Başlangıç > Mühendislik, İTÜ > An Overview of Ethanol

An Overview of Ethanol

Ethanol is simply a type of alcohol that people use in beverages. But ethanol is also used as an alternative fuel for oil. Brazil, USA and some other countries like Sweden use widely ethanol.

Ethanol is mainly produced from glucose as a byproduct with carbon dioxide. In the present, 5% of ethanol is produced from petroleum. It is made by the catalytic hydration of ethylene with sulfuric acid as the catalyst. It can also be obtained from ethylene or acetylene, from calcium carbide, coal, oil gas, and other sources. Bio-ethanol is obtained from agricultural feedstocks which are carbon based. Examples of these feedstocks are sugar cane, bagasse, miscanthus, sugar beet, sorgum, switchgrass and etc.

There are mainly four different ways of large scale production of ethanol. Microbial fermentation of sugar, mainly from sugar cane, is one of them. Also, water can be removed to be able to used as a fuel, this process is called as distillation. Ethanol can also be purified by a molecular sieve (ZEOCHEM Z3-03). And, there is another process called denaturing.

Pure ethanol (E100) is only used in some special cases. For instance, Indy Racing League (IRL) made its former fuel E100 in 2007. But mainly ethanol blends are used in daily life. E10 (10% ethanol-90% unleaded gasoline) can be used in normal engines. But for blends beyond 10% ethanol, special engines must be used. For example, for using E85, flexible fuel vehicles (FFVs) must be used.

Advantages of using ethanol blends are various. Most important issue in this point is environment. By some researches, some facts are shown useful of ethanol: Ethanol blends reduce carbon monoxide emissions in vehicles by between 10%-30%. The American Lung Association of Metropolitan Chicago states ethanol-blended fuel has reduced smog-forming emissions by 25% since 1990. The use of E10 reduces greenhouse gas emissions by 12-19% compared to conventional gasoline. Ethanol contains 35% of oxygen, making it burn more cleanly and completely than gasoline. E85 has the highest oxygen content of any fuel available and also contains 80% fewer gum-forming compounds than gasoline. Ethanol is highly biodegradable, making it safer for the environment. Furthermore, ethanol is considered renewable because it is produced from plants. With increasing usage of plant cellulose and other plants such as grasses, this point becomes more important. Moreover, using ethanol has economy and job creation benefits. It also brings development of agriculture, farmers and rural communities. As a final word, if ethanol is used as a gasoline additive, it is not as poisonous as MBTE and lead; is a soluble deposit-controler and is an anti-icer.

On the other hand, some features of ethanol aren’t beneficial. Aldehyde, a function of ethanol volume, is a threat to nose, eyes, throat and possibly causes cancer. E85 costs 33% more to consumer’s annual budget. Ethanol blends are not available everywhere, only in certain stations. Moreover, ethanol prices at the pump are a function of percentage of ethanol in the blend. Also driving ability of ethanol is lower: It has lower per liter energy value; it takes more to drive the same distance and consumers have to fill their cars more often. Consumers who are driving regular cars have to pay at least $1200 US to have their engines adapted and have to drive extra distances to special gas stations to buy ethanol. Furthermore, ethanol can absorb water and if water enters the fuel tank, it dilutes ethanol and causes problem with corrosion and phase separation. Also, ethanol absorbs and carries dirt and is highly flammable, so requires more attention.

In 26th October 2007, ethanol price is $1,768 per gallon in US markets. In USA, E85 is priced to be competitive with 87-octane gasoline. But in the future, by the help of increasing producing cellulose, the prices will be hoped to reduce.

In conclusion, ethanol has become more important day by day. With invents of new methods of producing and using ethanol as a fuel, in the future ethanol will become a major fuel, alternative to gasoline.

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