Underground Hydrogen Storage in Engineered Lenses

Hydrogen can play a significant role in Australian economy and Australia has set an ambitious goal to become a global leader in hydrogen industry as outlined in the National Hydrogen Strategy 2024. Hydrogen is an efficient energy carrier that can be used for both transporting and storing energy. Underground hydrogen storage (UHS) in aquifers, depleted gas and oil reservoirs, and salt caverns have been considered as a low-cost option for largescale storage of hydrogen. In this study, a method for hydrogen storage in engineered (shallow) lenses is proposed, where a lens is created in a very low permeability layered formation such as shales via opening the layers by a pressurised fluid. A preliminary overview of the Australian basins is presented, focussing on the most suitable/obvious units for the purpose of creating engineered lenses for storage of hydrogen. Major engineering aspects of lenses such as size, volume, storage capacity, storage time, and hydrogen loss are reviewed, followed by a Techno-Economic Analysis for the proposed hydrogen storage method. Initial modelling shows that up to 250 tonnes of hydrogen can be stored in shallow engineered lenses, incurring a capital cost of 35.7 US$/kg and total annual operational cost of 7 US$/kg, making the proposed storage method a competitive option against salt and lined rock caverns. Finally, Monitoring and Verification (M&V) as part of storage assurance practice has been discussed and successful examples are presented.