Assessment of the operating economics of a novel compressed CO2 energy storage system based on adsorption effect: Exergoeconomic analysis

Abstract

Compressed CO₂ energy storage technology offers high energy storage density and does not rely on specific geological formations. Unlike conventional compressed air systems that require large underground caverns, CO₂-based systems can be implemented above ground, making them more flexible and widely deployable. As a result, this technology has broad development prospects. This paper proposes a compressed CO₂ energy storage system based on adsorption effect (AE-CCES). Unlike conventional CCES schemes, the AE-CCES integrates a two-stage heater/cooler configuration to reduce irreversibility and enhance thermal control within the adsorption tower. The simulation results demonstrate that the system achieves excellent thermodynamic performance with a low unit exergy cost of 21.05 $/GJ, which demonstrates strong engineering feasibility under realistic material and cost constraints. Sensitivity analysis shows that raising the adsorption temperature increases compressor power but lowers the unit exergy cost, improving economic performance. Increasing the desorption temperature from 453.15 K to 483.15 K results in a 3.6 % rise in exergy efficiency but a 1.5 % drop in round-trip efficiency, due to reduced CO₂ adsorption capacity and improved energy quality. The increase in storage pressure negatively affects the cycle efficiency and operating economy but helps to raise the energy storage density. The rise in the temperature difference between the pinch points will enlarge the available energy loss in the heat transfer process, negatively affecting the thermodynamic performance of the system as well as the operating economy. Changes in isentropic efficiency have compound nonlinear effects on the system. These findings provide a scalable and cost-effective pathway for future adsorption-integrated energy storage system development.