Thermodynamic analysis of a novel adsorption-type trans-critical compressed carbon dioxide energy storage system

• A novel adsorption-type trans-critical compressed CO 2 energy storage system is proposed. • The low-pressure adsorption tank uses an adsorption strategy and significantly increases CO 2 storage density. • The dynamic charging and discharging process of the high-pressure storage tank is examined. • The influence of key parameters on the volume of the high-pressure storage tank is investigated. • The system does not need to rely on thermal storage heat exchangers and large underground caverns. Compressed CO 2 energy storage technology is a feasible resolution to stabilize the fluctuation of renewable energy output and has significant development prospects. The main challenge currently facing is how to achieve high-density storage of low-pressure CO 2 . To get rid of the engineering application limitations caused by low-pressure CO 2 liquefaction storage and large-scale cave storage, a new type of adsorption trans-critical compressed CO 2 energy storage system is proposed in this paper. Using Fe-MOR(0.25) as an adsorbent, the storage density of CO 2 can reach 390.94 kg/m 3 at 298 K and 0.1 MPa. The thermodynamic simulation is carried out based on the first and second laws of thermodynamics. The results demonstrate that the system round trip efficiency, exergy efficiency, and energy storage density under the design conditions are 66.68 %, 67.79 %, and 12.11 kWh/m 3 , respectively. The results of sensitivity analysis indicate that the storage pressure and storage temperature of the high-pressure tank have compound effects on the system, and they are the key parameters affecting the performance of the system. Releasing pressure at critical points can cause abrupt changes in system performance. Heat exchanger effectiveness, compressor, and turbine isentropic efficiency improvements positively affect the system performance.