Geothermal heating

Article on heating or cooling home using geothermal energy.
Apparently the trenches needed for this system in the author's home is:
300ft long 5 ft wide 5 ft deep. That probably is the downside of this kind of system, requirement for large amount of backyard space.
But the technology seems very simple, using PVC pipes and a compressor and a heat exchanger, heat and cool your home with minimal electricity requirement. Sounds cool!

Stumbled into this article while following an article: http://www.popularmechanics.com/science/earth/4245896.html?page=1

on low temperature geothermal power generation at Chena-alaska: http://www.yourownpower.com/