Underground hydrogen storage site suitability from the views of efficiency, cost, and risk — A site selection framework for decision-makers

Underground Hydrogen Storage (UHS) in porous media is emerging as a key enabler of large-scale, long-duration energy storage to support net-zero energy systems. However, determining suitable storage sites remains a complex, multidisciplinary challenge based on the integration of technical, economic, and risk-related considerations, often leaving an abstract “black-box” impression to non-specialists such as policy stakeholders and the public. This study presents a transparent and easy-to-grasp conceptual framework for UHS site suitability assessment, built around three interdependent pillars: efficiency, cost, and risk. Each is assessed using proxy parameters—such as permeability, depth, and well density—and combined into a unified visual model that defines a “suitability zone” representing the unified conditions under which all three aspects meet project requirements. The applicability of the framework is demonstrated by assessing a set of oil and gas fields in the Irish Sea Basin, resulting in the identification of ‘suitable sites’ for UHS that satisfy minimum thresholds across all criteria representing the three aspects. The conceptual framework supports transparent and structured decision-making by making explicit how geological, operational, and contextual factors interact to determine site suitability. The proposed approach offers a flexible and transferable decision-support tool for early-stage UHS project screening, ranking, and investment prioritisation. It is also adaptable to other subsurface technologies such as the storage of carbon dioxide and natural gas, and geothermal energy storage.