Designing and performance assessment of a hybrid CAES based CHP system integrated with solar energy and heat pump

Abstract

In this paper, a novel combined heat and power system based on compressed air energy storage (CAES) coupled with a solar collector system was introduced. Based on the significant effect of heat pumps in improving heat quality, the heat pump and solar energy are adopted to improve energy storage and economic performance. To maximize the effective utilization of solar energy, the energy dispatch scheme of the system has been studied in detail. The system's performance under multiple operating conditions has been evaluated. Moreover, to further explore the optimization potential of the solar-coupled compressed air energy storage system, important factors such as the distribution proportion of thermal oil and key temperature have been emphasized and analyzed. The optimization of key temperature, distribution proportion of thermal oil, and operating conditions can enhance the cascade utilization of energy, and also provide a comprehensive approach for the design and optimization of the proposed system. Parametric sensitivity analysis was first conducted. Results show that the charging pressure should be close to the discharging pressure and there is no local optimal distribution ratio for the thermal oil. The optimal condition under design constraints is also determined, the system power efficiency, energy efficiency, and power-to-power efficiency reached 0.297, 0.851, and 0.570, while the levelized cost of storage of the system is 0.527 $/kWh, the dynamic payback period is 9.516 and simple payback period is 7.428 under the specified conditions. The output power and heat in 6 h of discharging are 3829.50 kWh and 7147.48 kWh, respectively, with a total investment cost of 7373.57k$. Moreover, the exergy and economic analyses were then conducted. The highest exergy losses were caused by the solar collector system with 29.01% of the total loss. The turbines and the solar system also had the highest economic cost, indicating directions for further optimization.