Let’s Talk Trash: Cellulosic Ethanol is Around the Corner

29 décembre 2008, Jeanne Bernick

The simple corncob – what some consider field trash – could soon contribute to the nation’s fuel solution. Ethanol companies like Poet are gearing up to produce cellulosic ethanol from cobs and fiber by year 2011.
Now it’s up to the agricultural machinery industry to develop efficient equipment for getting cobs from the field to the biorefinery without adding major complications to the grain harvesting process
So far, equipment companies have developed three methods for collecting cobs:
Corncob Mix
The first is called corncob mix, or CCM, where modifications to combines allow for the corn and cobs to be collected together in the grain tank, transferred to grain carts and separated by trammel screens. Cobs are then piled at the end of the field for collection, while grain is transported to market.
Among the manufacturers of the CCM method of harvest are Case IH, John Deere and Claas Lexion for combines, along with Unverferth and Demco, grain cart manufacturers, and Wildcat, the manufacturer of trammel screen systems for cob separation.
“The CCM method requires the least amount of investment in cob collection equipment,” says Scott Weishaar, director of business development for POET. However, it does necessitate additional equipment for separating out the cobs. Farmers may want to join together to buy separation equipment.
Whole-cob collection
A completely different method is whole-cob collection, which uses a towable cob cart behind the combine. The combine’s chopper is disengaged and what comes out of the back of the combine goes onto a belt that carries it into a separation process. Then cobs go into the cob cart and non-cob stover blows back onto the field.
With this method, the combine has no modifications except for in-cab monitoring and control of the cob cart. Several different technologies are in development for towable systems to separate the cob and put the stalks and husks back out on the field, says Weishaar.
Manufacturers working on towable cart systems include Case IH, Vermeer Manufacturing and Redekop.
Dual-stream harvester
A third system under development at Iowa State University is a dual-stream harvesting system that harvests corn kernels as well as the stalks, leaves and/or cobs in one pass. In essence, the system uses a stover attachment that can be attached to a standard combine for an additional cost of $35,000 to $50,000, estimates Stuart Birrell, Iowa State University agricultural engineer.
With this system, the combine functions as normal, but instead of cob and stover going out of the back of the combine and onto the ground or into a towed cart for separation and collection, the forage chopper chops the cobs and blows them into a trailing forage wagon. Research on this system is funded by John Deere and the Department of Energy.
For More Information
Read more cob collection devices in the December and January issues of Farm Journal, at

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