Comparison of big bluestem with other native grasses: Chemical composition and biofuel yield

Multiple entry selections of big bluestems and three native C4 grass species, including switchgrass, miscanthus, and Conservation Reserve Program (CRP) mixture grass, were evaluated for their chemical composition and ethanol yields via diluted sulfuric acid pretreatment following simultaneous saccharification and fermentation (SSF). Big bluestem and switchgrass had a similar glucan content that was significantly higher than miscanthus and CRP grass. Big bluestem had the highest average mass recovery (55.56%) after acid pretreatment, and miscanthus had the lowest mass recovery (46.3%). A positive correlation was observed between glucan recovery and mass recovery. No significant difference in average efficiency of SSF was observed among four native grasses, but ethanol yields from big bluestem entries, which averaged 26.2%, were consistently greater than the other three grasses. The highest ethanol yield among the 10 entries was from big bluestem cultivar KAW (27.7%). Approximately 0.26 kg ethanol with 9.4 g/L concentration can be produced from 1 kg of big bluestem biomass under current processing conditions. A negative relationship exists between lignin content and the efficiency of SSF with R = −0.80, and a positive relationship exists between ethanol yield and glucan content with R = 0.71.