Heating with Sunflower Hulls
Thursday, November 1, 2001
filed under: Utilization/Trade
Heating with Sunflower Hulls
Minnesota School Saving Money by Heating with Sun Hull Pellets
It’s a good bet that students who attend Barnesville High School in Minnesota would probably get scolded for eating sunflower seeds in class. It’s a bit ironic, then, that the entire school is heated by sunflower hulls, and saving money by doing so.
The Barnesville school district, in the heart of the Red River Valley about 30 miles from Fargo, N.D., has been using solid fuel as a heating source for years.
About 20 years ago, the school district started burning wood pellets in its furnaces to help cut energy costs. That changed when the cost of trucking the pellets from northern Minnesota increased, and the school began searching for other solid fuel alternatives. The district then began using discarded sugar beet seed screenings to heat the elementary school, and sunflower hull pellets at the high school. “We did some experimenting, and found out they were user-friendly,” says Merlin Strom, the district’s buildings and grounds manager. “You can burn really any kind of commodity,” he says, pointing out that garbage, recycled tires, even defective tennis balls can be processed and incinerated as solid fuel.
The school district contracts with a local farmer to haul the sugar beet screenings from the American Crystal Sugar plant in Moorhead, Minn., and the sunflower hull pellets from Westway Trading Corp., located at Mapleton, N.D.
Strom says the BTU rating for the sugar beet screenings and the sunflower hull pellets is almost as good as the wood pellets, and much less expensive. The school district’s heating bill is about 20% less using sugar beet screenings and sunflower hull pellets as fuel sources. That’s based on a sunflower pellet cost of about $85/ton delivered, compared to fuel oil, which would be about 95 cents to $1.00. “The bottom line is that it gives us a locked-in price, and we’re not at the mercy of fluctuating (fossil fuel) prices,” he says.
The school will usually process about 120 to 150 tons of discarded beet seed during the heating season, and about 450 tons of sunflower pellets at the high school, which would compare to about 45,000 gallons of fuel oil, Strom estimates. “We used as much as 600 tons of sunflower pellets in the winter of ‘96-’97,” he says, which was a record year for snowfall in the area.
A 30-ton hopper bin adjacent to the high school is used to store the sunflower pellets, which are fed by conveyor into a 10-year-old Burnham boiler furnace, which is built for solid fuel heating. A fuel oil furnace sits next to the Burnham furnace as a backup. The hopper outside is equipped with an automatic timer that feeds pellets into the furnace, which has motors that signal when more energy is needed, or less. One drawback to burning solid fuel is more maintenance, says Strom, with ash that needs to be cleaned out periodically.
A few years ago, a Fargo company that specializes in energy efficiency management conducted an energy analysis of the Barnesville School District. When it came to the district’s unusual heating system, Strom says “they said they’ve never seen anything like that.” The analysis indicated that the system has indeed been helpful to the district in managing its fuel costs, but recommended some minor improvements that are being put in place, including off-peak control settings. “They felt we should have found more savings in our heating than we had,” says Strom.
Strom is also experimenting with using corn to supplement the sunflower pellets as a fuel source. “Because of its hard outer shell, it’s harder to get burning but once it’s started, it burns quite nicely.” The sunflower pellets stay put a bit better in the furnace, however, and burn somewhat cleaner. “I’d like to try burning a blend of hulls and corn. I think you’d have a pretty good product there.” – Tracy Sayler
Sidebar with images of UND worker, UND pile
Burning Sunflower Hulls for Fuel Focus of UND Study
Burning sunflower hulls with coal is a focus of a study recently completed at the Energy and Environmental Research Center, University of North Dakota, Grand Forks.
Funded through a U.S. Department of Energy grant, the study looked at the feasibility of cofiring biomass with coal in UND’s heating plants. Cofiring biomass with coal may have several benefits, resulting in a fuel mix that is less expensive and friendlier to the environment. It might also lead to new business opportunities for low value biomass resources.
The use of sunflower hulls was a key focus, since it is a readily available agricultural byproduct. “It basically burns real well with the coal,” says Phillip Hutton, a research scientist at the center. About 50 tons of sunflower hulls obtained from Dahlgren in Crookston, Minn. were used as fuel in the study, burned along with coal in about a 75% coal, 25% sun hull ratio. Burning the hulls along with coal may reduce air-born emissions of contaminants, such as sulfates and nitrates. It’s a plus that burning hulls along with coal requires no additional processing, notes Hutton. Cofiring sunflower hulls with coal will be studied further by the Center, to confirm benefits before investments in large-scale equipment are made.