By Jim Barlow
Butanol producers may return to the corn fields following a dramatic improvement in the fermentation process that is making the corn-based version of the chemical more than 60 percent cheaper to make than with traditional fermentation processes.
With support for ethanol production waning, the production of butanol could become more attractive, says Hans P. Blaschek, a professor of food science at the UI. Butanol is a better fuel extender than ethanol and is used widely in plastics, brake fluids and resins. Blaschek's corn butanol research has resulted in a provisional patent for the UI and the Illinois Corn Marketing Board.
An overview of the real-world use of the process was described in the June issue of Applied and Environmental Microbiology in an article written by Blaschek, his graduate research assistant Joseph Formanek and UI animal scientist Roderick Mackie.
The paper shows how researchers have raised the final concentration of butanol in corn-steep liquor -- a toxic unusable waste byproduct of corn wet-milling -- from 1 percent to 2 percent, "a small change that brings a huge reduction in energy costs required to recover the butanol," Blaschek said.
"This paper was our first step toward scaling up our process to see if it is an economical means for producing solvents," he said. "The described process shows results for a 20-liter batch. We've since gone up to 100 liters and the data look essentially the same as you see in the paper."
Corn wet-milling leftovers are thrown into a fermentation mix that includes either maltodextrin or glucose, as well as a mutated form of Clostridium beijerinckii, a readily available, spore-forming bacterium found in soil. The 20-liter research showed how the mutated bacterium led to 100 percent more butanol production than that attainable with traditional wild strains of bacteria.
"The end result is exceeding our expectations," Blaschek said. "This brings us closer to industrial viability of a process, based on the economics. That's the bottom line for industry. Companies want to make money, and this process looks like it would be competitive with petrochemical approaches, which have been used since the early 1960s, for butanol production. Before that, fermentation was used even though it was very costly."
The process, which continues to be tested at the UI Biotechnology Center and is attracting the interest of several U. S. companies, also has been effective in its ability to produce acetone, another solvent, but butanol results have been significantly more dramatic, Blaschek said.
Ten billion pounds of butanol, which sells for about 43 cents per pound, are produced annually around the world by petrochemical methods. The Illinois Corn Marketing Board projects that such an annual production of butanol made from corn would mean a new market for 136 million bushels of corn.
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