Tuesday, April 30, 2013
Exhibit Hall
The U.S. goal of producing 16 billion gallons of cellulosic ethanol by 2022 will be possible only by carefully making use of all available feedstock sources. Forest residues, including material remaining after logging or thinning, are an inexpensive and widely available feedstock, with estimated potentials between 30 to 120 million dry tons a year depending on the source. However, their heterogeneous nature and relatively low cellulose content renders them a challenge to current pretreatment and bioconversion methods. Forest residues typically consist of branches, needles/leaves, bark and wood in varying proportions and particle sizes, so some degree of homogenization prior to pretreatment is essential for consistent results.
Our objective in this research was to develop methods to utilize this material for production of ethanol via SO2 catalyzed steam explosion pretreatment, enzymatic hydrolysis and fermentation. Biomass consisting of Douglas-fir and Hemlock residues was chipped, homogenized and pretreated at temperatures ranging from 195 °C to 205 °C, with residence times from 5 to 20 minutes. From our data we compared sugar recovery, inhibitor concentrations, hydrolyzability and other factors to determine the best pretreatment conditions to use to increase the overall production of ethanol from heterogeneous forest residues.