Minnesota Home Says Goodbye To Carbon Footprint 

Efficiently Using the Land

Although geothermal may be a lesser-known option than solar or wind, it is an effective way to help cut carbon emissions. Geothermal systems do not generate electricity, but instead, use the earth's natural temperature to heat and cool a house more efficiently than traditional methods. The temperature of the ground is about 55 degrees year-round, at a depth of about six feet below the frost line. This constant temperature is a key factor for both summer and winter energy efficiency, especially in a state like Minnesota, where the weather can reach both extremely high and low temperatures.

A geothermal heat pump usually consists of a series of six 100-foot long underground loop pipes that circulate a mixture of water and antifreeze (usually glycol). The pipes do not freeze because of the fluid mix and that the pipes are below the frost line. In the summer, the lower temperature of the earth naturally cools the fluid. The fluid releases cooler air that is then compressed to an even colder temperature, which is then delivered as air conditioning into the home. In the winter, the opposite occurs. The pipes absorb the heat from the earth, carrying warmer fluid to the system. The warmer air is again compressed and released as hot air into the home. A great way to understand more about a geothermal system is through this informational video.

While some geothermal systems are implanted vertically into the ground, the Carlsons laid their unit horizontally. Horizontal construction can be less expensive to install, but it does require a much larger area of land.

Give Me The Numbers

Upfront costs can be scary, but carbon-reducing systems manage to pay for themselves in a matter of years. The Carlson's geothermal system took ten years to pay itself off and has been making them money ever since. Geothermal is less expensive to use for air conditioning than it is for heating, but it is still an efficient option for colder states.

Geothermal systems can do more than just heating a cooling a home: they can help heat water—which is one of the most energy-intensive and costly parts of running a household. With geothermal, you can add a desuperheater. A desuperheater is an auxiliary heat exchanger that works to pre-heat hot water whenever the geothermal heat pump operates. With this addition, the cost of heating water is dramatically lowered and allows the house to be free from natural gas.

In Mary and Gary's case, they avoided some of the solar installation costs by building the foundation and structure themselves. The average cost is about 40% more for the full installation done by a professional. While most home projects are paid off between 8 to 12 years, they were able to pay off their solar panels in just four years. Now, they use $2,000 worth of energy per year but produce $2,200 worth of electricity. The Carlsons are not only making an additional $200 a year off of their panels, but they are also avoiding an energy bill of $2,000. The savings and the income totaling $2,200 pay off their investment of the array and then provide additional savings for them every year after. In other words, over the next 25 years, Gary and Mary will save a total of $55,000 in energy costs due to their solar panels. (You can learn more about the economics of solar panels here.)

Despite having built 85 percent of the solar structure themselves, the most significant way Gary and Mary saved money was through tax credits and rebates. Without these incentives, most projects would take over 20 years to pay off and, therefore, not be very compelling financially.

Very Few Downsides

As with any home project, there are always some downsides to consider. Gary's first response to the question about the disadvantages was that solar panels "are an eyesore." It is a common concern. To hide the array, the Carlsons planted a row of trees between the solar panels and their house to make the system barely visible.

Another downside to installing solar panels is that on the rare occasion that traditional power lines are out, the house is without power. They are grid-tied and do not have backup battery storage. While the Carlsons have experienced a few power outages due to severe storms, most of these incidents were short-lived and did not have a significant impact on their lifestyle.

While building the base for the arrays saved a lot of money, it is not practical for most people. Gary advised that one must be a "handyman" to complete this project by saying, "On a scale 0 to 10, 10 being expert, this project requires a 7."

In terms of the geothermal system, the only inconvenience the Carlson family mentioned was that it takes longer to heat the house. This extended time is because the geothermal system is not able to blast out as hot of air compared to a traditional natural gas heater. However, both Gary and Mary said that this delay wasn't a huge problem. It is barely noticeable if you keep your house generally warm relative to the outside temperature.