We went geothermal on a house remodel about 12 years ago. Wells were recommended to me at the time as being more failsafe and efficient. I dont know if that is still accurate. Don't know cost comparisons either.

Think they drilled 4 pretty deep holes in my backyard, put in pipe and connected them somehow. Wish I had taken measurements and pictures before they covered it up and seeded the grass.

[Linked Image from i108.photobucket.com]