Thermodynamic Analysis of Hydrogen Storage in Lined Rock Cavern with Different Sealing Layer Materials and Thicknesses

This study investigates the effects of different sealing materials, steel lining and Fiber-Reinforced Polymer (FRP), on the thermodynamic properties of hydrogen storage in lining rock caverns (LRCs). A thermodynamic coupling equation for hydrogen storage in LRCs was developed, and its validity was confirmed by comparison with simulations and data from the Huntorf power station. The leakage rate, temperature changes, and stress distribution of steel and FRP sealing layers with varying thicknesses were analyzed over a 30-day period. The results show that the leakage rate of the FRP layer decreases significantly with thickness, with a peak leakage of 1.3 g/s for the 10 mm layer, stabilizing at around 0.1 g/s for the 100 mm layer. Temperature fluctuations within the cavern are periodic, with more pronounced changes in the FRP layer as its thickness increases. Steel lining experiences minimal temperature changes. Additionally, increasing the FRP thickness results in larger fluctuations in the principal stress of both the sealing and lining layers, impacting the surrounding rock mass. The FRP lining experiences higher tensile stress, while the steel lining shows smaller changes. A thicker FRP layer also increases normal and shear stresses in the surrounding rock, potentially affecting cavern stability. These findings emphasize the importance of selecting appropriate sealing materials and thicknesses to improve the efficiency and stability of hydrogen storage systems.