Published: July 02, 2008 01:23 pm            

Truly renewable energies warm up in Minnesota

Originally published in the June 27, 2008, print edition.

‘Nothing but a growing industry’ is how Derek Otteson, president of Empire Plumbing & Heating, analyzes the future of solar, wind and geothermal energy for Minnesota.

“These are the only real renewables out there, and as petroleum energy sources continue to ratchet upwards, these three energy sources are generating a whole new audience of interest,” Otteson said.

He recently assisted with the installation of 12 used solar panels for a special greenhouse project by Willmar Public School students on the new MinnWest Technology Center in Willmar. Formerly the Willmar Regional Treatment Center, solar panels were used extensively for pool heat, base heat and domestic water.

Otteson said there are three manufacturers of solar panels in Minnesota. His firm works with SolarSkies of Starbuck.

Reflecting on the boom in solar heating back in the 1980s, he indicated flat-plate collectors are highly efficient in harvesting solar power and new improvements in controlling the flow of water within a system make solar today much improved.

“Now we have computerized thermostats that basically run the system automatically. Earlier systems often required more maintenance and repairs and that’s why many early systems shut down, especially when fuel got cheap once again,” Otteson said.

Square footage of a given panel is how you determine heat production of a given system. “You get a certain amount of Btus per day per square foot of panel. Weather data over the past 15 to 20 years is analyzed averaging out the number of sunny days versus the number of cloudy days which determines the Btu production data, like about 20,000 Btus per day in this part of Minnesota.”

The variable weather is part of the challenge with solar heat and that’s why back-up systems are necessary. He indicated some days you might get five times the average Btu production, some days zero production.

Otteson said the best use for solar today is high-usage domestic hot water users such as car washes and hotels. For residential use right now he says you’re looking at about a 10-year payback, but escalating LP fuel prices are trimming that payback time.

The number of bedrooms and the number of people living in the house is his starting point for determining the square footage of solar panels needed. “We figure about 20 to 25 gallons of hot water per day per person, or with a three-bedroom house you better figure at least a 100-gallon system. Today, that system would cost $6,000 to $8,000.”

Geothermal more popular in new construction

“Geothermal is simply more tangible. Solar thermal still seems more unpredictable to most people plus you’re looking at less cost with geothermal systems,” Otteson said, noting it too has about a 10-year payback based on today’s costs.

Radiant in-floor tubing is the ideal usage of solar because you have lower water temperatures then needed for bathing and cooking for example but the key bonus of solar heat is that you have little or no moving parts, virtually nothing to wear out with age. “Once you get a system installed, you probably have 30 to 40 years maintenance-free operation,” Otteson said, noting that other than the electricity to power the pumps, a solar system is free energy.

Nonetheless, consumer acceptance of solar has been slow. Geothermal is the popular choice for most homeowners. “Some people just aren’t comfortable with the five- to eight-degree temperature fluctuation a solar system produces. Geothermal on the other hand, regardless of weather conditions outside is reliable year-round. And geo has been around for 25 to 30 years so it has a proven track record.”

Vertical wells (often 80 feet deep or more) versus a horizontal 8-foot-deep loop system pretty much depends on the lay of the land. Horizontal is generally cheaper but you’re tearing up more of the yard and you need more space. Wells are slightly more efficient. So what system best fits often depends on the neighborhood and available space. Farm residences generally don’t have space limitations.

Otteson summed up his outlook for geo and solar indicating both are right on the edge of becoming mainstream energy sources. “I see geo and solar as being what everybody does within five to 10 years.”

Initial cost is the biggest obstacle. A geo system adds about $8,000 to $10,000 construction costs to a new home. “We’ve done about 10 systems in our Benson area, with closed loop being most popular providing you don’t get into a water problem,” said Pat Hawley, Hawley’s Inc.

“We offer a $200 per ton rebate. So for example you put in a five-ton system (air conditioner capacity), our co-op would write you a $1,000 check. We advise folks to not overbuild when installing geo thermal systems — build big enough to take care of your summer-time air conditioning needs and then have a small backup furnace for the extra heat needed during winter,” said LeRoy Cluever, member services director for AgriLight Electric Co-op at Benson,

Old greenhouse becomes earth learning center

Rob Palmer, earth science instructor at Willmar Public Schools, has his students in this special greenhouse project called the Youth Energy Summit with a mission of being sustainable with solar power.

Besides the hot water solar collectors donated for the project, AquaTherm Technologies in Willmar donated a biomass boiler for use when the sun isn’t doing its job. A 265-gallon “hot water” storage tank also supplements the system.

“This became a great learning center because we had to figure out what was needed to make the project work, then learn to properly operate the system plus learn what greenhouse crops to grow to meet local demand,” Palmer said.

The Prairie Woods Environmental Learning Center north of Willmar put out a proposal to area schools last year to come up with alternative energy suggestions for their particular school and/or community. “I noted this old, unused greenhouse sitting here on this new technology campus. We suggested the idea of solar power for the greenhouse to decrease fossil fuel consumption while providing fresh greens for our school cafeteria and the weekly farmers market downtown Willmar,” Palmer said, adding that the general manager of MinnWest Technology Center was delighted that students are finding a way to harness free energy while also making good use of an old unused greenhouse (two wings, each 33-feet x 18-feet but only one wing is currently functional).

The biomass boiler is also a learning project for Palmer and his students. Alfalfa pellets, corn, corncobs and other biomass residue will be the feedstock choices. Some alfalfa meal from Minnesota Valley Alfalfa Producers has already been donated to the students for firing up the boiler when the sun doesn’t supply enough hot water energy.

On the day of this visit, student Nic Trapp was harvesting cilantro (for a local Mexican restaurant), broccoli, zucchini and salad greens. Intending to have the second wing of the greenhouse operational this fall, students hope the project is marketing enough produce to cover their material costs to make this project financially sustaining.

“I thought this was a neat project when we got started. And thanks to great help from Derek Otteson in designing and hooking up our 12 solar panels, we’ve got more than enough Btu capacity to operate both wings. But it’s been a lot of work, perhaps more than both my students and I anticipated. We see great progress already and what a tremendous focus for utilizing some of Mother Earth’s free resources,” Palmer said.

One of the bigger boosters is the dietitian at the public school. She agreed to pay $1 a pound for the greens brought to the student cafeteria this past school year. More recently the Willmar area League of Women Voters found out about the project and currently sponsors a booth for this student greenhouse at the weekly farmers market. When production picks up this fall, the Willmar area food shelf will also be getting free, fresh produce courtesy of this greenhouse.

        

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