On May 31 of this year, Administrator Andrew Wheeler of the U.S. Environmental Protection Agency (EPA) signed the final action to remove a key regulatory barrier to using E15 fuel during the summer months. This action was part of steps taken by the EPA to follow through on President Trump’s commitment to responsible environmental protection that promotes energy independence, regulatory reform, and increasing the use of biofuels to give consumer more choices and to support American farmers.
What is E10 and E15 fuel?
E10 fuel is a blend of 90% gasoline and 10% ethanol. E15 fuel is a blend of 85% gasoline with 10.5% to 15% ethanol. Ethanol is renewable fuel made from various plant materials. In the United States, 95% of ethanol is produced from corn.
In 1990, Congress amended the Clean Air Act to allow E10 fuel to be used in light-duty vehicles.
In 2010 and 2011 the EPA approved two waivers to the Clean Air Act that ultimately allowed E15 fuel to be used in model year 2001 and newer light-duty motor vehicles, subject to certain limitations. By approving these waivers, the EPA was certifying that vehicles using E15 would continue to meet emission standards over their “full useful life” and thus meet criteria under the Clean Air Act.
So why has E15 fuel been restricted?
Well, there was an issue with the Reid Vapor Pressure (EVP) of ethanol fuels. EVP is essentially the amount of pressure (psi) coming from fuel vapors at 100 degrees Fahrenheit. The higher an EVP is, the worse the emissions from using the fuel are. Currently, the EPA restricts using fuels with more than 9 psi. Pure ethanol has a EVP of 2 psi. E10 fuel has a psi of 10, which exceeds that limitation.
Thus, E10 was originally restricted from sale during the summer months, until 1990 when Congress amended the Clean Air Act to allow a “one pound waiver” so E10 could be sold all year long. Since this waiver was provided, most fuel sold in the United States is now E10.
But back in 1990 E15 didn’t exist, and so wasn’t included in the waiver. Because it is not economically feasible for gas stations to go through the process to change from E15 to E10 during summer months, only about 1% of stations across the U.S. have carried E15 fuel.
With a higher percentage of ethanol than E10, E15 has a better psi than E10, so its continued restriction during summer months has been a technicality.
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