Cobs for Cash

November 14, 2008 06:00 PM
Todd Mathisen has a habit of walking behind the combine and checking the ground for stray corn kernels. This harvest, he's also looking for corn cobs and what he hopes to be his next cash crop.

"I think farmers should warm up to the idea of saving cobs because we're going to be harvesting them for ethanol soon,” says Mathisen, a local farmer and shareholder in Poet's
Emmetsburg, Iowa, ethanol plant. Emmetsburg is the site of Project Liberty, Poet's expansion of a corn ethanol facility into one of world's first cellulosic ethanol plants.

Picking a corn cob apart with his knife, Mathisen looks at the energy potential in his hand. This simple cob—what some consider field trash—could soon contribute to the nation's fuel solution. Once complete in 2011, Project Liberty will produce 125 million gallons of ethanol per year, 25 million gallons of which will come from cobs.

Poet will need more than 700 tons of cobs and fiber per day to fuel its cellulosic ethanol plant. That's 275,000 acres of corn cobs annually, says Jim Sturdevant, director of Project Liberty. By year's end, the company's pilot plant in Scotland, S.D., will begin producing cellulosic ethanol on a small scale."Our long-term goal is for every farmer in the Corn Belt to harvest cobs as they are harvesting grain,” Sturdevant says. "But we know that for farmers to buy in, cob harvesting has to be economical and practical.”

Fast Facts
Poet's Project Liberty will convert an existing 50-million-gallon-per-year dry-mill ethanol plant into a commercial cellulosic biorefinery by 2011.
The facility will produce a total of 125 million gallons per year of ethanol; 25 million gallons will be made from corn cobs and fiber. By adding cellulosic production to an existing grain ethanol plant, Poet will be able to:
Produce 11% more ethanol from a bushel of corn
Produce 27% more from an acre of corn, while
significantly reducing fossil fuel consumption
Decrease water usage by 24%
Project Liberty is jointly funded by the Department of Energy. The State of Iowa is also funding the new cellulosic biorefinery.

Equipment gears up. It's too early to determine the price for cobs, but Poet estimates it will pay $30 to $60 per ton. "Market conditions will drive price, but equipment costs will have an impact,” Sturdevant adds. "The major equipment companies are committed to making cobs work. They think it is doable.” Currently, there is limited farm machinery available to harvest, handle or store corn cobs, but Sturdevant says he is encouraged by how ag equipment manufacturers are stepping up to the challenge of developing machinery.

Equipment manufacturers currently collaborating with Poet on Project Liberty include Case IH, John Deere, Claas, Vermeer, AGCO and Demco. Many of these companies will be showing their prototype equipment for harvesting corn cobs on Nov. 6 at the Project Liberty Field Day. Farm Journal will be there to cover the event, so watch future issues of the magazine and online at and for more information.

In working with equipment manufacturers in 2007, Poet and a farmer in South Dakota tested two cob harvesting techniques. The first involved connecting an existing combine to a piece of equipment called a cob caddy, which caught all of the field waste coming out of the back of the combine and separated out the cobs. The second method involved modifying a combine to collect grain and cobs together in the same tank to produce a corn-and-corn-cob mix (CCM). Separating the grain from the cobs occurred in a second operation at the side of the field.

There are more than two techniques for harvesting cobs, Sturdevant adds. To date, Poet has not recommended any certain techniques. Many companies, such as grain-handling systems manufacturer Demco, have spent the past year closely working with Poet to address farmer harvest concerns with cobs. Demco is developing a 2-SKU grain/cob cart that receives both grain and cobs from the combine but would require only one cart operator.

"Labor savings is what we are going for with this equipment,” says Ken Streff, Demco vice president of sales and marketing. Ideally, the Demco 2-SKU cart works with a combine that harvests corn into its grain tank and cobs into a cob harvest machine pulled behind the combine. When the combine is full, it unloads corn into the main Demco grain cart. An attached second Demco cart then swings around to the side to allow the cob harvest machine to dump its contents into the Demco cob cart. Once that is complete, one operator hauls both carts to the edge of the field for unloading grain and cobs. All operator functions of the Demco 2-SKU cart are performed from the tractor seat.

Vermeer Corporation, another company that is working to develop efficient equipment for cob harvesting, is introducing a wagon-style cob collection system that trails the combine to harvest grain and cobs in one pass. "What we're finding is that there are lots of different options for harvesting and collecting corn cobs,” says B. J.

Watch For More Coverage

Watch for upcoming television reports from Poet's Project Liberty Field Day highlighting advances in corn cob harvesting for cellulosic ethanol.

Schany, commodities manager of the Poet facility in Emmetsburg. "We want to provide options for the 300-acre farmer and the 3,000-acre farmer.” Aside from labor issues, farmers have also voiced concerns about investment in cob storage. Poet would prefer farmers to dump the cobs into piles at the edge of the field, and Poet would contract a third party to load and transport cobs to the ethanol facility, Schany says."Farmers should be relieved to hear that we want their responsibility with the cobs to stop at the edge of the field,” Schany adds.
Poet is researching various techniques for piling cobs in order to find the method that will best preserve the crop and provide Project Liberty with a steady supply of feedstock throughout the year. Luckily, the cob has several advantages compared with other parts of the corn plant from an ethanol production perspective, says Mark Stowers, vice president of research and development for Poet."The cob has higher bulk density than the other parts of the cornstalk, so it is easier to transport from the field to the facility,” Stowers says. "In addition, the cob has more carbohydrate content than the rest of the corn plant, giving us the ability to create more ethanol from the cob.”

As a result, Poet can expand the amount of ethanol that can come from a corn crop with minimal additional effort and little to no environmental impact, Stowers explains. As there is no other major market for cobs currently, Poet will be producing cellulosic ethanol from what amounts to an agricultural waste, he adds.

Doug Karlen, a soil scientist with USDA–Agricultural Research Service (ARS) National Soil Tilth Laboratory in Ames, Iowa, says he is impressed with the potential for harvesting cobs for cellulosic ethanol. Recent research from USDA–ARS shows cobs make up 15% to 23% of the nongrain, above- ground biomass. By only collecting the cobs, 67% to 85% of the nongrain biomass would be left on the ground to protect against wind and water erosion and to provide carbon needed to sustain the soil resource, Karlen says. "Cobs seem to be one of the best ways to get a cellulosic feedstock from the corn crop without being as hard on the soil as other options,” he says.

And compared with harvesting other biomass, cobs are relatively easy to collect, he adds. "The biggest hurdle I still see is the amount of time it takes to capture that corn cob, even when using a one-pass harvest system,” Karlen explains. "But we are all working on this logistical problem.”

Mathisen says it will take at least $60 per ton, plus government incentives, for him to consider harvesting all of his cobs and justify slowing his grain harvest in any way.
"Farmers are going to need some assurance that cobs are worth the harvest risk and the equipment investment,” Mathisen says. "Nobody wants to park an expensive piece of equipment in the grove.” He also wants the reward for harvesting cobs to equal the risk of taking on new contracts. There are still many unanswered questions about contracting cobs, such as when farmers would get paid and if cob prices will rise with the price of corn, he says.

The farm bill may offer Mathisen some help with the establishment of a new Biomass Crop Assistance Program that pays farmers a supplement for corn cobs produced for ethanol. It also provides payments to assist with expenses for collection, harvest, storage and transportation of cobs to a cellulosic ethanol facility.
But for now, farmers like Mathisen will be looking at results of the 2008 precommercial cob harvest as the first signal for whether cobs can truly be transformed into cash.

You can e-mail Jeanne Bernick at

Back to news


Spell Check

No comments have been posted to this News Article

Related News

Corn College TV Education Series


Get nearly 8 hours of educational video with Farm Journal's top agronomists. Produced in the field and neatly organized by topic, from spring prep to post-harvest. Order now!


Market Data provided by
Brought to you by Beyer