Evaluation of Free Surface Energy of H2+CO2/ Basalt /Brine System in Underground Hydrogen Storage

Summary Hydrogen(H2) is a promising option for energy transition purposes, however, large-scale surface storage will pose numerous technical and environmental challenges. Underground formations offer a viable solution for large-scale H2 storage, but understanding behaviour of H2 in different subsurface conditions is critical. This behaviour greatly affects the capacity and efficiency of H2 storage and is profoundly linked with rock surface properties such as wettability and interfacial properties. Basalt formations may serve as viable options for underground H2 Storage. Additionally, at different stages in injection, H2 is not purely exposed with the formation and can be mixed with other gases such as carbon dioxide (CO2). Following up on that, in this study, we investigated H2 and CO2 mixtures’ wettability in presence of basalt. We measured H2 and CO2 contact angle in various pressures and temperatures, and our findings reveal that mixed gases contact angles are significantly influenced by temperature and pressure. Moreover, we emphasize the importance of cushion gas in underground hydrogen storage as it plays a pivotal role in minimizing hydrogen trapping and enhancing CO2 capture in Underground Hydrogen Storage (UHS) and Carbon Capture, Utilization, and Storage (CCUS) projects for sustainable energy solutions.