Fuel Effects on Regulated and Unregulated Emissions from Two Commercial Euro V and Euro VI Road Transport Vehicles
Substantial advances in European road vehicle emissions have been achieved over the past three decades driven by strengthening revisions in emissions legislation and enabled by advances in fuel, vehicle engine and emissions control technologies. As both vehicle technology and emissions legislation in Europe continue to evolve, Concawe has conducted a study to examine the effects that fuels can have on emissions, in this case from commercial road vehicles.
A bus certified to Euro VI emissions level and a delivery truck certified to Euro V emissions level have been tested on a chassis-dyno over the World Harmonized Vehicle Cycle (WHVC) and Transport for London Urban Inter-Peak (TfL UIP) test cycles with six fuels: an EN590-compliant B5 (petroleum diesel containing 5% biodiesel by volume), a bioderived paraffinic diesel, a 50:50 blend of the aforementioned fuels, a low-density petroleum-derived B5, a B30 and the same B30 additized with a high dose of cetane number improver (CNI). Results show reduced NOx reductant (AdBlue) consumption with paraffinic diesel in the Euro VI bus due to lower engine-out NOx emissions. More surprisingly, higher hydrocarbon emissions were observed with some low-density hydrocarbon fuels in the Euro V truck.
Compared to B5, B30 with and without CNI did not affect tank-to-wheel (TTW) CO2, volumetric fuel consumption or NOx by statistically significant margins. When considered with the findings of a complementary light-duty study, it is apparent that low-density diesel fuels could offer overall benefits to both emissions affecting local air quality and to greenhouse gas emissions on a TTW basis. The addition of higher fatty acid methyl ester (FAME) levels to fuels can be used to increase renewable fuel contribution resulting in no penalty in NOx emissions from modern technology vehicles. Compatibility of these fuels with the existing vehicle fleet would require further specific consideration. Outside of fuel properties considerations, Euro VI after treatment systems can increase N2O emissions at the tailpipe through chemical reactions in the catalyst. This can translate into about 10% contribution of N2O emissions to the overall GHG emissions of the vehicle.