It looks serious.
This rig is up here drilling our bore holes for our ground source heat pump. It will be doing all the heating and cooling for our house. There will be four bores, each 200 feet into the ground.
The water flows through tubing, down, then back up, returning to the house to a heat exchanger. In the summer, the water in the pipe cools the fluid in the heat exchanger. In the winter, it warms it. If you really want to know the details, go to this website as a start.
The bore itself is only 5 inches in diameter. They'll be filling the shaft with "grout" (like a cement slurry) that will encase the tubing and make solid contact between the tubing and the earth.
The system is very expensive up front, but with the current incentives (tax credits for 30% of the cost), it pays for itself in 7 years or so. After that, we are saving money every year over standard systems.
Plus the technology is really cool, and as you know...Mark and I are total geeks. This system puts us in super-efficient, get-off-foreign-oil euphoria. Ahhhhh.