonnes, providing 2150 TWh of storage capacity, distributed in three discrete salt basins in the UK. The modelled cavern capacity has been interrogated to identify the practical inter-seasonal storage capacity suitable for integration in a hydrogen transmission system. Depending on cavern spacing, a peak load deliverability of between 957 and 1876 GW is technically possible with over 70% of the potential found in the East Yorkshire and Humber region. The range of geologic uncertainty affecting the estimates is approximately ±36%. In principle, the peak domestic heating demand of approximately 170 GW across the UK can be met using the hydrogen withdrawn from caverns alone, albeit in practice the storage potential is unevenly distributed. The analysis indicates that the availability of salt cavern storage potential does not present a limiting constraint for the development of a low-carbon hydrogen network in the UK. The general framework presented in this paper can be applied to other regions to estimate region-specific hydrogen storage potential in salt caverns