The Environmental Protection Agency, OEMs and many trucking fleets have committed themselves to a cleaner environment by reducing NOx (oxides of nitrogen). To reduce NOx emissions that are harmful to the environment and public health, most new diesel-powered engines are equipped with a Selective Catalytic Reduction (SCR) system.
What is SCR and what does this growing technology mean for your fleet?
SCR is an after-treatment emissions control technology that uses a urea based diesel exhaust ﬂuid (DEF) and a SCR Catalyst to signiﬁcantly reduce NOx emissions. SCR is currently used by almost all OEM manufacturers and its adoption across industries utilizing heavy-duty engines is projected to grow — it is predicted that more than 3 million DEF-equipped Class 1-3 vehicles will be on the road in 2016 and more than 5.1 million will be driven by 2018. Most diesel-powered on-road vehicles produced since 2010 utilize SCR technology, including heavy-duty trucks, diesel pick-ups, delivery vans and European luxury cars. In addition, diesel-powered off-road equipment such as agricultural and construction equipment has been required to use SCR technology since 2014.
What are the benefits to utilizing SCR technology?
SCR technology does not change the design or operation of the engine, but does allow manufacturers to tune engines to boost performance, increase engine reliability and achieve fuel savings.
Engines equipped with SCR are able to function at optimal combustion temperatures, which increases fuel efficiency and contributes to the production of engine power. One of the greatest benefits fleet managers recognize with SCR technology is the cost savings associated with increased fuel efficiency. Post 2010 heavy-duty trucks can achieve fuel savings of around 5% compared to 2007 models with similar engine specifications; off-road machines with SCR also report fuel savings of 5% and higher.
SCR also results in longer overall engine life, as there is a reduced dependency on exhaust gas recirculation (EGR), less heat rejection and greater component reliability.
How does SCR work?
To treat the harmful NOx exhaust that is released from diesel engines, SCR systems inject small quantities of diesel exhaust ﬂuid (DEF) into the exhaust upstream of a catalyst, where it vaporizes and decomposes to form ammonia and carbon dioxide. In conjunction with the SCR catalyst, ammonia (NH3) converts NOx to harmless nitrogen (N2) and water (H2O).
DEF is injected into the exhaust stream only as required. It is a non-toxic mixture of high purity synthetic automotive grade urea and deionized water. It is not a diesel additive and is stored independently in a dedicated tank.
How do I maintain my SCR system?
SCR technology has been proven as a beneficial, cost-effective way to comply with EPA regulations, increase fuel efficiency and reduce a fleet’s environmental impact. SCR systems do not require any additional driver training, as drivers need only to read the DEF gauge and fill the tank with high-quality fluids. The growth in SCR systems ensures that drivers will be able to locate DEF at truck stops nationwide to keep your fleet moving cleanly and efficiently for years to come.