Thermodynamic analysis of hybrid liquid air energy storage systems based on cascaded storage and effective utilization of compression heat

摘要

As a promising solution for large-scale energy storage, liquid air energy storage (LAES) has unique advantages of high energy storage density and no geographical constraint. In baseline LAES, the compression heat is surplus because of the low liquefaction ratio, which significantly influences its round-trip efficiency (RTE). In this paper, hybrid LAES systems based on the cascaded storage and effective utilization of compression heat is proposed and analyzed. In order to improve the storage temperature, cascaded-storage of compression heat is proposed. Meanwhile, the organic Rankine cycle (ORC) and Kalina cycle (KC) are considered to utilize the surplus compression heat to generate additional electricity. Based on the same conditions, the performances of the subcritical ORC using dry fluids, supercritical ORC using wet fluids, and KC are calculated and compared. It is found that the cascaded storage of compression heat can significantly increase the storage temperature and further improve the RTE of the system. Moreover, the RTE of the LAES system is increased by 10.9-19.5% owing to the additional power generation. The subcritical ORC using dry fluids is found to be more suitable in utilizing the surplus compression heat for its simple configuration and excellent performance.