Novel liquid air energy storage coupled with liquefied ethylene cold energy: Thermodynamic, exergy and economic analysis

Liquid air energy storage (LAES) technology, unrestricted by geographical conditions and capable of flexible integration with external energy sources, holds considerable potential. However, the efficiency of the LAES system is hindered by the shortage of cold energy, requiring the introduction of external cold energy. Currently, research on external cold energy coupling predominantly concentrates on the regasification cold energy of Liquefied Natural Gas (LNG), with scant attention to other cold energy sources, such as ethylene. The conventional regasification process of Liquefied Ethylene (LE) is accompanied by the wasting of abundant regasification cold energy, making it crucial to explore a method to effectively recover and utilize it. This study firstly presents two system cases that couple LAES with the regasification cold energy of LE, filling the research gap. Two cases are simulated: Case 1 utilizes the LE cold energy to cool the air after compression, similar to the common method of coupling LNG cold energy, and Case 2 innovatively applies LE cold energy in low-temperature compression and cooling after compression, along with the introduction of 350 degree celsius solar thermal energy. Key parameters in Case 2 are optimized through sensitivity analysis. Additionally, exergy destruction and economic analysis of the two cases are conducted. The main results indicate that: the round-trip efficiency (RTE) and exergy efficiency (EXE) of Case 1 are 63.3% and 59.5%, respectively; for Case 2, although the EXE of 57.06% is slightly lower than Case 1, the RTE can be markedly improved to 211.4%, and it has a lower initial investment cost, quicker return, and lower investment risk. This study systematically presents a novel technical solution for the integration of external cold energy with LAES systems, marking the first investigation into the coupling of LAES systems with liquefied ethylene regasification processes.