Ultra Low Sulfur Diesel
Ultra Low Sulfur Diesel (ULSD) is defined as diesel fuel with 15 parts per million (ppm) or lower sulfur content. As of December, 2006, almost all of the petroleum-based diesel fuel available in Europe and North America is of a ULSD type replacing LSD diesel.
Lower sulfur content is expected to substantially lower emissions from diesel engines. Petroleum-based ULSD is not considered an alternative fuel under the Energy Policy Act of 1992 (EPAct), but most ULSD fuels produced from non-petroleum and renewable sources are considered EPAct alternative fuels.