Seidel, C., Ostermann, L. & Clausen, J. (2025). An introduction to heat generation from river water. Berlin: Borderstep Institute.

In the last two years, interest in the use of heat from river water has grown in leaps and bounds. But how much heat can be extracted from the river on your own doorstep? What are the ecological consequences? Which locations are particularly suitable? Our guide attempts to answer these questions briefly and simply and thus aims to help integrate river water heat into municipal heat planning.

Download the study „An Introduction to Heat Recovery from River Water“ for free now and learn more.

Requirements for the sustainable use of river water heat

Using river water as a heat source offers substantial, yet largely untapped, potential for decarbonising heat supply. Key prerequisites include:

• suitable locations,
• integration into district heating networks,
• careful legal and regulatory planning, and
• environmental assessment.

Under these conditions, river water heat can make a significant contribution to the energy transition in the heating sector.

Why is this important?

Rivers and other flowing water bodies are found throughout most of Germany, providing a reliable and consistent source of ambient heat. This creates new opportunities for decentralized, efficient, and climate-friendly heat generation.

Where does the potential lie?

The study shows that cooling a river by just 2 Kelvin can unlock substantial heat potential. Across Germany, this amounts to up to 430 TWh per year through single-pass extraction, or around 1,400 TWh per year of usable heat through double-pass extraction combined with heat pumps.

This potential significantly exceeds Germany’s natural gas consumption for heating. By comparison, the combined natural gas consumption of private households and the commercial, trade, and services sector for heating purposes amounted to 352 TWh in 2022 (AG Energiebilanzen, 2023).

Using river water for heat recovery helps cool rivers that have become consistently too warm as a result of climate change. It combines energy efficiency with the protection of aquatic ecosystems, demonstrating that environmental responsibility and technological innovation can go hand in hand. – Dr. Jens Clausen, Borderstep Institut

More on the topic

• Study Altermatt, P., Clausen, J., Brendel, H., Breyer, C., Gerhards, C. et al. (2023). Replacing gas boilers with heat pumps is the fastest way to cut German gas consumption. Communications Earth & Environment, 4, 1–8.
• Wissen kompakt
• Project Solar heat pump – heating and cooling with the help of the sun
• Research Climate Change Sustainable Innovation

The authors

Christian Seidel, TU Braunschweig

Lars Ostermann, TU Braunschweig

Dr. Jens Clausen is a co-founder and shareholder of the Borderstep Institute. His research focuses on innovation and sustainability transitions, with particular expertise in energy systems, heating technologies, electric mobility, and digitisation.

Publisher

Borderstep Institute for Innovation and Sustainability gGmbH

How to cite

Seidel, C., Ostermann, L. & Clausen, J. (2025). An introduction to heat generation from river water. Berlin: Borderstep Institute.

Topics

Green Economy Ecological Footprint Diffusion Diffusion pathway System Innovation  Transformation • Environmental Innovations