Increasing Sugar Yield in Biofuel Manufacturing through Control of Cellulosic Biomass Particle Size

Kansas State University, Manhattan KS

Investigators

Abstract

Today's economy and society are highly dependent on liquid fuels for transportation. Currently, more than 90 percent of the liquid transportation fuels used in the U.S. are petroleum-based. It is imperative to develop alternative liquid fuels that are domestically produced and environmentally benign. Biofuels, derived from cellulosic biomass such as agricultural and forestry residues and dedicated energy crops, offer one of the best near- to mid-term alternatives. Size reduction of cellulosic biomass is the key step in the manufacturing of biofuels. Size reduction is an energy intensive process, and particle size dictates the energy consumption in this process. This award supports research to understand the relationship between cellulosic biomass particle size and biofuel yield. Successful completion of this research will build a foundation for future biofuel manufacturing technologies. This research will have a significant impact on the overall cost and energy balance of biofuel manufacturing, greatly benefiting the U.S. economy and energy security, as well as the environment and society, in general. This project will have a positive impact on engineering education. A new course accompanied by hands-on lab sessions will be created to strengthen the undergraduate engineering curricula and engage students in participating projects on renewable energy manufacturing. The research objective is to test three hypotheses to explain inconsistency in the relationship between cellulosic biomass particle size and enzymatic hydrolysis sugar yield. In this research, it is hypothesized that the inconsistences are caused by the use of different sugar yield definitions, particle size ranges, and pretreatment methods. The prevailing biofuel manufacturing technology and the three most widely used cellulosic biomass currently in the industry, wheat straw, corn stover, and switchgrass, will be used in the research. Experimental investigations on both lab and pilot scale biofuel conversion facilities will be conducted to test the hypotheses. Additionally, structural features, morphological changes, and chemical compositions of cellulosic biomass will be characterized by using electron microscopy, x-ray diffraction analysis, UV spectrophotometry, high performance liquid chromatography, IR spectroscopy, Simon's stain, and nuclear magnetic resonance techniques. Based on the experimental results, a sugar yield model, incorporating all the significant structural, morphological, and chemical features, will be developed and validated. The outcome of this research will provide insights in the dynamic degradation of sugar compounds during hydrolysis. It will advance the knowledge base needed to make both strategic and operational decisions in biofuel manufacturing.