In August 2007, the U.S. Department of Energy (DOE) initiated a test program to assess the potential impacts of higher intermediate ethanol blends on conventional vehicles and other engines that rely on gasoline. The test program focuses specifically on the effects of intermediate blends of E15 and E20-gasoline blended with 15 and 20 percent ethanol, respectively-on emissions, catalyst and engine durability, drivability or operability, and materials associated with these vehicles and engines. This DOE test program includes technical expertise from DOE's National Renewable Energy Laboratory (NREL) and Oak Ridge National Laboratory.
This preliminary report, the first in a series of peer-reviewed reports that will summarize the results of intermediate ethanol blends, provides results from testing E15 and E20 on 13 popular late-model vehicles and 28 small non-road engines, including lawn equipment and generators.
Vehicle results include the following when E15 and E20 were compared with traditional gasoline:
- Tailpipe emissions were similar;
- Under normal operations, catalyst temperatures in the 13 cars were largely unchanged;
- When tested under full-throttle conditions, about half of the cars exhibited slightly increased catalyst temperatures with E15 and E20, compared to traditional gasoline; and,
- Based on informal observations during testing, drivability was unchanged.
Small non-road engine results include the following when E15 and E20 were compared with traditional gasoline:
- As ethanol content increased:
- Regulated emissions generally stayed within allowed limits,
- Engine and exhaust temperatures increased;
- Commercial engines, as well as larger non-handheld residential engines in this limited study, exhibited no particular sensitivity to ethanol from a durability perspective; and,
- The effect of E15 and E20 on the durability of smaller, less-expensive handheld residential engines was not clear.
The full intermediate blend report is now available.
Jennifer Scoggins, (202) 586-4940