The University of California, Riverside has just released a peer-reviewed study that shows E15 ethanol blends provide notable emissions reductions compared to California’s regular reformulated gasoline.

According to the study, emissions of total hydrocarbons, non-methane hydrocarbons, and carbon monoxide all showed either marginally or statistically significant reductions for E15 compared to regular California gasoline. In addition, particulate matter (PM) and solid particle number emissions dropped substantially with E15, and E15 showed lifecycle greenhouse gas emissions savings when compared to E10. Nitrogen oxide (NOx) emissions when using E15 showed marginal reductions in many cases, but the changes in NOx were not statistically significant.

Renewable Fuels Association President and CEO Geoff Cooper says the report is proof of the value of E15 for The Golden State, which is one of only two states yet to allow the E15 blend to be used. “This new study shows what we’ve been arguing all along—that E15 offers emissions benefits that would help meet environmental goals in California, where the state’s 27 million drivers log more than 340 billion miles a year on the road,” RFA President and CEO Geoff Cooper said. “We continue to call on California’s regulators to move quickly to permit E15 to be sold in the state, a blend that also offers cost savings in a place where gasoline prices are higher than anywhere else in the country.”

Montana is the other state that has not yet approved E15. The research will appear in the October 2023 journal Fuel, and was supported by RFA, the California Air Resources Board and other organizations.