Parametric analysis and multi-objective optimization of a new combined system of liquid carbon dioxide energy storage and liquid natural gas cold energy power generation

Abstract

Liquid carbon dioxide energy storage is a potential energy-storage technology. However, it is hindered by the difficulty of condensing CO 2 using high-temperature cooling water because the critical temperature of CO 2 is close to the temperature of the cooling water. Therefore, this study proposes a new combined liquid CO 2 energy storage and two-stage condensation organic Rankine cycle system. Thereby, the condensation of CO 2 is realized, and liquid natural gas (LNG) cold energy is utilized. The impact of key variables on the performance of the system is examined by establishing a mathematical model of the system and analyzing the parameters. In addition, the systems that use pure working fluid and mixed working fluid are optimized and compared using a simultaneous multi-objective optimization method. The results indicate that the system using mixed working fluids is better than that using pure working fluids, with an η R T E of 375.49%, η E X of 81.09%, and LCOS of 0.08 USD/kW·h. The proposed system performs better than the combined liquid air energy storage and LNG cold energy system in the literature from thermodynamic and economic perspectives. • A new combined system of LCES and LNG power generation is proposed. • It improves the difficulty of CO 2 to be condensed by high-temperature cooling water. • The impact of key variables on the performance of the system is explored. • Simultaneous multi-objective optimization method is conducted. • System using pure and mixed working fluid is compared.