Geothermal is a great fit for dispatchable power to replace coal and fossil gas today (where able); batteries are almost cheaper than the cost to ship them, but geothermal would also help solve for seasonal deltas in demand vs supply ("diurnal storage").
https://reneweconomy.com.au/it-took-68-years-for-the-world-t...
https://ember-energy.org/data/2030-global-renewable-target-t...
I also love geothermal for district heating in latitudes that call for it; flooded legacy mines appear to be a potential solution for that use case.
Flooded UK coalmines could provide low-carbon cheap heat 'for generations' - https://news.ycombinator.com/item?id=45860049 - November 2025
Geothermal is not nuclear fission. The heat comes from a combination of primordial heat (from the gravitational energy turned to heat as the Earth formed) and radioactive decay (which is some combination of alpha and beta decays; spontaneous fission is extremely rare.)