You don't necessarily have to go that deep to get useful amounts of heat. This varies by location of course. https://arstechnica.com/science/2019/06/report-geot

You don't necessarily have to go that deep to get useful amounts of heat. This varies by location of course. https://arstechnica.com/science/2019/06/report-geothermal-could-power-up-to-16-of-us-grid-by-2050/ https://arstechnica.com/science/2019/06/report-geothermal-co... If you want a single project at a huge scale, check out https://news.ycombinator.com/item?id=15596350 https://news.ycombinator.com/item?id=15596350