Someone’s new geothermal system raises some interesting questions.
See: Looks Like a Hot Deal, by Christopher J. Gearon, Washington Post, Tuesday, March 02, 2010
Synopsis: With various govenment incentives, Gearon equipped his 4,400 sq. ft. home with an expensive geothermal heating and cooling system.

Several economic and technical questions arise from the article:

1. Gearon states that his new tankless water heater is more efficient than a conventional water heater. While tankless water heaters don’t have losses associated with stored hot water, those losses are relatively minor. One could only determine which water heater is more efficient by comparing specifications or tests on the competing systems.
2. Do the incentives, tax breaks, and grants that financed 60% of the cost of Gearon’s new system, make sense for the general public? I.e., Do these benefits bring a reduction in pollution that is commensurate with the amount of money being doled out?
3. Gearon could have gotten some of the tax benefits from a more conventional, but highly efficient system (e.g., a condensing oil furnace). These would lower the cost of those competing systems.
4. If Gearon is using wind or another alternative source, he didn’t state that in the article. If he uses coal-fired electricity, his claim that his heat is fossil free doesn’t hold.
5. When touring a LEED building, an energy engineer asserted that the heat transfer between the downward and upward pipes in a vertical well ground system, are more significant than the transfer to the ground. Thus he asserted that there would be little or no benefit from the portion of the well below several feet.
6. Because the ground is cooled in winter and heated in summer from the geothermal well, temperatures around the well will fall in winter and rise in summer. These temperature changes will make the system less efficient as we get into the respective heating and cooling seasons.

Several of these items would require detailed analyses.