Feasibility analysis of underground flow battery storage in bedded salt rocks of China

Abstract

Flow batteries are a promising method for large-scale energy storage. This paper proposes an underground flow battery storage (UFBS) system that uses a salt cavern as an electrolyte reservoir and combines wind and solar power. The types of flow batteries suitable for UFBS were investigated. According to the distribution characteristics of wind and solar energy and available salt caverns, potential areas for UFBS were identified, located in eastern, southern, and northwestern China. Taking the Jintan salt mine in Jiangsu Province as an example, a 220 MW/1100 MWh dual-cavern UFBS system is proposed. The effective volume of a single cavern is 170,000 m3, and the design cycle life is 20 years. A numerical simulation model was established to analyze the long-term stability of the system under different operating conditions. It was found that after 20 years, the maximum roof settlement and waist deformation were 0.113 m and 0.224 m, respectively, and the volume loss rate was <1.78 %. The system had good stability. Finally, the techno-economic profits of the UFBS system were calculated and the problem of permeability was examined. This study provides a novel and feasible solution for large-scale energy storage in salt-rich regions of China.