18-13: Techno-economic comparison of high solids loading vs stream recirculation in enzymatic hydrolysis of sugarcane bagasse for ethanol production

Tuesday, May 1, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Stefano Macrelli and Guido Zacchi, Department of Chemical Engineering, Lund University, Lund, Sweden
Nowadays bioethanol from lignocellulosic feedstock produced via the enzymatic process is very close to commercial deployment; however, the reduction in production cost is still an on-going challenge, aiming to reach the cost for 1G ethanol from sugar and starch.

From the transformation process perspective and excluding the raw material, the main cost in the cellulosic ethanol production is the combination of pretreatment effectiveness, enzyme efficiency and cost. These factors together also affect the energy demand in the distillation and the running cost. Indeed distillation is an energy intensive step, especially when the titre of ethanol in the fed stream is below 4 wt-%, but such concentration is seldom obtained after fermenting the enzymatically hydrolysed lignocellulose. For this reason promising strategies that allow achieving a higher final ethanol titre at low energy expense are currently under investigation with a special focus to high solids loading in the enzymatic hydrolysis. An alternative option is represented by the stream recirculation that permits to obtain a high ethanol titre and can avoid at the same time the reduction in hydrolysis rate and yield due to the high gravity hydrolysis, which may cause mixing problems and end product inhibition.

In this study a techno-economic evaluation based on experimental results using sugar cane bagasse is performed to assess the effects of streams recirculation on the cellulosic ethanol production cost as well as the process energy efficiency in comparison to high solids loading in enzymatic hydrolysis. Results from this study will be presented.

See more of: Poster Session 2
See more of: General Submissions