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| Purdue University researcher Michael Ladisch has discovered a method to improve ethanol production. His research will move from the lab to industry for testing this summer. (Photo by Tom Campbell ) |
Garbage in, power out
Not all ideas for alternative energy are born in the lab. Ladisch likes to jog several miles every morning, a practice that paid off while running with his friend Jerry Warner. Warner is a contractor with Defense Life Sciences, a consulting firm that develops projects for national defense and homeland security purposes.
The two started talking trash—literally—while running a 10-mile course. What came out of the dialogue was an idea for another renewable energy source from waste products, this one with military applications.
“Army battalions are restricted as to what they can leave on the battlefield,” Warner says. Waste products, such as food, plastics and paper, can act like a trail of breadcrumbs if left behind, showing the movement of troops and compromising their security. Removing refuse is expensive and difficult under battlefield conditions. Ladisch and Warner came up with an idea to create portable biorefineries that would convert litter into electricity, heat or liquid fuel.
While others have successfully found ways to recycle rubbish into power, their unique idea processes the entire waste stream at once. “You can take everything from the mess hall—food scraps, plastic and cardboard—and throw it into the bioreactor,” Ladisch says. The mini biorefinery then ferments the waste into ethanol, and the solids that don't process can be filtered out and gasified.
Computer modeling predicted the idea was risky, but had a good chance for success. This was enough to get Warner's Virginia company to subcontract with Purdue and pitch the idea to the military brass. Purdue researchers are now building a prototype with Army support. The unit, about the size of a U-Haul trailer, will go to a military base early next year for testing.
“Each portable unit could potentially produce about 60 kilowatts of power, enough for a couple houses, at least,” Warner says. Beyond its military applications, both Ladisch and Warner predict portable biorefineries could be useful during emergency events, for instance, in the aftermath of the hurricanes that swept through the Gulf Coast last fall.
It's all in the yeast
Purdue researcher Nancy Ho, a molecular biologist, also works on ways to make ethanol from waste products. Her work led to a patent for a yeast that can ferment corn stalks and straw into ethanol.
Ho and Ladisch are part of Purdue's Laboratory of Renewable Resources Engineering, or LORRE, a multidisciplinary research center that focuses on moving renewable fuels research from the lab into industrial applications.
Unlike corn kernels, the traditional ethanol feedstock, stalks and straw contain two major sugars, glucose and xylose, that can't be fermented by the yeast normally used in the industry to produce ethanol. Researchers altered the genetic structure of the yeast so it contains three additional genes, making it possible to convert the sugars in these cellulose materials into ethanol.
This technology can now be licensed and has found a home in Ottawa, Canada, where Iogen Corp. is the first in the world to produce ethanol from wheat straw. One of the great benefits of this technology is that it doesn't require retrofitting the plant, just changing the yeast.
“A barrel of oil produces almost 20 gallons of gasoline,” says Ladisch. “You could probably get 200 gallons of ethanol from just one acre of hay, and it's a resource that's renewable.”
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