Episode 170: Why does fuel contain 10% ethanol?

pumping gas

Stephanie Seki, a recent PhD graduate of Carnegie Mellon University’s Engineering and Public Policy Department, discusses why fuel contains 10% ethanol and how it affects the quantity of imported fuel.



Learn More

Ethanol Fuel Basics by the Department of Energy’s Alternative Fuels Data Center

Renewable Fuel Standard (RFS): Overview and Issues by the Congressional Research Service

EPA Finalizes Regulations to Mitigate the Potential for Misfueling of Vehicles, Engines and Equipment with E15 by the Environmental Protection Agency


HOST: Have you ever wondered why there are signs on fuel pumps that read, “May contain up to 10% ethanol”? On this week’s Energy Bite, Stephanie Seki, a recent PhD graduate of Carnegie Mellon University, has some answers.

STEPH: The reason you see these signs at gas stations is because Congress has required that gasoline sold in the United States contain up to 10 percent ethanol. This policy aims to increase the nation’s energy security by using ethanol, a type of alcohol produced from plants. These plants are a renewable energy source grown within the United States, and thus decrease our reliance on imported energy. Ten percent was chosen because all vehicles can operate with that amount of ethanol in their gasoline.

HOST: How well has this worked to reduce the quantity of imported fuel?

STEPH: The quantity of imported petroleum fuel HAS decreased, but it is not solely because of this mandate. Rather, the reduction likely results from a decrease in fuel consumption. Even considering this, however, the nation’s drivers have not used as much ethanol as expected, as most cars cannot refuel with even higher percentages of ethanol assumed at the time of the legislation.

HOST: Do you care that your gasoline has up to 10% ethanol? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.


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