Green Energy

Yep. It doesn't even have to be very deep. Helsinki is using some old "oil caves" (oil storage caverns excavated into granite, depth 80 m) to store some 10 GWh of heat for extraction during winter. Apparently, granite is an excellent insulator. They pump the heat from sewage (cooling the sewage and heating the cavern) during summer...

...but that wouldn't be classified as natural geothermal, and not primary production but seasonal storage.

But it works. But only on large scale. I ran the calculations for a private little project and the results looked bad. With anything related to thermal storage, it has to be big (energy loss scales with the square of volume, storage with the cube of volume).