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Green living: Off the grid families pioneer sustainable energy lifestyles

Once on the fringe, about 750,000 off the grid American households pioneer green living by tapping sustainable energy from the wind, sun, and earth.

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Commercial geothermal plants take volcanic heat deep in the earth to create steam to turn a turbine and generate electricity. But for individual homes, geothermal cooling and heating systems pump water through underground pipes that heat or cool the water to the constant temperature of approximately 55 degrees F. near the Earth's surface. "You are using water as the vehicle for moving the latent temperature of the Earth," says Martin Orio, general manager of the company Northeast Geo, a New Hampshire company. There are different models, but all essentially rely on fluid circulated through tubing that can be installed up to about 200 feet deep vertically, or horizontally about 10 feet deep and roughly as wide as the property. In winter, the fluid is warmed below the earth, then heats air using a compressor and standard technology known as the refrigeration cycle. In summer, the cycle is reversed so heat is essentially extracted from the home and sunk back into the earth.

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In relatively soft or sandy soil, pipes for a geothermal system can be run horizontally or in a variety of loops. On top of hard bedrock, one must drill down – a more expensive proposition – to create a "standing column" system where fluid is circulated through a vertical cylinder with a "riser pipe" in the middle. Water moves up the center, then flows back down the outer ring of the cylinder.

Geothermal systems are typically built with the home; retrofitting is expensive and difficult, though technological innovations may soon change that. As it has become more economically practical, geothermal systems also have gained "cachet" as a status symbol, says Andrew Collins of the New York City firm P.A. Collins P.E. Consulting Engineers. The firm has designed geothermal systems at the new Liberty Island Retail Pavilion and for upscale homes in Tribeca, the Upper East Side, and on Long Island.

Meanwhile, on or off the grid, experts say the cleanest, cheapest energy is the energy not generated at all. Weatherizing a home is the best thing for the environment and the wallet.

"It's great to have geothermal or photovoltaic [solar], but we like to stress you don't need those technologies to have a real energy-efficient home," says Nate Kredich of the US Green Building Council. "You need a tight envelope – good insulation, tight windows, everything air-sealed. That goes an awful long way."

And new types of solar, wind, and geothermal systems and energy-efficiency innovations are being developed all the time.

"People just start looking to see what resources are around them, attempting to tap anything and everything that makes sense," says Steve Brauneis, senior consultant at the Rocky Mountain Institute, a national leader in renewable-energy research. "We'll see all sorts of things sprout up. That's the human spirit."

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