Thermo-dynamic and economic analysis of s a novel near- isothermal pumped hydro compressed air energy storage system

With the large-scale use of intermittent renewable energy worldwide, energy storage systems are important for dealing with the fluctuation of renewable energies. In this paper, a novel near- isothermal pumped hydro compressed air energy storage system without thermal energy storage is proposed; The exhausted salt cavern of double well is employed as the air storage vessel in this proposed system. To detect the thermodynamic and economic of this system, the detailed thermodynamic and economic model of both the main components and the whole system have been built. The results showed that the electrical efficiency of the system can reach 61.6%, and the exergy efficiency can achieve 72.3%. Moreover, the economic performance of the system shows that the cost of cavern is more than 60% of the total energy storage system. The payback period of the proposed system decreases with the increase of output power of energy storage system. By numerical calculation, when the energy storage scale of the system is 4MW, the payback period of the system is reduced to 6.15 years.