4-25: Improving second generation ethanol production through optimization of first generation production process from sugarcane

The integration of second generation ethanol production process from lignocellulosic materials with conventional first generation ethanol production from sugarcane may improve the feasibility of the second generation ethanol production. In comparison with a stand-alone second generation unit, the integrated process will need a lower investment, since some operations (concentration, fermentation, distillation and cogeneration) may be shared between both plants. Besides, fermentation inhibitors generated during lignocellulosic materials pretreatment will have minor effects on yields since the hydrolyzed liquor will be fermented mixed with sugarcane juice. Electricity generation is larger on the integrated process as well.

Since sugarcane bagasse and trash are used as fuels in conventional bioethanol production, the amount of surplus lignocellulosic material used as feedstock for second generation bioethanol production depends on the energy consumption of bioethanol production processes (both first and second generation). Pentose and lignin, byproducts of the second generation bioethanol production, may be used as fuels and increase the amount of surplus bagasse, along with improved technologies for cogeneration and optimization of conventional bioethanol production process. Options for improving first generation ethanol production, maximizing surplus bagasse and trash, are thermal integration, low temperature fermentation (leading to high ethanol content on the fermented liquor), multiple effect distillation columns, efficient cogeneration systems, etc.

Alternatives for process improvement were analyzed through simulation of the integrated first and second generation bioethanol production from sugarcane and its residues using Aspen Plus. Production of bioethanol can be significantly increased in the integrated process when first generation production process is optimized.