The Environmental Protection Agency (EPA) is committed to reducing emissions from the more than 11 million diesel engines that make up the “legacy fleet.” As part of this commitment, EPA initiated a Clean Diesel Program.
The Clean Diesel Program focuses on several voluntary reduction efforts regarding diesel vehicles and engines. These programs include the Clean School Bus USA Program, the Voluntary Diesel Retrofit Program, and the SmartWay Transport Partnership. In addition to these voluntary measures, EPA is also utilizing regulatory strategies to reduce diesel emissions. On the regulatory side, EPA has developed stringent new standards for diesel fuel and new diesel engines, the 2007 Diesel Rule and the Nonroad Diesel Rule. According to EPA’s own website, “these standards are the critical foundation of EPA’s diesel control program.”
The 2007 Heavy Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements (commonly called “the ‘07 Diesel Rule” or “the 2007 Highway Rule”) establishes a single comprehensive national program to regulate heavy-duty diesel vehicles and fuels. The new sulfur standards for highway diesel fuel begin to take effect in 2006. The new emissions standards for heavy-duty vehicles take effect in 2007.
The phase-in of the fuel standards began on June 1, 2006 when refiners started producing diesel fuel with sulfur levels of only 15 parts per million (ppm) for use in highway vehicles. This represents a 97 percent reduction in the sulfur content of highway diesel fuel from its previous level of 500 parts per million. This ultra low sulfur diesel (ULSD) will be required at all pumps on October 15, 2006. The use of ULSD is necessary for diesel retrofit technologies, such as diesel particulate filters (DPF), to function correctly.
The engine standards for oxides of nitrogen (NOx) and non-methane hydrocarbons (NMHC) will be phased in from model year (MY) 2007 to 2010 on a percentage-of-sales basis. Fifty percent of all engines sold will need to meet the requirements from 2007 to 2009, with 100% compliance by 2010. Emission standards for particulate matter (PM) will take full effect with MY 2007 engines.
Additional Information on the ‘07 Diesel Rule:
EPA information on Heavy-Duty Highway Diesel
Congressional Research Service: “Diesel Fuel and Engines: An Analysis of EPA's New Regulations”
EPA estimates that the Nonroad Diesel Rule will reduce emissions from nonroad engines and equipment by more than 90%. Nonroad diesel engines and equipment currently account for nearly 50% of the diesel particulate matter (PM) and 25% of nitrogen oxides (NOx) from mobile sources in the US. EPA further estimates that the emission reductions due to this rulemaking will be the equivalent of removing two million trucks from use.
The fuel standards will begin to phase-in during 2007 by requiring diesel fuel sulfur levels to be cut to 500 parts per million (ppm). In 2010 the standard drops to 15ppm. The sulfur reduction is necessitated by sulfur’s destructive qualities on the catalyst in the emissions control equipment. Currently, diesel fuel may contain as much as 3,000 parts per million (ppm) of sulfur. These cuts will make it possible for manufacturers to introduce advanced engine technologies.
The engine standards will begin to phase-in during 2008 for the smallest engines. Larger engines will have until 2014 to meet the emission standard, with one additional year being granted to engines with a horsepower of 750 or greater. In order to meet the new standards, engine manufacturers will be required to produce new engines with advanced emission control technologies, similar to those expected for highway trucks and buses by the 07 Diesel Rule.
Additional Information on the Nonroad Rule:
EPA information on Nonroad Engines, Equipment and Vehicles