One of the advantages of coupling sugar and ethanol production is the possibility to use molasses, a residue generated during sugar production, to raise sugarcane juice concentration close to the levels required by the fermentation process. When second generation ethanol production from sugarcane bagasse and trash takes place, through pretreatment and hydrolysis processes, the hydrolyzed liquor presents low sugars concentration due to the low solids loading required on the enzymatic hydrolysis reactor. Thus, integrating sugar, first and second generation ethanol production presents potential to reduce process steam consumption required to concentrate the hydrolysis liquor. On the other hand, larger amounts of process steam are consumed on evaporators used in sugar production. Because distilleries produce their own energy through combustion of sugarcane bagasse and trash, steam consumption directly impacts the surplus production of electricity and the amount of lignocellulosic material available for second generation ethanol production.
Integrated first and second generation bioethanol production from sugarcane juice, surplus bagasse and trash was evaluated for autonomous and annexed plants using Aspen Plus. Different scenarios for hydrolysis process were analyzed, considering different yields, solids loading and destination of pentoses (biodigestion or fermentation to ethanol). Results showed the impacts of innovations on process feasibility – economic and environmentally – in the integrated process for both autonomous and annexed distilleries.