Perpustakaan Digital ITB

Global transition toward Net Zero Emissions has positioned hydrogen (H2) as a strategically important large-scale energy carrier, particularly when produced from renewable sources via water electrolysis. Underground Hydrogen Storage (UHS) in saline aquifers offers large geological storage capacity and wide geographic distribution, making it a technically and economically viable pathway for seasonal-scale energy storage. This study uses a synthetic saline aquifer model, Field-X, featuring a structured closed anticlinal trap with a brine-saturated porous sandstone reservoir, representative for evaluating UHS performance in water-bearing formations given hydrogen's low dynamic viscosity (approximately 8.9 × 10?6Pa·s) and high molecular diffusivity (approximately 0.6 cm2/s), which promote viscous fingering, gravity override, and diffusive mixing that progressively deteriorate hydrogen purity. This study presents a compositional reservoir simulation evaluating three cushion gas configurations, namely no cushion gas, CO2 + H2, and CH4 + H2, across nine cyclic injection-production rate combinations, yielding 27 scenarios in total for the operational period 2030 to 2050. Production rate is the dominant operational variable governing hydrogen purity, while injection rate exerts a comparatively secondary influence. At a production rate of 5 MMSCFD, H2 mole fraction remained above 0.95, whereas 30 MMSCFD induced premature breakthrough, driving H2 fractions below 0.80 within fifteen years. Hydrogen recovery efficiency (HRE) increased from approximately 82% to 95% as the cushion gas to hydrogen ratio rose from 0 to 1.0. Among the three cushion gas configurations, the CH4 + H2 system consistently outperformed the others in hydrogen recovery efficiency (approximately 90% by 2050), reservoir pressure maintenance, storage capacity (approximately 140 MMRB by Year 2), and produced H2 purity. Scenario S-5, combining an injection rate of 45 MMSCFD and a production rate of 15 MMSCFD with the CH4 + H2 cushion gas system, was identified as the most technically and economically balanced configuration, maintaining H2 mole fractions above 0.93 throughout the 20-year simulation period. These findings indicate that production rate control, rather than attempts to physically suppress the mixing zone, is the most effective operational lever for managing hydrogen purity in saline aquifer UHS systems. Scenario S-5 with the CH4 + H2 cushion gas system is therefore recommended as a quantitative, simulation-validated reference design basis for UHS feasibility planning in analogous saline aquifer formations within Indonesian sedimentary basins, supporting the national hydrogen energy roadmap.