Clearing the Air: To ’07… and beyond

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Urea injector (inside exhaust pipe) and injection control slave mounted on Mercedes-Benz engine.

Editor’s note: This is the third in a series of articles on what to expect from 2007/2010 engines, in terms of maintenance, durability, fuel economy and overall cost.

With a little more than a year to go before the next round of emissions regulations kick in, the technology and engineering path for 2007 heavy-duty diesel engines is becoming clear. That doesn’t mean, however, that everyone is happy and comfortable. As we have been reporting, fleet managers are concerned that:

  • The new engines will use a diesel particulate filter (DPF), which won’t be cheap and will require periodic maintenance to prevent performance and fuel economy losses due to exhaust backpressure. Another worry lies ahead for operations requiring active regeneration (see “Trapped!” page 54).
  • ’07 engines will use higher levels of exhaust gas recirculation (EGR), except for Caterpillar’s, which will use a second-generation of its Advanced Combustion Emissions Reduction Technology (ACERT) with Clean Gas Induction (CGI) – a lower-volume EGR system in which the exhaust gas is drawn aft of the DPF. This likely will mean even higher underhood temperatures in most cases.
  • Ultra-low-sulfur diesel (ULSD) fuel must be used, since combustion of sulfur creates particulate matter, which can poison DPFs. The new fuel will cost more and likely will have fewer BTUs than current fuel, thus causing increased consumption at a time when fuel prices already are at record levels. Moreover, depending on geographic area, the fuel still may not be available for some fleets who would like time to test the engines.
  • A new engine oil, code-named PC-10, must be used, since the ash found in today’s oils can plug DPFs. And it will have to be more resistant to thermal breakdown, since ’07 engines will run hotter. However, the new oil isn’t scheduled to be available until mid-2006.
  • And, finally, there aren’t many ’07 test engines to go around, and many fleets will have to wait until sometime in ’06. And some of those with engines don’t have the right fuel (see “Testing slowly gears up,” page 56).

With the exception of the ULSD fuel, which everyone will be using regardless of engine, carriers could postpone many of these worries with a pre-buy, although most agree that for the industry as a whole, a pre-buy is harmful (see “Mulling over a pre-buy,” below.) But even as questions remain about 2007, an announcement by one major engine manufacturer concerning the 2010 round of emissions and technology changes has many in the trucking industry already talking.

SCR for 2010?
EGR, ACERT and DPFs will be used to meet ’07 emissions regs. But another technology once considered as a possible solution for ’07 may become a key method of meeting even more stringent 2010 regs.

Unlike EGR – which uses exhaust gas to lower peak cylinder temperatures, thus driving down oxides of nitrogen (NOx) emissions – selective catalytic reduction (SCR) injects a urea/water mixture from a separate, vehicle-mounted tank into the exhaust, upstream of a catalyst, reducing NOx to its nitrogen and oxygen components. A DPF still will be used to curb particulate matter.

As a plus, an SCR system can do its NOx-reducing thing while allowing for an engine calibration that provides better fuel economy than is possible with EGR, by an estimated 3 to 5 percent. However, there have been concerns, such as additional tankage and weight, an infrastructure for obtaining urea, and ensuring that trucks won’t be operated without it.

At this writing, Cummins, Caterpillar, Mack and Volvo have declined to state clearly whether they’ll use SCR, EGR or a combination of both to meet 2010 emissions standards. But at a recent press event in Papenburg, Germany, Andreas Renschler, head of DaimlerChrysler’s Commercial Vehicles Division, surprised attendees by announcing that for 2010, all Detroit Diesel and Mercedes-Benz engines sold in the United States will be equipped with SCR. Detroit Diesel, CCJ has learned, will use a combination of EGR and SCR.

“This year, we have already successfully introduced SCR under the name BlueTec in Europe,” Renschler said. “By the end of 2005, we will have delivered around 5,000 trucks which meet upcoming Euro 4 and Euro 5 (emissions standards) with BlueTec. SCR is the best possible technology and is suitable for worldwide use.” Renschler added that the infrastructure for AdBlue, the urea additive, is in place in Europe – where it reportedly can be found at some 800 fueling stations – and he is confident that it also will be in place in the United States from 2010.

To ensure SCR-equipped vehicles won’t be operated without AdBlue, DaimlerChrysler will equip those vehicles with exhaust-mounted NOx sensors. If the additive is depleted, the engine’s ECU will sense an increase in NOx and will reduce engine power as an incentive to replenish the tank.

Chances are, other engine makers will incorporate SCR into their 2010 engines. Peter Karlsten, president and chief executive officer of Volvo Trucks North America, said in a panel discussion at the American Trucking Associations annual meeting last month that Volvo’s solution “should probably be SCR” in 2010, although he told CCJ that infrastructure issues surrounding urea distribution remain. In the same ATA session, Ed Pence, Cummins vice president and general manager of the heavy-duty engine business, noted that the company is using SCR in Europe. But Pence cautioned that any 2010 solution here likely would incorporate EGR.

Possible downsides to the use of SCR in North America could be the price of AdBlue and its consumption rate, neither of which has been determined – or, at least, revealed. In fact, it’s hard to know how much the stuff ultimately will cost even in Europe, since SCR won’t be in widespread use there until Euro 4 kicks in next October – except in Germany, where reduced road user charges serve as an incentive for its early adoption.

Right now, AdBlue is going for the equivalent of about $3.20 per gallon, according to Brian Weatherley – editor-in-chief of Commercial Motor in the United Kingdom – and the consumption rate is about 4 percent of diesel fuel burned. “So, no question, some of the good news about improved fuel economy is offset,” he says (see “mpg may not = cpm,” page 54).

Leapfrog, anyone?
If the price points for diesel fuel and AdBlue, and significantly improved fuel economy, make SCR economically attractive in North America, one might wonder if fleet operators will want to embrace the technology, perhaps minimizing their purchases of ’07-’09 engines and holding out for 2010.

Here again, there seem to be more questions than answers. “No, I don’t think you can do that and remain competitive,” says Tom Newby, director of field maintenance for Thomasville, N.C.-based Old Dominion Freight Line. “Plus, there are still concerns about SCR – an extra tank and more weight, for example.”

“We’d like to wait, but we can’t wait too long,” says Marty Fletcher, director of technology and training for Chattanooga, Tenn.-based U.S. Xpress. “That’s because of our trade cycles and the fact that our fleet is growing.”

“One thing to consider is, just exactly how much is all this great fuel economy going to cost upfront,” asks Dave Foster, director of maintenance for Southeastern Freight Lines, based in Columbia, S.C. “There will be increased product prices, support necessary for SCR and so on.”

Steve Duley, vice president of purchasing for Green Bay, Wis.-based Schneider National, agrees. “My understanding is that SCR is going to be expensive, and I don’t believe you eliminate other hardware to offset the cost,” he says. “So the fuel economy savings must be significant to justify holding off on 2007 engines in favor of 2010.”

Step by step
So, while there still are questions about ’07 engines, 2010 versions won’t come without their own concerns. And maybe, since EGR has been a known commodity for the last four years, the adjustment to ’07 will be easier to swallow than ’02. “That first go-round was more reactive than proactive,” observes Newby. “Just my opinion, but it doesn’t look like that’s going to happen again.”

Mulling over a pre-buy
Representatives from major carriers voiced concern about the economic impact of the lower-emissions ’07 engines during a panel discussion at the American Trucking Associations annual meeting in Boston last month.

“We think we’ll see an additional $18,000 [in operating costs] with this new engine,” said Christopher Lofgren, president and CEO of Schneider National. That’s on top of the $15,000 more the ’02 low-emissions engines cost than previous models, he said.

The initial purchase price of trucks with the new engines will go up “in the upper four-figure range,” said Chris Patterson, Freightliner president and CEO, but he added that they have not established pricing yet.

Cost and reliability issues they faced with the ’02 lower emissions engines will play heavily into decisions on the ’07 models, carrier panelists said. “We have been accelerating capital expenditures as we try to reduce the age of our fleets,” Lofgren said. “Until you put a lot of miles on these things, you don’t know the real issues.” Consequently, “to give ourselves some room, we are buying more tractors than we traditionally would.”

Unlike many carriers, Knight Transportation chose not to pre-buy prior to the introduction of the ’02 engines, said Kevin Knight, CEO and chairman. “It has been a very expensive process when you look at the price of engines and of fuel,” he said. Knight plans to continue its normal trade cycle in ’07.

“We made the decision to pre-buy as many engines as we could,” said Glen Brown, chairman and CEO of Contract Freighters, and held off purchasing ’02 engines until May 2004. “We wanted to change them out before ’07,” he said.

Issues surrounding the ’07 engines include use of a diesel particulate filter to reduce particulate emissions to ’07 levels. The filters will add weight and cost, and will need to be cleaned every 150,000 miles at a cost between $75 and $150. EPA mandates the initial cleaning be made at 100,000 miles.

But Cummins representative Ed Pence assured attendees that beyond the DPF, maintenance intervals on the ’07 engines wouldn’t change and that performance will be “comparable to today’s products. We’re well ahead of where we were with ’02 engines,” he said.

Another issue is that beginning next year, all engines will run on ultra-low-sulfur diesel fuel, which will cost 3 to 7 cents more per gallon to produce, although the retail price “will be market-driven,” said Jim McGeehan, Chevron global manager of diesel engine technology.

“Our biggest concern is the fuel,” said Knight. “When you think about it, it makes the introduction of ’07 engines secondary, because we’re going to have to run the fuel no matter what.”

Because ULSD has less energy content, fuel economy dropped by about 2 percent in test engines run by Schneider, Lofgren said.

But heads of two truck makers assured attendees that reduced fuel economy is not a major concern. “Freightliner is committed to keeping the competitive advantage in fuel efficiency,” Patterson said, through truck aerodynamics and by working to offset the negative effects of the new engine technology.

“We’re on track to deliver fuel economy equal to current engines,” said Peter Karlsten, Volvo Trucks North America president and CEO.

Despite reassurances by engine and truck makers about the viability of the ’07 technology, panelists acknowledged that the specter of a significant pre-buy, such as the industry saw prior to the introduction of the ’02 engines, remains. Freightliner’s Patterson cautioned against this approach. “We don’t have a lot of head room,” he said, referring to strong Class 8 truck sales that have truck makers building at capacity. “And it’s not as if anyone’s going to commit to bricks and mortar.”

Cliff events – large increases in production followed by a sharp drop – add cost, Patterson said, and put stress on the supply chain. “A pre-buy creates too much excess equipment,” said Knight. “I would recommend a don’t-buy instead of a pre-buy.”

“We are doing everything we can to make the ’07 engines a non-event,” Volvo’s Karlsten said.

If there’s an upside to 2007, it’s that it’s not 2010, some carriers say. The 2007 change is a concern, Lofgren notes, but “the one we’re worried about is the one waiting behind it.” CFI’s Brown agrees. “In our case, we’re pretty confident in the 2007 engines. We’re worried about 2010.”

A diesel particulate filter (DPF), sometimes called a soot or particulate trap, contains a porous substrate, often ceramic, that traps particulate matter from exhaust gas flowing through it. The particulates continually are burned off by exhaust heat in a process called passive regeneration.

When a vehicle’s duty cycle is such that the exhaust gas is not hot enough to burn the particulates – temperature thresholds still are being determined – a small amount of fuel is injected into the DPF to raise the temperature and burn off the particulates. This is called active regeneration.

Since exhaust temperatures can soar to more than 1,000 degrees F during active regeneration, a means of locking out this process when it could pose a danger – such as when a vehicle is in a shop – is a safety feature that, so far, Caterpillar and Detroit Diesel have confirmed they will provide. And Cummins, Mack and Volvo have said they currently are exploring control strategies.

After repeated regeneration cycles, the remaining ash in the DPF needs to be cleaned out, at a minimum interval of 150,000 miles. How the DPFs will be cleaned, how the residue will be disposed of, and whether fleets will perform this service or swap-out DPFs on a core-exchange basis, are questions that have not yet been answered.

mpg may not = cpm
While SCR promises a fuel economy benefit, that saving may or may not be realized in cost per mile, depending on: the price of diesel; the actual fuel economy benefit; and the price and consumption rate of the AdBlue urea solution.

For example, assume that: diesel is $3.00 per gallon; AdBlue is $3.20 per gallon; the consumption rate is 4 percent of fuel burned; and a vehicle’s baseline mpg is 6. That means 200 gallons of diesel would be $600. Without SCR, at 6 mpg, that would take a vehicle 1,200 miles at a fuel cost of $0.50 per mile.

With SCR (other variables equal), add 4 percent, or 8 gallons of AdBlue, at another $25.60, for a total of $625.60. Add a fuel-economy improvement of, say 5 percent, for 6.3 mpg. Now the vehicle will go 1,260 miles, at a fuel/AdBlue cost of $0.496 per mile. Not a stellar improvement.

Of course, as diesel gets more expensive and/or AdBlue becomes cheaper or consumed at a lesser rate, the cost per mile shifts in favor of SCR. But that’s assuming straight SCR is used, and not a combination of SCR and EGR, which could affect the AdBlue consumption rate, mpg and ultimately cost per mile.

Testing slowly gears up
While engine manufacturers insist that the engines will be tested and ready for the deadline, fleets have their own various strategies for dealing with ’07.

“We’ve got some ’07 Cats lined up for testing soon,” says Tom Newby, director of field maintenance for Thomasville, N.C.-based Old Dominion Freight Line. “And we’ve got a test location picked out where we can keep the vehicles fueled with ULSD. I’m looking forward to it.”

“We just received Cat engines to begin our evaluation, and the Detroit Diesels aren’t scheduled until near the end of the year,” reports Steve Duley, vice president of purchasing for Schneider National, based in Green Bay, Wis. “So we really don’t have any test results to date.”

“We’ll be one of the last to get test engines,” says Marty Fletcher, director of technology and training for Chattanooga, Tenn.-based U.S. Xpress. “That’s because we run automated manual transmissions, and the engine makers have a lot of electronic integration work to do.”

Getting the engines is only part of the testing equation. Ultra-low-sulfur diesel (ULSD) is required for the diesel particulate filter (DPF) to work properly. Otherwise, the DPF will plug quickly, and backpressure not only will degrade fuel economy but also stop the engine altogether.

Indeed, some fleets apparently have had engines available to test but put off testing due to fuel availability. Contract Freighters Inc., for example, finally purchased its own ULSD at premium prices – $4.30 a gallon, Glen Brown, CFI chairman and CEO, said during a panel discussion at the American Trucking Associations annual meeting last month. Phoenix-based Knight Transportation, meanwhile, is conducting its testing in California, where an adequate low-sulfur diesel supply exists.

For some carriers, however, testing engines in advance isn’t a high priority. “We don’t put stock in test engines because until they’ve run three years, we don’t really know,” said Robert Young, chairman and CEO of ABF Freight Systems. “There will be a lot of unknowns.”