What is ultra-low sulfur diesel?
Ultra-low sulfur diesel (ULSD) is diesel fuel with 15 parts per million (ppm) or lower sulfur content. The U.S. Environmental Protection Agency requires 80% of the highway diesel fuel refined in or imported into the United States (100% in California) to be ULSD. One hundred percent must be ULSD nationwide by 2010. Different requirements apply to non-highway diesel. Currently, the vast majority of ULSD is produced from petroleum. However, biodiesel; biomass-to-liquids, coal-to-liquids, and gas-to-liquids diesel; and hydrogenation-derived renewable diesel are inherently ultra-low sulfur fuels and could help meet ULSD requirements in the future. 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. For more information on ULSD, see the Clean Diesel Fuel Alliance.