Open Access

ARTICLE

Techno-Economic Analysis of a Power-to-Heat System with Waste Water Heat Recovery Powered Mainly by an Off-Grid Wind Turbine

Johannes D. Pelda^*, Sebastian Aichele, Dmitry Romanov, Stefan Holler

HAWK University of Applied Sciences and Arts Hildesheim/Holzminden/Göttingen, Göttingen, Germany

* Corresponding Author: Johannes D. Pelda. Email:

(This article belongs to the Special Issue: Selected Papers from the SDEWES 2025 Conference on Sustainable Development of Energy, Water and Environment Systems)

Energy Engineering 2026, 123(8), 25 https://doi.org/10.32604/ee.2026.079450

Received 21 January 2026; Accepted 28 April 2026; Issue published 12 July 2026

Abstract

The transformation of district heating systems in Germany is a central topic in energy and climate policy, given the 2045 climate neutrality targets. This study focuses on the main district heating system in the city of Göttingen in Germany, whose heat generation currently relies primarily on three Combined Heat and Power (CHP) plants subsidized under the German CHP Act, one wood chip boiler and two gas boilers. In 2025, the network’s heating demand amounted to 89 GWh, which was mainly covered by wood chips or biogas (41%) and natural gas (21%). This paper examines an option for increasing the share of renewable energy in the main district heating system of Göttingen. Therefore, this work analyses the integration of a power-to-heat system from a technical and economic perspective. The power-to-heat system consists of a Heat Pump (HP) that uses waste heat from a sewage treatment plant and is primarily powered by an off-grid wind turbine. The scenarios simulated vary in the temperature difference at the waste heat source and the part-load range of the HP. The optimum rated output of the HP is then determined based on the Levelized Cost of Heat (LCoH). The results indicate that the economic optimum is achieved with a HP of 2 MW capacity reaching a LCoH of 38.85 EUR/MWh. The integration of an on-site wind power plant ensures a self-sufficiency ratio above 0.55 in all investigated scenarios. Furthermore, the partial load range of the HP has a very positive effect on the LCoH. Overall, this analysis demonstrates a significant and economically viable decarbonization of the district heating system using local resources. Based on these results, it is recommended to investigate the potential benefits of integrating additional thermal or electrical storage systems. This could increase the share of renewable energies in the district heating system as well as the degree of self-sufficiency, and enable the provision of system services for the electricity market. Such measures could also contribute to a further reduction in the LCoH.

---

Graphic Abstract

---

Keywords

---