Storing heat in bedrock sounds like a good idea, but there are risks, e.g. https://www.thelocal.de/20170818/this-historic-german-town-is-falling-apart-in-slow-m

Storing heat in bedrock sounds like a good idea, but there are risks, e.g. https://www.thelocal.de/20170818/this-historic-german-town-is-falling-apart-in-slow-motion-catastrophe https://www.thelocal.de/20170818/this-historic-german-town-i...