Simulation and optimization of a Carnot battery process including a heat pump/organic Rankine cycle with considering the role of the regenerator

Abstract

Abstract The inherent nature of the renewable energies is to be intermittent. This leads to negative effects on the security and stability of the energy production system. A sensible solution to eliminate or reduce the negative effects is to integrate the energy storage system with a renewable source–based energy production system. Carnot battery is an emerging technology that allows storing electric energy at low cost with no geographical restrictions. To this end, this paper attempts to provide a comprehensive and accurate assessment of the thermodynamic and cost performances as well as energetic and exergetic analyzes of the considered Carnot battery. In this regard, the Carnot battery is comprised of an organic Rankine cycle (ORC), vapor compression heat pump (VHP) and a pumped thermal energy storage (PTES) (to connect the two ORC and VHP sub-cycles). In addition, in both charge and discharge processes, regenerators are utilized to recover waste heat to improve the performance of the storage system. The main objectives of this article are thermodynamic analysis, calculation of degraded exergy and energetic and exergetic efficiencies and obtaining levelized cost of storage (LCOS). Moreover, LCOS (as the objective function) is optimized using the optimization algorithm. The findings indicated that, at the desired temperature (i.e. 100°C), the values of LCOS and total initial cost are 0.3577 USD per kWh and 56.5 million USD, respectively. It was also found that if the regenerators are not used in both charge and discharge processes, the value of LCOS can be nearly 12% greater.