Numerical investigation of repurposing oil storage caverns for hydrogen storage using lined rock cavern (LRC) technology

Abstract

The growing demand for large-scale geological hydrogen storage has driven the exploration of resource-efficient methods for repurposing existing underground infrastructure. This study assesses the technical feasibility of converting underground oil storage caverns into lined rock caverns (LRCs) for hydrogen storage and evaluates the material costs associated with two proposed design schemes. Two retrofit schemes were analyzed numerically using parameters derived from an existing LRC demonstration project. The ultimate and maximum operating gas pressures were determined using the uplift failure model, considering cavern burial depth and the mechanical properties of the surrounding rock mass. Structural responses under pressurization were evaluated, followed by a comparative assessment of concrete and steel liner costs. The results indicate that dividing the original cavern into multiple lined sub-caverns separated by concrete pillars improves structural performance and reduces the maximum tensile stress in the steel liner, although tensile-stress concentrations may develop in the concrete pillars. Meanwhile, the proposed Single-cavern scheme offers significantly higher hydrogen storage capacity with lower concrete requirements but a larger steel liner area. A supplementary short-term cyclic thermo-mechanical analysis revealed response-dependent differences from the corresponding static analysis. The static analysis overestimated the maximum tensile stress in the steel liner and the plastic-zone volume in the concrete liner, while underestimating the plastic-zone volumes in the rock-mass and total system. These findings highlight the importance of cyclic thermo-mechanical effects on LRC response while supporting the applicability of static analysis as a preliminary assessment approach, provided that an adequate safety margin is adopted when determining the maximum operating gas pressure. Additionally, in both schemes, the tensile-stress level in the steel liner remains low, suggesting significant potential for liner optimization in material selection and liner thickness. Overall, the results indicate that repurposing oil storage caverns as LRCs is a technically feasible retrofit option, while overall economic feasibility should be further evaluated through life-cycle cost analysis.