Comparative techno-economic analysis of large-scale underground hydrogen storage

Hydrogen, serving multiple roles such as energy storage, feedstock, and fuel, is an energy carrier currently receiving significant attention. Underground hydrogen storage (UHS) is considered a safe, economical, and efficient solution for large-scale hydrogen storage, although few techno-economic studies have been conducted. This paper develops a model for calculating the levelized cost of hydrogen storage (LCOHS) in depleted gas reservoirs (DGR), salt caverns (SC), and lined rock caverns (LRC) based on engineering cases. The study focuses on the effects of hydrogen storage scale and injection-withdrawal frequency on LCOHS, providing data to support energy management and policy development from an economic perspective. The results show that: (1) For a storage capacity of 107 kg and one injection–withdrawal cycle per year, the LCOHS is $0.70/kg for SC, $0.76/kg for DGR, and $0.92/kg for LRC. These values are significantly more advantageous compared to surface hydrogen storage. (2) Although the capacity of DGR is difficult to adjust artificially, the LCOHS remains relatively low within the storage range of 105 to 109 kg. SC and LRC exhibit favorable economic performance when the storage capacity exceeds 106 kg. (3) DGR are more suitable for low-frequency injection–withdrawal operations. As the annual injection–withdrawal frequency increases to five cycles, the LCOHS drops to $0.38/kg for SC and $0.31/kg for LRC, demonstrating a clear economic advantage. The study's findings are informative for the development of large-scale UHS.