(548b) Energetic and Environmental Assessment of Biomass to Ethanol Processing in the Sugar-Cane Industry

Bio-fuels have come to be recognized as environmentally friendly alternatives to fossil fuels. This work studies the Bio-ethanol production process complementing a sugar mill.

The process flowsheet examined includes three major processing stages typical of distillery installations for fuel-grade production in sugar-cane processing facilities: (1) fermentation, (2) separation, and (3) dehydration stages.

Using plant data from a bio-ethanol pilot plant in the Northwestern of Argentina (NOA) a kinetic model is formulated for a fed-batch molasses fermentation process. The model for this unit, along with a user-defined separation module, is then integrated into a commercial process simulator. The distillation step is optimized by performing rigorous energy analysis and heat integration on the process utilizing the resources made available by the sugar mill, while pervaporation is used in the dehydration step. Different schemes meeting equivalent performance standards in terms of purity and recovery are examined in this paper.

Particular attention is given to energetic integration by performing a pinch-analysis to each of the fundamental stages to find a global optimum. Optimization is achieved by minimizing a given objective function that accounts for bio-ethanol recovery, separation efficiency, and minimization of effluents. Life Cycle Analysis is used to complete the assessment of operating parameters/conditions on environmental effects.