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Trucking study examines biodiesel efficiency
A new study underway examines the benefits of a 20%
biodiesel blend (B20) in an over-the-road trucking company. First-year results
of the study have shown that biodiesel performs similarly to diesel fuel in
"The trucking industry is by far the single largest
consumer of diesel fuel, using 38 billion gallons annually. This study
demonstrates in a real-world environment that biodiesel can be used
successfully year-round," says Grant Kimberley, director of market
development for the Iowa Soybean Association, a partner in the study.
The two-year study, called the "2 Million Mile
Haul," is believed to be the first comprehensive, publicly documented
demonstration of B20 in over-the-road trucks.
"Although we have data from only the first year of the
study, we are pleased with the results to date," says Don Heck,
coordinator of biotechnology and biofuels programs at Iowa Central Community
College in Fort Dodge, Iowa. "Preliminary results are that B20 biodiesel
performs similarly to 100 percent diesel. We found a slight decrease in overall
fuel efficiency for the B20 group of trucks, but it was not statistically
significant. In fact, the difference was several times smaller than the
driver-to-driver variability in fuel efficiency within each group."
The study also examines the effects of various fuel
additives on the cold-flow properties of biodiesel blended with the new 2007
Ultra-Low Sulfur Diesel (ULSD), focusing primarily on the cloud, plug and pour
Logging the miles
The study consists of two groups of 10 Decker Truck Line
Inc. semi tractors running with flatbed trailers on matched routes to either
Minneapolis or Chicago. The control group uses 100% No. 2 petroleum diesel. The
B20 test group uses a blend of 20% biodiesel from Renewable Energy Group, Inc.
and 80% No. 2 petroleum diesel. Data is routinely analyzed for fuel efficiency,
maintenance records and fuel quality.
More than 1.5 million miles had been logged by the end of
the first year leading up to October 1, 2007. Overall fuel efficiency,
including idle time, was slightly reduced in the B20 group. Average fuel
consumption for the control group was 6.29 miles per gallon (mpg) and for the
B20 group it was 6.15 mpg. The fuel efficiency difference of 2.2% between
groups is not considered significant, especially when compared to driver
Driver fuel efficiency ranged from 5.72 mpg to 7.40 mpg for
the control group, a 23% spread. For the B20 group, fuel efficiency ranged from
5.76 mpg to 7.00 mpg, an 18% spread among drivers.
Winter driving resulted in relatively few problems regarding
cold-flow issues. Fuel for both groups was treated with a commercial fuel
additive, and No. 1 diesel, a 40% blend, was used for a brief time during a
severe cold snap in February 2007. No drivers experienced fuel gelling
Other study notes
Early in the study, a few filter plugging problems occurred
in trucks using the B20 blend. After changes were made in blending of the
biodiesel fuel in early February 2007, the rate of filter plugging for the B20
group dropped significantly.
"We are continuing to investigate the causes of filter
plugging that occurred last winter. The problem could be from improper blending
techniques that have been remedied, or an interaction between biodiesel and the
waxy particulates in new ULSD, or some combination of those factors," says
Heck. "Right now, the B20 performs similarly to the 100% diesel fuel in
He notes that many people have told him anecdotally that
biodiesel has increased their mileage and that may be the result of
"cleaning out" an older engine.
"Oil test data shows no appreciable differences between
the fuels. We expect that the B20 group of engines will show less wear than the
control group," says Heck. At the conclusion of the study, engines from
both the control group and B20 group will be torn down for a closer analysis of