Salt Cavern Hydrogen Storage for Renewable‐Dominated Smart Energy Systems

Power systems with high shares of variable renewable energy increasingly face balancing challenges that extend beyond intraday variability to multiday shortages, seasonal mismatch, resource adequacy and system resilience. Salt cavern hydrogen storage (SCHS) has emerged as a promising underground hydrogen storage option for renewable‐dominated smart energy systems. It can act as the large‐scale storage component that connects renewable hydrogen production with downstream hydrogen use and power‐to‐hydrogen‐to‐power pathways. This review examines SCHS from a power‐system integration perspective. It synthesises the geological and operational characteristics that enable large‐scale hydrogen storage. It then evaluates the contributions of SCHS to renewable integration, multi‐timescale flexibility, clean firm capacity, ancillary services and resilience. The review also examines modelling approaches for coupled electricity–hydrogen systems, including cavern constraints, intertemporal dynamics and cross‐sector coordination. It further discusses the policy, regulatory and market conditions required for large‐scale deployment. SCHS is not a universal storage technology. It is a context‐dependent infrastructure option whose value becomes most important in renewable‐dominated power systems where short‐duration storage alone cannot meet long‐duration flexibility and reliability needs.