Emissions Authority
Clean Air Strategies
EGR is the new engine technology of choice for all but one engine manufacturer.
Steve Sturgess
Senior Editor
On the eve of the emissions summit held in conjunction with the spring meeting of the Technology and Maintenance Council of the American Trucking Assns., Detroit Diesel announced that it would be pursuing exhaust-gas recirculation as the technology to reach the stringent 2007 exhaust emissions levels.
The announcement follows similar pronouncements from Cummins, Volvo and Mack. Only Caterpillar has said it does not intend to follow the EGR strategy to get down to the anticipated 1.2 g per hp-hr for NOx and the 0.01 g per hp-hr limit for particulate matter.
The announcement from Detroit Diesel was significant, because the company had earlier said that selective catalytic reduction (SCR) could be the technology path it would pursue. That was also the strategy initially proposed by Volvo, in part because both these companies make and sell trucks in Europe. Detroit Diesel is a wholly owned subsidiary of DaimlerChrysler that sells Mercedes-Benz trucks and diesel engines in other parts of the world. Indeed, Detroit Diesel sells the Mercedes-Benz 4000-Series heavy-duty diesel in North America, accounting for a significant part of the more than 4,000 Class 8 truck engines the company sold in January.
As outlined by Cummins technology chief John Wall, (See February HDT, page 56) SCR makes more sense in Europe because the reagent replaced some of the diesel fuel and allows for injection optimization, thereby offering significant savings in a market where fuel is $5 a gallon. And the particulates limits are a little more forgiving in the Euro V regulation that is timed for 2008. For North America, Wall said Cummins felt EGR was the optimal route, with the possibility that some SCR may be needed in the final cleanup in 2010, when NOx drops to 0.2 g per hp-hr.
That would appear to be the same conclusion in the Detroit Diesel announcement. "As part of the largest commercial vehicle manufacturer in the world, Detroit Diesel was in a position to choose from a range of technologies, including SCR," said Carsten Reinhardt, president and CEO of Detroit Diesel Corp. "While we believe SCR is a viable alternative for 2010, we ultimately selected EGR for 2007 because of the system's greater familiarity with our customers and its ease of deployment."
The European emission regulation timing is important. Both Volvo and DaimlerChrysler are known to be working on complex new engine platforms to handle the stringent regulations on both sides of the Atlantic. Because of the enormous cost of development (DCX is expected to pony up $2 billion to develop its P7 engines) the investments have to be amortized over 150,000 engine units per year. This dictates the same base engine being sold in Europe and North America. Hence the expectation that both Volvo and DDC would push for SCR technologies to be adopted to ease the cost of development.
The Detroit Diesel announcement makes reference to the new Mercedes-Benz/Detroit Diesel engine. "A new heavy-duty engine being developed by DDC and parent company DaimlerChrysler, scheduled for release in 2007, will also employ EGR and diesel particulate filters (DPF) for North American applications," notes the press release.
It continues: "DDC has extensive experience with EGR. The company has built over 40,000 Series 60 engines with EGR, and the 2004 Mercedes-Benz engines are also equipped with EGR. These engines have performed well in their estimated 2.5 billion miles of service since October 2002. Detroit Diesel also has utilized EGR technology in bus engines since 2000. By 2007, there will be approximately 300,000 Detroit Diesel and Mercedes-Benz engines operating in North America utilizing EGR technology."
In their late January announcements, both Mack and Volvo said their decisions to go for EGR were much in line with the same thinking. Mack said the decision to concentrate on EGR for its 2007 engines reflected its experience with similar technology in its current ASET engine lineup.
"Mack ASET engines have been in customer trucks since early 2002, and that means no other engine manufacturer has more experience with EGR than we do," said Mack president and CEO Paul Vikner. "Our engines have all been in compliance with the EPA '02 emissions standards since they took effect, and the ASET technology continues to meet expectations in terms of fuel economy, uptime and performance. By building on what we've learned with the ASET approach, especially in optimizing engines to meet the unique demands of Mack customers, we're confident that our '07 engines will offer breakthrough quality and performance while meeting the new EPA emissions standards," he said.
Volvo also uses EGR to meet the current emissions standard, and said EGR and DPF will be used in North America on the new family of Volvo engines scheduled to be introduced in the 2007 time frame. Its 2007 engines will use ultra-low sulfur diesel fuel, which will be in use in North America by then. Volvo plans to have about 30 engines in field testing with selected customers around the spring of 2005.
Peter Karlsten, Volvo president and CEO said, "2007 poses a formidable challenge in terms of emissions reductions, but we are confident our Volvo engines will not only provide cleaner air to breathe, but will continue to meet the very high demands our customers have for reliability, fuel economy and performance." "And, Volvo engines will fully comply with the 2007 regulations from day one, just as they did with the 2002 U.S. emissions regulations."
Vikner said Mack expects to have engines with its EGR-based EPA '07 technology in field testing with selected customers in 2005, and he pledged to continue Mack's participation in industry efforts to ensure that customer needs and concerns are addressed as the 2007 deadline approaches.
That remark was echoed by Detroit Diesel's Reinhardt who - in the release - commented that his company's 2007 EGR engines are already in development, and the company intends to operate vehicles with the 2007 engines by the end of this year.
"Everyone in this industry wants to avoid the confusion and market upheavals that accompanied the EPA '02 emissions regulations," he said.
Caterpillar has resolutely maintained that its advanced combustion emissions reduction Technology (ACERT) engines have no exhaust gas recirculation as part of the overall package. Instead of pulling in cooled exhaust gas into the inlet stream, as do all the other diesel engine manufacturers, Cat uses extremely high boost pressure to push significant quantities of air through the combustion chambers along with high injection pressures and variable valve timing. Unlike its competitors, current Caterpillar engines require exhaust aftertreatment in the shape of an oxidizing catalyst tucked away in the muffler. For 2007, the company says it will use the same technology, and while nothing has been said officially about additional aftertreatment, there is wide speculation that Cat will have to adopt diesel particulate filtration as well.
