9-09: Techno-economic evaluation of bioethanol production using both the sucrose and lignocellulosic fractions from sugarcane

Today, bioethanol production from sugarcane juice in sugarmills-distilleries is efficient and cost-competitive since it relies on a well-established technology and has been developed under favorable conditions (high yield per hectare and high annual production, surplus of energy in the plant by bagasse burning, simple process)

However, there is a significant amount of sugarcane mills by-products, namely bagasse and stillage, which can be used to produce biofuels with higher sustainability benefits potential, such as, 2^nd generation bioethanol and biogas from process wastewater. This improvement could be done in a facility built in the proximity to the sugarcane mill.

The present work focuses on process modeling of the 1^st and 2^nd generation bioethanol form sugarcane, by implementing lab-scale data in the flowsheeting program AspenPlus.

The plant flowsheet model is divided in three main sections: a sugarcane mill where sucrose juice is extracted and fermented to produce 1G ethanol; a 2G section designed for the enzymatic process of sugarcane bagasse (acid-catalyzed steam pretreatment followed by Separate Hydrolysis and Fermentation); and a section for biogas achieved through anaerobic digestion of streams containing high COD.

The simulations consider several integration options and their effects on mass and energy balances as well as on operating and capital costs. The impacts of the following variables were analyzed: enzyme dosage on hydrolysis time and yield, solids loading (WIS) in the enzymatic hydrolysis, the addition of sugarcane trash (tops&leaves) as substrate for 2G , energy integration between 1G and 2G, biogas production.