Designing Geometrically Stable Salt Caverns for Underground Hydrogen Storage: A Case Study from Northeast England
Saeed Harati, Sina Rezaei Gomari
Abstract
High Resolution Image Download MS PowerPoint Slide Underground hydrogen storage (UHS) in salt caverns is essential for enabling seasonal energy balance and enhancing the resilience of future hydrogen-based energy systems. The long-term mechanical stability of such caverns is highly dependent on their geometry and the viscoplastic behavior of the host salt rock. This study presents a comprehensive geomechanical assessment of multiple cavern geometries within the Boulby Halite Formation in Northeast England, a region of increasing strategic relevance for hydrogen infrastructure deployment. Using a three-dimensional finite difference approach, the stability of spherical, bell-shaped, inverted bell-shaped, droplet-shaped, undulating-walled, ellipsoidal, and cylindrical caverns with varying aspect ratios was evaluated under realistic cyclic hydrogen injection and withdrawal scenarios over a 30 year operational period. Results demonstrate that the cavern geometry critically governs stress redistribution, deformation, and operational viability. Symmetrical or tapered configurations with broader bases, particularly spherical, droplet-shaped, and bell-shaped caverns, exhibited the most favorable performance, consistently maintaining strength-to-stress ratios above 1.0, effective strains below 0.1%, and volume shrinkage under 8%. In contrast, geometries with sharp curvature changes or enlarged caps showed stress amplification on the roof and floor, increasing the instability. Moreover, elongated profiles with high diameter-to-height ratios ( d / h ) in cylindrical and ellipsoidal caverns led to localized overstress, nonuniform strain, and up to 10.7% volume loss. Overall, the findings provide quantitative design insights for safe, long-term UHS in bedded halite formations, supporting robust hydrogen grid integration in Northeast England and similar geological settings.