A constant pressure compressed CO2 energy storage with water compensating: comprehensive thermo-economic analysis

Suzhen Yin, Kaiyue Zheng, Chuangang Bai, Xingpeng Yan and Zhan Liu

Energy, 2025, vol. 332, issue C

Abstract: High penetration of renewable energy poses difficulties for the security and reliability of power grid. One promising possibility is to combine it with compressed CO2 energy storage technology to meet the needs of peak shaving and load transfer. Several gas-liquid type compressed CO2 energy storage plants have been constructed over the world. However, abundant extra cooling source is required and about one-third size of high-pressure storage tank is parasitized to the current system. How to effectively store the high-pressure liquid CO2 is still supposed to be solved. This paper puts forward a constant pressure CO2 energy storage system with hydraulic cycle compensation, building on the existing gas-liquid type arrangement. The given system realizes the isobaric storage of liquid CO2 at the high pressure side through the pressure stabilizing device. The critical parameters are analyzed through the established thermodynamic and economic models. The findings suggest that an optimal storage pressure of 14 MPa is determined to minimize the levelized cost of storage. The 0.1 MPa is the first suggestion for the water storage pressure considering the system safety and simplicity. The effect of water machinery performance on system efficiency can be ignored compared to the CO2 machinery performance. The system achieves a round trip efficiency of 72.48 % and a levelized cost of storage of 0.7361 CNY/kWh for a 100 MW/700 MWh plant.

Keywords: Compressed CO2 energy storage; Constant pressure storage; Hydraulic cycle compensation; Thermo-economic analysis (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:332:y:2025:i:c:s0360544225029111

DOI: 10.1016/j.energy.2025.137269

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