Performance of compressed CO2 energy storage systems with different liquefaction and storage scenarios

Abstract

Energy storage technologies play a hard role in smoothening the fluctuations and improving penetrations of renewables. Compressed CO2 energy storage is a promising large-scale technology because of the excellent thermos-physical characteristics of CO2. As one of the primary constraints, the condensation of CO2 should be addressed to successfully develop compressed CO2 energy storage technology. In this paper, four compressed CO2 energy storage systems with different liquefication and storage scenarios are proposed and analyzed comparatively. The parametric analysis is conducted by establishing thermodynamic and economic modeling. Results indicate system A is advantageous with the highest round trip efficiency and the lowest levelized cost of electricity in comparison with other proposed systems in this paper. CO2 is liquefied by the two-tank cold storage subsystem and stored in the isovolumic tank in system A. It has 71.54 % of round trip efficiency and 40.61 kWh/m3 of energy density separately under designed conditions. With a mass flow rate of 37.86 kg/s, CO2 of 6.1*105 m3 in the gas holder is pressurized and stored in the liquid CO2 tank of 1970.03 m3. System A arrives at 0.1109 $/kWh for the levelized cost of electricity and 3.03 million$ for the net present value. The purchased cost of tanks takes the largest share over total system investment.