How Does Geothermal Heating Work?


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Geothermal Heating GraphicHere’s a bit of interesting trivia for you. The town I live in, Klamath Falls, was actually the second town in the United States to install a city wide geothermal heating utility. It’s because of this facility that I became interested in this type of heating.

Our town’s facility provides heat to government buildings as well as some commercial buildings. They even use it to keep the ice melted on the sidewalks and bridges in the winter time. Without this source of low cost geothermal heat, these types of luxuries that we enjoy just wouldn’t be cost effective.

What Is Geothermal Heating Anyway?

In areas of the planet where volcanic activity rises relatively close to the surface, high ground water temperatures can be harvested to heat buildings and/or water. The higher the water temperature, the more heat can be extracted from it but the ground in parts of the world where these volcanic hot spots don’t exist still contains enough heat to be effectively used. In areas of moderate climate, earth that is only ten feet below the surface maintains a consistent temperature of 55° F regardless of the season. With the use of a geothermal heat pump, this heat can be extracted from the earth to offset heating costs.

How Geothermal Heating Works

In some places on earth, hot water from natural hot springs can be pumped directly into either a geothermal heat exchanger or radiators. This eliminates the need for a boiler tank that burns fuel to heat water which results in a very cost effective source of heat. In other parts of the world, geothermal wells are drilled and the hot water or steam from these “hot wells” are used in the same way I described above.

While some areas are close enough to the super hot ground water temperatures that are created by volcanic activity, most aren’t. Let me take just a minute and explain how heat can be extracted from the earth for use in heating our homes and businesses in these areas. Even though the earth in these areas doesn’t product hot water or high heat, it’s still going to be warmer than the air at the surface. In virtually anyplace on earth, you only have to dig to a depth of about 10 meters (32.8 feet) to get to ground temperatures that are the same all throughout the year. These temperatures average around 52° F. As long as the air temperature at the surface is lower than the temperature of the earth, heat from the earth can be harvested effectively.

geothermal heat pump system

This diagram depicts the concept of geothermal heating. The blue represents the cold liquid being pumped through the ground and the red represents the warmer liquid that has absorbed the head from the earth.

Believe it or not, it takes less energy to extract the heat from the earth at these depths than it takes to heat the air to a comfortable temperature at the surface. This is done with the use devices called “geothermal ground source heat pumps”. These devices extract the heat from relatively shallow depths by pumping a mixture of water and anti-freeze through a system of pipes that are buried underground. This particular type of pump is known as a “closed loop geothermal heat pump”.

When this liquid is pumped thorough the pipes that are buried under the ground it absorbs heat from the surrounding earth. As it is circulated through the loop of pipes, this heat is extracted from the liquid with electricity at the geothermal heat pump. The reason this is cost effective is because it takes less electricity to extract the heat from this liquid than it does if electricity alone was used to produce the required heat.

After the heat has been extracted, the liquid is once again cool and it is then pumped back through the loop of pipes and the entire process repeats itself.

Does Geothermal Home Heating Qualify As Renewable?

Well it really depends on where the source of electricity comes from that powers the geo thermal heat pump. If it comes from electricity that is generated by burning fossil fuels, then the answer would be no. If it comes from a renewable energy source, then the answer would be yes.

Remember, not everything is black and white in our quest to live “greener” lifestyles. The use of a geothermal heating system will in fact reduce the amount of energy that your home needs to use to keep your family warm and toasty. It’s important to always keep in mind that anything we can do to conserve energy and reduce our dependency on fossil fuels adds up and makes an impact on the overall health of the planet.

If you would like to learn more about energy that can be extracted from the earth, you might want to read my articles called Some Interesting Facts About Geothermal Energy and
Is Geothermal Energy Renewable or Nonrenewable.

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