In recent years, ethanol replaced MTBE for the oxygenation of conventional fuel.
MTBE = methyl tertiary-butyl ether
MTBE is now banned from use in gasoline in the USA,
due to studies that revealed it causes groundwater contamination and cancer,
primarily due to leakage from underground storage tanks.
Several countries outside the U.S.A. still continue to use MTBE in gasoline.
The problem with replacing MTBE with ethanol, is that unlike MTBE ethanol has a greater ability to attract and absorb large amounts of water & moisture into the fuel. (MTBE is also soluble in water, but less so than ethanol).
Methanol is not the same as MTBE.
MTBE is manufactured by a chemical reaction that joins methanol and isobutylene.
Methanol is derived from natural gas, and isobutylene is made from crude oil or natural gas.
Methanol (wood alcohol) is not a desireable engine fuel because it is very corrosive, including to some metals such as aluminum.
MTBE has been used in U.S. gasoline at low levels since 1979 to replace lead as an octane enhancer (helps prevent the engine from knocking).
Since 1992, MTBE has also been used to meet the oxygenate requirements set by the Clean Air Act Amendment (1990).
In 2003, California was the first state to start replacing the MTBE with ethanol. Several other states started switching soon afterward.
Ethanol replacing MTBE also has dramatically changed the shelf life of fuel - Fuel that did not contain ethanol had a shelf life of several years; Unlike ethanol-blend fuels which remain stable for a maximum of only 90-100 days.
Test results on ethanol blend fuel shelf life were performed under ideal conditions (70 % humidity, properly sealed fuel system, lack of presence of rain/snow, etc.) - Therefore it is safe to assume that the shelf life and stability of fuels containing ethanol is much shorter than 90-100 days.
Gasoline is a refined product of petroleum crude oil, consisting of a mixture of hydrocarbons, additives, blending agents, dyes and more. Depending on the blend of gasoline, this mixture usually contains between 150 - 1000 different compounds. View gasoline composition and example - MSDS of Hess brand gas.
MTBE is no longer allowed in gasoline dispensed at public gas pumps.
MTBE may still be found in the USA in gasoline additives and specialty racing fuels.
The heating value (energy) of MTBE is higher than ethanol, but less than petroleum gasoline.
The autoignition temperature of MTBE is higher than both ethanol and petroleum gasoline.
View chart of properties of all fuels at http://www.afdc.energy.gov/afdc/pdfs/fueltable.pdf
Currently ethanol and ETBE are the only gasoline additives used in the U.S.A. to oxygenate gasoline to decrease pollution and emissions.
The recent E10 ethanol surge is not likely due to replacing MTBE for oxygenating gas,
since MTBE was only added to oxygenate fuel in targeted high ozone/pollution cities.
The recent E10 ethanol boom is more likely due to some false notion that it will dramatically decrease our dependence on foreign oil imports, leading to energy independence in the U.S.A.
Renewable and Alternative fuels such as E85 would decrease petroleum dependency. But E10 will not since E10 reduces gas mileage by 2 to 20% in most vehicles.
Newer vehicles in excellent condition have the lowest drop in mpg, usually below 3%.
Some may argue that due to our current failing economy, with fewer people replacing and servicing their older automobiles, those which expereince the highest drop in mpg (10 to 20%), E10 may INCREASE our petroleum oil consumption.
Despite all the controversey surrounding ethanol,
we can not place the blame on U.S. ban of MTBE,
as primary reason E10 is now being sold everywhere.