Transcritical carbon dioxide cycle as a way to improve the efficiency of a Liquid Air Energy Storage system.

The article deals with the subject of energy storage. This important issue relates to the ongoing transformation toward renewable energy sources. Liquid Air Energy Storage (LAES) is a mechanical energy storage technology that is suitable for large-scale energy storage. The article presents a method to increase the efficiency of LAES by coupling it with the transcritical carbon dioxide cycle. To this end, the paper presents a numerical analysis of two Kapitza LAES systems with the transcritical CO 2 cycle: in parallel and subsequent mode. In both cases, maximizing CO 2 pressure contributes to greater overall efficiency. It is only profitable to direct residual heat to the CO 2 cycle. In contrast, lowering the air temperature prior to expansion in hopes of providing a greater amount of heat to the CO 2 cycle actually delivers worse results. Parallel system implementation can add 5–6% to storage efficiency, depending on other factors. In comparison, the subsequent system only adds some 3.5%–5% to storage efficiency. [ABSTRACT FROM AUTHOR]