Common ethanol fuel mixtures

Ethanol (ethyl alcohol) and methanol (methyl alcohol) are two types of alcohol fuels. The use of pure alcohols in internal combustion engines is only possible if the engine is designed or modified for that purpose. However, in their anhydrous or pure forms, they can be mixed with gasoline (petrol) in various ratios for use in unmodified automobile engines. Typically, only ethanol is used widely in this manner, particularly since methanol is toxic.

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E5, E7, E10

  E10, sometimes called gasohol, is a fuel mixture of 10% ethanol and 90% gasoline that can be used in the internal combustion engines of most modern automobiles. According the Philippine Department of Energy E10 is not harmful to cars' fuel systems.^[1] On October 27, 2006, though, the Federal Aviation Administration published their Special Airworthiness Information Bulletin - Automobile gasoline containing alcohol (Ethanol or Methanol) is not allowed to be used in aircraft.

It has been introduced nationwide in Denmark and Thailand, and will replace high octane pure gasoline in Thailand in 2007. It is also commonly available in the Midwestern United States. It is the only type of gasoline (besides aviation grade fuels) allowed to be sold in the states of Connecticut and Minnesota, along with E85.^{[dubious – discuss]} About half of the gasoline used in the U.S. contains ethanol. [1] As of spring of 2006, due to the phasing out of MTBE as a gasoline additive, E10 use has increased throughout the United States. [2]

Similar blends include E5 and E7. These concentrations are generally safe for recent engines that run on pure gasoline. Some regions and municipalities mandate that the locally-sold fuels contain limited amounts of ethanol. One way to measure alternative fuels in the US is the "gasoline-equivalent gallons" (GEG). In 2002, the U.S. used as fuel an amount of ethanol equal to 137 petajoules (PJ), the energy of 1.13 billion US gallons (4.28 GL) of gasoline. This was less than 1% of the total fuel used that year.^[2]

The Tesco chain of supermarkets in the UK have started selling an E5 brand of gasoline marketed as 99 RON super-unleaded. Price-wise it is cheaper than the other two forms of high-octane unleaded on the market, Shell's V-Power (99 RON) and BP's Ultimate (97 RON).

Many petrol stations throughout Australia are now also selling E10, typically at a few cents cheaper per litre than regular unleaded. It is more commonly found throughout the state of Queensland due to its large sugar cane farming regions. The use of E10 is also subsidised by the Queensland government. Some Shell service stations are also selling a 100 RON E5 blend called V-Power Racing (as opposed to the normal ethanol-free 98 RON V-Power). This is typically a fair bit more expensive, approximately 17 cents dearer than regular unleaded.

In Sweden, all 95-octane gasoline is in fact E5, while the status of the 98-octane fuel is unclear for the moment. The product data sheets of the major fuel chains do not clearly state anything related to ethanol contents of the 98-octane gasoline. In the early-mid nineties, some fuel chains marketed E10 but today the sale of E10 is prohibited due to EU legislation.^{[citation needed]}

E15

E15 contains 15% ethanol and 85% gasoline. This is generally the greatest ratio of ethanol to gas that is recommended by auto manufacturers that sell vehicles in the United States, though it is possible that many vehicles can handle higher mixtures without trouble. Flexible-fuel vehicles are designed to take higher concentrations, up to 96% v/v ethanol (and no gasoline).

E20

E20 contains 20% ethanol and 80% gasoline. Since February 2006, this is the standard ethanol-gasoline mixture sold in Brazil, where concerns with the alcohol supply resulted in a drop in the ethanol percentage, previously at 25%. Brazilian flexible-fuel cars are set up to run with gasoline in such concentration range and few will work properly with lower concentrations of ethanol.^[3][4]. U.S. FFV can run below 20% ethanol, but up to E85.

This fuel is not yet widely used in Australia or the United States. It will be mandated by the U.S. state of Minnesota by 2013. Available also in Thailand with tax reductions for "E20" engine cars.

E85

For more details on this topic, see E85.

  E85 is a mixture of 85% ethanol and 15% gasoline, and is generally the highest ethanol fuel mixture found in the United States. It is common in Sweden, and there are more than 1000 public E85 fuel pumps in the U.S. as of 2006, mostly concentrated in the Midwest, with over half of those in Minnesota.

This mixture has an octane rating of about 105. This is down significantly from pure ethanol but still much higher than normal gasoline 87 octane. The addition of a small amount of gasoline helps a conventional engine start when using this fuel under cold conditions. E85 does not always contain exactly 85% ethanol. In winter, especially in colder climates, additional gasoline is added (to facilitate cold start). E85 has traditionally been similar in cost to gasoline, but with the large oil price rises of 2005 it has become common to see E85 sold for as much as $0.70 less per gallon than gasoline, making it highly attractive to the small but growing number of motorists with cars capable of burning it.

E85 contains approximately 27% less energy per gallon than conventional gasoline, although ethanol typically burns more efficiently. This results in a fuel economy loss of less than the energy content would imply^[5].

E95

  E95 contains just 5% gasoline and is used in some diesel engines where high compression is used to ignite the fuel, as opposed to the operation of gasoline engines where spark plugs are used.

E100

E100 is ethanol with up to 4% water, which is most widely used in Brazil and Argentina. Operation in ambient temperatures below 15 °C (59 °F) causes problems with pure, or so-called neat, ethanol for starting engines. The most common cold weather solution is to add an additional small gasoline reservoir to increase the gasoline content momentarily to permit starting the engine. Once started, the engine is then switched back to neat ethanol. Ethanol used as a fuel in Brazil is the azeotrope (the highest concentration of ethanol that can be achieved via distillation) and contains 4% of water. However, since the E nomenclature is not adopted in the country, one can tag hydrated ethanol as E100 so as to say that it doesn't have gasoline. Gasoline itself is sold as E20 up to E25, in accordance with current legislation (since February 2006, the concentration ranges from 19% to 21%), but since the value is not typically disclosed by gas stations, adulterations to lower gas costs^[6] could raise the ethanol concentration up to 40% in extreme cases^{[7] [8]}.

See also

• Ethanol fuel
• Ethanol fuel in Brazil
• Ethanol fuel in the United States

References

1. ^ http://www.doe.gov.ph/AF/Bioethanol.htm
2. ^ http://www.eia.doe.gov/cneaf/alternate/page/datatables/table10.html]
3. ^ "(Portuguese) Flagrado na contramão (Renault Clio 2006)", Best Cars Web Site, February 4, 2006. 
4. ^ "(Portuguese) Fiat lança Siena 1.4 com motor tetrafuel", Jornal da Mídia, June 19, 2006. 
5. ^ http://www.ethanol.org/documents/ACEFuelEconomyStudy.pdf
6. ^ {{ cite news Some cars made by the car manufacturer, Ford, have a "FlexFuel" logo on the back, to show that the car should run on cars with an amount of ethanol in the gasoline it uses. |url=http://oglobo.globo.com/petroleo/materias/2006/06/27/284450274.asp |publisher=Globo online |title=(Portuguese) Pesquisa mostra aumento de adulteração de gasolina no Rio |date=June 27, 2006 }}
7. ^ "(Portuguese) Blitz flagra combustível ‘batizado’", Diário do Grande ABC, June 29, 2006. 
8. ^ "(Portuguese) Cinco em cada dez postos de SP podem adulterar gasolina", estadao.com.br, June 2, 2006.