Conversion

The overall goal of this work program is to improve lignocellulosic biomass processing technologies for fermentable sugar production and subsequently their conversion to biofuel. An additional emphasis of this program is on the processing and utilization of waste streams for recovery of nutrients, bioproduct production and for reuse of wastewater. This approach goes a long way in ensuring that the biofuel is manufactured with minimal environmental impact and there are additional revenues from biorefining. Currently biodiesel and ethanol are the commonly used liquid biofuels for transportation. Ethanol is used after blending with gasoline. Butanol is touted as an alternate to ethanol as it can directly substitute for gasoline in engines. Butanol can also be made from biomass using the direct biochemical (or fermentation) approach or via the butyric acid pathway which involves both biochemical and catalytic method steps.

Mayfield Biorefinery Pilot Plant EquipmentRevenues from biorefining can also be enhanced by making co-products along with the biofuel. Corn ethanol plants, for example may produce corn oil and an animal feed stream called distillers dry grains with solubles (DDGS) to add value to the process. Unlike DDGS, the predominantly lignin fiber remaining in the stillage after distillation in a cellulosic ethanol process has poor nutritive quality. So other uses for the stillage have to be developed. A readily implementable option is to anaerobically digest the stillage to produce biogas. The biogas can be used as a fuel in the plant. Anaerobic digestion will also serve as a treatment process for stillage. With further treatment the water may be reusable. Appropriate wastewater treatment processes that recover plant nutrients (like nitrogen and phosphorus) can also be considered. These nutrients can be used for growing the biomass. Water reuse and nutrient recycling can greatly minimize the environmental impact of the biofuel production process.           

  • Improve lignocellulosic biomass processing technologies for fermentable sugar production and subsequently their conversion to biofuel
  • Develop processing and utilization of waste streams for recovery of nutrients, bioproduct production and for reuse of wastewater
  • Develop methods to ensure that the biofuel is manufactured with minimal environmental impact and there are additional revenues from biorefining

More Information?

  • Florida Center for Renewable Chemicals and Fuels (FCRC)
  • Biocatalyst development for production of advanced biofuels
    • Biocatalyst development for production of advanced biofuels
      (L. O. Ingram and K. T. Shanmugam, University of Florida) 

      Objective: to develop microbial biocatalysts for conversion of lignocellulose derived sugars to advanced biofuels and organic acids,  and integrate these biocatalysts with optimum biomass process conditions developed at our pilot plant, the Stan Mayfield Biorefinery. Due to the toxicity of our target advanced biofuel (butanol) to the fermenting microorganism, our objective is to develop microbial biocatalysts for production of butyric acid as the primary fermentation product at high titer and productivity. The butyric acid can be readily reduced to butanol using catalysts and the H2 produced during fermentation of sugars to butyric acid.

      Studies on advanced biofuels will be focused on the two critical physiological characteristics of the biocatalyst that influence productivity: tolerance to inhibitors present in acid hydrolysate of various biomass feedstocks, and rapid utilization of hemicellulose-derived sugars in the presence of glucose.               
      In the production of organic acids, biocatalysts will be optimized for high titer and yield using various biomass feedstocks at the pilot plant level.


      Deliverables:
      • Advanced biofuels - A biocatalyst that ferments both glucose and xylose, dominant sugars in biomass, simultaneously at high rate and titer even in the presence of metabolic inhibitors generated during pre-treatment of biomass to butyric acid for further reduction to butanol.
      • Organic Acids - A microbial biocatalyst that can grow in mineral salts medium for production of butyric acid at high titer and yield using acid-hydrolyzed bagasse and fibers from select biomass crops as feedstocks.