Research sponsored by the American Transportation Research Institute found that contrary to expectations, ultra-low-sulfur diesel fuel does not have lower energy levels.

The process used to remove sulfur from on-road diesel fuel was expected to reduce the amount of energy in the fuel. The U.S. Environmental Protection Agency anticipated an energy loss of as much as 1.5 percent to result from refining fuel to meet the new ultra-low sulfur diesel (ULSD) fuel standard.

But ATRI's fuel sample analysis found that, contrary to EPA's anticipation of an energy loss, the mean energy content of the ULSD samples was slightly higher than the same location non-ULSD samples.

However, the energy content did vary across the country. A per-gallon energy content variation of 2.2 percent was found among all ULSD samples collected in 2007. This "across country" variation in the energy content of ULSD was greater than the variation found when comparing same location ULSD to the prior year samples.

It was also determined through the laboratory analysis that ULSD's emission outputs were equivalent to several state "boutique" fuel samples that were included in the comparative research.

This study collected diesel fuel samples from multiple trucking fleet locations throughout the United States. Fuel samples were collected at the same on-site or primary fueling locations prior to and after implementation of the federal ULSD standard. A total of 15 diesel fuel samples were collected from each location during April - June 2006 and again during May - June 2007.

As expected, dramatic reductions in the sulfur content of on-road diesel fuel were found, with the sulfur content of all ULSD samples being below 10 ppm. In addition to sulfur, aromatics had the largest percentage change of all other mean fuel properties when comparing ULSD to the prior onroad diesel fuel.

A copy of the full report is available from ATRI's website by clicking here.