Switchgrass Pretreatment by Leading Technologies for Biological Conversion to Fuels and Chemicals
ID: 3489

Abstract: This Panel focuses on developing comparative performance information for pretreatment of switchgrass by leading approaches followed by enzymatic hydrolysis to sugars that can be fermented to ethanol or other products. Switchgrass is a leading candidate for large scale production of biomass that could be converted into fuels could enhance energy security, improve the economy, and reduce greenhouse gas emissions. However, yields are very low without a pretreatment step prior to biological conversion, and pretreatment is both expensive and has a major impact on other conversion steps. In 2000, many of the leaders in the development of these technologies formed a collaborative team the called The Biomass Refining Consortium for Applied Fundamentals and Innovation (CAFI) to develop comparative performance data for the first time for sugar yields from application of leading pretreatment operations followed by enzymatic hydrolysis of the resulting solids. Such data was developed initially for corn stover and then poplar wood through the support of the US Department of Agriculture and US Department of Energy, respectively. More recently, the Office of the Biomass Program at DOE elected to fund the CAFI Team to determine sugar yields from switchgrass for pretreatment by ammonia fiber expansion (AFEX), ammonia recycle percolation (ARP), dilute acid, hot water, lime, and sulfur dioxide steam explosion. Shared sources of switchgrass and enzymes and identical experimental protocols and material balance approaches were employed by all the members of the team to facilitate comparison of the results. In addition, three varieties of switchgrass, Alamo, Shawnee, and Dacotah, were provided by Ceres Incorporated from different locations and harvest times to determine whether such factors impact sugar yields from the combined operations of pretreatment and enzymatic hydrolysis. A review will be presented of the numerous pretreatments that have been tried over the years based on physical, chemical, and biological platforms, and only a few will be shown to achieve the low costs and high yields vital to economic competiveness. In addition, distinguishing features of switchgrass as a feedstock will be outlined. Then, descriptions of the pretreatment technologies employed and experimental methods will be presented. Performance data will be reported for sugar yields from pretreatment alone (Stage 1), enzymatic hydrolysis (Stage 2), and the two combined over a range of enzyme mass loadings and formulations for each pretreatment approach. These results should help select pretreatment technologies for commercial operations and define new directions to improve plants, enzymes, and pretreatment technologies.



Bruce Dale

Biofuels, especially second generation biofuels, can provide very large sustainability improvements in terms of greenhouse gas emissions, nitrate leaching, food/feed production, rural economic development and land use efficiency. However, these benefits will not occur automatically, but must be designed into the system. This presentation describes how a systems view and fundamental understanding of the driving forces behind biofuel production can be leveraged to provide a more sustainable world. In particular, we show how animal feed production and cellulosic biofuels can be integrated to essentially eliminate any new land that might be required for cellulosic biofuel production.



Moderator: Charles Wyman, University of California, Riverside (United States)

Presenter 1: Fundamentals of pretreatment and technical options
Michael Ladisch, Purdue University, (United States)  [Confirmed]

Presenter 2: Grassoline in Your Tank: Making Sure Biofuels Deliver on the Promise of Sustainability 
Bruce Dale, Michigan State University, Department of Chemical Engineering, (United States)  [Confirmed]

Presenter 3: Comparative Results for Pretreatment and Enzymatic Hydrolysis of Swtichgrass.”  
Charles Wyman, University of California, Riverside, (United States)  [Confirmed]

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Panel Organizer:
Charles Wyman, Mascoma Corporation, (United States)

Why should your submission should be selected for this year’s program?
This panel would present new comparative results from pretreatment and enzymatic hydrolysis of switchgrass, a leading energy crop, for application of leading pretreatment technologies. The insights shared and data presented will be very valuable to industry and others in understanding and selecting cellulosic conversion processes.