Renewable materials lignocellulose

Lignocellulose Biodegradation / Badal C. Saha, editor, Kyoshi Hayashi, editor sponsored by the ACS Division of Cellulose and Renewable Materials. 

Both in the USA and the EU, the introduction of renewable fuels standards is likely to increase considerably the consumption of bioethanol. Lignocelluloses from agricultural and forest industry residues and/or the carbohydrate fraction of municipal solid waste (MSW) will be the future source of biomass, but starch-rich sources such as corn grain (the major raw material for ethanol in USA) and sugar cane (in Brazil) are currently used. Although land devoted to fuel could reduce land available for food production, this is at present not a serious problem, but could become progressively more important with increasing use of bioethanol. For this reason, it is important to utilize other crops that could be cultivated in unused land (an important social factor to preserve rural populations) and, especially, start to use cellulose-based feedstocks and waste materials as raw material. 

The production of fuel ethanol from renewable lignocellulosic material ("bioethanol") has the potential to reduce world dependence on petroleum and to decrease net emissions of carbon dioxide. The lignin-hemicellulose network of biomass retards cellulose biodegradationby cellulolytic enzymes. To remove the protecting shield of lignin-hemicellulose and make the cellulose more readily available for enzymatic hydrolysis, biomass must be pretreated (1). 

Lignocellulosics are the most abundant renewable organic materials in the biosphere. They account for approx 50% of the total biomass in the world, with an estimated annual production of 1-50 x 1091 (4). Lignocellu-losic materials, particularly the residues obtained from wood processing, are usually much cheaper than sugar- and/or starch-derived feedstock, such as sugarcane and corn. They also have no competitive use as human or animal foodstuffs. 

The shortage of oil and natural gas has been reflected in shortages and spiraling prices for polymers based on petrochemical resources. Providentially, such polymers may be in part replaced by lignocellulosic materials that are the most abundant and most economical organic renewable resources available. In their natural state as wood and plant fibers, and as the principal constituent used in the manufacture of paper, textile fibers, and many other industrial products, lignocellulosic materials will continue to be fundamental to human welfare. 

Lignocellulosic biomass refers to plant-derived material such as bagasse, com stover, wheat straw, rice straw, wood chips and switch grass. It is an abundant and renewable resource which is also potentially carbon-neutral and potentially economically viable if appropriate processing methods can be developed to extract and... 

Lignocellulosics are the most abundant renewable resource in the world, and bioconversion of lignocellulosics into fiiel ethanol could contribute to renewable energy supplies. Hemicelluloses, the second most abundant polysaccharides in nature, represents about 20-30% of agricultural residues [1], The utilization of hemicellulose is essential for whole components utilization of lignocellulosic materials, as well as for the economy of the bioconversion process in industrial applications. 

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