Adding EGR to SCR at Euro VI could cut AdBlue demand

Several of the speakers at Integer Research's Diesel Emissions Conference '07 in Frankfurt said the next - post Euro V - stage in EU truck and bus emissions legislation was likely to require a combination of SCR and EGR technologies. That likelihood depended however on the European Commission's response to the call from several manufacturers, notably Iveco and DAF, urging the reduction in permitted emission levels to be made in two stages, as reported in the last issue of VENT. The EC has to consider that request in the context of the six alternative so-called 'Euro VI scenarios' - pairings of NOx and PM limits - offered for consultation earlier this year.

Truck makers committed to EGR at Euro V, that is Scania and MAN, have expressed quiet confidence that advances in technology now in the pipeline will enable them to meet any of the proposed Euro VI standards without the help of SCR. Likely innovations include higher injection pressures and combustion strategies now emerging as a spin-off from HCCI research. Frankfurt conference speakers from Scania and from Caterpillar both gave upbeat reports of their HCCI developments.

There is concern among some AdBlue suppliers that, should a truck or bus manufacturer currently reliant on SCR for NOx control then add EGR to its engines in order to meet Euro V requirements, the necessary urea dosing rate would fall sharply, with a corresponding drop in demand for AdBlue. But vehicle registration forecasts, particularly of Euro III and older replacements, suggest that the European fleet of SCR trucks and buses will grow at a sufficient rate to more than compensate for falls in average vehicle AdBlue consumption.

Integer Research managing director Tim Cheyne, in his conference presentation,
focussed on the supply and demand for AdBlue, pointing out that though tough competition was holding AdBlue prices down, an opposite effect was now starting to be felt. Increased demand for urea-based fertilisers from growers of the so-called energy crops needed to produce biofuels like bio-diesel and ethanol, was coming up against urea manufacturing plant limitations. That in turn was set to boost the cost of raw urea for AdBlue production, tending to drive up its per-litre price.