Thermodynamic evaluation on a new CO2 energy storage system assisted by adsorption bed

Abstract

The share of renewable energy in energy systems is increasing under the background of the accelerated transformation on the current energy structure. Energy storage technologies enjoy excellent functions in dealing with the problems arising from the extensive applications of renewable energies. A compressed CO2 energy storage system configured with adsorption bed is proposed with the merits of high efficiency and large energy density in this paper. The gaseous working fluid at the turbine outlet is directly absorbed and stored by the adsorbent material in the adsorption bed, which solves the low-pressure CO2 storage problem. The thermodynamic performance and parametric analysis are investigated by establishing mathematical models of the proposed system. Results demonstrate that the maximum efficiency can be identified and the optimized HPC exit pressure is shifted to the right when the HPT inlet pressure is lower than 14 MPa, and then it is located at 15 MPa. The curve of system efficiency declines almost in a layered manner with the increase in HPT inlet pressure. The maximum efficiency is ensured by locating HPC exit pressure at 13 MPa and HPT inlet pressure at 12 MPa. Under this condition, the efficiency and energy density can reach 68.79 % and 17.44 kWh/m3, which reveals that the system efficiency is competitive and its energy density is more superior with about 5–6 times of that of the adiabatic compressed air energy storage technique.