Daimler Trucks North America defends its decision to adopt SCR (May 01, 2008)

by James Menzies

LOUISVILLE, Ky. – During its press conference at the Mid-America Trucking Show, Daimler Trucks North America took aim at what it referred to as “misinformation campaigns” and “scare tactics” about the future of Selective Catalytic Reduction (SCR), the technology Daimler has chosen to meet impending EPA2010 emissions standards.

“SCR is not some hypothetical, future technology, as some would have you believe,” Michael Delaney, senior vice-president of marketing with Daimler Trucks North America, announced. “It is a technology that has been thoroughly tested and proven in realworld applications.”

He pointed out that Daimler alone has already placed more than 100,000 SCR-equipped trucks into service around the world. Here in North America, Daimler and Volvo Group have both chosen to use SCR to meet the 2010 emissions standards. International Truck and Engine, on the other hand, has opted for increased use of exhaust gas recirculation (EGR) and Cummins has a foot in both camps – SCR for mid-range engines and higher levels of EGR on the heavy-duty side. Delaney said Daimler’s decision to pursue SCR was based on the fact “SCR works for everyone. It works for OEMs, it works for truck customers and it works for the EPA.”

“We and most other truck OEMs like it a lot because it brings value to our customers without trade-offs,” he explained. “We can hit the most stringent emissions targets and hit our reduced fuel consumption targets at the same time.”

Most notably, Delaney said SCR allows companies to improve fuel mileage by 3-5% compared to today’s technologies. On the other hand, he noted “increases in exhaust recirculation, heat rejection and altered combustion processes demand trade-offs we’re not willing to make.”

Some proponents of EGR have raised questions about the viability of SCR in North America. Daimler officials dedicated the majority of the company’s press conference to dispelling some of those statements.

Will urea be available?

A chief concern about the use of SCR is whether or not diesel exhaust fluid (DEF, or urea) will be readily available. SCR systems consist of a separate tank that houses the exhaust fluid. That fluid is injected into the exhaust stream, creating a reaction that emits only harmless water and nitrogen.

Delaney pointed to Europe to show availability of urea won’t be a problem. There, the demand for AdBlue (the European version of urea) increased from 55,000 tonnes in 2006 to more than 415,000 tonnes in 2007. Meanwhile, points of supply have increased from 200 retail pumps to about 1,600 in the same time frame.

In North America, Delaney said there will be more than 1,700 points of DEF supply in the early stages of SCR adoption. “One would have to work pretty hard to run out of DEF,” he said.

Top-ups are only required every 5,000-6,000 miles, Delaney pointed out, so drivers should have no difficulty in ensuring they have adequate access to DEF.

Urea – is it toxic?

Delaney also challenged statements that ammonia, a by-product of SCR, is toxic.

“Urea is widely used as fertilizer for food crops, in chewing gum and in skin cream and in many, many other applications that you touch or consume every day,” he said.

“It is not harmful to the environment, poses no real hazards when used properly, and it certainly is not under scrutiny for government regulation.”

Delaney admitted some ammonia is created during the SCR process. However, he added “it exists for just a fraction of a second before it is immediately decomposed again into harmless nitrogen and water in the SCR catalyst.”

He went on to explain an oxidation catalyst is also included in the SCR system to capture any trace amounts that happen to escape.

Will it be accepted?

Daimler officials were adamant that SCR will be embraced by the North American trucking industry, largely because it can meet emissions targets while also improving fuel economy.

“There is no disaster looming,” Delaney insisted. “There is only opportunity and that opportunity is taking shape all around you…SCR will play a major role in our industry’s future – that’s a certainty. The toughest remaining issue is not the technology. And it’s not the infrastructure. The only real issue remaining, and the toughest ground to cover, will be education.”

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