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Diesel Engine Technology: Emissions Control – 2010

Whether the choice is SCR or enhanced EGR, manufacturers describe their solutions as ‘proven technology’

By Tom Gelinas
Good news! You won’t be faced with any new engine technology in a couple of years. While engine makers are planning on using various means to qualify their products for the enhanced emissions regulations that will take effect in 2010, all will use technologies long proven on the road. Most manufacturers, especially those with European ties, have indicated that they be using selective catalytic reduction (SCR) to reduce nitrogen oxides emissions (NOx) from tail pipe emissions. This is a technology that has been used in Europe for a number of years but has not yet been used to any extent in the automotive market here in North America.

It’s certainly not a new technology. SCR was first patented here in the United States in 1957 and has undergone development ever since. It is widely used to control NOx emissions from large stationary diesel engines as well as coal-fired power generating plants. It is, in short, a well known and proven technology.

What is SCR?

The Diesel Technology Forum is an organization dedicated to raising awareness about the economic importance of diesel engines. According to the organization, clean diesel technology involves three pieces: low sulfur diesel fuel, low-emitting diesel engines and advanced emissions control devices. Selective catalytic reduction is one of the latest technologies in the last category to be applied to automotive engines. It is capable of almost eliminating NOx, thereby helping engine manufacturers meet the stringent new air quality regulations that take effect in 2010.

All SCR systems inject a chemical through a catalyst into the exhaust stream of an engine. While urea is the primary reducing agent (often referred to as diesel exhaust fluid) presently used in SCR systems, alternatives are possible. The urea sets off a chemical reaction that converts nitrogen oxides into nitrogen and water. These exit harmlessly through the engine’s exhaust system. The Diesel Technology Forum describes SCR as one of the most cost-effective and fuel-efficient technologies available to help reduce emissions. It can reduce NOx emissions up to 90 percent, hydrocarbon and CO emissions by 50 to 90 percent, and particulate matter (PM) emissions by 30 to 50 percent. SCR systems can also be combined with a diesel particulate filter to achieve even greater emission reductions for PM.

North America will see SCR technology playing a key role in achieving emissions reductions that will allow light-duty diesel powered vehicles to meet emissions regulations that will be phased in through 2009.

Since the diesel exhaust fluid must be carried in an onboard tank, refills will be needed periodically. The major challenge to the widespread application of the SCR technology is the need to establish a nationwide distribution network of high quality urea to locations that can be easily accessed by truckers. While vehicles could continue to function normally even without the urea solution, the emissions system would not meet NOx reduction requirements. The EPA considers this to be a very serious problem that needs to be solved before the 2010 deadline. Manufacturers are currently working with the EPA to address these technology and emissions performance challenges and fully expect to have them solved in time.

Avoiding SCR

One obvious way to handle these concerns is to avoid using SCR, and that’s just what Navistar is planning on doing. Bob Carso, the director of marketing and brand strategy for Navistar’s engine group, says, “We explored both EGR and SCR technologies and found both to offer viable solutions for meeting the 2010 emission requirements. We made our choice in terms of what we believe to best for our customers and selected to pursue the EGR path.”

A recent report published by Frost & Sullivan, a consulting firm, outlined a number of attributes offered by SCR-independent technologies. Included in them are: attractive upfront cost for fleets intending to keep vehicles for a relatively short period, no driver intervention issues, no necessity for developing a urea infrastructure, independence from urea price volatility, fewer design challenges and no onboard urea storage and delivery system. These are all attractive attributes, but they come at a cost –– decreased fuel economy compared to engines using SCR technology.

Carso says, “As a result of increasing EGR rates as modestly as we see will be necessary, about 10 percent, we expect only a 1.5-to-two percent degradation in fuel economy compared to today’s engines. We planned for an EGR solution as we developed our MaxxForce engine technology. We will have higher injection pressures as we move forward. That means we need a very robust structure in the engine line, and we designed that structural capability into our complete line of MaxxForce engines. This allows us to go ahead with an EGR solution with a high degree of confidence. Aftertreatment will remain as it is today. We’re simply advancing proven technology and anticipate no reduction in performance from a driveability point of view. We have proven and reliable technology in place, and we’re going to extend that into 2010. For our customers, it will make 2010 a seamless issue for their businesses. We believe EGR is the best technology to offer our customers at this point in time.”

Proven yet unfamiliar

SCR technology has been mentioned in technical meetings and trade journals for several years, but it is a subject with which few people, and almost no equipment managers, have any first-hand experience –– at least not here in North America. It is, however, a technology that has been around awhile in Europe. Most North American engine manufacturers chose to use EGR when engines were first required to comply with emissions regulations. In Europe truck builders chose to use SCR. That continues to the present. Ed Saxman, product manager for drivetrain at Volvo Trucks North America, says, “In Europe, Volvo uses straight SCR. We currently have at least 150,000 SCR equipped trucks in service there.”

That company chose to take advantage of its own experience when selecting the technology it would use to qualify its engines for the 2010 emission regulations. Saxman says, “We considered all available technologies, but all directions led to selective catalytic reduction in combination with cooled EGR. The more EGR you have, the greater the heat rejection requirement will be. This lowers efficiency and power density, resulting in poorer fuel economy. Volvo’s objective is to maximize fuel economy and offer the lowest cost of operation to include both fuel and diesel exhaust fluid (urea). We expect that for every dollar a fleet spends on diesel exhaust fluid it will spend $2.00 less for diesel fuel. Fuel economy of SCR engines will be better than today’s engines and performance will be better because we will have a lower percentage of EGR. SCR is going to deliver the lowest overall cost.”

Detroit Diesel Corp. (DDC) recently announced plans to use Daimler’s BlueTec solution in its 2010 engines, which utilizes SCR as a critical component of its system. “We will be utilizing BlueTec technology for our Detroit Diesel engines beginning in 2010,” says Chris Patterson, president and CEO of Daimler Trucks North America. “The technology is clearly the best choice for our customers. It is the only means of meeting the stringent NOx standard for heavy-duty diesel engines in 2010 while actually reducing diesel fuel consumption in comparison with the technology used in 2007 engines.”

According to Mike Delaney, the company’s senior vice president of marketing, the BlueTec system is expected to increase fuel efficiency by three to five percent in a typical North American truck fleet.

“We’ve known for quite awhile that we would be using BlueTec but felt compelled to make a formal announcement so people would understand that we will be using a technology that is globally accepted and not a brand new hardware design,” says David Siler, DDC’s director of marketing. “We will be using technology that has been in use in Europe on Mercedes Benz trucks for several years.” Since early 2005, Daimler has delivered more than 100,000 trucks and buses around the world utilizing this technology.

According to Siler, the availability of diesel exhaust fluid (DEF or urea) is more of a concern than acceptance of the engines themselves, but the company is working very closely with truck stop chains as well as urea manufacturers to assure adequate availability. Delaney points out that Daimler Trucks of North America alone has over 850 locations where it will be available. “Add the truck dealers, diesel distributors and service points of the other OEMs committed to SCR, and there will be over 1700 points of supply going in,” he says. “With a range of 5,000 to 6,000 miles — or nearly twice the width of the whole country — one would have to work pretty hard to run out of DEF. The toughest remaining issue about SCR is not the technology, and it is not the infrastructure. The only real issue remaining, and the toughest ground to cover, will be education.”

Some of each

Cummins announced some time ago its plans for 2010 compliance. The company’s on-highway marketing director, Louis Wenzler, says, “Cummins will continue using the Cummins particulate filter (DPF) and EGR in 2010 on both our heavy-duty engines as well as our midrange products. For heavy-duty, Cummins will use a no-NOx aftertreatment solution. Cummins midrange products will use SCR. We expect engine performance will be equal to or better than the 2007 Cummins products. Both heavy-duty and midrange products will be comparable to the fuel economy offered by our 2007 products.”

He says, “Development of our 2010 product is right on schedule. We’ve already produced our first round of field test units, which are scheduled to go into service in tandem with our development efforts in the tech center.”

Using products originally designed by DAF, the Dutch truck builder and a PACCAR division, both Kenworth and Peterbilt will be introducing proprietary engines late in 2009. These engines, like the Mack/Volvo and DDC families, will build on emission control technologies from their European origins and use SCR to achieve 2010 compliance. Alan Treasure, PACCAR’s director of marketing, says, “For 2010 we will be using SCR technology to meet the NOx regulations in conjunction with the existing EGR and DPF technology that has been required for 2007 engines. This decision was based on our European experience.”

PACCAR’s two North American truck divisions, of course, will still offer engines built by their independent partners, so its customers will have an option regarding what exhaust emission technology they will use.

Tom Gelinas is Editorial Director of Fleet Equipment, Engine Builder’s sister publication. For information on the Diesel Technology Forum visit www.dieselforum.org.

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