Pressurized cryogenic air energy storage for efficiency improvement of liquid air energy storage

Abstract

With the development of renewable energy sources, large-scale energy storage has been studied such as advanced compressed air energy storage (CAES) and liquid air energy storage (LAES). In this study, a novel pressurized cryogenic air energy storage system (PCAES) is proposed and analyzed. The conventional LAES system produces and stores the liquid air at the ambient pressure. The system achieves 40% to 60% of round-trip efficiency depending on the use of liquid turbo-expander. Meanwhile, this proposed system stores the air near the critical point by expanding it at 40 bar using turbo-expander. This significantly reduces the energy input in comparison to liquefying the air. This system is modeled with commercial process simulation software, Aspen HYSYS v.8.8. It significantly improves the round-trip efficiency of the conventional stand-alone liquid air energy storage system. However, this system requires pressurized tanks for the supercritical air storage. The economic evaluation for energy storage cost should be analyzed depending on variables such as storage time, storage to generation power ratio, and size of the power system. The above-ground CAES, LAES, and the proposed system would be the competitive system without geological limitations and are potentially applicable for the various energy demand-supply environments and the markets.