COLUMBUS, Ind. — Cummins will use selective catalytic reduction (SCR) technology in its 2010 heavy-duty ‘X’ engines after all.

That reverses its announcement of not quite a year ago, when the Indiana engine-maker said it could meet the 2010 emissions standard with an enhanced version of cooled exhuast gas recirculation (EGR) for its 15-liter engines, needing no NOx aftertreatment and thus no SCR. At the same time it announced two new diesels in the 2010 ISX lineup, a 12- and a 16-liter model, all three sharing the same architecture. Now, all three will use SCR.

The company had previously announced that its medium-duty motors would use SCR.

"Cummins will combine recent advancements in catalyst technology with its unique engine systems,” Cummins said. “This will provide customers with significant fuel economy improvements, in addition to meeting the near-zero emissions levels required by the Environmental Protection Agency’s (EPA) 2010 regulations.”

The SCR aftertreatment system will be built in-house by Cummins Emission Solutions.

“As previously announced, Cummins heavy-duty ISX engine family will incorporate the XPI fuel system, proven cooled exhaust gas recirculation, the Cummins VGT turbocharger, Cummins particulate filter and advanced electronic controls… We have the capability to make the engine systems and aftertreatment technologies work together seamlessly," said Steve Charlton, vice president, heavy-duty engineering.

Presumably, the EGR system in use here will be less aggressive than the one originally planned.

"This move demonstrates Cummins ability to adapt to a changing environment by leveraging technology advancements from our mid-range engine development and Cummins Emission Solutions," said Ed Pence, vice president and general manager, Heavy-Duty Engine Business. "Our 2010 engine development is progressing on plan, and customers can depend on Cummins to deliver these new products on time."

Cummins ISX engines to use SCR in 2010

Details on the Cummins decision to switch to SCR were not available as this story was being prepared, but an informed source close to the action told TodaysTrucking.com that it has everything to do with the proven ability of SCR engines to increase fuel economy compared to EGR motors.

With fuel prices skyrocketing, the logic here seems solid, as the use of EGR alone would, at best, maintain the status quo regarding fuel economy. SCR, and less aggressive in-cylinder tools, will likely accomplish a fuel economy improvement of at least 2 or 3 percent. A conference call with Cummins later today will fill in some information gaps.

Cummins made itself unique in terms of 2010 strategies, because it also announced last fall that its medium-duty engines would indeed use SCR for 2010. The addition of such a NOx-reduction system would be straightforward, it said, because in 2006 the company launched this very technology in Europe to meet the Euro 4 standard in its mid-range engines.

Asked at the time why the company would use both EGR and SCR, Cummins vice president and heavy-duty engine chief Steve Charlton just said it would, as always, provide “the right solution” for the application.

SCR is the right technology for medium-duty customers who want a simple solution, Cummins said then. With trucks coming back to home base every night, the potentially spotty availability of urea would not be a challenge. Its decision to go with SCR for heavy-duty motors in 2010 implies that it’s reasonably confident about the development of a North American urea distribution system.

Last year’s Cummins announcement about using EGR in 2010 ISX engines, not unexpected, set the scene for what was looking like a war of sorts, as Detroit Diesel and Volvo/Mack said they would leave EGR behind in favor of SCR.

In both cases, their European parent companies already had SCR engines sold and rolling in meeting Euro V emissions standards. Later, Paccar said it would use SCR in the DAF-based 13-liter engines it will soon build and sell in North America. International, on the other hand, said it too would stick with EGR on the Maxxforce engines it’s developing for 2010 in concert with German truck and engine maker, MAN.

International is now the lone player in the 2010 EGR camp.

The fuel-economy advantage of SCR is said by Detroit Diesel to be 3 to 5 percent, but one European fleet recently visited by Today’s Trucking has seen more like 10 percent with Euro V SCR engines compared to earlier EGR models.

LKW Augustin of Strasswalchen, Austria, is a large fleet by European standards – about 1000 power units – that has some 700 MAN and Mercedes-Benz tractors on the road meeting Euro 5 emissions rules via SCR.

Oskar Berger, majority owner and president, said the Euro 5 trucks are getting in the range of 34 liters per 100 kilometers, with some drivers hitting 30, down from a fleet average of 37-38 L/100km with SCR. To translate, Augustin trucks have gone from an average of just over 6.0 mpg to slightly under 7.0 or even 8.0 using SCR. Fuel costs more than $8.00 a gallon there, so this is no small gain — specifically, about $3 million a year.

The trucks are normally filled with both fuel and urea (called AdBlue over there) at the same time — the tanks hold 1300 liters of diesel and 85 liters of urea. That’s 286 gallons vs 19, or 348 and 22.5 U.S. gallons respectively.

We’ll have more detail on Cummins’ plans later today.