[trashb]

Create a small sun a mile under the ground, what could go wrong?

Also the actual article it seems has nothing to do with fission, they are focusing on extracting the heat already down there. "superhot rock needed for next-generation geothermal power"

[leonidasrup]

There many kinds of geothermal power and if you don't have access to hot fluids found naturally in basement rock, you have use hot dry rock geothermal energy.

https://en.wikipedia.org/wiki/Hot_dry_rock_geothermal_energy

Here the biggest obstacle to economy of the geothermal power is the very low heat conductivity of rock.

"The conductive heat flux averages 0.1 MW/km2. These values are much higher near tectonic plate boundaries where the crust is thinner. They may be further augmented by combinations of fluid circulation, either through magma conduits, hot springs, hydrothermal circulation. "

https://en.wikipedia.org/wiki/Geothermal_energy#Resources

For comparison: Thus the solar energy arriving at the surface with the sun directly overhead can vary from 550 MW/km2 with cirrus clouds to 1025 MW/km2 with a clear sky

https://en.wikipedia.org/wiki/Solar_constant

[da-x]

The sun performs fusion, not fission.