Cogeneration systems of solar energy integrated with compressed air energy storage systems: A comparative study of various energy recovery strategies

Abstract

Compressed air energy storage (CAES) is considered to be one of the most promising large-scale energy storage technologies to address the challenges of source-grid-load-storage integration. However, the integration strategies of CAES with renewable energy sources (RES), driven by the goal of enhancing system efficiency, have not been fully explored. In this paper, a unique energy allocation strategy is introduced for a CAES system when coupled with solar energy. Intermittent solar energy is transformed into a consistent heat source, jointly preheating the air entering the turbines with compression heat. Besides, three cogeneration systems with different waste heat recovery strategies are designed and compared. Based on the basic integration of CAES and solar collection system (SCS), heat pump (HP) and organic rankine cycle (ORC) are progressively introduced to recover waste heat from compressors and SCS, respectively. Finally, parametric studies and energy, exergy, economic (3E) analysis for the three cogeneration systems are conducted. The results show that the system integrated with HP presents the best system power efficiency (SPE) of 38.9% and system energy efficiency (SENE) of 99.6%. The basic integration system presents the best power-to-power (P2P) efficiency of 57.4%. Additionally, it offers the best economic performance with a levelized cost of storage (LCOS) of 0.520 $/kWh. Besides, the introduction of HP can improve the economic and electricity conversion performance when the air release pressure is in the low-pressure region, but also increases exergy destruction caused by the large temperature difference of heat exchangers. The introduction of ORC raises the overall costs caused by its complex components, but has little effect on system exergy destruction. Finally, by comparing with existing studies, the superiority of the proposed CAES and SCS integration strategy is validated.