Techno-Economic Analysis of Operating Temperature Variations in a 4th Generation District Heating Grid—A German Case Study

Karl Specht (), Max Berger and Thomas Bruckner
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Karl Specht: Institute for Infrastructure and Resources Management, University of Leipzig, 04109 Leipzig, Germany
Max Berger: Department of Food and Resource Economics, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg C, Denmark
Thomas Bruckner: Institute for Infrastructure and Resources Management, University of Leipzig, 04109 Leipzig, Germany

Sustainability, 2025, vol. 17, issue 9, 1-33

Abstract: The decarbonization of the heat supply is crucial for the German energy transition. Integrating Power-to-Heat technologies like heat pumps (HPs) into district heating grids (DHGs) can support this process. The efficiency of HPs can be increased through temperature reduction in the DHG, though decentralized reheating may be required to supply sufficient heat for the end consumers. In order to investigate the associated trade-off, this study evaluates the economic, ecological, and technical effects of temperature reduction in DHGs using the software tool nPro. In a three-step process heat demand, the DHG design and operation are modeled. Three operating temperature scenarios are considered: 60 °C, 50 °C, and an ambient dependent flow temperature varying between 40 and 50 °C. As the temperatures decrease, the balance shifts between centrally produced HP heat and decentralized heat from instantaneous electric water heaters (IEWHs). The initial temperature reduction leads to reduced CO 2 emissions, primary energy demand, heat losses, and total annual cost (TAC). However, with a further reduction in the operating temperature, an increase in these parameters occurs. While the necessary cost and primary energy for central components decrease, an increase in the decentralized heat generation is necessary to properly supply the heat demand. This leads to higher TAC and CO 2 emissions overall.

Keywords: 4th generation district heating; power-to-heat; heat pump; operating temperature reduction; techno-economic analysis; nPro (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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