The Battle Over E15 and What It Means for Your Gas Tank

November 11, 2010

There's a new fight raging in Washington. It pits food producers, oil companies and automakers against farmers and renewable energy advocates. It's over the EPA's recent finding that gasoline containing up to 15% ethanol (E15) is not harmful to cars made in model year 2007 or later.

Until now, regular gas could only contain up to 10% ethanol, but the new finding supports a waiver to increase the allowable amount of ethanol in gasoline to 15%. A change in the amount of ethanol in gas would have an impact on almost every driver in America.

So what does this decision mean to you? Some answers to your questions:

Is there more ethanol in the gas I buy now?
Maybe, but you would know if there was. Because the waiver only applies to vehicles built in 2007 or later, all gas stations must clearly mark pumps dispensing gas containing more than 10% ethanol. In fact, proposed regulations would forbid vehicles not covered by the waiver from using E15, so gas stations would need to provide E10 to serve customers with pre-2007 vehicles.

Will the higher amount of ethanol harm my vehicle?
This is the million-dollar question. The EPA declares that it won't harm vehicles built in 2007 or later, but a coalition of food trade associations and oil companies have a lawsuit pending to challenge that claim. The jury is still out on cars built before 2007. If you have a choice between E10 and E15, check your car's owners manual before choosing the higher level of ethanol. If you have a “flex-fuel” car, that means it can handle gas with up to 85% ethanol, so a switch from E10 to E15 should cause no harm.

What kinds of damage can ethanol do to a car?
When used in concentrations higher than a given vehicle can handle, ethanol can corrode metal and damage plastic and rubber parts it comes in contact with. It can lead to water contamination and phase separation (where the ethanol and water in the gasoline separate and sink to the bottom of the tank).

Will ethanol cause my car to be less fuel-efficient?
Ethanol has a lower energy content than regular gasoline, so it will make a car less efficient. Both the EPA and the American Coalition for Ethanol report that cars are typically one to three percent less efficient on existing ethanol blends than on pure gasoline. There are no solid numbers yet on E15, but logic dictates its effect on fuel economy would be slightly greater.

Why is there ethanol in gasoline to begin with?
In the early 1990s the government began to require the use of oxygenates in gasoline in certain parts of the country to reduce vehicle emissions. At first, the most popular substance used to meet this requirement was methyl-tert-butyl ether (MTBE). However, when localities started finding MTBE in their water supplies, it fell out of favor and ethanol became the new additive of choice to meet the oxygenate requirement.

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