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Ethanol Production
[top] [end]Physical propertiesEthanol (ethyl alcohol, grain alcohol) is a clear, colourless, flammable liquid with a molecular formula of C2H60. In dilute aqueous solution (drinking alcohol) it has a somewhat sweet flavour with a characteristic, agreeable odour. In more concentrated forms (industrial use, fuels), it is generally termed as hydrous ethanol when it has a 5-7% water content by volume, or anhydrous ethanol (absolute, fuel grade) when at less than 1% water by volume. At this higher concentration it has as an energy per unit volume, or heating value, some two-thirds that of petrol and paraffin (kerosene). Ethanol can be denatured (rendered unfit for human consumption) by the addition of various additives.[top] [end]Ethanol ProductionEthanol can be produced from both biomass and fossil fuel sources, with the majority of industrial ethanol being produced by the acid-catalysed hydration of petroleum derived ethylene. Traditionally, starch or sugar rich plants have been fermented using biocatalysts (micro-organisms including yeast and bacteria) to produce ethanol in a relatively dilute aqueous solution (beer, wine). The process takes place in the absence of oxygen and produces ethanol, carbon dioxide and waste products. On a commercial level fermentation is a well-established technology and its use for non-drinking purposes has been improved significantly during recent decades due to the growth of the ethanol fuel industry. In the large scale production of biomass sourced ethanol (bio-ethanol), fermentation can only achieve a maximum azeotropic mixture of 96% ethanol and distillation is required to achieve fuel grade ethanol.Whilst ethanol can be made from a wide variety of plants, the two main feedstocks currently in use are sugarcane and corn (maize). By using biomass to produce ethanol the fuel is classed as a renewable energy source, because the green house gasses (ghg) released in its production and consumption are theoretically equivalent to those absorbed during its growth cycle. [top] [end]Ethanol Fuel ProgrammesBy far the largest market for ethanol is its use as a transport fuel. This idea is not new as some of the first petrol (gasoline) powered motor cars were also designed to run on ethanol, over one hundred years ago. In fact Henry Ford’s Model T (1908) was designed to use any combination of the two, a feature now being reintroduced on modern cars. To aid performance, petrol engines require an ‘anti-knocking’ agent in the form of additives such as lead or MTBE, resulting in potentially harmful emissions from the exhaust pipe. However, a relatively small amount of ethanol, when blended with petrol, will give a similar performance without the emissions. Given the high energy density of ethanol, it can also be used to partially or fully substitute petrol. A common blend is 10% ethanol to 90% petrol, a popular choice as most cars do not need any transformation in order to operate with what is known as E10. In some countries flexible fuel vehicles, those modified to run on higher ratio ethanol blends, use E85 (a mix of 85% ethanol to 15% petrol).There are numerous bio-ethanol fuel programmes worldwide, each with the common purpose of reducing the importation of petroleum products, for a variety of reasons including cost and the security of supplies. To see how ethanol is produced around the world click here In many countries the sugarcane processing/ethanol facilities are in need of greater investment, with the better utilisation of feedstock waste (sugarcane bagasse) to provide power back to the processing facility and externally to the plant. A flexible production strategy, where sugar/ethanol production and the petrol blending ratio are altered to suit market conditions would better optimise a countries resources. [top] [end]Alternative FeedstocksRead more about alternative ethanol feedstocks here[top] [end]Small Scale ProductionRead more on the small scale production of ethanol here[top] [end]Ethanol and CarbonTo see the issues around Biofuels and Carbon click here[top] [end]Supply ChainsTo see the issues around Liquid Fuel Supply Chains click hereUser:James Robinson 10 April 2007 | |
Page created:
10 April 2007; Last edited:
08 September 2008; Version: 5 | |
Pagename: EthanolProduction @HEDON: HGEA | |
