More miles per BTU -- or more miles per unit of energy. That's what you get with higher ethanol blends, according to a University of Nebraska study released yesterday by the Nebraska Corn Board. The Nebraska Corn Board funded the study.More miles on less energy means higher ethanol blends provide better energy conversion (improved efficiency) in engines.
“What this suggests is that the increased efficiency of ethanol has a more positive impact as a replacement for petroleum fuel than what it is commonly given credit for,” said Randy Klein, director of market development for the Nebraska Corn Board, in a news release.
“It also suggests that e85, which contains 85 percent ethanol and only 15 percent petroleum-based gasoline, may be the most efficient and often the most cost-effective fuel for flex fuel vehicles,” he said. “Since e85 is also the cleanest fuel on the market and contains so little petroleum-based gasoline, it has a very positive impact on the environment and can significantly reduce our use of foreign oil.”
You can download the full report here (.pdf).
The report said e85 improved energy conversion by 13, 9 and 14 percent, respectively when compared to e10, for the light, medium and heavy loaded vehicles tested.
(Click on the chart to see the results, showing that as ethanol content of the fuel increased from e10 to e20, e30 and e85, the energy conversion within the engine increased as well.)
The researchers acknowledged that higher ethanol blends like e85 have a lower energy density, or fewer BTUs per gallon, than e10. That often leads to fewer miles per gallon for higher ethanol blends, but that gets partly offset by ethanol’s improved efficiency.
“While fewer BTUs typically means fewer miles per gallon, energy density is only part of the equation when considering fuel economy,” said Loren Isom, one of the researchers in the study.
“Fuel economy is actually a combination of fuel efficiency and fuel price, and on that point, higher ethanol blends may be the better choice,” said Isom, who is with the University of Nebraska’s Industrial Agricultural Products Center. “It just depends on fuel prices at the time. Specific vehicles may test out differently based on engine design and settings, but increased efficiency from ethanol blends make sense, and for the fuel prices we looked at in the study, e85 was the best choice every time.”
In addition to Isom, the study was conducted by the University of Nebraska’s Dr. Milford Hanna and Robert Weber. While the Nebraska Corn Board funded the project, additional support was provided by the State of Nebraska Transportation Services Bureau, which provided the flex fuel vehicles used in the tests, and The Shop Inc., where the tests were conducted.
The photo at the top of this post shows one of the cars being tested on the chassis dynamometer at The Shop Inc. in Lincoln.
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