Iowa Central Community College and Decker Truck Line, Inc, Renewable Energy Group, Caterpillar Engine Company, the Iowa Soybean Association, the National Biodiesel Board, and the U. S. Department of Agriculture all joined together for an extensive study of the long term effects of B20 biodiesel in big trucks over a two year period.
The study consists of a control group with 10 units and a matching B20 test group, for a total of 20 units (Table 1). All units have a Peterbilt chassis with C-13 Caterpillar engines (2006 model) and 9-speed transmissions. The control and test group each contain one unit with an engine that complies with the new 2007 emissions requirements. All units are running with flatbed trailers on matched routes to either Minneapolis or Chicago. The control group uses 100% #2 petroleum diesel whereas the B20 test group uses a blend of 20% soy biodiesel with 80% #2 petroleum diesel. Data is routinely collected and analyzed for fuel efficiency, maintenance records, and fuel quality. At the conclusion of the study, it is anticipated that several control and test engines will be dismantled and analyzed for engine wear.
Over the first year of driving only a statistically insignificant reduction in fuel efficiency was noticed between the test group and the control. In fact the difference between the two groups of trucks was less than the difference between individual drivers within each group. Theoretically biodiesel contains slightly less energy than petroleum diesel so a very slight difference would be expected in a test like this.
But while mileage is important a trucking company also has to figure in maintenance costs. The biodiesel powered trucks required routine maintenance only slightly more often than the traditionally powered vehicles; the most significant increase was the number of fuel filters needing to be replaced during the winter months. The increase in fuel filters was reduced by the introduction of new blending methods later in the year. Most importantly, the oil analysis showed no increase in trace metals which could indicate more severe problems.
So after the first year of testing things look hopeful. The reduction in efficiency was insignificant and the increased maintenance will likely be greatly reduced by better blending techniques that are being tested over this winter. Tests are scheduled to conclude in October 2008.
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