Benefit/risk assessment of deNOx technologies

Is blue technology green enough yet? DeNOx technologies currently used for on-road diesel vehicles are not where they should be. This has become clear not only because of recent scandals but is evident when looking at long term trends of on-road emission data which proved that gasoline vehicles followed the NOx emission limits which were lowered by 95% from 1990 to 2009. The opposite was found for diesel passenger cars and light duty vehicles. On road measurements indicate that NOx emissions, especially those of toxic and highly reactive NO2 have increased from 1990 until 2005 and are only slowly decreasing and one order of magnitude higher than those of comparable gasoline vehicles.

These findings indicate that deNOx technologies in real world operation are not efficient enough and have to be improved considerably. It is evident that current deNOx technologies emit toxic and environmentally relevant reactive nitrogen compounds like NO2, NH3, HNCO and N2O. These compounds contribute to the overall exhaust toxicity but are not limited by current vehicle legislation which lacks behind here.

Like for particle filters, our lab and partners have established specific analytical procedures to assess the efficiency of deNOx technologies and to monitor secondary emissions like NO2, NH3, HNCO and N2O.

In case you want to use deNOx technologies possibly in combination with particle filters, Empa can also help you to assess benefits and risks of such systems, best in an early stage of development.