Two points:
- “Only 50km” is still pretty deep.
- Geothermal energy suffers from problems of being low-quality heat, and from having high operating and maintenance costs due to the entrained chemcials and minerals in it. You absolutely cannot send that water directly through a turbine and expect it to last for very long. You have to use a closed-loop heat exchanger process, which has further efficiency losses. Summary - it works, but it’s expensive - very expensive, except in places like Iceland.
And then there is keeping the pipes and valves and loops clean and free from scaling, which can shut down a plant very quickly. Even Seasonal Thermal Energy Storage in acquifers suffers from this problem (I designed an entire solar/acquifer STES system from scratch for a 50,000 square-foot building, and the cost of maintenance was horrifying.)
In theory, yes. In practice, unfortunately, no. There are people on this Board who in the past have explained some of the serious problems with this much better than I can. It’s good reading - search for “solar” and “satellite” in GQ and GD, and you will find many threads on it that can be good reading.