Enhancing Biosynthesis of Biofuels from Cellulosic Biomass

There continues to be a need for production of biofuels from agricultural sources. Butanol is a more attractive fuel than ethanol because it leads to better gas mileage, it achieves higher blends with gasoline than bioethanol, it has greater compatibility with existing fuel infrastructure, it is less volatile, it is more amenable to transport via pipeline due to low water absorption, there is no need for an engine retrofit, and it allows to use numerous existing agricultural feedstocks, as well as next generation feedstock including cellulosic biomass and algae. To produce butanol efficiently the fermentation process must be run continuously while maintaining low butanol concentration in the fermenter. This requires that butanol be removed from the fermenter at the same rate that it is produced. This can be done by conventional distillation, which requires that the fermentation broth be first processed for removing the microorganisms for recycle to the fermenter. The clarified broth must be heated and distilled to produce a butanol concentrate in the distillate. The bottoms product from the distillation must be cooled down and recycled to the fermenter. The conventional process requires a solids-liquid separation step and is energy intensive. If an alternate technology were developed to a) Do the butanol recovery without an extra step to do the solids-liquid separation, and b) Reduce the heating/cooling energy requirements of the distillation step It would reduce butanol production costs, save energy and reduce emissions of greenhouse gases. Thus the process for producing biobutanol from agricultural sources and its economical attractiveness would be enhanced. The objective of this program is to develop a membrane system that accomplishes the above at a cost that is at least 30% lower than the cost conventional techniques. The Phase I was extremely successful and produced the data to give high probability of success in this Phase II program. This will be run experimentally and we will use best practices and statistically designed experiments to insure the highest quality data. Anticipated Results: Overall fuel market is 150 billion gallons per year domestically. With USDA/DOE plus executive mandates projecting 30% of fuel being renewable the market potential is 45 billion gallons/yr. Given biobutanol's superior performance to bioethanol, much of this 45 billion gallons/yr market is available to biobutanol if it can be supplied economically. Potential commercial applications: In addition to butanol, many other valuable chemicals can be derived from agricultural sources, e.g., acetone, glycerol, THF, isoprene, propanediol, gluconic acid, succinic acid, etc. All of these materials, assuming biochemical or fermentation routes to produce these materials are developed, would benefit from the CMS membrane technology and the proposed product concept.