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The International MaaxForce eingine for 2010 will...
SCR system functional design. (Courtesy of the Di...
Volvo has considered all technology for its 2010 ...
DDC will use Daimler’s BlueTec (SCR) product for ...
PACCAR engines will be using SCR technology to me...
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
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
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.
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
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
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
Tom Gelinas is Editorial Director of Fleet Equipment, Engine Builder’s sister publication. For information on the Diesel Technology Forum visit www.dieselforum.org.