16 December 2003

US engine manufacturers announced their technology plans for meeting the 2007 emission standards for heavy-duty diesel engines. While, as expected, all manufacturers will use diesel particulate filters for PM control, there is still no agreement on NOx control methods. Cummins, Caterpillar and International intend to meet the 2007-2009 NOx requirements using technologies similar to those featured in their 2004-complaint engines, which are generally based on various forms of exhaust gas recirculation (EGR). Detroit Diesel Corporation (DDC) on the other hand is still considering the use of urea-SCR technology, the solution which will be used in the European Union from 2005 (Euro IV). Other supporters of the SCR route in the US market—Volvo and Mack—did not issue statements at this time.

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Technology plans announced by manufacturers can be summarized as follows:

  • DDC announced plans for certification of its 2007 Series 50 urban bus engines, focused on two possible technical solutions: (1) urea-SCR, and (2) EGR. A final decision as to which solution will be applied to the 2007 Series 50 will be made in 2004, said DDC.
  • Cummins confirmed that it will use cooled EGR, the technology that has been employed by Cummins for heavy-duty trucks in North America since October 2002. At the same time Cummins said it will use urea-SCR to meet Euro IV standards in European trucking applications. Cummins utilized in-cylinder combustion technologies to meet the nonroad Tier 3 standards in North America.
  • Caterpillar said it can meet 2007 regulations using the ACERT technology, without the need for SCR. ACERT is a combination of in-cylinder techniques involving fuel injection, air charging and combustion technologies. While Caterpillar has not released technical details, industry insiders believe that internal EGR is one of the NOx reduction means in ACERT engines.
  • International said its 2007 engines will meet the NOx requirements without the need for SCR (or NOx adsorber) technology.

All manufacturers will meet the 2007 PM emission standard of 0.01 g/bhp-hr (down from the current 0.1 g/bhp-hr) through the use of diesel particulate filters.