Modeling Thermal Energy Storage — The Effect of Self-Discharge Rates on Dispatch

This paper investigates the impact of different selfdischarge rates on the dispatch of pit thermal energy storage (PTES) within the sector-coupled energy system model Enertile. We analyze how varying self-discharge rates of PTES influence district heating (DH) generation across different DH type networks with distinct renewable heat potentials. Our findings indicate that lower self-discharge rates facilitate increased integration of heat pumps, particularly in DH networks with high shares of these technologies. Additionally, low self-discharge rates lead to a more long-term pattern in storage dispatch. This relationship between self-discharge rates and dispatch behavior significantly affects the overall efficiency and operational strategy of PTES in DH systems. The results underscore the need to account for self-discharge dynamics in energy system modeling, as traditional efficiency metrics may not adequately represent real-world performance without context on dispatch conditions.