Large‐Scale Hydrogen Storage: Surface and Subsurface Challenges

ABSTRACT This review assesses underground hydrogen storage (UHS) with a focus on surface facilities, such as compressors, purification units, and buffer tanks. Many studies emphasize reservoir behavior, yet surface systems strongly influence injection stability, withdrawal rates, energy use, and subsurface parameters. The inherently fluctuating flow rates and variable thermodynamic conditions of renewable hydrogen affect surface operation and also propagate to the subsurface. These variations alter mixing behavior, gas composition, and well integrity. In reverse, subsurface processes—including well and cement integrity, geochemical and biochemical reactions, and compositional changes—create feedback on wellhead pressure, temperature, and flow composition that influences surface‐facility performance. A review of recent modeling frameworks highlights major gaps, especially in transient‐flow treatment, thermodynamic interactions, equipment sizing, and the absence of a complete system model that couples surface facilities with subsurface behavior. The findings underline the need for fully integrated surface–subsurface modeling to support reliable and cost‐effective UHS deployment.