Thermodynamic and economic analysis of a trans-critical CO2 energy storage system integrated with ORC and solar energy

Abstract

In this paper, a CO₂ energy storage system that integrates an organic Rankine cycle (ORC) with solar energy is proposed to support grid peaking, enhance the efficient use of renewable energy sources, and optimize system performance. A thermodynamic analysis of the system has been performed and the performance under different operating models is evaluated. In model A, the energy storage efficiency of the system is 77.28 %, the solar energy conversion efficiency is 30.7 %, and the exergy efficiency is 66.1 %. In models B and C, the energy storage efficiency is 76.72 % and 80 %, the solar conversion efficiency is 32.2 % and 31.5 %, and the exergy efficiency is 66.8 % and 65.2 %, respectively. To evaluate the thermodynamic and economic performance of the system, the effect of the decision variables on the system performance is analyzed. Then, the NSGA-II optimization algorithm was applied to optimize the system, and the TOPSIS method was used to evaluate the optimization results. The results show that the energy storage efficiencies under optimal operating conditions are 78.8 %, 77.5 %, and 81.1 % for operating models A, B, and C, respectively. In addition, the levelized cost of storage (LCOS) for operating models A, B, and C are 0.307$/(kW∙h), 0.316$/(kW∙h), and 0.318$/(kW∙h), respectively.