Minnesota utility harvests cobs for test burn

By Ryan C. Christiansen
Web exclusive posted Nov. 21, 2008 at 9:57 a.m. CST

Willmar Municipal Utilities, the electric utility for the city of Willmar, Minn., harvested 450 tons of corn cobs from a local farmer this fall and will test burn cobs with coal at its power plant this winter.

According to Jon Folkedahl, a consultant for the renewable energy venture, the Willmar utility submitted a request to the Minnesota Pollution Control Agency on Nov. 18 for a temporary permit to burn the cobs.

If the test burn is successful, the utility plans to apply for a permit to permanently burn 20 to 30 percent cobs with 70 to 80 percent coal at its 16-megawatt power plant, said Bruce Gomm, general manager for Willmar Municipal Utilities.

Folkedahl said the cobs were harvested using the Vermeer Corp. CCX770 Cob Harvester. He said numerous growers volunteered for the harvest, but in the end logistics, timing, and equipment availability led to working with a single grower.

The Willmar utility's harvest was the second harvest in central Minnesota this fall. Nearby Benson, Minn.-based Chippewa Valley Ethanol Company LLLP held three corn cob harvesting demonstrations near the Minnesota communities of Holloway, Donnelly, and Priam, harvesting 5,000 acres of cobs from more than a dozen farmers. CVEC plans to use a Frontline BioEnergy gasifier to convert cobs to syngas to replace natural gas at the company's 45 MMgy ethanol plant. In nearby Morris, Minn., the University of Minnesota campus also plans to use cobs at its new biomass gasification plant.

"The development of cobs as a fuel material by several different entities is good," Folkedahl said. "We want to develop the market in the local area and so we think that will help generate enough interest. The farmer will feel more comfortable investing in cob harvesting equipment if he knows that there is more than one market available in the area. On the other hand, competition will probably drive the prices up."

Gomm said the utility, the ethanol plant, and the university are all aware of what each other is doing to generate demand for a supply of cobs. "Our research indicates that there is quite a large quantity of cobs available," he said. "When you look at total corn acres in the immediate area, if we could get a pretty high percentage of cob collection, there would be plenty to meet everybody's needs." Folkedahl said there were 150,000 acres of corn planted in Kandiyohi County, Minn., last year.

Because Minnesota has mandated that all utilities produce 25 percent of their energy needs through renewable resources by 2025, Gomm said the Willmar utility has been looking for a source of biomass to produce energy for some time. Corn cobs appear to be the solution.
"The best way for biomass to be economical is for it to be a fuel of opportunity," Gomm said. "The traditional fuel of opportunity for biomass has been wood waste. Unfortunately, there is just not a lot of that around here." Another large biomass resource is turkey litter from turkey farming operations in the Willmar area, he said. However, that resource has already been spoken for. Fibrominn, a subsidiary of Philadelphia-based Fibrowatt LLC, is using the turkey litter to fuel a 55-megawatt power plant in Benson, Minn.

Gomm said Folkedahl approached the utility with the idea of using cobs about a year ago. "I came to the conclusion that corn cobs were probably the ideal fuel source," Folkedahl said, "because the equipment to harvest them was just becoming available. I give you better-to-even odds that this will take off. Cobs are the hottest thing going in terms of renewable fuels."