Economic, energy and exergy assessments of a Carnot battery storage system: Comparison between with and without the use of the regenerators

Abstract

Energy storage plays a critical role in balancing the power distribution grid and can provide more flexible and reliable grids. In addition, renewable energy based-systems integrated with energy storage systems can be a desirable solution to energy challenges nowadays. Carnot battery is one of the candidate systems for energy storage that allow storing electricity at low cost with no geographical constraints. The aim of this paper is to provide an economic, energy and exergy analyses of a Carnot battery based on the organic Rankine cycle (ORC) and the vapor compression heat pump (HP) with the use of regenerators in both subsystems. Providing thermodynamic analysis and calculating the exergy destruction and Levelized cost of storage (LCS) of the proposed energy process are the main objectives of the present study. In addition, LCS (as the objective function) is minimized using the genetic algorithm. The results showed that at a thermal storage temperature of 125 °C, the value of LCS for the proposed process is approximately $ 0.3 per kWh. In addition, the total cost of investing in such a system is nearly k$ 5700. It was also found that if the regenerators are not used, the value of power to power efficiency can be lower. However, the use of regenerator in the HP subsystem has a significant impact compared to the ORC. The performance of the proposed system is also discussed according to the optimization results.