Tuesday, May 3, 2011
The world-wide increased energy demand and the limited supply of fossil fuels prompt exploration of alternative renewable energy sources for sustainable economic development. Switchgrass is a promising bioenergy crop for ethanol production not only because it has the potential to reduce our reliance on fossil fuels but also bring environmental benefits. With the help of genetic technology, conventional switchgrass can be modified to reduce its lignin content and increase its carbohydrates content for effortless conversion of biomass to fermentable sugars during pretreatment and enzymatic hydrolysis. The objective of this study is to investigate the effects of sodium hydroxide (NaOH) and lime (Ca(OH)2) pretreatments on improved production of total reducing sugar as well as glucose and xylose from transgenic switchgrass. For sodium hydroxide pretreatment, the conditions being studied are 121°C, 0.5-2% NaOH, and a range of residence times from 15 min to 60 min. To make a comparison with the impact of sodium hydroxide pretreatment on biomass digestibility, the conditions examined for lime pretreatment are 121°C, lime loadings of 0.05-0.15 g lime/g dry biomass, and a set of residence times of 15-90 min. Preliminary results show that total reducing sugar production from transgenic switchgrass was improved by 17% as compared to conventional switchgrass after sodium hydroxide pretreatment with 1% NaOH and a residence time of 30 min at 121°C. The effects of alkaline pretreatment of transgenic switchgrass at other conditions stated above on sugar yield are being explored, and optimal pretreatment conditions will be reported at the symposium.