Monday, May 4, 2009
5-25
Second generation bioethanol from sugarcane bagasse: SSF operative conditions and flowsheeting implementation
Stefano Macrelli, Dept. of Chemical Engineering, Lund University, Getingevagen 60, Lund, 22100, Sweden and Guido Zacchi, Dept. of Chemichal engineering, Lund University, Getingevagen 60, Lund, 22100, Sweden.
It is a general opinion that future expansion in bioethanol production has to be based not only on bioethanol from starch and sugar, but also from lignocellulosic materials, i.e. second-generation bioethanol. A promising option is to integrate sugarcane bagasse, a lignocellulosic and abundant feedstock, with sugarcane molasses. The main purpose of this study was to investigate the enzymatic process for ethanol production using sugarcane bagasse as raw material at different Simultaneous Saccharification and Fermentation (SSF) conditions and subsequently implement a plant flowsheet in order to study the energy efficiencies in the bioethanol production process. After steam explosion pretreatment with catalyst addition, the material was then simultaneously hydrolysed by a cellulase enzyme mixture and fermented by ordinary baker’s yeast in batch mode. The screened SSF conditions regarded mainly the variation of the most important parameters such as nutrients, bagasse load (WIS), and molasses addition, in order to check if the SSF ethanol yield can be improved. Experimental data are used as input data for simulation of the integrated bagasse-to-ethanol process using ApenPlus. The plant flowsheeting model also comprises co-products from the bioethanol production, which still have useful heating value, such as pellet from the solid fraction (mainly lignin) and methane from the anaerobic digestion of the stillage stream. The simulations combined with a sensitivity analysis on the whole plant products (ethanol, pellet and methane) are used to determine the energy efficiency, which is starting data to evaluate the environmental performances in biofuels production. Results from this study will be presented.