Farm and Field

New fermentation technology improves ethanol production

By Herald-Whig
Posted: Mar. 25, 2018 12:01 am

Research at the Integrated Bioprocessing Research Laboratory at the University of Illinois continues to improve the dry-grind process used to produce ethanol from corn.

"One of the major challenges in the dry-grind process is use of high corn solid loadings needed to achieve high ethanol concentrations and make distillation more economical," said Vijay Singh, director of IBRL and a professor in the U of I Department of Agricultural and Biological Engineering.

Use of high solids reduces heat demand for the drying of distillers dried grains with solubles, lowering the capital cost due to smaller size equipment and decreasing water use for slurry preparation.

Together with Deepak Kumar and Ankita Juneja, both postdoctoral research associates in agricultural and biological engineering at U of I, Singh is studying the use of increased corn solids in this process.

In the dry-grind process, corn starch in the solids is converted to glucose, and the glucose is fermented by yeast to produce ethanol. However, too much ethanol built up during fermentation inhibits the yeast, and it can no longer efficiently convert the sugar into alcohol.

"The typical dry-grind corn process uses a slurry consisting of 30 to 33 percent corn solids. We increased the corn solids up to 42 percent," Kumar said. "Of course, with high solid concentration comes high ethanol build-up in the fermenter. We use an intermittent vacuum flashing process to remove some ethanol from the fermentation tank as it is produced. This keeps the ethanol concentration below the inhibitory levels and allows complete fermentation of corn solids up to 42 percent."

Applying the vacuum-flashing technology also speeded up fermentation time to 32 hours, instead of 48 to 72 hours, "which would allow existing plants to process more material with the same equipment, and new plants could use smaller fermentation tanks," Kumar said. "Both would lead to lower capital and operating costs."

Singh and Kumar are working to develop process models to perform a detailed techno-economic evaluation of the process to determine benefits of using the technology on a commercial scale.

Frost/freeze guide

The free online Missouri Frost/Freeze Probabilities Guide helps farmers and gardeners make planting decisions.

University of Missouri Extension integrated pest management specialists created the website at ipm.missouri.edu/FrostFreezeGuide. The guide also is available as a free downloadable PDF at extension.missouri.edu/IPM1033.

MU Extension climatologist Pat Guinan said both provide frost and freeze probabilities, tables, maps and dates for the 103 National Weather Service cooperative weather stations in Missouri. Search for the location nearest you by using the weather station search tool, Guinan said.

The Missouri growing season typically runs from April to October. Where you live in Missouri makes a big difference in when the first or last freeze occurs, Guinan said.

Climatologists can predict frost timing based on temperature records and the region's topography.

The median date maps provide the last spring and first fall median frost/freeze dates for specific temperature thresholds. In this guide, climatologists define the median date as the date when there is a 50 percent chance a frost or freeze temperature will occur before or after a given date.

Extreme date maps give the latest spring and earliest fall frost and freeze dates using weather stations with more than 100 years of temperature observations.

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