Optimization of dynamic compressed CO2 energy storage system: The role of supercritical fluid properties

Yuandong Guo, Jinliang Xu, Xiongjiang Yu, Enhui Sun, Jian Xie and Guanglin Liu

Energy, 2025, vol. 328, issue C

Abstract: The rising demand for efficient energy storage has spurred the development of technologies like liquefied CO2 energy storage systems, which reduce pressure fluctuations by storing CO2 as a liquid. Traditionally, the storage temperature of CO2 is the saturation liquid temperature because evaporation compensation helps maintain stable pressure during gas release. However, the liquefied CO2 energy storage system suffers low round-trip efficiency due to low temperature for liquefaction. Here, we propose a compressed CO2 energy storage (CCES) system using the properties of supercritical fluids to extend the discharging time. The core optimization strategy involves storing sCO2 near the pseudo-critical temperature during the charging process, which facilitates more efficient expansion of sCO2 during the discharging process, thereby extending the discharging time. Then, a dynamic CCES system incorporating three-stage compression and three-stage expansion are proposed. With the compression power consumption of 100 MW, the high-pressure tank is set to be 14.00 MPa and 7.50 MPa before and after discharging. Based on the discharging optimization method, the round-trip efficiency improves from 66.50 % to 69.32 %, and the discharging time extends from 0.96 h to 3 h. Our work fills the gap in the selection criteria for storage parameters of CCES system, and significantly improving the performance of CCES system.

Keywords: Compressed CO2 energy storage; Supercritical CO2 tank; Discharging optimization method; Pseudo-critical temperature (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:328:y:2025:i:c:s0360544225020596

DOI: 10.1016/j.energy.2025.136417

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