COLUMBIA — The MU Power Plant has whittled its way to wood chips in a quest to find a renewable, biomass fuel to mix with coal.
Power plant superintendent Gregg Coffin said burning wood chips will reduce greenhouse gas emissions by 7,000 tons, eliminate 90,000 trucking miles, 16,000 gallons of diesel fuel and save $40,000 to $50,000.
The plant released 362,433 tons of carbon dioxide in 2005, according to a city study.
The campus has been experimenting with burning different agricultural products, called biomass fuels, since it started with corncobs in 2006 and later tried switch grass. Biomass fuels are often waste products thrown into landfills or burned because there is no other way to get rid of them.
Using biomass to produce energy is “still in the infant stages,” said Bill Casady, an MU agricultural engineering professor who helped research different options for the MU plant. “People have been burning biomass for millennia, but not as a supplement for major energy production.”
The plant’s goal is to reduce costs while improving the environment. Burning biomass reduces the amount of sulfur, nitrous oxide, carbon dioxide and methane released into the atmosphere.
Sulfur emissions, a component of acid rain, and nitrous oxide emissions, a component of smog, are regulated by the U.S. Environmental Protection Agency, whereas carbon dioxide and methane, other common greenhouse gases, are not regulated, Coffin said.
“Greenhouse gases create a shield over the Earth that traps heat,” said Leon Schumacher, another MU agriculture professor who worked on implementing biomass. “They’ve been really forward, serving as a catalyst and a place to perfect and test different systems.”
The plant started experimenting 10 years ago with burning waste tires broken into coal-sized nuggets. The tire-derived fuel produces 20 percent more heat than coal, releases half the sulfur and saves the university $300,000 annually.
“A lot of people ask us why there isn’t any black smoke,” Coffin said. “The smoke is black when there isn’t enough air for combustion. We regulate combustion and filtration.”
About 5 percent of the plant’s burn mix is tire-derived and 5 percent is biomass, Coffin said.
It’s mixed with coal and placed on a grated conveyor that carries it to the boiler where it’s burned. Each type of biomass the power plant has tried presents its own set of problems.
“We’ve learned enough to know that burning grass isn’t easy, and corn, well, it’s hard to get a hold of,” Coffin said.
Switch grass wasn’t dense enough to mix well with the coal and didn’t work well with the plant’s equipment.
Corncobs burned well, providing 75 percent the amount of heat as coal, but the challenge was supply. There are only a few businesses that collect corncobs. The university got its cobs from a family-owned contractor in Nebraska City, Neb., according to Missourian archives. Wood chips are similar in density to coal, providing 70 percent as much heat when burned, and can be found locally.
“The drawback is that we have to work through handling, storing, regular supply issues,” Coffin said. “We have a limited site here, but those aren’t insurmountable engineering challenges.”
The power plant has a one-year contract with Missouri Mulch in New Florence, for 7,000 tons of wood chips. In the future, wood could come from development and construction sites, tree branches knocked down during storms, or anything that creates waste wood.
Coffin said the university has tested the wood chips at 5 percent of the burn mixture with success and has asked the state Department of Natural Resources to approve a temporary conveyor that could increase it to 10 or 15 percent.
He said he’s working with the Department of Natural Resources to make wood-chip burning permanent.
“When I look at the future of coal, you have to look at alternatives,” Coffin said. “Our country may never get 100 percent away from coal, and if you can use waste, I see value in that.”
Wind and solar power are other alternative ways to produce energy, but neither are practical yet for large scale energy production in mid-Missouri, Casady said.
“Look out the window,” Casady said in a phone interview Tuesday. There isn’t the sunshine of California or the wind of northwest Missouri to make wind or solar technology feasible now.
“Us in the Midwest look at biomass because it’s here,” Coffin said. “It can be used in existing facilities, is the quickest and most cost-effective way.”