The Advantages of SCR for Trucks
SCR's major advantage is its ability to deliver excellent fuel efficiency, especially compared to engines using higher rates of exhaust gas recirculation (EGR) for NOx control. By controlling NOx emissions in the exhaust through SCR, instead of in the combustion process through EGR, diesel engines can be tuned for optimum fuel efficiency - a critical concern with oil at $100 a barrel.

Using lower rates of EGR also results in lower heat rejection, so no massive coolers made from exotic metals are required, resulting in an efficient cooling system. Furthermore, SCR enables greater power densities, which means a smaller displacement engine can deliver the horsepower which otherwise would demand a larger, heavier engine.

While Selective Catalytic Reduction (SCR) is a new system for North American trucks, it is not a new technology. SCR is a reliable and proven technology, and is now the dominant emissions reduction technology for heavy-duty trucks in Europe. In addition, SCR has been used for several decades in marine and large stationary diesel engines.

SCR is a straightforward aftertreatment technology that only requires the addition of DEF approximately every other diesel fill-up. The SCR system itself requires very little maintenance and no driver action while the truck is operating.

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