ARS | Publication request: Ethanol Production Yield of Five Warm-Season Perennial Forage Grasses

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 7, 2010
Publication Date: September 28, 2010
Citation: Read, J.J., McLaughlin, M.R., Dien, B.S. 2010. Ethanol Production yield of five warm-season perennial forage frasses. Proceedings Sustainable Feedstock Roadmap Workshop. CD-ROM.

Technical Abstract: Developing a favorable biomass supply for conversion to biofuels will require high production and conversion efficiency. In this work, five warm-season perennial grass species were evaluated for their potential as bioenergy crops within the southeastern USA. The plant materials were part of a field study that compared grass hay crops for manure-nutrient management in a swine effluent spray field near Crawford, MS. Adapted varieties of bermudagrass, eastern gamagrass, indiangrass, johnsongrass, and switchgrass were transplanted to the field in July 1999. An initial assessment of feedstock conversion to ethanol was based on the aboveground biomass harvested in August 2001, following six weeks of regrowth. Total carbohydrates and the monosaccharide products of enzyme digestion were determined separately in the laboratory. Initial results indicated indiangrass and switchgrass had the highest average (n=4) yield of glucose and xylose in grams monosaccharide per kg dry biomass. Due to species difference in biomass production and carbohydrate-to-ethanol conversion efficiency, potential ethanol yield ranged from 4368 liters per hectare in bermudagrass to 1767 liters per hectare in indiangrass. Because the harvest in August indicated relatively high ethanol yield in ‘Coastal’ bermudagrass (1248 l/ha) and ‘Alamo’ switchgrass (929 l/ha), their season-long production yields were estimated based on laboratory assays of forage from four harvests in summer 2001. Results should influence the selection of these forage crops as bioenergy feedstocks for the Southeast, where familiarity with these grasses, their documented responses to manure fertilizer, and an abundance of manure enable conversion of animal wastes into energy, thus addressing two regional problems.