Mack, Volvo say OK to SCR solution for 2010

LEHIGH VALLEY, Pa. Mack Trucks has joined parent truckmaker Volvo trucks and other OEMs in declaring that Europe’s preferred emission reduction technology will also be the company’s solution to meet stringent 2010 North American EPA regulations.

Mack and Volvo will use a combination of current exhaust gas recirculation (EGR) technology and selective catalytic reduction (SCR) to satisfy the nitrogen oxides (NOx) portion of the 2010 federal diesel engine rules, which cut emission levels another 80 percent from the upcoming ’07 standard.

The base engines for Mack’s 2010 solution will be its MP series, which utilize High-Performance Exhaust Gas Recirculation (HEGR). The company also confirmed its ’10 solution will still feature the diesel particulate filter (DPF) being deployed for 2007, as the required particulate matter emissions levels remain the same for 2010.

“We’re confident that the combination of HEGR and SCR is the best choice for our customers,” said Mack President and CEO Paul Vikner. “We intend to continue working closely with EPA and other stakeholders to finalize the infrastructure to ensure the widespread availability of urea to our customers.”

A urea tank, like this one ahead of the fuel
tank on a Mercedes, would likely hold 25-40 gal.

SCR is what most European OEMs are presently using to comply with the Euro 4 emissions regulations. It is an aftertreatment system that involves injecting a liquid urea solution into the engine exhaust stream, which then reacts to produce ammonia to break down NOx.

Manufactured primarily from natural gas, urea is a soluble nitrogen-based compound widely used in agricultural fertilizers and considered a non-hazardous substance by the EPA.

Critics of SCR — including Caterpillar, which last year warned the technology is not the best choice for North American on-highway applications — insist that regulating the required urea addition will be a challenge since new infrastructure must be built for the logistically complicated North American market.

Furthermore, the combined cost for fuel and urea would negate nearly all of the fuel-saving benefits of SCR, claims Cat, which has been marketing its own proprietary ACERT technology since the 2002 emission rules took effect. Others also point out that urea is known to gel in cold climates and the tank system itself could be vulnerable to external damage.

However, several engine manufacturers on this side of the pond have either committed to or hinted that SCR is the only viable path for meeting the 2010 EPA standards.

“We believe it’s the only technology that’s mature enough to fulfill the [2010] emissions requirements,” DaimlerChrysler’s technical chief Dr. Gerald Weber said in a prior interview with Today’s Trucking. (DaimlerChrysler is the parent company of Freightliner, Sterling and Western Star brand trucks in North America, as well as Detroit Diesel).

Volvo Powertrain vice president of Engine Engineering Tony Greszler told Today’s Trucking in a recent interview that he expects roadside suppliers to gear up to meet the urea demand by 2010. Besides, by then urea will be needed in much lower concentrations than what’s currently demanded in Europe, he predicted at the time.

However, there’s also a good chance that urea may not be as big a factor as first thought. As reported in an exclusive story this week (link below), Eaton Corp. announced it is working on a new SCR-based diesel exhaust aftertreatment technology which, quite uniquely, does not need urea to produce ammonia and therefore eliminates the need to carry the substance on board. The system makes its own ammonia.

Eaton said it’s been working on the solution for three years and has engaged in talks with engine and truck manufacturers globally. It’s the company’s first foray into the diesel exhaust aftertreatment business.

As for Mack, Vikner says the company has been successfully running SCR systems on prototype trucks since 2000, logging more than two million miles on 10 customer vehicles. He also noted that Volvo has logged more than 23 million miles of SCR road testing in Europe.

“Our experience indicates that vehicles utilizing SCR can achieve better fuel economy than those using only EGR for NOx control, while at the same time meeting the dramatically lower emission standards coming in 2010,” Vikner said.

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