What is E15 and Why Is It Important?

The technical details behind the push for year-round E15 sales in the U.S.

Published on Feb. 3, 2026

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E15 is a fuel blend containing 15% ethanol, which was first approved for use in new vehicles by the EPA in 2010 and extended to 2001 and newer vehicles in 2011. However, the Clean Air Act requires gasoline sold during the summer ozone season to meet lower Reid Vapor Pressure (RVP) standards, and E15 typically has a higher RVP than E10. This has led to a statutory problem that has prevented widespread summer sales of E15 across most of the U.S. until recent temporary waivers were issued.

Why it matters

The issue around E15 sales has been a long-standing problem that has plagued the industry for over a decade, as it is a technical issue that is difficult to explain in simple terms. Resolving the E15 summer sales restriction is important for farmers, consumers, and refiners, including small and mid-sized refiners, as it would allow for year-round nationwide sales of the fuel blend.

The details

E15 was first approved for use in new vehicles by the EPA in 2010, and extended to 2001 and newer vehicles in 2011. However, the Clean Air Act requires gasoline sold during the summer ozone season (generally June 1–September 15) to meet lower Reid Vapor Pressure (RVP) standards to reduce evaporative emissions. E15 typically has a higher RVP than E10 and therefore doesn't automatically qualify for the summer gasoline waiver that E10 enjoys, meaning E15 normally cannot be sold in most of the U.S. during summer. In 2019, the Trump administration tried to fix this by having the EPA issue a regulatory action to extend the 1-psi RVP waiver to E15 during the summer, but this was later overturned by a federal court. Since 2022, the Biden EPA has issued temporary emergency waivers to allow summer sales of E15, but a permanent legislative fix is still needed.

  • E15 was first approved for use in new vehicles by the EPA in 2010.
  • E15 was extended to 2001 and newer vehicles in 2011.
  • In 2019, the Trump administration tried to fix the summer sales issue through EPA regulation.
  • In 2022, the Biden EPA began issuing temporary emergency waivers to allow summer sales of E15.
  • The temporary waivers have been renewed multiple times each summer since 2022.

The players

President Trump

The former U.S. president who tried to address the E15 summer sales issue through EPA regulation in 2019.

President Biden

The current U.S. president whose EPA has issued temporary emergency waivers to allow summer sales of E15 since 2022.

EPA

The U.S. Environmental Protection Agency, which has played a key role in regulating and approving the use of E15 fuel.

Clean Air Act

The federal law that sets the Reid Vapor Pressure (RVP) limits for gasoline sold during the summer ozone season, creating the statutory problem around E15 sales.

E15 Rural Domestic Energy Council

A newly-formed group that is attempting to get Congress to amend the Clean Air Act and permanently resolve the E15 summer sales issue.

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What they’re saying

“I promised to support E15 all year round... I am trusting speaker Mike Johnson and Leader John Thune to find a deal that works for farmers, consumers, and refiners, including small and mid-sized refiners, to get E15 approved and they're working on it and they're very close to getting it done.”

— President Trump (agwired.com)

What’s next

The newly-formed E15 Rural Domestic Energy Council is attempting to get Congress to amend the Clean Air Act and permanently resolve the E15 summer sales issue, but the chances of this happening by the end of the month are uncertain.

The takeaway

Resolving the technical and statutory issues around E15 summer sales is an important goal for the Biden administration, Congress, and various industry stakeholders, as it would allow for year-round nationwide sales of the fuel blend and benefit farmers, consumers, and refiners.