ForConstructionPros.com

For 2010, the U.S. Environmental Protection Agency (EPA) will require a reduction in nitrogen oxide (NOx) from diesel engine exhaust. All but one engine supplier for medium- and heavy-duty trucks have announced they will be using a technique known as Selective Catalytic Reduction (SCR). While this is a proven technology, it will be the first time it is implemented on heavy-duty trucks in North America.

"The SCR system is in addition to the exhaust aftertreatment that is generally already in place - in our case, that would be the diesel particulate filter (DPF)," says David McKenna, director of powertrain marketing and sales, Mack Trucks. "The EGR valve and the EGR cooler remain the same, and the DPF remains essentially the same with some very minor updates and improvements."

Mack Trucks asserts SCR is a proven technology that delivers improved fuel economy and near-zero emissions. "It's already being successfully used around the world by hundreds of thousands of trucks every day, including those in extreme operating conditions," says Dennis Slagle, president and CEO. "And it clearly works here in North America, as our test trucks have been demonstrating."

David Siler, director of marketing, Detroit Diesel, adds, "SCR has absolutely proven to be reliable and cost efficient around the world. Nearly 100% of all vehicles meeting the latest Euro 5 standard are doing so with SCR. It has been around in the stationary power generation business since the 1980s, and has evolved into one of the most cost-effective emissions-reducing technologies that just so happens to deliver economic improvements."

Cummins also has significant experience with SCR. "In 2006, Cummins launched its midrange engines certified to the Euro 4 standard using SCR for commercial vehicle applications in Europe," notes Christy Nycz. "Cummins has built and shipped over 45,000 SCR engines to date. Cummins Emission Solutions has built and shipped over 200,000 SCR systems."