Unlocking and converting starch into simpler sugars so yeast can ferment them into ethanol is all in a day's work for microscopic enzymes, such as amylase.
But as tiny as they may be, enzymes other than amylase may quickly become the heavyweight champions in producing ethanol more efficiently and in greater quantities from corn and other crops.
“There's no question that enzymes will help unleash more of the bound-up energy potential of the agricultural and biomass feedstocks that can be converted into fuel,” says John Biondi, president of C5-6 Technologies, of Middleton, WI. “Our firm is already testing two sets of enzymes that will significantly boost the ethanol yield from a bushel of corn.”
These unique, thermally stable enzymes were originally found in some hot springs in Yellowstone National Park. Other enzymes have been isolated from compost heaps and even silage.
The ability of these enzymes to withstand high temperatures makes them ideal for use in dry mill ethanol plants. These new enzymes take over where the existing amylases leave off, converting more of the ground corn materials into simpler sugars for ethanol fermentation. And they also perform well under harsh pH conditions.
“Presently, about 15% of the corn material is left unconverted due to the limitations of existing amylases,“ explains Biondi. “The enzymes that we've isolated have the capability to convert much of that 15% into sugars which can then be turned into alcohol by yeast fermentation.”
Based on laboratory data, C5-6's enzymes could boost the per-bushel ethanol yield by 10-13%.
That is significant, considering about 2.7 gal. of ethanol can now be produced from a bushel of corn compared to 2.4 gal. back in 1984. Much of that increase resulted from better milling and fermentation methods combined with higher starch content in select corn varieties.
Lab trials of one group of these enzymes began in January at Wisconsin ethanol plants.
Once the enzymes, which are being called Cornbuster 1 & 2, have been approved by the Environmental Protection Agency (EPA), pilot trials will be conducted in early 2007 at ethanol plants throughout the Midwest, according to Phillip Brumm, Chief Scientific Officer, of C5-6 Technologies.
Editor's Note: C5-6 Technologies is a spin-off company of Lucigen Corp., Middleton, WI. Lucigen is known for its versatile and efficient enzyme cloning technology used in medical diagnostics and the pharmaceutical industry.
Besides its work in corn ethanol, C5-6 Technologies and its parent firm, Lucigen Corp., won a $1.3 million grant from the U.S. Department of Energy and USDA to expand its research to develop the process for converting soybean meal carbohydrate into ethanol.
Based on last year's soybean harvest, an additional 2 billion gallons of ethanol could be produced this way in the U.S., according to C5-6 Technologies.
“We're already pretty confident that our technology will provide the right enzymes to do the job well,” says Phillip Brumm, chief scientific officer. “However, we are still looking for partner companies on the commodity and technology sides to help us source the soy and build the plants that will accomplish what we envision.”
Brumm says that after producing the ethanol, the remaining protein will be a 90-95% concentrate. “In addition to livestock feed, some of this concentrated protein, if handled correctly, could also be channeled off and sold to the higher value food-grade market,” he says.