Steam pretreatment of dry and ensiled industrial hemp for ethanol production

Biomass can be converted into liquid and gaseous biofuels with good efficiency. In this study, the conversion of industrial hemp (Cannabis sativa L.), a biomass source that can be cultivated with a high biomass yield per hectare, was used. Steam pretreatment of dry and ensiled hemp was investigated prior to ethanol production. The pretreatment efficiency was evaluated in terms of sugar recovery and polysaccharide conversion in the enzymatic hydrolysis step. For both materials, impregnation with 2% SO2 followed by steam pretreatment at 210 °C for 5 min were found to be the optimal conditions leading to the highest overall yield of glucose. Simultaneous saccharification and fermentation experiments carried out with optimised pretreatment conditions resulted in ethanol yields of 163 g kg−1 ensiled hemp (dry matter) (71% of the theoretical maximum) and 171 g kg−1 dry hemp (74%), which corresponds to 206–216 l Mg−1 ethanol based on initial dry material.