Geothermal heat is becoming a hot commodity

With constantly rising energy costs, property owners are looking toward alternative and renewable energy sources, including geothermal, a proven technology that can eliminate the use of fossil fuels, save energy and money and reduce carbon gas emissions.

Geothermal technology uses the earth’s natural thermal energy to heat or cool a home or building. Other names for the technology include geoexchange, earth-coupled heat or green heat. But no matter what you call it, geothermal systems are good for both the wallet and the earth and are edging up on the list of preferred heating systems.

The U.S. Environmental Protection Agency has identified geothermal systems as “the most energy-efficient, environmentally clean, and cost-effective space conditioning systems available today.”

How goes a geothermal system work? It takes advantage of the planet’s ability to store vast amounts of heat in the soil – 50 percent of the sun’s energy is stored in the earth. And just a few feet beneath the surface, the earth’s temperature remains fairly constant year-round, ranging from 45 degrees or so in northern latitudes to about 70 degrees in the deep south. (It’s 52 degrees, give or take a degree or two, here in New England). Geothermal takes advantage of this constant temperature to provide extremely efficient heating and cooling.

In winter, water from a well, which has absorbed heat from the earth, is pumped into the home and passed through a heat pump. The compressorized refrigeration system within the heat pump extracts heat from the well water by cooling the water. The refrigeration system then releases the heat into the house.

In the summer, the process is reversed. Liquid refrigerant passes through the evaporator where it vaporizes and absorbs heat from the house. The heat is then released into the well water where it circulates back into well, allowing the earth to cool it.

The external energy needed for a geothermal system is the electricity needed to operate the well pump and the heat pump. Because geothermal systems can be installed on almost any size lot, they are appropriate for new construction as well as retrofits of older buildings.

Geothermal heating has increased in use in recent years as a result of the many improvements made in the materials used, the installation methods and the rising prices of fossil fuels.

Cost savings

While a desire to protect the environment is reason enough for some to turn to heating efficiencies, there are other, less altruistic benefits to geothermal technology. The cost savings typically mean a geothermal heat pump system designed and installed in a new house will have a payback within five to 10 years.

The EPA has confirmed that geothermal systems operate at 75 percent greater efficiency than oil furnaces and 48 percent greater efficiency than gas furnaces. In addition, hot water during warm weather months is almost a “free” byproduct of operating a geothermal system in the cooling mode.

And greater building design freedom can be had since these underground systems eliminate the need for exterior mechanical equipment.

Individual states offer incentives to those using geothermal systems in their home.

Massachusetts has a 5 percent sales tax exemption statute in place for systems in use in an individual’s principal residence – this exemption, however, is not available to commercial users.

The New Hampshire Electric Cooperative offers a residential new construction program of up to $6,000 per dwelling for homes that choose geothermal heat pumps for their primary heating system.

And the Connecticut Housing Investment Fund offers single-family energy conservation loans from $400 to $10,000 to owners of one-to-four-unit family homes who meet established income limits. These loans may be used for a variety of conservation improvements, including geothermal heat pump installations.

More than a million geothermal system have been installed in the United States. Although this is a small percentage of the total HVAC market, the number of people choosing to install geothermal is growing rapidly – about 20 percent every year – as more learn about this technology that can help save both planet and pocketbook “green.” nhbr

D.J. Quagliaroli is president of Dragin Geothermal Well Drilling, Gilford.