U.S. Department of Energy - Energy Efficiency and Renewable Energy
Bioenergy Technologies Office
This area focuses on the research, development, and demonstration of biological and chemical processes that convert biomass to biofuels, chemicals, and power.
Lignocellulose (mainly lignin, cellulose, and hemicellulose) is the primary component of plant residues, woody materials, and grasses. The cell wall structure of this plant matter is partially comprised of long-chain sugars (carbohydrates), which can be converted to biofuels. Biological and chemical conversion processes break down the cell wall through the introduction of enzymes, acids and bases, solvent, or other reagents in order to yield pure sugars or a sugar-rich stream (called hydrolyzate), which can then be converted to biofuels using microorganisms or catalyst. Due to the obstinate, recalcitrant nature of the cell wall, it is often difficult and complicated to completely hydrolyze the carbohydrate components into sugars and usable intermediates, making this material expensive to convert to biofuels.
Keys to developing cost-competitive cellulosic biofuels include reducing the processing and capital cost and improving the efficiency of separating and converting cellulosic biomass into sugars. Current research and development focuses on high-sugar yielding feedstocks; improved biomass pre-treatment processes, which engender difficulties to downstream processing; improved enzyme efficiencies; non-enzymatic systems that can yield clean sugars; developing robust (i.e. impurity, pH, and temperature tolerant) microorganisms for biofuel production; developing and scaling catalytic systems for producing hydrocarbons and fuel-blend oxygenates from lignocellulosic material; and utilizing and valorizing lignin residue that remains after the carbohydrate and sugars have been extracted.
For more information on biochemical conversion, see the fact sheet: Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to Make Fuels and Chemicals.