With the increasing consumption of oil, the decreasing amount of landfill space, the increasing awareness of the environment, etc, green chemistry and the use of biodegradable materials has became popular in the last few years. These materials are created from natural resources, so that in the decomposition process nothing harmful is added back to the earth. Biomass sources include wood, crops, manure, and some garbage. Energy is retained from biomass by burning (wood), the release of methane gas (human and agriculture waste), and the conversion to ethanol (corn or sugar cane) or biodiesel (food products).  Wood is a primary source for several biomass sources. Wood is a mixture of three natural polymers (cellulose, lignin and hemicellulose) in an approximate ratio of 50:25:25. The ratio varies depending on species, biological variations such as genetic differences within species and growing conditions. These three polymers have been and are still currently being investigated for their ability to be formed into plastics, paper, lubricants, pigments, insulation, etc. Forest and woodland, covering 32% of the earth’s land surface, provide an ample opportunity for the development of biodegradable, green chemistry materials. Figure 1: Types of Biomass Sources Municipal solid waste is another souce of biomass. Today the average American throws away 4.5 pounds of trash every day. This waste can be burned in waste-to-energy plants, where steam is made to heat buildings or to generate electricity.The animal and plant products in garbage are a source of a second type of energy, biogas. As the products decay, methane gas (also called biogas and landfill gas), the major component in natural gas, is released. 
Figure 2: Schematic drawing of a waste-to-engery plant Argricultural crops such as corn, sugar cane, sugarbeets, etc., and some cellulosic materials are converted to Bioethanol through hydrolysis and sugar fermentation processes. Bioethanol comes from renewable sources, has cleaner combustions and lower carbon dioxide emissions, and provides energy security by less of a dependence on crude oil. It is utilized in multiple ways: as hydrous ethanol that acts as a gasoline subsititute, anhydrous ethanol that is blended with conventional gasoline in ratios from 5%-85%, and as ethyl-tertiary-butyl-ether (ETBE) a fuel additive for conventional gasoline. Figure 3: Cycle of Bioethanol Biodiesel is another type of transportation fuel obtained from renewable sources that can be used in compression-ignition (diesel) engines with little or no modification. Biodiesel is biodegradable, nontoxic, and lacks sulfur compounds and aromatics. It is obtained from the transesterification of fats from vegatable oils and animal products. Today it is used as fuel for diesel engines and as burning fuel for domestic and commercial boilers.
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Biomass Sources 