Underground hydrogen storage in aquifers, depleted oil and gas reservoirs, salt caverns, and hard-rock caverns has long been regarded as a cost-effective option for large-scale hydrogen storage. However, subsurface storage introduces several technical challenges arising from the specific physicochemical properties of hydrogen. These include potential reactions between hydrogen and the reservoir or caprock, mixing with residual hydrocarbons, losses to surrounding formations or microbial consumption, and the requirement for cushion gas to maintain adequate reservoir pressure. This study proposes an alternative approach for short-term hydrogen storage in shallow shale formations. The method involves creating an engineered lens by hydraulically opening shale layers horizontally using a pressurised fluid. A preliminary assessment of Australian sedimentary basins is conducted to identify shale units most suitable for the development of such engineered lenses. Key engineering considerations – including lens dimensions, storage volume, capacity, storage duration, and hydrogen loss mechanisms – are examined, followed by a techno-economic analysis of the proposed storage concept. The analysis indicates that engineered lens storage is cost-competitive with salt caverns and lined rock caverns of comparable capacity. Finally, the integrity of the storage system can be reliably assessed using established monitoring and verification techniques, which enable confident tracking of lens geometry, position, and volumetric changes.
Salimzadeh et al. (Thu,) studied this question.