Exergoeconomic analysis of a Carnot battery system for energy storage

Electric energy storage is recognized as an essential technology in enabling a more reliable and resilient power grid, facilitating the integration of renewable energy sources, enhancing energy efficiency, and providing critical support during peak demand periods. In this context, Pumped Thermal Energy Storage (PTES), also known as the Carnot battery, emerges as a promising technology for electricity storage. It comprises systems for converting electricity to heat, storing heat, and transforming heat into electricity. In this work, a Carnot battery based on a heat pump and an organic Rankine cycle configuration is investigated using exergoeconomics. A mathematical model was developed in Matlab software to assess the energy, exergy, and economic performance of the energy storage system. The developed model was validated to ensure its accuracy and reliability. Exergy and exergoeconomic analyses were performed under the selected assumptions. The results show that significant exergy destruction occurs when converting electricity into heat rather than transferring heat from the storage to the ORC. In addition, the findings from the exergoeconomic analysis reveal that the lowest and highest contributions of the investment cost rates are related to the storage system and charging process, respectively. The results further suggest that due to the high exergoeconomic factors attributed to the pump and compressor, optimizing the system may involve reducing the capital investment for these components.