Evaluation of Various Biomass Feedstock for Degradability and Energy Content.

A study was conducted to investigate biofuel production potential of high biomass accumulating annual and perennial crops using analysis techniques such as fiber digestibility, fiber composition, and calorie content. These applications are extended from the conventional feed value analysis approaches such as fiber or lignin concentrations after treating with acid detergent and 72% sulfuric acid as quality determining factors. All collected feedstock samples were incubated with ruminal microbes to measure actual fiber degradation potential through accumulated gas measure, and the kinetics of gas production was quantified using a fiber degradation model. Energy content in biomass was measured using a bomb calorimeter. More than 600 lignocellulosic biomass samples were collected from 22 different sources and include various species, varieties, regions, maturity levels, etc. to cover the potential variations in the crops. The species list included switchgrass (Panicum virgatum), miscanthus (Miscanthus giganteus), sugarcane (Saccharum spp.), energycane (Miscanthus and Erianthus crosses), sweet sorghum (Sorghum bicolor), and elephant grass (Pennisetum purpureum). Some genotypes of low lignin sorghum, sorghum-sudangrass hybrids, and sudangrass were also included. Based on analysis results, the average ADF concentration of sweet sorghum bagasse ranged from 190 to 510 g kg^-1 DM. The average fiber degradation measured by the in vitro method was 78%, demonstrating a large variation depending on maturity. Lignin and fibers are less immediately fermentable to ethanol, however, may contain high energy when co-fired. The correlation between lignin and fiber degradation range was broad from -0.43 to -0.86. Energycane did not demonstrate significant correlation. The average lignin content in switchgrass tended to be greatest among the biomass and lowest in energycane, due to the growth stage of harvest. The energy content per gram of lignocellulose biomass ranged from 3,853 to 4,308 cal g^-1 DM. Conversion of bio-energy from lignocelluosic biomass varies depending on harvest maturity or final energy use form.