On-road Emissions of Conventional and Hybrid Vehicles Running on Neat or Fossil Fuel Blended Alternative Fuels

Fuel consumption is already one of the parameters taken into account for the final ranking of some competitions organized by the Federation International de l'Automobile (FIA). Pollutant emissions, such as CO, HC and NOx, could also be taken into consideration in the near future. In occasion of a competition organized by the FIA in the framework of the “Alternative Energies Cup” championship, several vehicles were equipped for demonstration and scientific purpose with portable emission measurement systems (PEMS) in order to measure the gaseous emissions during the competition. The competition took place at the Autodromo Nazionale of Monza on the same track used for the Formula 1 Grand Prix as well. For this competition the track was divided into three sections simulating respectively the typical speeds and driving patterns on urban roads, on extra-urban roads and on motorways. To be admitted to the competition the vehicles had to use either neat alternative fuels or fossil fuels containing at least 50% of alternative fuels like biofuels. Of the nine vehicles monitored during the competition, four were hybrid vehicles using different fuels (gasoline/ethanol, Compressed Natural Gas-CNG, Liquified Petroleum Gas - LPG, biodiesel), three vehicles were running on natural gas, one running on LPG and one on biodiesel. The Joint Research Centre of the European Commission, in collaboration with Sensors Europe GmbH, provided the instrumentation and the expertise to measure the vehicle emissions during the competition. The data collected were not only used to generate the final ranking of the competition but were also analysed with the purpose of assessing on-road emission performance of some vehicles and fuels, like gaseous ones, that are usually considered environmental friendly by public opinion and even by local/national authorities. The picture emerging from this exercise points out that there is no clean fuel in absolute terms. The emission performance of a vehicle actually depends on a combination of closely intertwined factors as engine technology and settings, after-treatment devices, fuel quality and driving conditions. In addition, on-road emissions resulted in some cases higher than the limits the vehicles had been certified for. In this respect, on-road NOx emissions resulted to be the most critical. Moreover it was demonstrated that bi-fuel cars running on gaseous fuels and equipped with after-market kits improperly tuned may exhibit higher emissions than identical models in their original configuration.