“Our plant is a 47-million-gallon-per-year plant. We’re grinding about 17 million bushels per year and we’re getting the corn from 110,000 acres. If we took the cobs off that same 110,000 acres, we think that would displace about 75 percent of the energy (natural gas) needed to run our plant.”

That’s Bill Lee talking. Lee is CEO of Chippewa Valley Ethanol Cooperative in Benson. This 12-year-old ethanol operation — noted for being at the cutting edge of new technologies for more efficient corn processing — just launched a cooperative project involving the Minnesota Corn Growers Association and the University of Minnesota’s West Central Research Outreach Center in Morris.

The project: Finding a better way to harvest corncobs as a feedstock for gasification projects both at the CVEC and at the U of M Morris campus. A $250,000 grant is helping to find this better way.

Corn, cob harvest

Interviewed Oct. 15 as about 140 acres of corn were being harvested on the Lonnie and Ryan Fosso farm in Kandiyohi County, 3 1/2 miles south of Priam, you could sense the excitement in Lee and many other onlookers who were seeing for the first time the simultaneous harvest of corn and corncobs by two different machines.

“This could indeed be the start of a huge industry for the American corn belt,” said Wally Nelson, now retired but for 34 years the superintendent of the U of M Southwest Experiment Station at Lamberton. He sees this as an entirely new income source for corn producers from a product that mostly had little value, and also a new biomass feedstock for renewable energy that doesn’t need to be provided in some other way.

“Back in the last energy crisis of the 1970s we did some work at the station where we shelled the corn, then used the cobs to fire up our crop dryer. We found it took only about half the cobs produced to have enough heat source to dry corn from 25 percent moisture down to 15 percent,” Nelson said. The challenge has been to develop a system that allows farmers to harvest corn at “normal” harvest speeds while collecting the cobs in a separate mechanical conveyance unit.

“The intent of this field day is to show farmers that they now have a potential second income from their corn acres,” Lee said. “And these two machines are the key to making that happen.”

The machines

One machine, called a Ceres Ag Residue recovery system, is a bolt-on unit to the combine that transports cobs as they are being discharged to a “cob caddy” bin piggybacked atop the regular combine grain tank. The other machine, a Vermeer CCX770 Cob Harvester, is pulled behind the combine, with cobs conveyed into the trailing cob cart. Both machines performed well in this field, which was yielding 175 bushels and better with moisture at 21 to 22 percent.

The Vermeer machine will likely go through a year of field testing before it gets launched into the market, said Jay Van Roekel, segment manager for Vermeer. He definitely sees an opportunity for this new technology in a niche market that is just now being looked at as a potentially huge new commodity for the biomass renewable fuels industry.

Perfect biomass feedstock

Is harvesting cobs stealing some valuable nutrients that ordinarily would contribute to soil fertility? Not in the least, said various ag specialists at this field demonstration. “Soil scientists tell us the cob is the least functional part of the entire corn plant in terms of nutrient value to maintain a healthy soil,” Lee said.

More important is that the corncob is just about the perfect biomass feedstock for a gasifier system. They handle easily with little or no preprocessing required. Cobs have about one-third the ash content of corn stover, so much less potassium and phosphorous is removed from the land than if the corn stalks were baled and used as a biomass feedstock.

Cobs also have low nitrogen content, which makes for low N emission in the gasification process. The BTU content of cobs is good compared to corn stover and other biomass feedstocks.

Lee doubts if cobs will ever become the exclusive feedstock for CVEC but he predicts it to be the primary fuel (90-plus percent) especially with current and recent natural gas prices. Only if natural gas prices spiked down to $4 per decatherm (1 million cubic feet) might it stay competitive with biomass feedstocks.

Logistical concerns

He said corn growers getting into cob harvesting will likely set up a distribution system much like the sugar beet cooperatives, which have various piling sites throughout the territory of the beet growers.

“We don’t yet know what will be the best way to stage these materials,” Lee said. “Multiple sites among our corn growing area seems most logical at this time. We’re fairly certain that hauling them all into our plant site and building a mountain of cobs is not the way to go.”

Cob production runs about 1 ton of cobs from a 200-bushel corn yield, or about three-quarter ton of cobs from a 150-bushel field.

The challenge complicates, however, when you realize this harvest window only lasts about 30 days each fall even though cobs will be used throughout the year — both at CVEC, and likely at the U of M Morris campus gasification project.

“I view this demonstration today as a break-through day for agriculture,” said MCGA Research and Project Manager Riley Maanum. “With input costs continuing to escalate for agriculture, any value-added opportunity is a real plus. I’m hearing $25 per ton of cobs for the corn grower. And if these new mechanical systems let the farmer harvest his corn without slowing the process, this is a real winner. It also looks like new opportunities for custom harvesters.”

No slowdown

Todd Wentzel, a Murdock-area farmer operating his Case/IH 2588 combine with the trailing Vermeer cob collector unit, indicated no slowdown from his normal harvesting speed of 5 to 6 mph. With his wife, Sheri, driving the grain cart, the only down-time for his rig was stopping to dump cobs. The unit has about a 7,000-pound cob capacity.

“I see potential for a new market for cobs if energy prices stay high and the economics of collecting and handling the cobs works out for ethanol plants and other users,” Wentzel said. He agreed that if cob harvesting gets to be widespread, piling sites like those used by sugar beet growers would be logical.

“This is an exciting day in agriculture,” Nelson said. “Today we are seeing the mechanical equipment that permits the simultaneous harvest of both corn grain and corncobs. There’s no doubt this will start a new trend. Corn is still the No. 1 crop in America and if the producer can now get $20 to $25 additional income per acre from the cobs that normally tie up some nitrogen as they decompose, this is simply a good deal.”