Ethanol, fermentation feedstock

A more abundantiy produced substance is ethanol for use in alcohoHc beverages, and as a fuel, solvent, and feedstock for organic syntheses. Ethanol (qv) production from sucrose is carried out in Europe (eg, France and the Netherlands), India, Pakistan, China, and on a very large scale in Brazil, where it is used as a motor fuel. A valuable by-product of ethanol fermentation is industrial CO2 (see Carbon dioxide). 

Hemicelluloses can be hydrolysed into their component sugars and used as a fermentation feedstock for the production of ethanol and other alcohols (e.g. butanol, arabitol, glycol and xylitol), organic acids (e.g. acetic acid), acetone and gases (e.g. methane and hydrogen). The wider monosaccharide profile offers opportunities to develop different products to those derived from glucose alone. 

Research to improve ethanol fermentation has also focused on the development of a high solids, continuous feeding process as well as improved yeast strains. Other related developments include processes for the use of biomass feedstocks, such as cellulosic waste material.40"44 The Genencor-NREL collaboration funded by the U.S. DOE has (a) put in place the tools required for continual improvement of biomass-derived cellulases, (b) built a suite of enzymes with enhanced thermostability and improved specific performance at elevated temperatures, (c) developed an improved production strain for the enhanced cellulase components and demonstrated an enhanced production process. Therefore, plans are in place to provide a developmental product(s) in support of continued industry development. 

In the fermentation, experimental results are presented for the rheological behavior of high-solids ethanol fermentation for biomass conversion using Solka Floe as the model feedstock. A recombinant strain of Z. mobilis 39679 pZB4L was used in SFF processes as a function of varying initial concentration of Solka Floe and constant enzyme dosage. The initial viscosities ranged from 0.024 to 0.028, 0.423 to 0.067, and 0.840 to 0.087 Pa s for shear rates up to 100 reciprocal seconds at combined temperatures (50 and 30 °C) at 10, 15, and 20% initial solids (w/v), respectively. At 120 rpm, the viscosities were 0.019, 0.078, and 0.105 Pa s at 10, 15, and 20% initial solids (w/v), respectively. One can see that the... 

Resources that contain sugars can be used as a feedstock for ethanol fermentation. There are many biomass resources in the world that can be used to produce ethanol by fermentation. According to the traditional approach, they can be divided into three categories - starch, sugar, and cellulose materials-... 

Bai FW, Anderson WA, Moo-Young M. Ethanol fermentation technologies from sugar and starch feedstocks. Biotechnol Adu January/Fehtuary 2008 26(1) 89—105. 

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. 

Starches. In the United States, all potable alcohol, most fermentation industrial alcohol, and most fuel alcohol is currendy made principally from grains com is the principal feedstock for fuel alcohol. Fermentation of starch from grain is somewhat more complex than fermentation of sugars because starch must first be converted to sugar and then to ethanol. This process was known to the ancient Egyptians and Mesopotamians who brewed beer almost 5000 years ago (202). The simplified equations for the conversion of starch to ethanol are... 

Ethanol has been used in the United States to a considerable extent as an antifreeze but it has largely been replaced for such use by ethylene glycol. The use of fermentation alcohol in automotive fuel has been discussed above. Several tropical countries consider ethanol, produced from regenerable resources, an attractive petrochemical feedstock. 

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