Comparative analysis of thermodynamic and mechanical responses between underground hydrogen storage and compressed air energy storage in lined rock caverns

Underground hydrogen storage (UHS) and compressed air energy storage (CAES) are two viable large-scale energy storage technologies for mitigating the intermittency of wind and solar power. Therefore, it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes. This study employs a multi-physical coupling model to compare the operations of CAES and UHS, integrating gas thermodynamics within caverns, thermal conduction, and mechanical deformation around rock caverns. Gas thermodynamic responses are validated using additional simulations and the field test data. Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes. Hydrogen reaches higher temperature and pressure following gas charging stage compared to air, and the ideal gas assumption may lead to overestimation of gas temperature and pressure. Unlike steel lining of CAES, the sealing layer (fibre-reinforced plastic FRP) in UHS is prone to deformation but can effectively mitigates stress in the sealing layer. In CAES, the first principal stress on the surface of the sealing layer and concrete lining is tensile stress, whereas UHS exhibits compressive stress in the same areas. Our present research can provide references for the selection of energy storage methods.