Final report on intermediate ethanol blends research published

Mileage accumulation dynamometers at subcontractor facilities were used to “age” many of the vehicles being researched. Program research was co-sponsored by DOE’s Vehicle Technologies and Biomass Programs.

ORNL published a final report on the Intermediate Blends Catalyst Durability Study in February 2012. The two-year program, led by researchers from the Fuels, Engines, and Emissions Research Center, involved driving 82 vehicles over 6 million miles with periodic emissions tests to evaluate the effects of ethanol blends (E10, E15, and E20) on emissions control system durability. The program was closely monitored by DOE, the Environmental Protection Agency, and industry, and garnered the attention of Congress, the Secretary of Energy, and the EPA Administrator.

Statistical analysis of the data showed that aging vehicles produced increased emissions. However, aging vehicles fueled by ethanol blends showed no differential effect over those fueled by ethanol-free gasoline. Immediate effects of ethanol were consistent with prior studies: addition of ethanol to certification gasoline decreased carbon monoxide, nonmethane hydrocarbons, and fuel economy, while increasing nitrogen oxides, ethanol, and aldehyde emissions.

The study results were the basis of the recent EPA rulings on the Growth Energy E15 waiver. EPA described the study as unprecedented in size and scope when they cited the E0 and E15 data in granting partial approval of the Growth Energy waiver, allowing E15 use in 2001 and newer light-duty vehicles. The report’s analysis also addresses the emissions impacts of E20; intermediate blends (E15 and E20) were not found to contribute to more rapid emissions control system degradation compared with ethanol-free gasoline.

Reference: ORNL. 2012. Intermediate Ethanol Blends Catalyst Durability Program report, ORNL/TM-2011/234,


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