Carnot battery integration in a geothermal power plant: study case of Zorlu Enerji

Waste heat generated by the industrial sector is a major source of unused energy. Integrating technologies into this process improves energy efficiency and contributes to the reduction of greenhouse gas emissions. In this scope, the SEHRENE project presents a novel approach to industrial waste heat recovery, increasing process flexibility and efficiency. The concept integrates an Electro-Thermal Energy Storage (ETES) system, including a High-Temperature Heat Pump (HTHP), a Phase Change Material (PCM) storage and an Organic Rankine Cycle (ORC). This study evaluates the optimal integration of an ETES in the largest Geothermal Power Plant (GPP) of Türkiye. The 80 MWe Kızıldere-2 GPP belongs to the Zorlu Enerji group. This plant is composed of a triple flash-binary (ORC) combined GPP. Several ETES architectures and refrigerants are analysed, to select the optimal configuration. This paper presents the results of this study case including system performance and a sensitivity analysis of various system parameters. These were then chosen to get the best design out of the trade-off between the potential performance and industrial feasibility of the machine. The main findings indicate that cyclopentane is the optimal working fluid for the given operating temperatures, where with different system architectures the round-trip efficiency (RTE) can reach values higher than 80%. Also, the performance sensitivity of the varied parameters was assessed. The most impactful varied parameters were the PCM melting temperature and the turbine isentropic efficiency. These results show the promising integration of ETES in geothermal power plants and all other processes with usable low and medium-temperature waste heat.