Screening and ranking Japanese gas fields for underground H2 storage potential: Impact of the reservoir drive mechanism

To accomplish the net-zero goal, Japan intends to increase its reliance on renewable energies such as solar power (36-38 % in 2030). However, considering the intermittent nature of solar power, the resulting energy must be transformed to a secondary energy carrier such as H2. Japan, on the other hand, is expected to import 20 x 106 tons of H2 each year by 2050. Because of these large volumes, new H2 storage techniques must be developed, in particular underground hydrogen storage (UHS). This paper ranks eight gas reservoirs out of 106 oil and gas fields in four Japanese prefectures regarding their suitability for UHS, and then suggests a H2 injection and withdrawal scheme based on the history of electricity consumption and solar power curtailment. Then, a reservoir simulation study was performed to investigate the effects of factors such as hysteresis, repeated cycles and cushion gas on the performance of these fields. The outcomes for water-drive and volumetric gas reservoirs were compared to better understand the effects of an aquifer on the long-term performance of a gas reservoir when used for UHS. Finally, it was demonstrated that the technology sought for the conversion of H2 back to electricity after withdrawal from a UHS site governs the overall efficiency of a power-H2-power process.