Process Energy Evaluation of Fuel Butanol Production from Sugar Cane-Sweet Sorghum Juices by Acetone-Butanol-Ethanol Fermentation Associated with a Gas Stripping System

Butanol production from sugar cane and sweet sorghum juice was studied using batch and fed batch acetone butanol ethanol (ABE) fermentation coupled to a gas stripping process. The variations of the juice sugar content, butanol yield, and sugar conversion on the energy consumption of the industrial process were studied using experimental data with the Aspen Plus software. Butanol yield was the most significant factor. Clarification and butanol recovery stages showed the major energy consumption (12.0% and 72.3% of total energy consumption, respectively). For a fed batch strategy where a concentration step is required, renewable energy sources are needed to have a favorable overall energy balance. The butanol production process by ABE fermentation showed higher energy consumption per kilogram of product than an ethanol plant for a similar raw material which suggests that a substantial improvement in the upstream and downstream of the ABE process is needed.