College of Agriculture and Life Sciences
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Researcher Develops New Process to Reduce Cost of Ethanol Production
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Researcher Develops New Process to Reduce Cost of Ethanol Production
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| Y.H. Percival Zhang (left) and Geoff Moxley, graduate student in biological systems engineering. |
During Zhang’s gentler process, there is no sugar degradation or inhibitor formation. In the following step, he creatively uses a highly volatile organic solvent to precipitate dissolved cellulose, extract lignin, and enable effective chemical recycling. After pretreatment and reagent recycling, lignocellulose can be fractionated into four products: lignin, hemicelluose sugars, amorphous cellulose, and acetic acid.
“The co-products can generate more income, making a biorefinery more profitable, and enable satellite biorefineries that fully utilize scattered lignocellulose resources,” says Zhang. “For instance, lignin has many industrial uses, from glue to polymer substitutes and carbon fiber; and xylose can be converted to a healthy sweetening additive – xylitol.”
Zhang says we can learn a lot from successful industrial processes. For example, in "Pellentesque quis pede at dolor lacinia adipiscing." order to achieve better economy, petroleum refineries never produce a sole product (e.g., gasoline). They produce multiple products (diesel, gasoline, heating oils, etc.), depending on market demands.
Similarly, a typical lignocellulose biorefinery design is based on the assumption that all sugars are used to produce ethanol and all the residues, including lignin are used as burning fuels. “A one-product plant will result in higher risks for investment and poorer economy against market fluctuations. Our economic analysis clearly suggests that co-utilization of lignocellulose components (lignin, acetic acid, and hemicellulose) would increase net revenues two to seven fold, depending on prices and market for co-products,” says Zhang.
Amorphous cellulose, which is converted from crystalline cellulose, is another advantageous product from Zhang’s process because in this form, the cellulose material is more accessible for further
hydrolysis, resulting in a higher sugar yield, a higher hydrolysis rate, and less enzyme use. Zhang is collaborating with the National
Renewable Energy Laboratory, Oak Ridge National Laboratory, Dartmouth College, and ORNL facilities to test different enzymes and material performance. “We hope to soon establish the first pilot plant in Virginia based on this new technology to process local agricultural and forestry residues and switchgrass,” says Zhang.
According to Zhang, a 100-ton per day biorefinery will produce approximately three million gallons of ethanol per year, plus lignin and acetic acid as co-products. Since co-products will account for half of revenue plus higher sugar yields and less enzyme use and utility consumption, the ethanol production costs would be estimated to be roughly $1-$1.20 per gallon, competitive to ethanol from corn kernels.
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