Integration of a salt cavern for large-scale hydrogen storage into a solar-wind-storage power system: Technical and economic advantages

The problem of cross-seasonal mismatch between power supply and demand is becoming increasingly prominent in high proportion renewable energy generation systems. Relying solely on mature energy storage technologies, such as electrochemical and thermal energy storage, cannot address this challenge. In this paper, salt cavern is utilized for large-scale hydrogen storage, and complements battery and thermal energy storage to achieve multi-time scale power regulation of solar-wind power systems. The optimal combination and capacity parameters of the system are obtained through multi-objective optimization of levelized cost of energy (LCOE), loss of power supply probability (LPSP), and curtailed power amount, and the comprehensive performance is compared with the system without hydrogen devices and the system with hydrogen tanks. Results show that when the power supply reliability is extremely high, the integration of low-cost and large-scale salt cavern hydrogen storage can significantly reduce the installed capacities of power generation and energy storage devices, thereby reducing LCOE and improving power consumption ability. When the annual power demand is fully met, the LCOE of the proposed system is $0.244 /kWh, which is $0.216 /kWh lower than the system with hydrogen tanks, demonstrating a huge economic advantage. While compared to the system without hydrogen devices, the LCOE can be reduced by $0.055/kWh. More importantly, the annual curtailed power can be reduced by 76% under tri-objective optimization. Although salt cavern hydrogen storage technology has advantages in certain power supply scenarios, accelerating the reduction of unit investment costs for electrolyzer and fuel cell is particularly important.