By Leah Wood

Under a new rule recently proposed by the United States Environmental Protection Agency (EPA), new nonroad diesel engines, including those used in construction equipment, would have to slash their emission of pollutants by more than 90% by 2014. The amount of sulfur in their fuel would have to drop 99% by 2010.

The new emission standards, depending on the horsepower range of the engine, would apply only to 2008 and later model-year diesel engines. Engines in older equipment would not be regulated. When fully phased in, the rule would reduce emissions (from current levels) of nitrogen oxides (NOx) by 825,000 tons and of particulate matter (PM) by 125,000 tons, according to EPA estimates. EPA also estimates that equipment affected by the proposed rule generates 44% of all mobile source PM emissions and 12% of all mobile source NOx emissions.

EPA's proposed rule would mark the first time advanced emission control technologies would be incorporated into nonroad equipment. However, nonroad diesel engines built since 1996 have had to comply with "three tiers" of moderate emission standards, with the focus on reducing NOx emissions. The new rule would be considered a Tier 4 nonroad regulation. Small manufacturers of engines would be allowed an additional one to three years to meet the emissions standards.

Drastic Cuts in Sulfur Content of Nonroad Fuel

To meet the targeted engine emissions reductions, nonroad diesel equipment would have to use diesel fuel with a lower sulfur content: 500 parts per million (ppm) (which highway diesels currently use) beginning in 2007 and 15 ppm (which highway diesels will begin using in 2007) in 2010. The sulfur content of nonroad diesel fuel currently is unregulated and at a level of 3,400 ppm. Low-sulfur fuel is necessary for the advanced emission control technologies to be effective.

Refiners have warned EPA about potentially requiring the 15-ppm standard earlier than 2010. Requiring ultralow-sulfur diesel fuel for both on-road and off-road engines at the same time would potentially impact supply and distribution. Setting the fuel standards in a two-phase approach eased those concerns but did not eliminate them. Small refiners would be allowed two to three additional years to comply with the 2010 deadline for 15 ppm.

Other Industry Concerns

EPA said in its rule-making documents that it "believes that a new generation of emission control technologies that manufacturers will use to meet the 2007 heavy-duty highway emission standards can likewise be successfully transferred to many if not all nonroad diesel applications provided that low sulfur diesel fuel is available." But any conclusion that on-road and nonroad equipment and engines can successfully swap emission control technologies causes significant concern among the regulated.

The following concerns have been voiced by the Diesel Technology Forum, representing manufacturers of engines, fuel, and emission control systems: the diversity of nonroad engines and equipment, extreme duty-cycles compared to highway engines, a wide range of engine exhaust temperatures (equipment operates under harsher conditions), significant space constraints, and the current high sulfur content of nonroad diesel fuel.

In addition, while it might be technically feasible to apply highway technologies to certain types of construction equipment, the added cost might push the price of new products "beyond the limit" of economic hardship, according to engine manufacturers. As a result, EPA would not accomplish its emission reduction targets because customers might not be willing to purchase new equipment. Instead they might choose to rebuild and continue to use their current equipment. Moreover, according to equipment dealers, engine modifications might require the whole dimensions of the equipment to change, preventing them from fulfilling their intended purpose and requiring more equipment on the job site.

Although the new fuel and equipment might be more costly than current versions, they could help keep many areas of the country from violating Clear Air Act standards; such violations are threatening to highway and other construction.

Comments on the nonroad proposal are due August 20, 2003. Three regional public hearings will be held this summer. EPA expects to finalize the rule in the spring of 2004. Documents related to the proposed rule, as well as information on the public hearings and the comment process, are on EPA's Web site at www.epa.gov/nonroad.

Leah Wood is environmental counsel with the Associated General Contractors of America in Alexandria, VA.

MSW - July/August 2003