Geothermal Heating

Geothermal energy is considered a type of global renewable energy that can be sustainably extracted to provide residential or commercial heating.
Photo credit: Department of Energy

Geothermal Energy

Our planet's geothermal energy originated with the formation of the Earth approximately 4.54 billion years ago. Earth's core is constantly generating heat. Temperatures at the center of the Earth are extreme, reaching approximately 9,000 degrees Fahrenheit (5,000 degrees Celsius).

The Earth's heat radiates to the surface where temperatures below the surface remain relatively constant all year round, regardless of geographic location. The ground temperature under Phoenix, Arizona, for example, is not far off from the ground temperature under Minneapolis, Minnesota.

Geothermal Heating

A heat pump is a component in geothermal heating and cooling systems that captures the heat at the Earth's surface before transporting the heat via a loop system to warm or cool a structure. Geothermal heat pump technology is among the most efficient heating and cooling technologies, and has been shown to provide homeowners and businesses with substantial savings in energy costs over time. However, due to the widespread use of conventional fossil-fuel energy derived heating and cooling sources, and relatively high up front investment, the use of this technology has been limited.

As a general rule, installing a geothermal heat pump will cost about $3,000 more per ton than an air-to-air heat pump. According to the National Association of Homebuilders Research Center, “Overall, one could expect to pay between $4,000 and $11,000 more for a 3-ton GHP system than for an air source heat pump system”. An article in Scientific American states that geothermal systems are often “$7500 or more”.

According to the Environmental Protection Agency, geothermal heat pumps can save homeowners 30 to 70 percent on heating and 20 to 50 percent on cooling costs over conventional systems. Depending on the cost of electricity and/or type of fuel being used, a 2,000 square foot home may save between $300-350 per month. According to the NAHB, “reports by builders who monitor their in-place systems indicate heating and cooling savings between $358 and $1,475 annually”. To estimate how much a geothermal system will cost based on your location and current energy usage, you can use simple or detailed geothermal savings calculators.

This shows that the payback period of your geothermal system will vary greatly depending on the initial cost and your heating and cooling savings. Your best option is to find an experienced geothermal installer who will give you a cost estimate based on your available resource, current energy usage, incentives, etc.

Geothermal Pool Heating

Swimming pools can be heated with geothermal energy, using heat from the Earth to warm a swimming pool’s water. Alternatively, water to water geothermal heat pump systems may be used to heat a residential or commercial pool using heat from a body of water, such as a pond or lake.

Just like a conventional gas pool heater, a geothermal pool heater can heat water quickly to a specified temperature year round, but may be 80-90% more efficient than conventional gas-fired heaters. Heat is collected from Earth's surface, lake or pond, then it is concentrated with a heat pump and used to heat the pool.

When comparing renewable energy pool heating options in climates where temperatures range between 40-50 degrees F. at night, geothermal pool heaters may be more effective than a solar thermal system in maintaining temperature due to more constant underground heat source temperatures. Also, due to the fact that a solar thermal pool heating system may require an array that is equivalent in size to the pool's surface area, solar thermal systems are not feasible for most property owners. This could result in hundreds of dollars per year in energy savings.

A geothermal pool heating system may involve a higher cost up-front, however this investment is offset by the fact that geothermal heat pump systems are long-lasting and often carry warranties of up to 10 years.

Federal Geothermal Tax Credit for Energy Star Qualified Products

From now through December 31st, 2016 all existing and new construction residential properties (both principal/primary residences and second homes) qualify for a federal tax credit. The amount of the credit is 30% of the cost of the system, including installation costs, with no upper dollar limit. Installed products must be ENERGY STAR qualified, and meet the requirements of the program that are in effect at the time of the expenditure.

Qualified products include both water-to-air and water-to-water closed loop systems, as well as direct expansion systems. Products meeting ENERGY STAR qualifications are over 45% more efficient than standard heat pumps. For more information visit ENERGY STAR.

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