At the halfway point of a two-year study, a road test of biodiesel performance is working well despite a few exceptions.
The “Two Million Mile Haul” is a joint venture of the Iowa Central Community College, Decker Truck Line of Fort Dodge, IA, and interested partners including the National Biodiesel Board and the U.S. Department of Agriculture.
Decker put a control group of 10 trucks running on pure petroleum diesel against 10 trucks running on B20, a blend of 80 percent petroleum diesel and 20 percent biodiesel derived from soy.
The goal of the study is to see how biodiesel performs compared to petroleum diesel, and the interim summary is mostly positive.
Trucks running on the biodiesel blend since October 2006 have gotten slightly lower fuel mileage than the control group, however. Control trucks running on pure petroleum diesel have averaged 6.29 miles per gallon, while the biodiesel trucks averaged 6.19 mpg.
Study author Donald Heck, director of biotechnology and biofuels at Iowa Central Community College, said the difference is not significant.
“Although the B20 group showed a slight decrease in mileage, the amount was not statistically significant,” Heck stated in a one-year summary. The difference of 2.2 percent, he said, could easily be accounted for with individual driver efficiency.
Filter clogging in the biodiesel trucks was also an issue at the one-year mark despite a need for further study, Heck stated.
“The only major maintenance issue so far has been a significant number of fuel filter-plugging episodes in the B20 group,” Heck stated. “This was not anticipated and most of these incidents came during the cold weather from October 2006 through April 2007.”
Heck stated that clogged filters could be attributed to factors other than the switch to a biodiesel blend.
The first few months of the “Two Million Mile Haul” coincided with the rollout of ultra-low sulfur diesel. ULSD replaced low-sulfur diesel in January 2007 as the predominant on-highway diesel fuel as part of a mandate by the Environmental Protection Agency to reduce sulfur emissions.
Heck said that ULSD may be “partially responsible for some of the plugging due to the fact that the procedure for removing sulfur also removes aromatic structures ... and increases the concentration of wax molecules.”
Other than the filter issue, winter driving and maintenance was comparable in both sets of trucks.
“Winter driving produced relatively few problems regarding cold-flow issues,” Heck’s report stated. He added that none of the drivers experienced fuel gelling.
Heck said he hopes that laboratory research will reduce the number of plugged fuel filters heading into 2008.
Overall, Heck reported that the biodiesel blend is holding up to the test, which is scheduled to be complete in October 2008.
– By David Tanner, staff writer