Ethanol has been used by humans since prehistory as the intoxicating ingredient in alcoholic beverages. Dried residues on 9000-year-old pottery found in northern China imply the use of alcoholic beverages even among Neolithic peoples. Distillation of ethanol from water yields a product that is at most 96% ethanol, because ethanol forms an azeotrope with water. Absolute ethanol was first obtained in 1796 by Johann Tobias Lowitz, by filtering distilled ethanol through charcoal. Some basic properties of ethanol (also called EtOH) are as follows:
► Pure ethanol is 200 proof
► Empirical formula = C2H6O
► Molecular formula = CH3CH2OH
► EtOH is toxic
► Density = 49.3 lbs/ft3 (water = 62.4 lbs/ft3)
► EtOH is fully miscible in water
► Boiling point = 173° F
► Energy content = 84,315 Btu/gal
► Regular unleaded gas = 124,858 Btu/gal
► Pure EtOH has 67% energy of regular gas
► Pure EtOH octane rating = 113 (E85 = 105)
Ethanol is also known as ethyl alcohol, grain alcohol, or just alcohol, is a volatile, flammable, colorless liquid, and is the oldest known recreational drug. Ethanol is a versatile solvent and mixes with water without separation (miscible) and with most organic liquids, such as aliphatic hydrocarbons. Organic compounds of low molecular weight are usually soluble in ethanol. Monovalent salts are somewhat soluble, but polyvalent salts are practically insoluble in ethanol. Ethanol-water mixtures have less volume than heir individual components; a mixture of equal amounts has only 96% of the volume of the unmixed ethanol and water. The addition of ethanol to water sharply reduces the surface tension of the mixture, which explains the “tears of wine” phenomenon, causing wine to “bead up” on the sides of a glass. Ethanol can be oxidized to acetaldehyde and acetic acid; in the human body, these oxidation reactions are catalyzed by enzymes. Combustion of ethanol results in a blue flame and produces carbon dioxide and water.
HOW ETHANOL IS MADE
Ethanol can be prepared by the fermentation of sugar (e.g., from molasses or sugar cane), which requires an enzyme catalyst that is present in yeast; or it can be prepared by the fermentation of starch (e.g., from corn, rice, rye, or potatoes), which requires, in addition to the yeast enzyme, an enzyme present in an extract of malt. The concentration of ethanol obtained by fermentation is limited to about 14% since at higher concentrations ethanol inhibits the catalytic effect of the yeast enzyme. The ethanol is then concentrated by distillation and filtering to obtain fuel grade ethanol, about 99.9% pure alcohol. For non-beverage uses, ethanol is more commonly prepared by passing ethylene gas at high pressure into concentrated sulfuric or phosphoric acid to form the corresponding ester; the acid-ester mixture is diluted with water and heated, forming ethanol by hydrolysis, and the alcohol is then removed from the mixture by distillation, usually with steam. New technologies are being developed to convert cellulosic feedstocks into ethanol using acid-hydrolysis with conventional fermentation, and gasification with catalysts or microbes to convert the syngas into ethanol; Powers Energy uses gasification technology.
HOW ETHANOL IS USED
Ethanol is the alcohol in beer, wines, and liquors. The largest single use of ethanol in the U.S. is as a motor fuel and fuel additive. Ethanol is used extensively as a solvent in the manufacture of varnishes and perfumes; as a preservative for biological specimens; in the preparation of essences and flavorings; in many medicines and drugs; in finger nail polish remover; as a disinfectant and in tinctures (e.g., tincture of iodine); in medical wipes; and in most common antibacterial hand sanitizer gels, to name a few uses. Many U.S. automobiles manufactured since 1998 have been equipped to enable them to run on either gasoline or E85, a mixture of 85% ethanol and 15% gasoline. E85, however, is not yet widely available. Over 99 percent of the ethanol produced in the United States is mixed with gasoline to make E10, the gas found at most public fuel pumps. Over 60 percent of America's gasoline now includes some amount of ethanol. Indy 500 race cars have switched to pure ethanol from methanol and have been able to reduce fuel tank size from 37 to 22 gallons and annual fuel costs by $65,000 per car. Denatured, or industrial, alcohol is ethanol to which poisonous or nauseating substances have been added to prevent its use as a beverage; a beverage tax is not charged on such alcohol. Medically, ethanol is a soporific, i.e., sleep-producing; although it is less toxic than the other alcohols, death usually occurs if the concentration of ethanol in the bloodstream exceeds about 5%. Behavioral changes, impairment of vision, or unconsciousness occur at lower concentrations.
HISTORY OF ETHANOL
1826: Samuel Morey developed an engine that ran on ethanol and turpentine.
1876: German inventor Nicholas Otto develops first combustion engine - it ran on ethanol and gasoline. Otto used ethanol as early as 1860.
1896: Henry Ford built his first automobile, the quadricycle, to run on pure ethanol.
1908: Henry Ford produced the Model T - a "flexible fuel" vehicle that ran on ethanol, gasoline or a combination of both fuels.
1917-18: The need for fuel during World War I drives ethanol demand to 50-60 million gal/yr.
1920’s: Gasoline became the motor fuel of choice. Standard Oil began adding ethanol to gasoline to boost octane (reduce engine knock).
1930’s: More than 2,000 gasoline stations in the Midwest sell gasohol - gasoline blended with between 6 percent and 12 percent ethanol.
1945-1978: Virtually no commercial fuel ethanol used in the U.S. due to low cost of gasoline.
1974: The Solar Energy Research, Development and Demonstration Act prompts research into the conversion of cellulose and other organic materials into useful energy or fuel.
1975: U.S. begins to phase out lead in gasoline. MTBE eventually replaced lead until 2004-06, when MTBE was banned in most states.
1978: Gasohol defined for the first time in the Energy Tax Act of 1978 as a blend of gasoline with at least 10 percent alcohol by volume. A subsidy of 40 ¢/gallon of ethanol was applied.
1980: First U.S. survey of ethanol production finds fewer than 10 ethanol facilities producing roughly 50 million gal/yr.
1984: The Tax Reform Act increases the ethanol subsidy to 60 ¢/gallon.
1985: Despite the subsidies, only 74 commercial ethanol plants are operating at the end of 1985, producing 595 million gallons of ethanol/yr.
1995: The EPA began requiring the use of reformulated gasoline year-round in metropolitan areas with the most smog.
1997: U.S. auto manufacturers begin mass production of flexible-fueled vehicle models capable of operating on E-85 and/or gasoline.
2001: Ethanol subsidy reduced to 53 ¢/ gallon.
2002: U.S. automakers continued to produce E-85-capable vehicles to meet federal regulations. Some 3 million of these vehicles in use.
2006: Renewable Fuel Standard (RFS) signed into law to encourage blending of renewable fuels (ethanol & biodiesel) with gasoline.
2007: Energy Independence and Security Act signed into law requiring 36 billion gallons of advanced biofuel production/use by 2022.
2007: Indy Racing League switches to 98% ethanol fuel.
2008: 204 ethanol plants in the U.S. with a capacity of 12.6 billion gal/yr; all use corn as feedstock. 35 plants were closed due to low oil and high corn prices. Ethanol subsidy reduced to 45 ¢/ gallon in 2009 and beyond.
2010: Federal Government is considering increasing maximum allowable
ethanol content in gasoline to 15%.