A new study indicates that higher ethanol blends in gasoline might be optimal for better fuel mileage. Funded by the American Coalition for Ethanol and the U.S. DOE, the study found that ethanol blends between 20 percent and 30 percent, and possibly as high as 45 percent, will yield a higher fuel economy than revealed in the past.

The study was conducted by the Minnesota Center for Automotive Research in Mankato, Minn., and the University of North Dakota Energy & Environmental Research Center in Grand Forks, N.D. Four ethanol companies—VeraSun Energy Corp., Poet LLC, Fagen Inc. and ICM Inc.—contributed to ACE's share of the funding.

ACE has heralded the results as revolutionary, especially in light of a fivefold increase in ethanol use mandated in the Energy Independence and Security Act of 2007 (see page 66). Ron Lamberty, ACE vice president of marketing development, called the study "groundbreaking."

Meanwhile, EERC chemist Ted Aulich is more reticent. Aulich, process chemistry research manager, said much more research is warranted before such conclusions can be drawn. The study appears to debunk popular assumptions that ethanol's lower energy content corresponds with lower gas mileage. However, it also supports the industry's push for blender pumps across the country. "We need to put this in perspective," Aulich cautioned. "We don't want to oversell this small, small study."

Four 2007 model vehicles—three nonflexible-fuel cars and one flexible-fuel car—were road- and laboratory-tested: a Toyota Camry, a Ford Fusion and two Chevrolet Impalas. One Impala was the flex-fuel vehicle.

Researchers started with regular gasoline and performed nine separate tests, increasing the ethanol blend at 10 percent increments up to E85. Vehicle speeds ranged from 0 to 60 mph, with an average speed around 20 mph. Scientists noted the point at which each vehicle engine experienced a "fault code"—when the vehicle detected either an ethanol or oxygen level that wasn't operable. Each test was conducted in triplicate for verification purposes.

The vehicles had varying responses to the test blends of ethanol compared with gasoline. "It's conceivable that [the results] are vehicle-specific," Aulich said. "The optimal blend could vary from vehicle to vehicle."

The Toyota and Ford operated best with an E30 blend, while the flex-fuel Impala gained 15 percent over its standard fuel economy with an E20 blend. Unexpectedly, the nonflex-fuel Impala's optimal blend appeared to be E40. "Some of the results surprised us," Lamberty said. "The study shows that the correlation between [British thermal units] and mileage is a myth." Fuel economy had previously been based on the per-gallon Btu content.

A secondary aspect of the study concluded that vehicle emissions weren't significantly impacted by the increased amount of ethanol.
Both Lamberty and Aulich said they hope the DOE and U.S. EPA will continue the testing methodology on a larger scale in hopes of sanctioning the use of mid-range ethanol blends. "From an energy security standpoint, the study might be used to decrease our dependence on foreign oil," Aulich said.