Benson, Minn. — Minnesota corn farmers may soon become cob farmers too — if Bill Lee has his way.
Lee, general manager of the Chippewa Valley Ethanol Cooperative, is investigating cob’s potential to fuel a gasifier the co-op started operating this spring. The gasifier supplants nearly 90 percent of the plant’s natural gas use.
CVEC, a diverse 980-member producer-owned co-op, operates a 48 million gallon-per- year ethanol plant and distills Shakers vodka. This fall, CVEC will conduct in-field harvest trials on two different systems for collecting corn cobs.
“We’ve been in the ethanol business for 12 years and now we’ve made the commitment to gasification,” Lee says. “We’re always looking for ways to lower cost through biomass. There may be some cost advantages with cobs. They’re about the most plentiful and available biomass we have in our area.”
CVEC, with support from AURI, Minnesota Corn Research and Promotion Council and Minnesota Commerce Department, will harvest cobs from 5,000 acres of corn or an estimated 4,000 tons of cobs. Two different technologies will be used in the one-pass process designed to collect cobs and corn at the same time. Besides testing collection systems, the project will also evaluate storage systems and address handling and transportation issues.
“Some of the biggest hurdles for any type of large-scale utilization of biomass are densification, handling, storage and transportation,” says Alan Doering, head of AURI’s coproduct utilization program in Waseca. “Every time you handle biomass or have to do something to it, it adds cost. Having a one-pass collection system would improve the economics.” Lee says CVEC is interested in proactively reducing its carbon footprint as carbon regulations may be coming. But “we need to understand the economics of cob removal, transportation and storage so we can develop cobs as an economically viable biomass source,” Lee says.
Renewed interest
Cobs used to be widely available — when the whole corn ear was harvested and the kernels separated later. Among other uses, cobs were burned for fuel or used as animal bedding. But as combines simplified the process into a single step, cobs were returned to the field along with other corn waste or stover.
In recent years, interest in cobs for chemical extraction and biomass energy has reignited, but there isn’t a commercially-available technology for harvest and collection. The two systems CVEC is testing this fall could soon be commercially available. In fact, Lee expects one major materials- handling manufacturer to have a system available next year.
Corn-cob removal will not harm soil health. While stover is important for erosion control and organic material builds soil structure, cobs have little value. But as a biomass fuel, it is one of nature’s only perfectly-densified feedstocks.
“When it comes to the corn stover, cobs are the least functional ingredient,” Lee says. “But they do have about one-third to one-fourth the ash of stover, they are more dense than stalks and can be handled in bulk like wood chips.”
CVEC currently uses wood chips to power its gasifier, which it wants to replace with cobs collected from its own producer-shareholders. Lee says about one ton of cobs can be collected from each acre of 200 bushel-per-acre corn. He estimates cobs from 108,000 acres of corn needed for the
co-op’s ethanol production would provide 75 percent of the plant’s thermal energy needs.
Sharing the info
While CVEC is conducting the trials, its intent is to share results with others to build the industry.
“The state stands to benefit from this work, as does our company,” Lee says. “We want this information out there. We want corn farmers to be cob farmers as well.”
“A big hindrance to the widespread development of things like green ethanol, gasification or cellulosic ethanol is logistical systems,” says Michael Sparby, AURI project director in Morris. “So it is very valuable to be able to test cob collection on this large of a scale.”
Lee says the CVEC project will include demonstrations, field days and a video of the process. Researchers from the U of M West Central Research and Outreach Center and the North Central Soil Conservation Research Lab in Morris will be involved in agronomic research.
Lee says the effort will help develop better tools for developing the biomass industry — tools that could move corn cobs to prominence.
