Pretreatment, proper harvest time boost ethanol from switchgrass

Michael Ladisch, a distinguished professor of agricultural and biological engineering, and Youngmi Kim, a research scientist, compared switchgrass based on growing location, harvest time and whether it was given a pretreatment step. They found that location wasn't important, but the other two factors could significantly increase the amount of ethanol obtained from the feedstock.

“Switchgrass harvested in the spring had more cellulose, but also more lignin,” said Kim, whose findings were published in the early online version of the journal Bioresource Technology. “You do not get the advantage of the increased cellulose content because it's more difficult to extract those sugars because of the lignin.”

Lignin, a rigid substance found in plant cell walls, is one of the most significant problems with cellulosic ethanol production. Besides the harvest time, a pretreatment step – cooking switchgrass in hot water under pressure for about 10 minutes – would also help work around lignin.

Before pretreatment, Kim said about 10 percent of cellulose was converted to glucose, the yeast-fermentable sugar that produces ethanol. After pretreatment, that number jumped to as much as 90 percent. The pretreatment dissolves hemicellulose, which bonds cellulose and lignin in the plant. Once it is gone, there is more access to the sugars contained in the cellulose.

“There is more surface area for the enzymes to digest cellulose,” Kim said.

Ladisch said advancements in techniques to work around lignin could make spring switchgrass more attractive. But he said that fall switchgrass given a pretreatment and fermentation with special yeast shows potential to give as much as 800-1,000 gallons of ethanol per acre per year, compared with 150-250 gallons per year without pretreatment. Ladisch said corn ethanol from grain produces about 500-600 gallons per acre per year.

“This shows that we can improve the processes and increase the amount of ethanol we get from switchgrass,” Ladisch said.

Ladisch is chief technology officer at Mascoma, a renewable fuels company based in New Hampshire. He received no funding from the company for this research, which was supported by the U.S. Department of Energy.

The work is part of a concerted research effort on pretreatments by a consortium made up of the University of California Riverside, Auburn University, Texas A&M University, Michigan State University, Genencor and the National Renewable Energy Laboratory together with Purdue University.

Abstract on the research in this release is available at: http://www.purdue.edu/newsroom/research/2011/110831LadischSwitchgrass.html

Media Contact

Brian Wallheimer EurekAlert!

More Information:

http://www.purdue.edu

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors