With the announcement by Cummins that it will add selective catalytic reduction (SCR) aftertreatment to its heavy-duty product line to meet 2010 Environmental Protection Agency (EPA) diesel-engine emissions regulations, only one U.S. engine maker — Navistar — will not offer the alternative for 2010.

Cummins said recent advancements in catalyst technology, specifically its use of copper zeolite, will allow its 2010 engines to achieve up to a 5% improvement in fuel economy while meeting EPA regulations.

According to Steve Charlton, vp of heavy-duty engineering for Cummins, copper zeolite has been around for a long time, but wasn't in research labs until two or three years ago and only became available for automotive applications in the past nine to twelve months. “Copper zeolite is very, very efficient at reducing NOx compared to other catalysts,” he said.

“Everyone in the industry will be using EGR [exhaust gas recirculation],” Charlton said. “It's really the combination of EGR and SCR that makes this work, along with the diesel particulate filter…we are running prototype systems right now, and we're confident that the SCR results we're expecting can be delivered.”

The announcement leaves Navistar as the only U.S. engine maker that will not be offering an SCR engine for 2010. Navistar currently does not plan to offer an SCR option. “We have our strategy, and we're sticking to it,” Roy Wiley, Navistar spokesperson, told Fleet Owner. “Our engine platform has been thoroughly tested using EGR, and we believe this is the best path for us to take for our customers.”