Sunday, May 4, 2008
1-18

Cultural practices influencing ethanol from sweet sorghum in Kentucky

Michael D. Montross1, Todd W. Pfeiffer2, and Czarena L. Crofcheck1. (1) Biosystems and Agricultural Engineering, University of Kentucky, 128 Barnhart Building, Lexington, KY 40546, (2) Department of Plant and Soil Sciences, University of Kentucky, 329 Plant Science Building, Lexington, KY 40546

Traditionally sweet sorghum has been used as a feedstock for producing sorghum syrup to be used for human consumption.  Although a number of researchers have started to investigate the feasibility of utilizing sweet sorghum for ethanol production. The objective of this project is to evaluate the feasibility of using sweet sorghum as an ethanol feedstock.  Two varieties (Dale and Sugar Drip) were investigated during 2007.  The field was planted on May 20 and subsequent plantings on June 2 and June 10 were performed.  Plants were hand harvested, juiced, sugar concentration measured and total volume of juice recorded starting September 25 until November 15.  The juice was centrifuged prior to the addition of commercial yeast to verify the potential for fermentation to ethanol.  The fermentations were performed at room temperature without sterilization and 98% of the sugar was fermented into ethanol after 10 days.  Dale consistently out produced Sugar Drip in terms of juice yield.  However, the sugar concentration of both varieties was approximately the same.  Early in the harvest season (between September 25 and October 10) the ethanol yield per plant was between 60 and 70 ml ethanol per plant with Dale.  Later in the harvest October 16 to November 1 the ethanol yield per plant in Dale was 80 ml.  Two nights of below freezing air temperatures occurred on November 3 that decreased the potential ethanol yield per plant to 50 ml by November 15.  The ethanol yield per acre would be competitive with corn, over 500 gal/ac.