Underground hydrogen storage: Comprehensive screening and ranking of depleted oil and gas reservoirs for their potentials

Underground Hydrogen Storage (UHS) in depleted oil and gas reservoirs is critical to the hydrogen economy, providing a means to balance seasonal fluctuations in renewable energy supply and demand. The key to ensuring a stable and efficient UHS is to select a suitable storage site. Here we reviewed existing and potential UHS projects worldwide and developed a comprehensive screening and scoring system for UHS site assessment. We first propose a novel set of criteria covering three principal areas: enhancing storage and withdrawal efficiency, minimizing risks, and addressing environmental and economic impacts. These criteria are further divided into a framework of sub-criteria, with disqualifying thresholds defined based on their effects on UHS. The screening criteria with thresholds could be used for preliminary screening for UHS sites. Next, we establish an associated scoring system for each criterion, ranging from 1 (least suitable) to 5 (most suitable) for UHS. In practice, each criterion could be weighted according to its significance to the project, and a total UHS site score could be obtained by the weighted sum. Unlike previous studies, we investigate each criterion and its threshold on previous experiments and simulation results to ensure an evidence-based UHS site evaluation system. By establishing clear thresholds and scoring metrics for UHS sites in depleted oil and gas reservoirs, we ensure that the criteria are practical and applicable across various geological and operational contexts. Looking forward, further validation and integration with operational, economic, and infrastructure considerations are essential for long-term success. • A novel screening and scoring system for UHS in depleted reservoirs is proposed. • Criteria integrate geological, technical, and economic factors for site assessment. • Thresholds are based on experimental and simulation data for robust evaluation. • The framework ensures systematic, evidence-based UHS site selection.