• Apr 11, 2011
When gassing up your vehicle, you've likely noticed a sticker on the pump that reads "this fuel may contain up to ten percent ethanol" or something similar. Have you ever asked yourself, "what's up with this ethanol in gasoline?" Well, get ready 'cause we've dug up an answer.

Way back in 1992, the U.S. government amended the Clean Air Act to include the requirement of oxygenated gasoline, which means a minimum oxygen content of two percent (by weight) for reformulated gas. One of the oxygenates used back then was methyl tert-butyl ether (MTBE). In 1995, California discovered that trace amounts of the dangerous MTBE was contaminating drinking water. Ethanol (a biofuel commonly derived from corn), which was thought to be safer than MTBE, was considered as a replacement oxygenate and, with strong backing from the agricultural industry here in the States, the biofuel slowly took over.

So, now that we know why most gasoline has some ethanol in it. The next logical question is: do you need to worry? The answer is a qualified no. Modern cars and trucks can capably burn E10 (a blend of 10 percent ethanol and 90 percent gasoline) and some automobiles should not have any problems running E15, a gasoline blend that will likely start to appear at fueling depots across the nation this summer. There is still a debate going on about E15, but any pump carrying that fuel should be clearly labeled. For more on ethanol, check out this Greenlings article in our archives.

Note: To mark the 41st anniversary of Earth Day* this year on April 22nd, we're running a series called Countdown to Earth Day that we want to be very welcoming to new readers, both in topic and tone. We'll be returning to our Greenlings series for inspiration here, and if you have friends who you'd like to introduce to AutoblogGreen, perhaps these introductory posts and the coming "holiday" will be the spark to light their green car fire interest.

[Image: futureatlas.com - C.C. License 2.0]

*Ironically, the apparent traditional gift for a 41st anniversary is land. Since land – earth – is something we can't easily create, how about we give ourselves the gift of stewardship of the land this Earth Day.


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