Geothermal heat pumps are very common in the Nordics. It’s a one day operation, they come in, drill a 150M hole and run a brine loop hooked up to a heat pump. Sorts the heating and hot water for a 180 m2 house above the attic circle with less than 7000 kWh per year.
that is a ground-source heat pump as the heat energy is mostly from ambient solar. But yes very common and I used to have one in my home before I moved away. It cost practically nothing to keep the house at t-shirt temperature during -25c cold weather snaps.
No it's not.
The bore-hole is lined with a outer steel pipe until the drill hits bedrock, keeping it very much insulated from the ground.
And the upper-most part of the energy-well that's lined is considered inactive, and is not counted in the "150 m deep energy well".
