CALGARY, Alta. – Some of the fog surrounding the 2007 emissions standards and how they’ll be met has cleared, as manufacturers have begun revealing their plans for meeting the next round of stringent emissions limits.

For the most part, it’ll be Exhaust Gas Recirculation (EGR) and ACERT – much like in 2002. However, diesel particulate filters (DPFs) and possibly some form of aftertreatment will also be required. It appears however, that the much talked about Selective Catalytic Reduction (SCR) technology will not be commonplace in 2007.

Engine manufacturers began making their intentions known in the final weeks of 2003. On Dec. 15, Cummins announced EGR would provide the foundation for its 2007 engines.

“Since the 2007 standard in North America applies to on-highway engines where there is a great deal of air flow through the engine and fuel economy is very important, Cummins believes that EGR technology is best suited for that application,” says Karen Battin, Cummins’ executive director, investor relations.

Cummins continues to develop SCR for European (and some North American off-road) applications.

While an advanced EGR system is capable of controlling NOx (one of the two primary pollutants targeted by the EPA), DPFs will be required to reduce particulate matter (PM).

It appears every manufacturer will use particulate filters, which will require some additional maintenance.

“Filters trap the soot particles and burn them under certain operating conditions. Since there is a small amount of ash (non-combustible material) in diesel exhaust, it will be necessary to clean out the filter,” says Anthony Greszler, vice-president, engine product development, Volvo Powertrain. “At this point, it looks like this will be required approximately every 150,000 miles.”

Cummins’ Battin adds: “Similar to catalytic converters, these filters reduce emissions levels coming out of the engines. For 2007, it will require the use of ‘active’ filter systems versus passive filters used today. This means that it will require interaction with the engine to monitor things such as temperature and particulate matter levels within the filter.”

Volvo has opted for EGR coupled with a particulate filter, despite the fact there was much speculation that the manufacturer would choose SCR as a 2007 solution.

Greszler says Volvo Trucks North America hasn’t yet ruled out SCR for 2010, when EGR alone may not be enough.

“We believe EGR will be a key part of Volvo’s 2010 technology,” he says. “We expect 2010 will require the addition of NOx aftertreatment, and SCR is a strong candidate for that.”

Not surprisingly, Mack shares the same line of thinking as its parent company, Volvo.

“EGR has proven itself to be a very reliable, effective way to meet more stringent emissions regulations while also delivering the performance customers have come to expect,” says Mack spokesman, John Walsh. “By continuing to develop EGR, we are continuously building toward the tough 2010 requirements. But we have not abandoned our research into other technologies, including SCR, which is the Volvo Group’s technology path for Europe.”

He adds: “We believe that there may still be a role for SCR in North America at some point in the future, including 2010. But it’s just too soon to say right now precisely if and when SCR might be feasible for North America.”

While EGR engines have already racked up countless millions of miles on North American highways, there will be some differences between the EGR systems found in 2002 models and the EGR systems of ’07.

“There will be more exhaust gas recirculated back through the combustion process. The technology will involve additional changes to the combustion process (timing, angle of fuel injection, etc.) and it will also require the use of some form of aftertreatment,” explains Cummins’ Battin.

Meanwhile, Caterpillar has announced it is forging ahead with its own technology – ACERT- and will not adopt SCR.

“Our goal is to provide the North American trucking industry with engines that meet EPA’s 2007 regulations without sacrificing performance or fuel efficiency,” says Richard L. Thompson, Caterpillar group president. “We can meet EPA’s 2007 regulations and customer needs without SCR. Our ACERT technology provides a significant breakthrough because our customers will avoid the burden of complex and costly technologies associated with SCR.”

Detroit Diesel has yet to formally announce its 2007 intentions.

“We are still evaluating several technologies and expect to make an announcement sometime in the coming month or so,” says Tom Freiwald of Detroit Diesel.

While manufacturers are beginning to make their intentions for the future known, there are still many unanswered questions. For instance, how much more will heavy-duty truck engines cost in ’07? And will there be further fuel efficiency losses such as those experienced in ’02?

With regards to cost, there’s little doubt 2007 engines will cost more than today’s truck engines. The EPA has predicted engines prices will rise between US$1,200 and US$1,900.

That comes as no surprise to Mack’s Walsh.

“It’s too soon to say at this point, but we do expect that there will be added cost to the customer,” he says.

Battin agrees it’s too early to guess at potential cost increases.

“It is unknown at this time what the pricing of the 2007 compliant engines will be. While we understand the technology recipe, there is still work being done to determine the exact form of aftertreatment to be used and the amount of precious metals required to be used in the aftertreatment system,” she says. “These things will affect pricing decisions, so it is premature to discuss pricing at this time.”

Fleet managers and O/Os still coming to grips with the loss of fuel economy inherent with the first phase of EGR-equipped engines will undoubtedly be wary of any further fuel mileage losses. There is some reason for optimism on this front, as the 2007 engines may well remain fuel-neutral.

“Our goal is to make the ’07 solution as efficient as possible to prevent degradation in fuel economy,” says Walsh.

Battin says it’s too early to predict fuel efficiency, as work is underway to maximize the efficiency of EGR engines.

Cat is also confident it can meet the 2007 standards without compromising fuel mileage.

But are those words of assurance enough to give fleet owners the peace of mind to avoid another pre-buy? The manufacturers certainly hope so.

“Since we have already made so much progress on our 2007 engines, and we plan to have our technology available for market testing well in advance of the emission standards change, we believe it will reduce concerns or ‘fear of the unknown’ among OEMs and truck fleets,” Battin says. “A large spike, then dramatic fall off in demand is not good for our industry, so we are focused on alleviating concerns and the need for ‘pre-buying.'”

Walsh adds: “We do not see any reason for customers to alter their buying cycles in the months leading up to ’07. We are confident that we have the volume base and technical expertise to deliver the best new engines available for North American customers. And we plan to do everything we can, including ample field testing with selected customers starting in 2005, to assure our customers that this is the case.”