Engine makers oppose Navistar’s SCR court challenge

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Most suppliers of heavy-duty diesel engines that will rely on selective catalytic reduction (SCR) in 2010 are opposing Navistar’s legal challenge to the U.S. Environmental Protection Agency’s certification requirements for SCR. On June 1, Cummins, Daimler Trucks North America, Detroit Diesel, Mack Trucks and Volvo Group North America filed documents with the U.S. Court of Appeals for the District of Columbia Circuit opposing Navistar’s position.

Navistar on March 31 filed its challenge in a federal appeals court to EPA’s Feb. 18 certification requirements for heavy-duty engines using SCR. On May 4, the truck maker submitted a statement of issues to the DC Circuit raising the question of whether EPA can adopt the 2009 SCR guidance without a rulemaking proceeding.

In its May 4 filing, Navistar noted that EPA’s 2001 rule established a 0.2-gram nitrogen oxides (NOx) standard for 100 percent of trucks sold with model year 2010; it also found SCR not to be a feasible technology to meet the standard for several reasons. Navistar charges that the 2009 SCR guidance relaxes the 0.2 gram standard and approves a control technology that EPA in 2001 concluded would not allow the standard to be met on a fleetwide basis.

The Feb. 18 document provides guidance to manufacturers on various issues surrounding SCR, including the size of the diesel exhaust fluid (DEF) tank, the performance of DEF in freezing conditions and the various actions to compel drivers to replenish DEF. Navistar’s challenge appears to rest on the notion that EPA is allowing SCR-equipped trucks to be operated for a number of miles or hours – albeit at significantly reduced torque – without DEF, with poor-quality DEF or with a partially inoperable SCR system.