Engine Manufacturers in Line to
Meet 2007 Requirements

By Ryan Gray | Senior Editor

Much discussion of late has centered on the EPA regulations to reduce particulate matter by 97 percent and oxides of nitrogen (NOx) by 95 percent using new heavy-duty diesel engines and ultra low sulfur diesel fuel (ULSD). But what implications are at stake for fleet operators? How does horsepower match up with existing engines? And in this era of pain at the pump, what about fuel economy?

The answers on a national scale so far have been vague (see accompanying sidebar). But next year will still mark an important step in cleaning up the nation's diesel school buses when ULSD is introduced to cut emissions to miniscule levels. The EPA says the sulfur in diesel fuel contributes to acid rain and smog.

With compliance dates closing in - petroleum producers must have ULSD widely available nationwide by June of this year with a phase-in period extending through 2009 - over 80 percent of new engines must use the fuel, which emits only 15 parts per million of sulfur content. By 2010 that figure rises to 100 percent. The EPA in November announced a 45-day extension for retailers to begin offering ULSD at the pump. The previous deadline was Aug. 1 of this year.

How that all shakes out is still unclear.

"Nobody really knows what's going to happen," said Richard Cregar, an automotive instructor with the National Alternative Fuels Training Consortium (NAFTC) at West Virginia University. "When the EPA set forth these standards, the diesel engine industry said, 'We can't meet those standards without after treatments. You have to meet us halfway or do away with (the ULSD requirement).'"

The reduction in particulate matter is a good thing, he added, but reducing the sulfur content also reduces the lubricity of diesel engines. That's where biodiesel comes in. Any kind of biodiesel can technically be pumped directly into the diesel engine with no adverse affects, granted it meets ASTM 6571 certification. By definition that makes all biodiesel B100. It takes on such acronyms as B2 or B5 based on the percentage of blend with regular No. 2 diesel. But so far engine manufacturers have only been able to verify blends of B5 and lower as meeting EPA NOx requirements in the 2007 engines.

As many questions center on biodiesel as do the latest engine technologies for 2007.

Any other claims could result in a federal penalty, Cregar added. Then there are industry concerns regarding how bio will affect the new engines.

Cost an Issue

International's school bus division, IC Corp, was one of the few engine OEMs to announce that the new 2007 heavy-duty diesel engines could increase purchase prices by an estimated $5,000 to $6,000 per vehicle. The new engines are expected to drive up manufacturing costs, at least in the short term.

"After 2010 emissions standards, which we will meet with diesel engines, reducing emissions further will be largely unnecessary and certainly not cost-effective," the company said in a release. "We are, though, supporting research on alternative diesel fuels like biodiesel and researching the development of advanced power train designs like hybrid diesel-electric engines, which could improve fuel efficiency and reduce dependence on petroleum-based fuels."

Meanwhile, General Motors also reiterated its dedication to diesel.

"Clearly, the cost of updating the engine design to meet new emissions standards, as well as the addition of costly emissions recovery systems such as a diesel particulate filter, add to the cost of producing and offering a diesel engine without providing a noticeable performance benefit to the customer," said GM spokesman Nick Richards. "However, diesels are an important part of GM's power train portfolio, and an important power train (solution) to the transportation industry and therefore we will do what is necessary to continue to offer diesel engines in the U.S. beyond 2007."

Manufacturers Ready for Market

Regardless the engine manufacturers are poised to meet the stricter standards for particulate matter and hydrocarbons. The EPA has recognized International Truck & Engine's Green Diesel Technology and its 2007-compliant emissions since 2001. For just as long, the company has provided the engines to school bus fleets throughout California. The company said it also has an evolutionary engine combustion process in the works that will meet required oxides of nitrogen (NOx) levels of 1.2 g/hp-hr and an integrated particulate filter to satisfy lowered PM levels.

With regard to ULSD, International added that it was possible but unlikely that customers could experience an approximate 1 percent decrease in fuel economy, specifically mileage per gallon.

"It's still up in the air," said Roy Wiley, a spokesman for International. "People have said that you could get up to 1 percent degradation. As you know we have a lot of school buses sold in California. We've had the green diesel technology there for years and (reduced mileage) just hasn't happened."

Karl Knecht in International's bus marketing group said final calibration reports for ULSD, which has a slightly lower BTU per gallon rating, is due to the EPA before the end of the 2006 calendar year.

Cummins said emissions solutions set in motion over a decade ago will help it meet the EPA 2007 and beyond on-highway emission levels by integrating its current-cooled Exhaust Gas Recirculation (EGR) with the Cummins Particulate Filter.

"Providing stable engine architecture assures customers that the engine they are operating today will be the same basic engine in 2007," said spokesperson Cyndi Nigh. "Performance and fuel efficiency will be similar to today and service intervals will be unchanged."

She explained that the Cummins Particulate Filter, developed and manufactured by Fleetguard Emissions Solutions, a subsidiary of Cummins Inc., is designed to replace the existing vehicle muffler, adding minimal weight to the vehicle.
Cummins features the ISB and ISC diesel engines with the EGR technology and a fully integrated Cummins particulate filter for school bus applications. On the side of alternative fuels, natural gas engines currently meet the EPA's 2007 emissions requirements. Cummins said it continues to offer its closed-loop, lean-burn B Gas Plus and the EPA- and CARB-approved ISL G natural gas engines for even lower emissions.

"There's even a propane fueled model (B LPG PLUS)," Nigh added. That engine, she said, is "ideal for a 20-passenger bus."

Meanwhile, Caterpillar continues to work on various after treatment solutions including diesel particulate filters and NOx after treatment. Cat relies on its C7 school bus engine with ACERT technology to meet the 2007 emissions levels.  

"The engine platform will include an advanced fuel system, a Variable Turbine Geometry Turbocharger, a Diesel Particulate Filter (DPF) with active regeneration, and Clean Gas Induction (CGI)," Nelson added.

As with ACERT Technology, Cat is working on combining combustion technology, fuel system technology, electronics and after treatment - a system solution - to meet the 2010 EPA standards, company officials have said.

Meanwhile, General Motors turns to its new Duramax 6.6L V-8 four-valve turbo diesel for Chevrolet and GMC 4500/5500 chassis.

"We'll achieve these standards through both engine modifications as well as the use of a diesel particulate filter," said spokesman Nick Richards. "We'll begin to offer vehicles that meet these standards in January 2007."

Richards said GM made numerous changes last year to the Duramax to improve fuel efficiency and noise vibration harshness (NVH) and additional updates are expected next year to meet the EPA's emissions requirements. He added those specific alterations will be announced "closer to the start of production."

Detroit Diesel has its own version of EGR, the Mercedes-Benz 900, with an accompanying after-treatment system including a diesel particulate filter, closed crankcase and hydrocarbon doser.

Alternative Fuels 

"As for 2010, DDC will rely on many of the same technologies, as well as the SCR (Selective Catalytic Reduction technology)," said company spokesperson Liane Bilicki.

SCRs are essentially an extra catalytic converter that injects urea into the engine to after treat NOx and basically reduce levels to almost zero. But the technology is still subject to EPA scrutiny.

"I think you're going to see that for 2010 engines," said the NATFC's Cregar. "It's the most promising NOx abatement technology (engine manufacturers) have come up with."

He admitted questions do remain, such as, "How does the engine run when urea runs dry?"

Caterpillar said it is already has engines in the lab that are running in compliance with 2010 standards without using SCR. Jason Nelson, Cat's OEM account manager within the Bus & Specialty Vehicle Group, said Nelson said the engine manufacturer currently uses SCR in other industries, most notably in electric power generation, but at this time the technology is not proven for on-road diesel applications and no infrastructure is in place to support it.

"Our position has been our primary path is not SCR," he said. "We have every intention of not using SCR, but we're not leaving anything out. The 2010 platform is not finalized. A lot of that comes down from the EPA."

As with the other manufacturers surveyed, GM currently only approves B5 biodiesel blend in its engines but added that it is working to validate B20.

"This will not have any bearing on the changes or after treatment requirements to achieve 2007 emission standards, since the engines may be run on either petroleum diesel or biodiesel blends," Richards added. "In some markets, gasoline engines are considered as an alternative fuel, and we do offer our Vortec 8100 8.1L gasoline V8 in this size chassis as well."

While biodiesel at relatively low blends (under 5 percent, or B5) remains a viable alternative, the engine manufacturers were in general agreement that even more stringent 2010 requirements will make regular diesel as clean as any other fuel available.

"By 2007 and particularly 2010, "clean" diesel will be as clean as any alternative fueled engine at a lower cost," Nelson said.

Source: School Transportation News, January 2006. All rights reserved.