Truck and engine manufacturers that have chosen selective catalytic reduction (SCR) technology to meet new diesel emissions requirements are not happy that  regulators are considering changes to rules governing SCR use.  “We question the need to make modifications to SCR strategies just six months after SCR products were brought to market,” said Steve Berry, Volvo Powertrain dir. of government relations.

Berry was just one of the SCR defenders that included representatives from Cummins, and Daimler Trucks North America (DTNA) offering comments at a public workshop sponsored by the California Air Resources Board (CARB) and Environmental Protection Agency(EPA).  At the start of that workshop, the state and federal agencies indicated that they were considering changes to rules governing SCR systems that might take effect as soon as Jan. 1, 2011.

The workshop was held as part of an agreement with Navistar International to withdraw a suit over EPA and CARB rules governing SCR use. Navistar is the only U.S. diesel manufacturer that has chosen not to use SCR technology to meet strict NOx emissions restrictions that took effect Jan. 1. Manufacturers using SCR systems were particularly vocal about the agencies’ use of the workshop to settle a legal challenge by the one competitor that is not using the technology. 

“Let’s make sure that what we do is truly in the interest of the environment and the public,” John Mies, vp of corporate communications for Volvo Trucks North America.  “And let’s not penalize those who have worked with you in good faith, and reward those who are trying to manipulate the system for their own competitive advantage.”

The crux of the issue involves diesel emissions fluid (DEF), a urea-based liquid that is required by current SCR systems to bring NOx emissions below the 0.2 g/hp/hr. level required by 2010 emissions standards. In approving the use of SCR for 2010, EPA issued “guidance” on “inducement strategies” that would slowly de-rate engine power and eventually shut down a vehicle if it were to run out of DEF.  Those rules were also adopted by CARB, which separately certifies diesel engine emissions for vehicles traveling within California.

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