Thermodynamic analysis of a compressed air energy storage system with constant volume storage considering different operating conditions for reservoir walls

Abstract

Abstract In the search for alternatives to fossil fuels, renewable energy sources such as wind and solar are gaining increasing importance in the global energy grid. Despite its reserves are abundant, this type of energy is intermittent, which causes some unpredictability in meeting energy demand through these resources. To mitigate this problem, energy storage systems can be used combined with renewable sources. Compressed air energy storage (CAES) systems stand out for their high efficiency and affinity with the environment. In the present article a thermodynamic analysis of an operating cycle of a small scale CAES system with constant volume reservoir is conducted, taking into account three different operating conditions for compressed air storage walls. The conducted analysis of the CAES system considered includes an energetic and an exergetic investigation, aiming to determine and assess which are the most relevant points of exergy destruction in the system, as well as the effects of air storage conditions on the thermodynamic performance of the global system. Among the main results it was observed that the combustion chamber presented the highest rates of exergy destruction, and that the throttle valve installed on the exit of the air storage reservoir was responsible for an average of 9% of the total exergy destroyed in the CAES system over a complete work cycle.