Indian-origin scientist unveils new, efficient technique of biofuel production

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An Indian-origin researcher and her colleagues at North Carolina State University have unveiled a more efficient technique for producing biofuels from woody plants. The procedure significantly reduces the waste that results from conventional biofuel production techniques.

Study co-author Dr. Ratna Sharma-Shivappa, associate professor of biological and agricultural engineering at NC State, said: "This technique makes the process more efficient and less expensive. The technique could open the door to making lignin-rich plant matter a commercially viable feedstock for biofuels, curtailing biofuel's reliance on staple food crops.

"Our eventual goal is to use this technique for any type of feedstock, to produce any biofuel or biochemical that can use these sugars."

Traditionally, to make ethanol, butanol or other biofuels, producers have used corn, beets or other plant matter that is high in starches or simple sugars. However, since those crops are also significant staple foods, biofuels are competing with people for those crops.

Other forms of biomass - such as switchgrass or inedible corn stalks - can also be used to make biofuels. But these crops pose their own problem: their energy potential is locked away inside the plant's lignin - the woody, protective material that provides each plant's structural support. Breaking down that lignin to reach the plant's component carbohydrates is an essential first step toward making biofuels.

At present, researchers exploring how to create biofuels from this so-called "woody" material treat the plant matter with harsh chemicals that break it down into a carbohydrate-rich substance and a liquid waste stream. These carbohydrates are then exposed to enzymes that turn the carbohydrates into sugars that can be fermented to make ethanol or butanol.

This technique often results in a significant portion of the plant's carbohydrates being siphoned off with the liquid waste stream. Researchers must either incorporate additional processes to retrieve those carbohydrates, or lose them altogether.

But now researchers from NC State have developed a new way to free the carbohydrates from the lignin. By exposing the plant matter to gaseous ozone, with very little moisture, they are able to produce a carbohydrate-rich solid with no solid or liquid waste.

Sharma-Shivappa said: "This is more efficient because it degrades the lignin very effectively and there is little or no loss of the plant's carbohydrates. The solid can then go directly to the enzymes to produce the sugars necessary for biofuel production."

Sharma notes that the process itself is more expensive than using a bath of harsh chemicals to free the carbohydrates, but is ultimately more cost-effective because it makes more efficient use of the plant matter.

The researchers have recently received a grant from the Center for Bioenergy Research and Development to fine-tune the process for use with switchgrass and miscanthus grass.
Sharma-Shivappa said: "Our eventual goal is to use this technique for any type of feedstock, to produce any biofuel or biochemical that can use these sugars."

The research, "Effect of ozonolysis on bioconversion of miscanthus to bioethanol," was presented June 23 at the 2010 Annual International Meeting of the American Society for Agricultural and Biological Engineers in Pittsburgh, PA. (ANI)

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Author: Preeti Aggarwal