The American Transportation Research Institute (ATRI) recently initiated a research study to track what changes occur to on-road diesel fuel properties as a result of the transition to ultra low sulfur diesel (ULSD).

New U.S. Environmental Protection Agency standards require ULSD (diesel fuel with a sulfur content of no more than 15 parts per million) to be the dominant highway diesel fuel produced in the U.S. and to be available at many retail outlets by Oct. 15, 2006.
Results from the first phase of this research, which involved samples collected prior to the introduction of ULSD, indicate sulfur levels averaged 276 ppm and ranged from a high of 415 ppm to a low of 48 ppm.
While sulfur content had a low correlation to the fuel’s energy content, other fuel parameters that more closely affect energy content may be affected as sulfur is removed during the refining process. The two fuel properties with the highest correlation to energy content were density and aromatic content. Aromatic content is regulated under boutique diesel fuel standards in the states of California and Texas. Overall, the per gallon energy content of the samples varied by as much as 2.3 percent.
ATRI worked with a number of trucking companies to obtain fuel samples from on-site or primary fueling locations this past April and May.
The next step in this research involves pulling ULSD samples next April and May from the same locations to determine what changes in fuel properties have occurred and whether these changes have an impact on energy content.
The primary focus of ATRI’s research is to determine what, if any, changes occur to the energy content of diesel fuel as a result of this transition.