Chemicals, biomass sources

Wood is one of our most important renewable biomass resources. Unlike most biomass sources, wood is available year round and is more stable on storage than other agricultural residues. In the United States, wood residues from iadustrial by-products totaled 60.8 x 10 metric tons ia 1993 (73). Increasiagly, residues are iacorporated iato manufactured wood products and are used as a fuel, replacing petroleum, especially at wood-iadustry plants (73) some is converted to charcoal but most is used ia the pulp and paper iadustry. Residues are also available for manufacturiag chemicals, generally at a cost equivalent to their fuel value (see Fuels frombiomass Fuels fromwaste). 

Another emerging area m biofuels is pyrolysis, which is the decomposition of biomass into other more usable fuels using a high-temperature anaerobic process. Pyrolysis converts biomass into charcoal and a liquid called biocrude. This liquid has a high energy density and is cheaper to transport and store than the unconverted biomass. Biocrude can be burned in boilers or used in a gas turbine. Biocrude also can be chemical by altered into other fuels or chemicals. Use of pyrolysis may make bioenergy more feasible in regions not near biomass sources. Biocrude is about two to four times more expensive than petroleum crude. 

Uncertainties with the availability and suitability of biomass resources for energy production are primarily due to their varying moisture content, and to a lesser degree to their chemical composition and heating value. As the moisture content of biomass increases, the efficiency of thermal conversion process decreases. At some point more energy may have to be expended to dry the biomass than it contains. Uncertainties can be reduced by conducting a detailed chemical and physical analysis of the biomass sources. 

When contrasting processes in the energy and chemical industry with processes using biomass sources, which are in general more efficient What could be the reason for this ... 

Carbohydrates, in the form of gums, polysaccharides, oligomers, and monomeric sugars, are readily obtainable from renewable biomass sources. Each of these has potential use in the formulation of adhesives. This has been true historically and will be increasingly true in the future as petroleum-derived chemicals become scarce and their prices rise. 

Physical and chemical properties were determined using standard procedures and are to be described below. The feedstocks of this project will mainly comprise orujillo as well as some woody biomass fuel. The fuels for the analyses were chosen to represent typically two significant biomass sources ... 

Biomass Sources Biomass Production and Supply Thermo-Chemical Conversion Physico-Chemical Conversion Blo-Chemical Conversion Outlook... 

Separation of biomass components is the very important initial step for the upcoming efficient utilization of biomass sources. Several physical and chemical separation methods are currently employed to overcome the recalcitrance of lignocelluloses. These methods include acid hydrolysis, alkaline hydrolysis, ammonia fiber expansion, hot water, organic solvent, and ionic liquid separation technologies. In this section of the chapter, all of the above separation methods are discussed. 

With the appropriate conversion technology, plant-derived biomass could become the primary source of energy, chemicals and materials over the next century. It is estimated that by dedicating a third of current forest and marginally arable land to production of short-rotation hybrid species or grassy energy crops it would be feasible to supply all transportation needs and a large fraction of petrochemical needs from biomass sources (2,7). 

There are twelve important platform chemicals listed that are derived from biomass [26]. They include succinic acid, itaconic add, and glycerol. Some other important biobased renewable chemicals such as lactic acid and 1,4-butanediol are produced via fermentation and/or chemo-enzymatic processes from various biomass sources like com, sugarcane, wheat, etc. These platform chemicals have been used as starting materials for the production of polymers. 

Alternative feedstocks for petrochemicals have been the subject of much research and study over the past several decades, but have not yet become economically attractive. Chemical producers are expected to continue to use fossil fuels for energy and feedstock needs for the next 75 years. The most promising sources which have received the most attention include coal, tar sands, oil shale, and biomass. Near-term advances ia coal-gasification technology offer the greatest potential to replace oil- and gas-based feedstocks ia selected appHcations (10) (see Feedstocks, coal chemicals). 

Because oil and gas ate not renewable resources, at some point in time alternative feedstocks will become attractive however, this point appears to be fat in the future. Of the alternatives, only biomass is a renewable resource (see Fuels frombiomass). The only chemical produced from biomass in commercial quantities at the present time is ethanol by fermentation. The cost of ethanol from biomass is not yet competitive with synthetically produced ethanol from ethylene. Ethanol (qv) can be converted into a number of petrochemical derivatives and could become a significant source. 

Renewable carbon resources is a misnomer the earth s carbon is in a perpetual state of flux. Carbon is not consumed such that it is no longer available in any form. Reversible and irreversible chemical reactions occur in such a manner that the carbon cycle makes all forms of carbon, including fossil resources, renewable. It is simply a matter of time that makes one carbon from more renewable than another. If it is presumed that replacement does in fact occur, natural processes eventually will replenish depleted petroleum or natural gas deposits in several million years. Eixed carbon-containing materials that renew themselves often enough to make them continuously available in large quantities are needed to maintain and supplement energy suppHes biomass is a principal source of such carbon. 

H. F. Feldmann and co-workers, ia D. L. Klass, ed.. Biomass as a Nonfossil Fuel Source, ACS Symposium Series 144, American Chemical Society,... 

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