Before reaffirming Navistar’s intention to be the sole U.S. truck manufacturer not to use selective catalytic reduction (SCR) to meet the upcoming 2010 diesel emissions requirements, Tim Shick, dir. of business & product strategy told an online audience that, “We think SCR is a very viable technology. We can’t find anything negative about it.”
The company, which has filed a federal suit against the U.S. Environmental Protection Agency over its rules approving SCR for 2010 emissions control, has instead chosen to use high levels of exhaust gas recirculation (EGR) to meet new NOx emissions limits because “we wanted to minimize the customer’s burden in 2010,” Shick said during a web presentation that was hosted by the Truck Rental and Leasing Assn. (TRALA) and included all of the major heavy-duty truck and engine manufacturers.
Before turning to the specific attributes of what Navistar is calling “advanced EGR,” Shick added that the company would move to SCR if “a non-liquid form of urea” currently under development were ready for commercial application. “We don’t like liquid [urea, or diesel exhaust fluid], and the non-liquid is not ready yet … so we will run with EGR to reduce NOx,” he said.
Addressing critics of Navistar’s emissions approach, Shick said “We are ready for 2010 in spades.” In particular, he said that development work on its common rail fuel system would “restore” regeneration cycles for its diesel particulate filters (DPFs) and oil-change intervals “to 2007 levels.” He added that its high-EGR engines would also have “basically the same fuel economy” as its 2007 engines.
The first of the SCR users to address the conference, Mike Breeden of Cummins Engine Co., said that the DEF aftertreatment approach “allows us to optimize engines for driveability, better torque response and quieter operation.” Specifically, he pointed to fleets tests showing “5% or better MPG than our 2009 ISX” heavy-duty diesel engine. The decrease in fuel consumption, however, is partially offset by DEF use, bringing the total fluid use reduction down to 3%, he noted.Technical presentations from Mack Trucks, Volvo Trucks of North America and Detroit Diesel Corp. outlined other benefits and characteristics of the SCR approach for TRALA members. Cited were widespread use of SCR in Europe without significant technical problems, reduction or complete elimination of active DPF regeneration cycling, little modification of existing engine hardware or maintenance requirements, and higher horsepower outputs without displacement increases.