Abstract
Emission legislation has been tightened over the last years in European Union (EU) countries. Euro 4 emission standard is mandatory since 1st of October 2006. Euro 5 will be mandatory in October 2009. Meanwhile especially Japan and the US set similar maximum permissible values for nitrogen oxides (NOx) and particulate matter (PM) for reducing exhaust emissions that cause health damages and pollution.
In the EU countries two different technologies, exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) have been marketed by commercial vehicle manufacturers to achieve compliance with emission standards. EGR recirculates parts of exhaust gases to reduce NOx emissions. Particulate matter is mainly filtered in PM Filters. SCR exhaust gas treatment injects an urea solution as a reductant (so-called AdBlue) into the exhaust gas stream prior to a catalytic converter. A chemical reaction inside the catalytic converter neutralizes the NOx emissions. PM is scarcely produced due to the higher combustion temperature. Cost advantages of better fuel economy of SCR engines are partially absorbed by the need for AdBlue.
Most commercial vehicle manufacturers in the EU rely on SCR technology to meet conformity with Euro 4 emission standards. Sales figures show that many customers even skip compliance with Euro 4 legislation to early conform with the stricter Euro 5 standard already today. This reasons especially in incentives that have been introduced in various countries such as road toll reductions or tax exemptions. Additionally better fuel consumption and favourable residual value compared to Euro 4 systems (with EGR) lead to early compliance with the Euro 5 standard.
Keywords: Commercial vehicles, emission, SCR, EGR, European market overview