Imagine heating your home without burning fuel in your furnace.
Geothermal heating and cooling has been around for centuries, but it’s just recently become more popular because of rising energy costs.
When the Minnesota winter stakes its claim, all is warm and cozy inside the Deering home without natural gas or propane. Their heat comes from the earth.
“With the ground being at a constant about 50 degrees temperature basically all year round,” said Jim Deering.
Denise and Jim Deering chose geothermal over a regular furnace when they built this 5800-square-foot house nine years ago.
“The basement has in-floor heat and then also the garage has in-floor heat as well. So that’s all tied in to the geothermal unit as well,” said Jim.
And with all that you won’t even believe how much it costs them to heat in the winter and cool in the summer.
“Typically in the winter a monthly bill would maybe be average maybe $120 — $150 and then summer probably $25 to $30,” said Jim.
They figure if they were using a conventional system their winter cost would be three times as much. They feel pretty smart about that.
In order to understand how geothermal works, we have to understand the second law of thermodynamics.
For demonstration purposes of thermodynamics use the refrigerator.
What you do is place boiled water inside the refrigerator. Contrary to logic, the refrigerator doesn’t actually inject cold into the hot water — it removes heat from it.
That’s basically the second law of thermodynamics. Anything that’s hot will eventually get not so hot.
So where does all the heat energy go from the eggs and the milk and the butter and that hot Jello you put in there yesterday?
Ever feel the hot air coming out from underneath your fridge? In part, that heat is being extracted from all of the food inside your refrigerator and being exhausted into the ground.
“It’s just a cycle where the geothermal heat pump is extracting heat out of the ground,” said Jim Cusack, of Bergerson-Caswell, who installs geothermal systems in homes and businesses.
Right now the company is drilling geothermal holes for a prison being built in Wabasha.
The holes go down about 180 feet where the sun has kept the ground temperature at a constant 47 degrees.
David Henrich, also from Bergerson-Caswell, explains how looping pipes like these go down into the holes with a fluid inside.
“You’re going to have two pipes coming into your house — one supply and one return. You’re going to hook that up to your heat pump. Your heat pump is then going to pump a colder fluid down the supply side of your piping. That colder fluid is going down through these loops and they’re going to be warmed up by the heat of the earth,” said Henrich.
So no matter how cold the Minnesota ground is in winter, the return pipe is going to come back from below the freeze line with a warmer fluid. Which takes us back to the refrigerator and the fact you can extract that heat.
“The fluid comes into the geothermal heat pump at about 47-degrees. The compressor pulls about 5 degrees of heat off of the fluid. It compresses that heat which then serves to heat the house either with a forced air system or through a radiant floor,” said Cusack.
That compressor can raise those 5 degrees to as high as 165 degrees.
“This isn’t rocket science. This is simple. It’s just heat transfer. It’s plastic pipe running a fluid down a hole and you circulate it and it comes out. It’s very simple,” said Henrich.
The geothermal system does use electricity, and the Deerings have a separate meter to measure how much the heat pump actually uses.
Compared with furnaces that burn fossil fuel, geothermal produces far less CO2, but you don’t have to be a believer in global warming, to be a believer in geothermal.
“We really went after it as this is just simple and this is going to save us money. And now looking at it … it’s kind of a green effort or a green step for us,” said Denise Deering. “It’s an extra plus that we get that too.”
This is where I got a headache.
That heat can be extracted from substances even as cold as 450-degrees below zero.
On the low end, a geothermal system will add about $50 to a monthly mortgage payment, but you’ll save as much as $100 on your energy bill per month. So you’ll be $50 dollars, according to the people who install geothermal systems.
As for the Deerings, their unit has already paid for itself.