SCR, or no SCR ...

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That seems to be the big question today as engine makers focus on the 2010 emission standards: do you incorporate selective catalytic reduction (SCR) into your emission solution ... or not?


International Truck & Engine Corp. joined Cummins Engine Co. in the 'No SCR' catergory today, announcing that it won't use SCR at least for its highway products. Cummins said Sept. 24 that it would use SCR only for its medium-duty engines, not its big bore units. Meanwhile, Volvo and Detroit Diesel Corp. are both adopting SCR to meet 2010 emission regulations -- and may be joined by Paccar, which is bringing its European-built MX heavy-duty engine line to the U.S. sometime in 2009, after it opens a new $400 million engine plant in Missouri.


Paccar's MX line uses SCR to meet European truck emission regulations, as do Volvo and DDC's products, so it's a no-brainer to do the same in the U.S. as all three build "global engine platforms" designed to be tweaked only slightly for the specific regions of world they are sold in. For example, DDC -- which unveiled its new DD15 in mid-October -- said only 10% of the components in its new global engine platform change from market to market; the rest remains the same.


Though Caterpillar as yet hasn't committed to a 2010 solution, it's already on-record against SCR. In 2005, J. Parker -- then-VP at Caterpillar Power Systems Marketing -- issues a statement urging the on-highway market to keep the technology options open regarding 2010 emissions. "Several engine manufacturers have indicated that SCR is the only viable path for meeting the 2010 EPA standard--however, our research indicates SCR might not be the best choice for on-highway applications," he said two years ago.


What's the hang up with SCR? Basically, it's an emissions after-treatment technology that relies on injecting urea -- an amonia compound -- into the exhaust stream to reduce NOx emissions. Not only does such a system require its own complex array of sensors and electronic controls, it needs a tank or urea solution on board that must be refilled as the truck travels down the highway. Dan Ustian, chairman, president nand CEO of Navistar (International's parent company) said that means North America's highways would need a urea distribution infrastructure to be operationally mature when 2010 vehicles hit the road.


Also, while International found SCR to be a way to effectively meet 2010 emissions standards, it adds to the cost and complexity of use of commercial vehicles for truck and bus fleet operators. I've heard that "extra cost" could be another $10,000 above what truckers are paying for 2007-compliant engines, but I caution that this is only an estimate. Urea itself is a cheap chemical compound and requires no special storage -- a simple plastic tank will do. Even if it freezes, it's still good -- once it thaws and becomes liquid again, it's ready for use. And DDC and Volvo both believe using SCR can help boost fuel economy, recovering MPG lost to the technology demands of 2007.


The upshot is that 2010 is already looking very different that 2007, as the engine makers are going to be offering different emission compliance solutions -- something that didn't happen this year. How that affects trucking's bottom line, however, remains to be seen.

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