Comparison of real driving emissions from Euro VI buses with diesel and compressed natural gas fuels

• Published in: Fuel (Guildford) Vol. 289; p. 119836
• Main Authors: Gómez, Arántzazu, Fernández-Yáñez, Pablo, Soriano, José A., Sánchez-Rodríguez, Luis, Mata, Carmen, García-Contreras, Reyes, Armas, Octavio, Cárdenas, M. Dolores
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-04-2021; Elsevier BV
• Subjects: Air pollution; Buses; Chemical reduction; Circuits; Compressed gas; Compressed natural gas; Diesel; Diesel fuels; Driving; Driving ability; Emission analysis; Emission measurements; Environmental conditions; Euro VI; Flow rates; Greenhouse gases; Heavy-duty vehicles; Mass flow rate; Modular equipment; Natural gas; Nitrogen oxides; Pollutant emissions; Pollutants; Public transportation; Real Driving emission procedure; Selective catalytic reduction; Temperature; Euro VI; Pollutant emissions; Real Driving emission procedure; Diesel; Heavy-duty vehicles; Natural gas
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2020.119836

•Emissions from Euro VI-C Diesel and Compressed Natural Gas (CNG) buses were compared.•Euro VI In Service Conformity (ISC) route requirements were chosen for testing both buses.•Both buses were tested in Madrid, Spain, city with approximately a 6.5 million population.•NOx and particles emitted along the route are mainly affected by the traffic under urban driving.•Both Diesel and CNG buses produced very low emissions compared to Euro VI C limits.
Public transport bus service is extended in big cities and cleaner bus fleets are encouraged to reduce greenhouse and air pollutant emissions in high populated areas. In this work, real driving emissions produced by two Euro VI-C buses, one fueled by diesel fuel and one fueled by compressed natural gas, were measured. Both vehicles with different engine technologies but with the same pollutant emission certification, were tested in Madrid (Spain), in order to compare their emissions under the same route. The buses were instrumented with a modular on-board Portable Emissions Measurement System, the OBS-ONE by Horiba. Regulated gaseous emissions and particle number were registered together with different vehicle parameters: speed, exhaust mass flow rate, air and fuel consumption, environmental conditions and global position coordinates during the route. THC emissions from CNG bus doubled those obtained with Diesel bus. Slightly higher NOx emissions from the Diesel bus, with selective catalytic reduction, were obtained during those parts of the circuits (mainly urban) where both the exhaust and the operation temperature of the after-treatment device were below the light-off temperature. However, the CNG bus emitted a greater number of particles, mainly on the rural sector of the circuit. Finally, NOx and particle number concentrations along the route showed that traffic is a determining factor in creating areas with high concentrations of pollutants.