Biorefinery: Conversion of woody biomass to chemicals, energy and materials

Conversion of biomass to chemicals and energy is imperative to sustain our way of life as known to today. Fossil fuels have become the predominant energy and chemical source today. However, fossil deposits are limited and not renewable on a human civilization time scale. Woody biomass is a reliable source of chemicals and energy that could be replenished at a rate of consistent with our needs. The biorefinery is a concept for the collection of processes used to convert biomass to chemicals and energy. The Biorefinery is a "catch and release" way of using carbon that is beneficial to the environment and the economy. Woody biomass presents more challenges than cereal grains for conversion to platform chemicals due to its stereochemical structures. Woody biomass can be thought of as comprised of at least four components: extractives, hemicellulose, lignin and cellulose. Each of these four components has a different degree of resistance to chemical, thermal and biological degradation. The Biorefinery concept proposed at ESF (State University of New York - College of Environmental Science and Forestry) aims at step-wise fractionation/conversion to achieve efficient separation of major components. Hot-water extraction is the first step which removes extractives and hemicellulose fractions from woody biomass. A mass balance for sugar maple woodchips subject to hot-water extraction at 160 degrees C for two hours was presented. While extractives and hemicellulose are largely removed to the extraction liquor, cellulose and lignin largely remain with the residual woody structure. Xylo-oligomers and acetic acid in the extract are the major components having greatest potential value for development. Four other technological steps are also discussed: hydrolysis; membrane separation/concentration; biological conversion of sugars to biofuel, chemical, and biopolymers; and utilizations of the extracted woody biomass for reconstituted wood products, particle board, fuel pellets, further conversion to platform chemicals, pulp, electricity, etc.