Our geothermal heating and cooling system is installed and already saving us money. We know because we have hot wateror warm water, anyway.
As I described before, the HVAC system relies on the natural ground temperature to heat and cool our house. We had the system installed after learning we had to replace an aging gas furnace and electric air conditioner. The new design is a green choice, in that it uses less energy. Unlike hybrid cars, it also makes economic sense without tax breaksafter six to eight years, lower utility bills should recoup the added cost, which was about twice that of a conventional system. We haven't seen enough utility bills to draw any conclusions from them.
As part of the change, we connected our water heater to the geothermal system, which sheds hot water, particularly in the summer. Our contractor says some customers switch off their water heaters in warm months, relying entirely on "free" hot water pulled from the geothermal condensers.
Still, the first weekend with the new system, we had only tepid water coming out of the faucets. The water heater itself was also new, so we wondered what was wrong. We figured it must be something with the geothermal gear, which seems newfangled but is mature technology, having been around in modern systems for a couple of decadesand for thousands of years in crude forms (think Roman baths).
With enough warm water to get through our showers and baths, we waited until Monday to ask our contractor.
Hah. Turns out the water heater wasn't even fired up. The warm water was coming off the geothermal condensersnot enough in chilly weather for a hot, satisfying shower. But warm enough to be reassuring that just maybe this green choice will pay off.