A Review of Research on Underground Energy Storage in China

With the rapid development of clean energy in China, the demand for underground energy storage is increasing. This paper reviews the current status of underground energy storage and advances in safety assessment and environmental-impact mitigation. Depleted oil and gas reservoirs and salt caverns are the primary geological formations for natural-gas and compressed-air energy storage in China. As of October 2024, eight salt-cavern and 26 depleted-reservoir facilities had been constructed, accounting for approximately 90% of large-scale underground storage facilities. Oil and natural gas are the most mature storage media, followed by compressed air and carbon dioxide (CO2), whereas underground hydrogen and helium storage remain at earlier stages of development. The review compares salt caverns, depleted reservoirs, aquifers, and rock caverns in terms of capacity, sealing, cost, cycling capability, and risk. It further synthesizes theoretical, numerical, experimental, and monitoring studies. The principal risks include well or fracture leakage, caprock or cavern sealing loss, pressure-induced fracturing, salt creep, cyclic damage, hydrogen-related microbial and geochemical reactions, material degradation, and CO2 plume migration. Long-term monitoring should combine pressure, temperature, flow rate, gas composition, well integrity, deformation, microseismicity, groundwater chemistry, surface-gas geochemistry, and plume imaging. Future development should advance abandoned-mine pumped-storage hydropower, CO2 geological storage, and underground hydrogen storage through field-scale validation, coupled multi-physics models, hydrogen-compatible materials, and unified integrity standards.