Cyborg IM1 wrote:
Both good ideas. My concern with geothermal power was ground instability. If you have an unstable region, how can your caves maintain air integrity? Especially long-term. I figured quakes would cause cracks and eventually the cave system would lose its air - at least over hundreds or thousands of years.
The area doesn't have to be unstable to have a bit of geothermal energy. Britain has very few and rather pathetic earthquakes, but it also has hot springs in Harrogate and in Bath: https://www.thermaebathspa.com/news-info/about-the-spa/spa-history/ https://www.geolsoc.org.uk/GeositesBath
Bits of Bath are liable to collapse into underground caverns not because of quakes, but because people have been quarrying limestone out from under the town for centuries, plus groundwater dissolving the limestone away.