If you stand by a river or lake early in the morning after a cool night, you can sometimes see it: the fine mist hovering over the water, making boats appear romantically blurred—just like in a painting by Caspar David Friedrich. The explanation for this phenomenon: the water is warmer than the air and releases this heat. So simple, so mundane. And so promising for the heat transition in Germany. Because river heat could be one of the key solutions to finally accelerate it.

In conversation: Jessika Gappisch, doctoral candidate in aquathermal energy at the Department of Hydraulic Engineering and Hydraulics at the Technical University of Darmstadt

Read the article on zeit.de.