My neighbor has done some experimenting with geothermal heating and cooling but not of this kind.
He buried PVC pipe below the frost line all over his yard and pushes air through it. The ground stays at between 53 anf 55 degrees year round so you can see the advantage. He’s looking at doing the same but pushing water through the lines at his other house.
He just might develop a slight problem with flooding if he uses the same set-up he did for air.
http://www.patentgenius.com/patent/5509462.html
Ground Source Geothermal Heat Pumps are an incredible opportunity for energy savings.
Free energy just below the Earth’s surface can be exploited cost-effectively for heating and cooling.
Imagine heating and cooling a 2,000 sq. ft. home for a few hundred dollars each season!
Capital costs are somewhat higher, but not significantly. And geothermal heat pumps can last as long as 25 years.
Also, there is no noisy exterior heat exchanger for air conditioning - it is an integral part of the heat pump.
If he hasn’t already, he should contact the alternative energy institute at West Texas A&M University. They have done some research on this and had some very good information when I asked about it several years ago.
One thing they learned was that if you use straight-edged PVC (normal pipe), the air close to the edges is cooled a lot, but the air that flows through the middle doesn’t cool much. They tried pipe with a corrugated wall and it created turbulence in the air stream, cooling the entire stream.
I’m sure the same thing would happen in a water-based system.
Another thing to consider with an air-based system is that they are humidity traps. If the air is humid upon entry, the water will condense in the pipe and you eventually will have a mold problem.