Apprasial Notes

Geothermal heat has not taken off due to its link to air heat pump style systems and their initial up front costs. However, with average air conditioning and heating costs rising to prohibitive levels the return of investment is making these systems more than practical and nothing can be greener. Basically, these are heat pump systems that use the constant below ground temperature of the earth, typically around 55 degrees, instead of the air temperature. The following article claims heating and air conditioning cost of $500 per year for a 2,300 sq. ft. home. with installation costs around $23,000. 

http://www.treesfullofmoney.com/2008/07/heating-your-home-with-geothermal.html