Seasonal and Long-Term Underground Hydrogen Storage in Tight Reservoir: Hysteresis Effects and Scaling Assessment for Energy Transition at the Mae Moh Coal-Fired Power Plant.

Thailand's largest coal-fired power plant at Mae Moh is transitioning toward renewable energy, yet no scalable storage solution is currently available. The current study assesses underground hydrogen storage (UHS) in the basin's tight sandstone formation, emphasizing the critical but often overlooked role of hysteresis in governing multiphase flow. A representative geological model was developed and tested through 50-year reservoir-scale simulations to evaluate hydrogen plume migration, reservoir pressure evolution, and recovery under seasonal storage cycles. Results show that hysteresis effects in tight sandstone substantially reduce recovery, limiting the base case to 37% by the final cycle with significant pressure build-up. An improved dual-production well design enhanced pressure management and raised final-cycle recovery to 65%, which had not yet fully plateaued at the end of the 50-year horizon. Scaling analyses, however, indicate that the basin's limited areal extent (<150 km2) is smaller than the ∼242 km2 required to meet regional demand. These findings indicate both the technical feasibility and spatial limitations of UHS in tight formations, offering a first-order basis for site selection and storage design.