Monday, April 30, 2007

Development of a process for ethanol production from barley

John Nghiem1, Kevin Hicks1, David Johnston1, Andy McAloon1, Winnie Yee1, Mian Li2, Jay Shetty2, and Gerhard Konieczny-Janda2. (1) Eastern Regional Research Center, USDA Agricultural Research Service, 600 E. Mermaid Lane, Wyndmoor, PA 19038, (2) Genencor, 925 E. Page Mill Rd., Palo Alto, CA 94304

Corn is the primary feedstock for fuel ethanol production in the U.S. but due to its limited supply and recent surge in cost an alternative grain feedstock is needed.  Barley has great potential as an alternative feedstock for ethanol production, especially in the Mid-Atlantic and other states, where it is a winter crop, allowing double cropping with soybean.  It is estimated that barley can provide at least one billion gallons ethanol per year, which is about 20% of the total ethanol production in the U.S. in 2006.  One problem associated with using barley for ethanol production is that it contains high levels of β-glucan, which will result in very high viscosity of the liquefied mash.  We have developed a barley-based fermentation process for ethanol production, which overcomes that technical hurdle.  In this process commercially available β-glucanase and β-glucosidase are used.  The combined application of these two enzymes allows complete hydrolysis of β-glucan to monomeric fermentable sugars, thus solving the high viscosity problem and at the same time increasing the ethanol yield.  An economic model using SuperPro Designer also has been developed to guide the process development effort.  Process parameters including enzyme dosages, particle size, and times and temperatures of the gelatinization and liquefaction stages were optimized for ethanol yield.  The effects of process parameters on ethanol yield and details of the economic model will be discussed.