Modelling and optimization of liquid air energy storage systems with different liquefaction cycles

Liquid air energy storage (LAES) is one of the large-scale mechanical energy storage technologies which are expected to solve the issue of renewable energy power storage and peak shaving. As the main energy loss of a standalone LAES occurs in the liquefaction process, this paper focused on the thermodynamic analysis of LAES systems with different liquefaction cycles. Six liquefaction cycles were considered. To obtain a higher system efficiency and fair comparative analysis of the performance of different LAES systems, authors used a combined genetic algorithm (GA) and HYSYS process simulation method to perform the multi-parameters global optimization. Subsequently, energy and exergy analyses were conducted on the optimized LAES systems. The results show that the system efficiency of the LAES based on turbo-expander refrigeration (i.e., the Claude cycle, Kapitza cycle, and Heylandt cycle) increases with an increase in the split ratio. The LAES with Kapitza liquefaction cycle shows the most competitive system performance compared with the other liquefaction cycles based-LAES systems. The LAES with Kapitza liquefaction cycle exhibits the lowest optimal charging pressure of 10.73 MPa and achieves the highest round-trip efficiency, system storage exergy efficiency, and system recovery exergy efficiency of 60.02 %, 86.41 %, and 84.98 %, respectively. The obtained GA optimization and thermodynamic analysis results of LAES systems with different liquefaction configurations can provide significant theoretical guidance for further industrial applications of LAES.