Ethanol Fuel

U.S. capacity for producing biofuels manufactured by biological or thermal conversion of biomass must be dramatically increased to approach the potential contributions based on biomass availabiUty. For example, an incremental EJ per year of methane requires about 210 times the biological methane production capacity that now exists, and an incremental EJ per year of fuel ethanol requires about 14 times existing ethanol fermentation plant capacity. 

Because most fuel ethanol manufactured ia the United States is made from com, price plays a cmcial role ia determining the competitive position of ethanol ia an open market. With com priced at about 2.50/bu, the embedded feedstock cost of product ethanol is about 0.14—0.23/L ( 0.52—0.87 gal), depending on over-all yield and by-products ignored (125). Euel ethanol plants may have contingency plans to close if com prices rise to a certain level, eg, 3.50/bu or above (126). 

Gasohol in the United States. Over 90% of the fuel ethanol in the United States is produced from com. Typically, 0.035 m (1 bushel) of com yields 9.5 L (2.5 gal) of ethanol. Ethanol is produced by either dry or wet milling (87). Selection of the process depends on market demand for the by-products of the two processes. More than two-thirds of the ethanol in the United States is produced by wet milling. Depending on the process used, the full cost of ethanol after by-product credits has been estimated to be between 0.25—0.53/L ( 1—2/gal) for new plants (88). Eeedstock costs are a significant factor in the production of fuel ethanol. A change in com price of 0.29/m ( 1.00/bushel) affects the costs of ethanol by 0.08/L ( 0.30/gal). 

More recently, interest has developed in the use of enzymes to catalyze the hydrolysis of cellulose to glucose (25—27). Domestic or forest product wastes can be used to produce the fermentation substrate. Whereas there has been much research on alcohol fermentation, whether from cereal grains, molasses, or wood hydrolysis, the commercial practice of this technology is primarily for the industrial alcohol and beverage alcohol industries. About 100 plants have been built for fuel ethanol from com, but only a few continue to operate (28). 

U.S. ethanol imports were greatiy influenced by the rapid increase of world fermentation capacity in the late 1970s and the rapid increase in U.S. demand for fuel ethanol. Imported alcohol from Brazil reached 140 x 10 L in 1980, mosdy for the fuel market. In 1981, the U.S. Government passed an import duty on fuel ethanol. The duty was raised to 0.158/L in 1985 (248), after BraziUian imports reached 314 x 10 L in 1984. Total ethanol imports in 1984 were 568 x 10 L, with 95 x 10 L going to the industrial market, where the import duties do not apply. Another factor influencing ethanol imports... 

In 1997 a total 1.3 billion gals of ethanol fuel was produced in the United States. Proposed new low sulfur conventional gasoline standards could greatly increase the demand for ethanol since desulfurization may lower gasoline octane. Almost all fuel ethanol is used as gasohol, but some is used to make E-85 (85% ethanol and 15% gasoline). E-85 can be used in flexible-fuel vehicles (FFVs) which can operate on gasoline or ethanol blends of to 85 percent ethanol. 

Target CNG Synthetic Fuel Ethanol Biodiesel Hydrogen... 

Singh, V., Johnston, D.B., Rausch, K.D., and Tumbleson, M.E. 2003. Fermentation characteristics of mash with germ and pericarp fiber removal. Proceedings of the 19th Annual Fuel Ethanol Workshop , Sioux Falls, SD. 

Taylor, F., McAloon, A.J., Craig, J.C., Jr., Yang, P., Wahjudi, J., and Eckhoff, S.R. 2001. Fermentation and cost of fuel ethanol from com with quick-germ process. App. Biochem. Biotech. 94, 41-49. 

A more recent assessment [8] has re-evaluated six representative analyses of fuel ethanol, evidencing that the studies reporting negative net energy incorrectly... 

Oxygenated fuels Ethanol 10% (ElO), Methanol, Methyl tertiary butyl ether (MTBE), Ethyl tertiary butyl ether (ETBE), Tertiary butyl alcohol (TBA), and Tertiary amyl methyl ether (TAME)... 

Small reformers R D areas include compact and low cost reformers (1-5 kW) to convert fossil fuels (natural gas, gasoline) or biomass fuels (ethanol) to hydrogen via different processes (steam reforming, partial oxidation, auto-thermal, non catalytic hybrid steam reforming). Improvements in reformer efficiency, capacities and response times, and integration of purification unit are also being studied. Examples of projects include ... 

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