Ethanol, methane, or both? Enzyme dose impact on ethanol and methane production from untreated energy crop switchgrass varieties

Comparative Study on Pretreatment Processes for Different Utilization Purposes of Switchgrass

“…The switchgrass raw material used in this study has a composition of 39.42 ± 0.52% w/w cellulose, 20.25 ± 0.01% w/w hemicellulose, and 21.22 ± 0.62% w/w lignin. However, the concentrations of cellulose, hemicellulose, and lignin obtained in this study had a marginal variation from the values reported by others, 25 which could be mainly attributed to species, cultivar differences, harvest maturity of the sample, and so on. The high cellulose and low lignin of switchgrass in this study indicate that this switchgrass is not only suitable as a feedstock for biofuel production but also an excellent resource for nanocellulose production and the pulp and paper industry.…”

Low Indirect Land Use Change (ILUC) Energy Crops to Bioenergy and Biofuels—A Review

“…Switchgrass (Panicum virgatum L.) Switchgrass belonging to the family Poaceae/Gramineae, order Cyperales, and class Liliopsida is considered a C4 plant and perennial grass that develop in hot seasons, able to grow under different climates, weather conditions, and soil types, with great longevity, adaptability, and versatility. It has low water and nutritional requirements, needs less intensive agricultural management practices, needs low herbicide input requirements together with the capacity to generate biomass that presents a high content of carbohydrates (cellulose and hemicellulose), and lastly, outstanding resistance against pests and diseases that occurs naturally in this species [240], with no annual reseeding [241].…”

“…Considering energy-based biorefineries, two different conversion pathways can be used. Following the biochemical conversion pathway, a list of proposed technologies is as follows: fermentation after pre-treatment and enzymatic hydrolysis unit operations for bioethanol [247] or biomethane [if a dark fermentation (DF) is chosen] or in alternative AD towards biogas [240,248]. When directed to fermentation of its sugar fraction, a pre-treatment step has been suggested to increase the production of fermentable sugars.…”

“…Depending on the pre-treatment type, glucose and xylose yields have been reported from 70% up to 90% and from 70% to 100% after hydrolysis, respectively. Considering pre-treatment followed by hydrolysis, ethanol yielded from 72% to 92% of the theoretical maximum [240,248]. The application of an enzymatic hydrolysis step with cellulase and b-glucosidase incremented maximum ethanol production by 211.9% when compared with the control that does not present enzymes [240].…”

“…Considering pre-treatment followed by hydrolysis, ethanol yielded from 72% to 92% of the theoretical maximum [240,248]. The application of an enzymatic hydrolysis step with cellulase and b-glucosidase incremented maximum ethanol production by 211.9% when compared with the control that does not present enzymes [240]. Continuous ball milling during fermentation by Clostridium thermocellum allowed more than 85% total carbohydrate solubilization of switchgrass without exposing the feedstock to high temperatures or chemicals.…”