So You Think You Might Like Home-Based Geothermal Energy?

280px-NesjavellirPowerPlant_edit2As one informative web site notes, geothermal’s power source never varies – at least on the human scale of plus or minus 75 years. More important, geothermal energy provides more than half the energy needed to deliver heating and cooling, whether in the Deep South or the frigid northern half of the United States.

The trouble is most people, hearing the word “geothermal,” immediately think of vast steam fields and manmade (or natural) vents which feed huge turbines that can power a small city.

These geothermal fields currently exist in California and Oregon, with more across the Pacific Northwest as far inland as Montana in the north and New Mexico in the south. But all of these, whether extant or proposed, are utility-scale projects, an example of which can be found in the Salton Sea area in California under the name of the John L. Featherstone plant.

Geothermal fields, with their pipes and tubes and turbine buildings and vents puffing out huge clouds of fog, sometimes look like a scene straight from hell. Appearances aside, they provide clean, renewable, reliable energy to power 50,000 homes on average. According to the Geothermal Energy Association, the United States leads the world in installed geothermal capacity, with about 3,187 megawatts (MW), or enough to power 3.18 million homes.

Home-based geothermal energy is quite different. Relying on the fact that earth’s temperature at 4 to 6 feet deep is a constant 50 degrees, a closed loop of 1-inch, highly durable polyethylene pipe filled with water and/or antifreeze cycles between the earth under and around the house to bring lukewarm water to the house.

This water serves to circulate warmed water, from which the slight bump up (or down, to 70 degrees) is obtained through the geothermal system, or ground source heat pump, which acts like both a furnace and an air conditioner. Tack on a desuperheater – also known as an attemperation or steam conditioning machine, and the homeowner also has a jumpstart for hot water.

Once the temperature is at the desired level, standard heating and cooling ducts circulate the air throughout the house in such a way that the geothermal system is easily mistaken for standard HVAC (heating, ventilation, and air-conditioning) units.

But the most important part of geothermal energy is its consistency. When the sun doesn’t shine, solar energy is useless. When the wind doesn’t blow, the same can be said for wind energy. And even plugging in the fact that the sun usually shines when the wind isn’t blowing (and vice versa), a geothermal system is so reliable it’s “set and forget”. The same will likely never be true of solar or wind energy.

A residential geothermal unit has other advantages. It wires to a 50-amp circuit and operates without vents and without the possibility of fire or carbon-monoxide poisoning. Furthermore, on new installations, payback can be as fast as three years, thanks to a federal residential renewable energy credit (in the form of a personal income tax credit) which pays for 30 percent of a homeowner’s system costs without any limitation. Other credits may be available from your city, state or local utility.

This credit is good through December 31, 2016 and is non-taxable, even where the subsidy is provided by a public utility as part of its renewable energy standard as required under state law. For California, this standard is 33 percent (of energy from renewable resources) by 2020.

Unlike utility-scale geothermal, which generates electricity from steam, home-based geothermal is used simply for heating and cooling the home, with the possible addition of hot water in the summer, when heat taken from ambient air is used to moderate the temperature of water in the hot-water tank. The costs run about $30,000. Subtract the federal renewable energy credit (and utility-based credits if available), and factor in lowered energy costs for heating and cooling. Also, don’t forget the cost of a low-interest loan, and you have a HVAC system that costs about 10 percent less than traditional boiler/radiator or gas forced-air, or combination systems, and up to 50 percent less to operate than gas, propane or fuel-oil systems.

Not only that, but geothermal systems are hardy, with underground piping guaranteed from 20 to 50 years and heat pumps lasting 20 years or better. They are also noise-free, unlike outside air-conditioner condensing units, and control ambient air humidity superbly, maintaining a steady 50-percent indoor air ratio that is precisely right for humans, pets, fabrics, upholstery and furniture.

One caveat; installation by amateurs is not recommended. You would need a degree in geology and hydrology, as well as an electrician’s certification. The systems are far from simple, in spite of which they work reliably for decades and are commonly covered under a standard homeowner’s insurance policy (but make a courtesy call to confirm that). Also write a letter to inform your agent that you have one. You may even be entitled to a rebate.

Silent, inconspicuous, inexpensive and highly reliable, geothermal is a good way to go to cover your home’s heating and cooling needs in an era of rising fuel and energy costs – costs which your utility automatically passes on to you.


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