Cheaper Than Dirt: Geothermal Heating and Cooling Combat Rising Energy Prices
How would you like to maintain your home at a comfortable temperature year round while reducing both your energy costs and your impact on the environment? It's not science fiction. It's geothermal energy, and homeowners and commercial real estate owners are flocking to this form of alternative energy.
"People are definitely beginning to enjoy the benefits of geothermal energy," says Mark Miller, President of Miller Environmental Group (MEG), a Calverton, NY, environmental response, remediation, and alternative energy solutions company. "We believe in it so strongly, that we have just invested in installing a complete geothermal heating and cooling system in our headquarters."
What is geothermal energy?
The earth absorbs the sun's heat, so that between five feet and several hundred feet underground, the temperature remains relatively constant at about 55 degrees Fahrenheit. A geothermal system allows us to "harvest" the earth's heat energy by bringing it indoors in the winter and by using it to discharge the heat extracted from the building in the summer. There are several different types of ground temperature exchange systems that can be used to provide this transfer of heat depending on geological conditions. These exchange systems consist of vertical or horizontal closed loops, open loops, and pond/lake loops.
The main component of a typical closed-loop geothermal system is a ground-source or geothermal heat pump that cycles a water-based solution through a continuous loop of flexible piping buried underground, either horizontally or vertically, depending on soil conditions and available land.
Ground-source heat pumps move energy from one place to another; they do not create energy. The result is that, with the exception of the minimal amount of electricity needed to operate the heat pump and air circulators, no fossil fuels are burned in heating or cooling the building. A U.S. Environmental Protection Agency study reported that ground-source heat pumps are as much as 44% to 72% more efficient than conventional heating and air conditioning systems, which translates into substantial energy cost savings.
Environmental concerns
While there is no doubt that geothermal systems are friendly to both the earth and the wallet, how and where they are installed make a difference. "From our extensive work in groundwater remediation," Miller explains, "we know that the composition and properties of the soil in which you install the geothermal exchange system makes a difference in the range of efficiency. We also know that it’s important to consider the effects on environmentally sensitive factors such as the aquifer."
MEG, which was founded in 1971, installed the first groundwater treatment system on Long Island more than 30 years ago and was one of the first companies to be awarded a groundwater remediation contract by the New York State Department of Environmental Conservation. It is now using its extensive soil studies experience to benefit its growing list of geothermal system clients.
The geothermal heating and cooling system installed at MEG headquarters consists of eight heat pumps and thirty 200-foot closed loops of piping installed by drilling holes vertically on both the north and south sides of the building for increased efficiency. The depth of the loop field was designed for and installed entirely in the upper glacial
aquifer to prevent drilling in the deeper aquifers (Magothy) and avoid penetrating any confining clay layers. "We take special care to study the geology and hydrogeology around an installation so as to eliminate any negative environmental impact and maximize system efficiency," Miller says.
Some municipalities around the country, including Shelter Island, NY, are studying the environmental impact of geothermal systems. Because of increasing salt water intrusion potential to aquifers in coastal zones, open-loop systems are of particular concern. In an open-loop system, groundwater that travels through the heat pump returns to the environment through an injection well or through surface discharge.
"As with all geothermal exchange systems, proper subsurface evaluation of such factors as the geology, groundwater transport flow directions, and groundwater quality, to name a few, are necessary to insure that there is no disruption to the subsurface environment. Open-loop systems generally may not be practical for some conditions," says Miller, "and we strongly recommend a proper understanding of hydrogeologic conditions before the final design of the ground source exchange method is installed."
Costs and payback
The upfront costs of installing a residential geothermal system are higher than that of a comparable conventional furnace and central air conditioning system, but the month-to-month operating cost savings can range between 30% and 60%, according to the U.S. Department of Energy (DOE). As a result, the DOE estimates that a homeowner may recoup the initial investment in as few as five years at today's energy costs. This estimate does not consider future costs of energy.
Installation of a geothermal system during construction is easier and cheaper, but, retrofitting an existing home is often done and yields impressive energy cost savings. "At Miller, we are convinced that, under the right conditions, geothermal heating and cooling is the alternative energy source of choice," says Miller. "Everyone here works every day to make our planet a cleaner and healthier place. That's our business. So,finding a way to help homeowners and commercial building owners meet their heating and cooling needs in an environmentally responsible way, is very rewarding."
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