Thermo-economic and life cycle assessment of pumped thermal electricity storage systems with integrated solar energy contemplating distinct working fluids

The applications of renewable energy sources are an effective way to reduce carbon emissions. However, its intermittent nature presents challenges for large-scale application. Energy storage technology shows great potential in addressing this issue. Thermally integrated pumped thermal electricity storage systems are a promising technology for power storage due to its outstanding role in integrating renewable energy sources. In this work, the pumped thermal electricity storage system incorporates solar energy, utilizing five different working fluids: R1233zd(E), R1336mzz(Z), R123, Pentane, and R245ca. Comparative analyses of the thermodynamic and economic performance of the system under the five working fluid conditions were conducted, followed by multi- objective optimization using genetic algorithm. Additionally, under optimal solution conditions, life cycle assessment analyses are conducted for the system that employs the five working fluids. The results indicate that the performance indexes of the system under different parameter conditions show the variation rule of either increasing or decreasing, and the variation trend of the same performance indexes is basically coincident for different industrial materials. The results of multi-objective optimization show that the power-to-power efficiency of the system has an obvious competitive relationship with environmental impact load and Levelized Cost of Storage, and the larger the value of power-to-power efficiency is, the larger the values of environmental impact load and Levelized Cost of Storage are. Under the optimal solution conditions, the life cycle assessment analysis shows that for the five environmental impact potentials, the percentage of environmental impact potentials is higher in the construction and operation phases, while the environmental impact load has the maximum (4.09 x 10-5-5 mPE) and minimum (3.94 x 10-5-5 mPE) values when the system uses Pentane and R1336mzz (Z), respectively. This work can provide a valuable reference for the study of TI-PTES in terms of environmental impact.