Could Reduce Ethanol Production Costs
By Jim Core
April 15, 2002
Corns not just for dinner. Most
of the crop is used in livestock feed, and it is also processed into many food
and industrial products, including starch, sweeteners, corn oil, and beverage
and industrial alcohols. Corns starch is also converted to sugar and then
fermented into fuel ethanol by brewers yeast.
Ethanol is increasingly being combined with gasoline to lift octane levels
and make a cleaner-burning fuel. But production of ethanol from corn has
created a surplus of corn byproducts that are becoming more difficult to sell.
One such byproduct is zein, a valuable protein thats used mostly as an
edible, water-resistant coating for nuts, confectionary products and
pharmaceutical tablets. Zein sells for about $10 per pound. But in the
dry-milling ethanol process, zein stays behind in the dried distillers grain
(DDG) thats used in livestock feed. With the rapid expansion of ethanol
production, the DDG supply is expected to far exceed demand.
Engineers at the Agricultural Research Services
Eastern Regional Research Center in
Wyndmoor, Pa., realized that if they could find a way to extract zein at a
lower cost, it would become more attractive as a commodity, increasing
potential profits from non- starch corn byproducts.
The ARS researchers engineered and
built an ethanol pilot plant to find ways to boost economic returns of
commercial corn-fermentation plants where ethanol is created. Then they
developed a system that uses ethanol as the solvent to extract zein from dry-
milled corn. This method could represent significant savings because the
necessary solvent would already be available since ethanol is the primary
product of the corn- fermentation plants. After the corn is fermented into
ethanol, part of the ethanol is used for the zein extraction, then recycled
back into the system.
This method gives corn-ethanol plant owners an option of producing a
value-added coproduct--the zein--that would provide more revenue and reduce the
overall cost of the ethanol production. Efforts are now under way to determine
the maximum concentration of zein that can be directly extracted from corn.
A more detailed story on this research is available in the
April issue of
Agricultural Research magazine.
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.