SCR, or Selective Catalytic Reduction, is an emissions control
technology first employed on coal-fired power stations to clean
oxides of nitrogen (NOx) from the exhaust gasses. In 2006, the
technology successfully crossed into the European heavy-duty diesel
market, where it enabled trucks to meet the Euro IV and V limits.
An SCR system uses AdBlue and a vanadium or base metal catalyst mounted in the vehicle's muffler to reduce NOx to water vapour and atmospheric nitrogen. This reaction takes place downstream of the engine in the exhaust system and is known as "after-treatment". Unlike the alternative EGR technology - championed by MAN and Scania - SCR tackles the problem outside of the engine and has the potential to achieve >80% NOx reduction rates, allowing the engine to be tuned for maximum efficiency. Having the engine set up for maximum efficiency allows for an estimated fuel saving of 3-5%, giving operators the opportunity to save thousands on their annual diesel fuel bills.
• Daimler (Mercedes)
• Renault Trucks
The European Commission sets the limits for harmful pollutants - including NOx and particulate matter (PM) - within its Euro IV and V legislation. The legislation is binding and limits the emissions of all vehicles >3.5t registered after the implementation date. Euro IV was implemented in 2006, and Euro V in October 2009. All new registrations within the European Union must meet Euro V emissions standards.