Biomedical Engineering Reference
In-Depth Information
12 Lignocellulosic Biomass Processing
Fei Yu and Jonathan Y. Chen
12.1 INTRODUCTION
Currently there is a great concern about the sustainability of the environment and energy
sources and consumers are demanding biomass-based products. Therefore, scientists are
putting intensive efforts into exploring renewable biomass sources and expanding the
utilization of these resources for bioproduct development. A lot of attention is drawn to
lignocellulosic biomass, one of the major renewable energy sources, due to its many
advantages over other energy sources. Biomass-based energy and materials lessen green-
house gas effects and can be generated locally. Some biomaterials, such as lignocellulosic
ethanol, polylactic acid (PLA) and polyhydroxyalkanoate (PHA) can be produced through
biological processes, for example fermentation, while some biofuels are obtained through
thermochemical processes, such as biopolyols, bio-oils and synthesis gas.
The United States federal government, state governments and industries are stepping up
efforts to shift the current fossil-oil-based economy to a renewable bio-based economy. The
non-renewable resource and fossil-oil-based economy has adverse impacts on our
environment and is non-sustainable. In contrast, an economy based on renewable resources,
such as lignocellulosic biomass, will supplement energy and material production from fossil
resources, and offers a strong possibility of replenishing or displacing the use of petroleum.
Firstly, biomass resources are domestic, reducing dependence on foreign oil and reducing
concerns over the stability and sustainability of that supply. The conversion processes from
lignocellulosic biomass sources also have a major advantage over petroleum refining
processes in that they release far fewer pollutants to the atmosphere and generate less toxic
waste during production. Perhaps most importantly to the agricultural sector, producing
chemicals and materials from renewable biomass resource means a new market for
agriculture and forestry. Exploring new uses for agricultural and forest residues and their
derivatives can reduce the effect of food commodity market limits on agricultural product
prices, delivering higher profits to producers.
12.2 AVAILABILITY OF LIGNOCELLULOSIC BIOMASS
Agricultural and forest processing always generates a tremendous amount of biomass that
can be utilized to produce bioproducts, biopolymers or biofuels. Forestry and crop residues
have been traditionally used as animal feed directly or, after pretreatments, to improve
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