Ethanol, fermentation corn feedstock

The processes for manufacturing methanol by synthesis gas reduction and ethanol by ethylene hydration and fermentation are very dissimilar and contribute to their cost differentials. The embedded raw-material cost per unit volume of alcohol has been a major cost factor. For example, assuming feedstock costs for the manufacture of methanol, synthetic ethanol, and fermentation ethanol are natural gas at 3.32/GJ ( 3.50/10 Btu), ethylene at 0.485/kg ( 0.22/lb), and corn at 0.098/kg ( 2.50/bu), respectively, the corresponding cost of the feedstock at an overall yield of 60% or 100% of the theoretical alcohol yields can be estimated as shown in Table 11.12. In nominal dollars, these feedstock costs are realistic for the mid-1990s and, with the exception of corn, have held up reasonably well for several years. The selling prices of the alcohols correlate with the embedded feedstock costs. This simple analysis ignores the value of by-products, processing differences, and the economies of scale, but it emphasizes one of the major reasons why the cost of methanol is low relative to the cost of synthetic and fermentation ethanol. The embedded feedstock cost has always been low for methanol because of the low cost of natural gas. The data in Table 11.12 also indicate that fermentation ethanol for fuel applications was quite competitive with synthetic ethanol when the data in this table were tabulated in contrast to the market years ago when synthetic ethanol had lower market prices than fermentation ethanol. Other factors also... 

Figure 6 shows the projected selling price for a 15% return on investment after taxes for the 50,000.000 gal/yr Gulf cellulose alcohol plant and for fermentation corn and synthetic ethylene-alcohol plants of the same capacity (Table VI). The ethylene costs are escalated at 9%, per industry projections, cellulosics at 7%. and according to USDA projections, corn at 5%. Feedstock costs used as a basis for these graphs are (starting 1983 as in Tables V and VI) MSW 14.00/oven-dried ton (ODT), SMW 21.00/ODT, Pulp mill wastes 14.00/ODT, Ethylene 0.18/pound and corn 3.00/bushel. Thus, the total feedstock cost per gallon of ethanol produced is 0,104 in the case of cellulose. 0.75 for ethylene, and 1.20 for corn. By-product credits used escalated from prices listed in 1983 at a 7% rate. 

Recent studies have proven ethanol to be an ideal liquid fuel for transportation and renewable lignocellulosic biomass to be an attractive feedstock for ethanol fuel production by fermentation (1,2). The major fermentable sugars from hydrolysis of lignocellulosic biomass, such as rice and wheat straw, sugarcane bagasse, corn stover, corn fiber, softwood, hardwood, and grasses, are D-glucose and D-xylose except that softwood... 

One of the most common feedstocks for ethanol production is corn, which has been widely used in the USA. The starch in corn is converted to glucose after grinding in a dry mill, reacting it with dilute acid and then reacting it with amylases, e.g. a-amylase and glucoamylase. The free glucose is then available for fermentation to ethanol. 

There are continuing efforts to develop cost-effective processes for fuel alcohol production, although the economics are often dependent on the availability of subsidized feedstocks to compete with traditional fuels derived from oil. The pretreatment and fermentation of such feedstocks, derived from corn, sugar cane, and even municipal waste, yields a dilute aqueous solution of ethanol which must be separated from a complex mixture of waste materials and then concentrated by distillation to remove water. Both batch and continuous production processes have been developed, with the requirement for effective bioseparations during both the pretreatment and ethanol recovery parts of the process. 

Ethanol has traditionally been and is currently still produced from glucose-based food crops, such as cane sugar, corn starch, and other starch-rich grains, via fermentation of glucose present in these feedstocks by Saccharomyces yeasts. However, these agricultural crops are expensive and in limited supply. 

More than twenty years ago, it was recognized that cellulosic biomass, including agricultural residues (such as corn stover, rice and wheat straws, and sugarcane bagasse), municipal wastes (such as yard and paper wastes), and industrial wastes (such as wastes from paper mills), is an attractive feedstock for ethanol-fuel production by fermentation because cellulosic biomass is not only renewable and available domestically in most countries but also available at very low cost and in great abundance. 

Ethanol is a molecule you are probably familiar with it s the alcohol found in alcoholic beverages that makes you feel intoxicated, and humans have consumed it for hundreds of years. Additionally, it is useful as a solvent, an antiseptic, a sedative, and a component in perfumes, lacquers, cosmetics, aerosols, antifreeze, and mouthwash. Ethanol can be produced from a raw feedstock, like corn or grain, by fermenting it in the presence of microbes, which can readily digest sugars and produce ethanol as a byproduct. 

The C4-Platform is accessible by fermentation using corn or sugarcane bagasse as feedstock by acetone-butanol or acetone-butanol-ethanol (ABE) fermentation using Clostridium acetobutylicum or Clostridium beijerinckii under anaerobic conditions. This process has been industry standard since decades and produces the three solvents in a ratio ABE = 3 6 1. More recently, microbial fermentation technologies which genetically... 

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