Research from the U.S. Department of Energy’s National Transportation Research Center at Oak Ridge National Laboratory (ORNL) helped clear the way for gasoline with 15% ethanol, or E15, to enter the marketplace. As ethanol use expands across the nation, the impact of the 2011 study continues to fuel consumer savings, support farmers and boost American energy independence.
Why it matters:
Drivers look for lower-cost fuel options, and E15 typically costs about 7.5% less per gallon than regular unleaded. Ethanol, primarily made of corn, is made in the United States and the nation leads the world in producing and exporting the fuel blend.
For years, the U.S. Environmental Protection Agency (EPA) capped ethanol blends in gasoline at 10%. However, the research conducted at ORNL was crucial in the EPA’s landmark 2011 decision to break the “blend wall” and raise the limit to 15% for light-duty vehicles from model year 2001 and beyond.
Real-world impact:
As of 2023, E15 was available at 3,400 fuel stations across 33 states. In 2023 alone, Americans bought 1.1 billion gallons of this affordable, domestic blend. And in 2025, the EPA issued another emergency waiver to ensure continued summer availability, keeping fuel choices open and prices down.
The benefits:
- Expands access to lower-cost fuel, giving more options at the pump
- Supports U.S. farmers and ethanol producers
- Offers a domestic energy alternative to foreign oil
- Works in 2001-and-newer vehicles with no modification
- Grounded in rigorous, real-world testing
The innovation:
Over the course of 24 months, ORNL engineers drove 86 vehicles a combined 6 million miles — the equivalent of 12 round trips to the moon. The goal was to age their emissions control systems while fueling them with ethanol blends up to 20%. They ran more than 1,000 emission tests to evaluate the impacts of ethanol blends on tailpipe emissions. Their findings helped clear the way for E15 fuel sales nationwide.
This study answered key questions about E15’s performance, safety, and compatibility, which helped the EPA move forward with approval. Researchers found that:
- 15% ethanol is not harmful to vehicle emissions control systems
- E15 is safe, effective, and vehicle-compatible
Backed by science:
The study was led by ORNL and the National Renewable Energy Laboratory. Research was conducted at the National Transportation Research Center at ORNL.
- Informed major EPA policy decisions
- Enabled expansion of consumer choice and domestic fuel access
Deep dive:
Read more about how ORNL’s research delivers innovation to the U.S. transportation fuel market and enables wider access to lower-cost energy solutions.
The big picture:
ORNL’s science-driven fuel and transportation research opens doors for reliable, affordable and American-made fuel options at the pump.