As the BBC reports, a German energy company called MVV Environment is building two enormous heat pumps that draw water from the Rhine to provide an appreciable 40,000 homes with heat. Heat pumps are also being used to extract heat from water in unused mines in the UK. Other places, like Helsinki, Finland, are already harvesting the heat from the surrounding air for the local district heating system. The Mannheim heat pumps are expected to cost an eye-watering $235 million — making it a costly, but ultimately worthwhile, solution. More on heat pumps: Residents Annoyed by Crypto Mine That Emits Constant, Horrible Noise