Comprehensive evaluation of green hydrogen storage in an ultra-deep horizontal salt cavern

Driven by the demand for green and low-carbon development, the underground salt cavern has emerged as a significant method for large-scale hydrogen storage and mitigating cross-seasonal peak load. However, the extreme migration behavior of hydrogen presents a challenge in accurately assessing the suitability of bedded salt formations for hydrogen storage. Consequently, there is an urgent need to establish a feasibility assessment framework tailored to salt cavern hydrogen storage. In this work, a feasibility evaluation framework encompassing the geomechanical stability, airtightness performance, and economic viability is proposed. Based on the Jianghan salt mine in Hubei, the viability of horizontal salt caverns for hydrogen storage is comprehensively demonstrated. The potential shape of the Jianghan salt cavern is analyzed using the physical simulation method. A three-dimensional geomechanical model is developed to assess the mechanical stability and tightness of the surrounding rock. Furthermore, an economic evaluation model that encompasses the life cycle was constructed to determine the optimal economic indicators for the operation of storage. The findings demonstrate that the permissible operating pressure range is 14∼36 MPa, with an optimal gas extraction rate of 0.5–0.6 MPa/d, and an annual average leakage rate is maintained at below 1 %. The preferred internal rate of return is 10 %, the project payback period is 5.6 years, and the levelized cost of hydrogen storage is calculated to be 14.76 yuan/kg. The research results hold significant theoretical implications for the construction and operational management of salt cavern hydrogen storage.