Earth power at Grace Lutheran
Grace Lutheran Church in Detroit Lakes is growing -- in fact, by this summer, the facility at the corner of Roosevelt Avenue and Highway 34 will be twice its former size.
The church addition, which nearly doubles the square footage of the current facility at just under 8,000 square feet (bringing the total to nearly 16,000 square feet), is expected to house new offices, a fellowship hall and fully-equipped kitchen. But the big news is what lies beneath.
Buried approximately 10 feet underground, in a 150-square-foot pit, are a total of 20, 800-foot coils of pipe that will be used to transfer natural heat from beneath the earth's surface into five heat pumps inside the church building. That heat will then be compressed and distributed throughout the facility. Conversely, in the summer, this same equipment can be used to cool the facility.
"We've never had air conditioning before," said Wally Rawson, who chaired the building committee for the project.
This geothermal heating and cooling technology is relatively new -- and with a $70,000 price tag for the five pumps, pipe coils and associated materials, it's easy to see why it's not for everyone. But to Rawson and the other building committee members, it made sense.
"It's the most economical heating and cooling system you can find," he said. "With an estimated 60 percent cost savings over gas and electric heat, it pays for itself in 3-10 years (depending on usage)."
They didn't go into the project on blind faith, however. The committee members visited with officials from just under a dozen area churches, schools and other facilities that had been using geothermal heat for 5-10 years or more.
"It was difficult to find (geothermal units with a long track record), because the technology is so new," Rawson said. "But there were at least 10 we contacted. Basically, they supported what our vendors were saying -- that 60 percent (in energy cost) savings was realistic."
Maintenance also didn't appear to be a major issue with the churches and schools they contacted, Rawson added.
So the committee began looking into the possibility of obtaining an energy grant. Though they were unsuccessful, the City of Detroit Lakes did grant them an energy rebate of $20 per 1,000 BTUs used, up to $5,000.
The rest of the building project, estimated at $700,000, was funded through congregational donations -- and volunteer work.
"We're doing a lot of self-contracting on this," Rawson said. "The members volunteered to do all the sheet rocking, and there are licensed plumbers in our congregation who did all the plumbing. We're doing all the painting ourselves. Basically, we're trying to scrape up just enough to get this done."
For the portions that they can't do themselves, however, the congregation has retained the services of general contractor R.A. Bristlin & Sons. Mid-Valley Contracting of Reynolds, N.D., was hired for the geothermal installation.
Construction is proceeding apace.
"The addition is completely enclosed," Rawson said. "The roofing is done, and the plumbing is 100 percent done except for the fixtures. The electrical is 90 percent done, and the siding is in progress. It's about 60 percent done.
"The windows and doors are all installed, though some windows still need glazing. We're in the process of doing the insulating and sheet rocking."
Rawson estimates that the project will be done on or before May 1.
"We've been working on this for five years, and now it's developing in front of our eyes," he said. "It's exciting to see it come together."
How geothermal heat works
Furnaces must create heat by burning a fuel -- typically natural gas, propane, or fuel oil. With "geoexchange" systems such as the one at Grace Lutheran, there's no need to create heat, hence no need for chemical combustion, according to the Geothermal Heat Pump Consortium.
Instead, the Earth's natural heat is collected in winter through a series of pipes, called a loop, installed below the surface of the ground. A biodegradable fluid circulating in the loop carries this heat to the building. This system, which is one of two alternatives that were considered, is known as a "slinky system," Rawson said.
The heat is then transferred to the heat pumps inside, which then use electrically-driven compressors and heat exchangers in a vapor compression cycle -- the same principle employed in a refrigerator -- to concentrate the Earth's energy and release it inside the building at a higher temperature. The blowers inside the heat pumps then send the heated air into ductwork distributed throughout the facility.
At Grace Lutheran, the geothermal system will be used to heat and cool all portions of the building except the main sanctuary, which will still use electric heat, Rawson said.
In the summer, the process is reversed to cool the building. Excess heat is drawn from the church, expelled to the loop, and absorbed by the Earth. The GHPC says geoexchange systems provide cooling in the same way that a refrigerator keeps its contents cool -- by drawing heat from the interior, rather than by injecting cold air.