Thermo-economic analysis and comparative study of different thermally integrated pumped thermal electricity storage systems

Pumped thermal electricity storage (PTES) is a cost-effective and little geographic confinement technology for large-scale energy storage. In this work, a comprehensive analysis is conducted on four different types of thermally integrated pumped thermal electricity storage systems, including thermodynamic, economic, and optimization aspects. The results are compared and evaluated to determine the most efficient and cost-effective system. Parameter analysis and optimization are conducted on four systems to determine the effects of various factors on system performance. The factors considered include thermal storage temperature (Tts), evaporation temperature of the heat pump cycle (Teva,hp), pinch point temperature difference of heat exchanger (Tpp), flash pressure (Pf), and temperature of the heat pump cycle (Teva,hp). Under the effects of Tts on system performance, among the four systems, the thermally integrated pumped thermal electricity storage systems with regenerators, which consists of a heat pump cycle and an organic Rankine cycle, shows the highest power-to-power efficiency (ηPTP), with a maximum value of 79.81%. Furthermore, based on the results of multi-objective optimization, it can be concluded that the thermally integrated pumped thermal electricity storage systems with regenerators, which consists of a heat pump cycle and an organic flash cycle is the most suitable system, and the final solution of the system is obtained by considering the multi-objective optimization results. The exergy destruction and economic analysis of the thermally integrated pumped thermal electricity storage systems with regenerators (including a heat pump cycle and an organic flash cycle) are conducted in the optimal working conditions. For the thermally integrated pumped thermal electricity storage systems with regenerators, which consists of a heat pump cycle and an organic flash cycle, the component with the greatest exergy destruction is the evaporator, and the cost of the expander is the highest, followed by the evaporator, and it has the optimal system performance.