Research Collaboration

The Decker Study
The nationwide plea for alternative fuels has prompted Iowa Central Community College to position itself as the leader in providing highly skilled workers for the rapidly growing ethanol and biodiesel industries. The Biofuels Technology degree will provide students with the skills necessary to perform biofuels process operations, and to perform quality assurance analyses in accordance with the American Society for Testing and Manufacturing (ASTM). To offer this program we have assembled a biofuels testing laboratory which, according to Steve Howell, NBB Technical Director and Chair of the ASTM Biodiesel Task Force, “is the best equipped biodiesel laboratory I have seen at a community college.” This high tech laboratory has presented the College with a unique opportunity to partner with Decker Truck Line Inc. (a local trucking company), Caterpillar Inc., the Iowa Soybean Association, the National Biodiesel Board, and the USDA to participate in a field documentation study dubbed the “Two Million Mile Haul”. This is the first-ever comprehensive study to examine the benefits of a 20% soy biodiesel blend (B20) in an over-the-road trucking company. Iowa Central is responsible for the collection and analysis of engine performance data as well as periodic in-house testing of the petroleum and B20 blend fuels for purity and consistency. Additionally, we are studying the effects of various fuel additives on the cold-flow properties of biodiesel blended with the new 2007 Ultra-Low Sulfur Diesel (ULSD). These studies are focusing primarily on the cloud, plug and pour points. This project gives our students an opportunity to participate in an actual research project that has a direct application to what they are studying, thus contributing significantly to the quality of their educational experience.

Summary of Results
As of April 2007, we have logged over half a million miles in the study using 10 trucks in the control group (100% #2 petroleum diesel) and 9 trucks in the B20 test group (20% biodiesel, 80% petroleum diesel). We have found a slight decrease in fuel efficiency in the B20 group through the winter driving season (Figure 1). Average fuel consumption for the control group was 6.01 miles per gallon (mpg) while average consumption for the B20 group was 5.80 mpg, or a 3.5% reduction. This value is not statistically significant (p = 0.125). In fact, we have found that driver-to-driver variability in fuel consumption within each group is 2 to 3 times greater than the 3.5% overall difference in fuel consumption between the two groups (Figure 2).


Figure 1. Average fuel efficiency for petroleum and B20 trucks.

Figure 2. Fuel efficiency by driver in petroleum and B20 trucks.

Winter driving produced relatively few problems regarding cold-flow issues. Fuel for both groups was treated with a commercial fuel additive, and #1 diesel (40% blend) was used for a brief time during a severe cold snap. No drivers experienced fuel gelling problems, however we did experience a couple episodes of fuel filter plugging. The residue plugging the filters was an off-white substance that had the consistency of petroleum jelly and a melting point of approximately 150 to 160 degrees F (data not shown). This substance was analyzed with gas chromatography using the method outlined in ASTM D6584-00 (Test Method for Determination of Free and Total Glycerine in B-100 Biodiesel Methyl Esters by Gas Chromatography, ASTM International, West Conshohocken, PA, 2005). GC analysis of the substance revealed a mixture consisting of the B20 blend and several unidentified, higher molecular mass compounds with retention times between 14 and 20 minutes on the column (Figure 3). We do not believe these are contaminants from the biodiesel transesterification procedure or from the petroleum diesel itself, as these compounds were not present in the B100 soy biodiesel or the B20 blend created with it (Figures 4 and 5). From anecdotal evidence, we believe we may be observing a phenomenon resulting from the inherently different physical and chemical properties of the new 2007 ULSD fuel and how it interacts with biodiesel, especially relating to cold weather conditions. We are continuing to investigate this in the laboratory.


Figure 3. GC analysis of solid residue from plugged fuel filter.


Figure 4. GC analysis of soy methyl esters (B100)


Figure 5. GC analysis of B20 blended fuel.



We feel that the first quarter of the study has been a success. We found no significant difference in fuel consumption between the two groups, and we were able to get through the winter driving season without any major complications. We also found that the driver-to-driver variability is larger than the slight difference in fuel efficiency observed to this point, and we will need to complete an entire 4-season driving cycle before we can make any conclusions on fuel efficiency. Regarding cold-flow issues, we did not experience any fuel gelling during the cold snaps, and the plugged filters that we did experience were not related to fuel quality as outlined by ASTM D6751.