Converting underground natural gas storage for hydrogen: A review of advantages, challenges and economics

In the natural gas era, an underground gas storage capacity of more than 10 trillion cubic feet has been developed globally. However, as the global energy demand shifts toward hydrogen, the potential for repurposing these storage facilities for hydrogen has not been systematically investigated. In the hydrogen era, failing to utilize this substantial volume could result in significant resource wastage. This study systematically analyzes the feasibility of Converting Underground Gas Storage (CUGS) for hydrogen for the first time. We establish a new conceptual framework by carefully exploring the reuse potential of surface facilities and evaluating the effects of reservoir environment changes. Based on these analyses, we summarize the advantages and challenges of this technical framework. In addition, an economic assessment is conducted by comparing the CUGS route with the traditional method of Converting Depleted Gas Reservoirs (CDGR) for hydrogen storage. Our results show that the CUGS route will face significant challenges, including water intrusion, geochemical reactions, leakage, and potential integrity damage. Nevertheless, it remains a rapid, stable, and low-cost method for underground hydrogen storage. In particular, our findings indicate that it can increase economic benefits by 3.1 times compared to the traditional CDGR route. Such evidence suggests that the CUGS route offers a large-scale, stable, and economical option for underground hydrogen storage, while also avoiding the abandonment of existing underground natural gas storage facilities in a future hydrogen-oriented society.