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August 15, 2009 @ 1:35 pm
Geothermal Heat Pumps Save Energy and Suction Taxes

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Geothermal heat pumps (aka GeoExchange, earth-coupled, ground-source or water-source heat pumps) are a remarkable, yet simple green technology that has been around for about 60 years. Anyone that’s visited a cave to see stalactites/stalagmites or do some rugged camping will remember the constant temperature that is cooler in summer and warmer in winter than at the surface. The ground is an efficient insulator, and depending on latitude, underground temperatures range from 45°F (7°C) to 75°F (21°C) year-round despite seasonal extremes at the surface. Heat pumps are able to take advantage of these temperature gradients for heating and cooling purposes, but how?

There is a detailed explanation here, I will summarize. Traditional heat pumps transfer heat utilizing a refrigerant that is acted on by an exchange medium (air in a standard A/C unit or liquid in a geothermal heat pump). The refrigerant absorbs heat and is compressed into a high temperature, high pressure liquid for heating purposes or allowed to expand into a low temperature, low pressure gas for cooling purposes. In winter, heat pumps pull heat from the air to be circulated in the home and during summer they take heat from inside and push it into the air. Significant amounts of electricity are used in this process because temperature extremes need to be overcome and air is an inefficient heat transfer medium. On the other hand, the liquid water or antifreeze solution of geothermal heat pumps is 30% more efficient than air. In summer, heat is pulled from the building and deposited in the much cooler earth very efficiently. In winter, the constant, relatively warm temperature of the earth provides much more than heat than the air so much less compression (and therefore less energy consumption) is needed vs. a conventional system. 

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In fact, according to U.S. Department of Energy studies, geothermal provides system efficiencies of 300-600% on the coldest winter nights while air-source systems can reach only 175-250%. Integrated systems can handle all of your heating, cooling and hot water needs year-round. The result is significant energy savings over your current costs of electricity, heating oil, etc. While installation of geothermal systems costs more upfront, these energy savings cover the additional costs over 5-10 years. 50,000 units are now installed annually in the U.S. alone. The benefits outlined by the U.S. Department of Energy and the U.S. Environmental Protection Agency are listed below: Read More…

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