Effects of biodiesel, biodiesel blends, and a synthetic diesel on emissions from light heavy-duty diesel vehicles

Over the past several years, there has been increased interest in reformula ted and alternative diesel fuels to control emissions and provide energy in dependence. In the following study, a California diesel fuel was compared w ith neat biodiesel, an 80% California diesel/20% biodiesel blend, and a syn thetic diesel fuel to examine the effects on emissions. Chassis dynamometer tests were performed on four light heavy-duty diesel trucks using each of the four fuels. The results of this study showed that biodiesel, the biodie sel blends, and the synthetic diesel produced generally lower THC and CO em issions than California diesel. NOx emissions were comparable over most of the fuel/ vehicle combinations, with slightly higher NOx emissions found fo r the two noncatalyst vehicles on 100% biodiesel. Particulate emissions wer e slightly higher for two test vehicles and significantly higher for a thir d test vehicle on the biodiesel fuels. Chemical analyses showed elemental a nd organic carbon to be the primary constituents of the diesel particulate, accounting for 73-80% of the total mass for the four vehicles. Neat biodie sel had the highest organic carbon fractions for each of the test vehicles. PAH emissions for all fuel combinations were relatively low, probably due to the low fuel PAH levels.