ADVANCED EXERGY ANALYSIS FOR PUMPED THERMAL ENERGY STORAGE SYSTEMS

Kurzfassung

Large-scale electricity storage is becoming increasingly important to balance supply and demand imbalances as variable renewable energy expands. One category of energy storage systems, commonly referred to as pumped thermal energy storage (PTES), offers a potential solution. This research aims to evaluate process designs for PTES systems. For this purpose, a new approach to perform the advanced exergy analysis is developed based on the system modeling and simulation procedure of the free and open-source library Thermal Engineering Systems in Python (TESPy). Thermodynamic optimization potentials and component interactions are determined in order to develop improvement proposals. The methodology distinguishes between endogenous exergy destruction caused by the inherent inefficiencies of a component and exogenous exergy destruction caused by the inefficiencies of other components. The idealization of the system and its components, a crucial aspect of advanced exergy analysis, is developed and applied in the PTES case study. A system with a high-temperature heat pump, an organic Rankine cycle, and a pressurized hot water tank serving as the thermal energy storage is selected. The round-trip efficiency of the PTES is about 43%. Recommendations for technical improvements are derived from the analysis, and the components with the highest thermodynamic optimization potential are specified. The methodology is expected to be adaptable to different energy conversion systems