Bus emission evaluation: 2002-2004 Summary report

Nils-Olof Nylund, Kimmo Erkkilä

    Research output: Book/ReportReport


    Within 2002 – 2004, VTT measured altogether 34 different Euro 1 – EEV certified city buses. All measurements were made on VTT’s new chassis dynamometer. The output of the measurements is truthful emission factors in the form of g/km.

    There were large variations in the regulated emissions. Diesel Euro 1 vehicles and EEV natural gas vehicles make up the extreme ends. The NOx emission varied from some 20 g/km for Euro 1 diesel vehicles to around 2 g/km for the most advanced natural gas vehicles. For particulates, the spread was even greater, i.e., from 0.6 to 0.003 g/km, a difference of a factor of 200. Good news is that real-life emissions seem to be falling with advancements in Euro classes.
    The work included PM emissions of low-emitting CRT diesel vehicles and natural gas vehicles. To stay operational, a CRT filter needs some service. Natural gas vehicles showed extremely low PM values independent of mileage. Older CNG vehicles show rather high THC or methane emissions. For a detailed diesel/natural gas bus comparison, seven modern buses, three diesel-driven and four CNG vehicles, were tested for emission performance. The measurements included regulated emission components and a number of speciality measurements. A CRT type particle filter improves the emission performance of a diesel vehicle in many ways. However, with current technology the best natural gas buses outperform the CRT diesel vehicle in most respects.
    Original languageEnglish
    PublisherVTT Technical Research Centre of Finland
    Number of pages51
    Publication statusPublished - 2005
    MoE publication typeD4 Published development or research report or study

    Publication series

    SeriesVTT Processes. Project Report


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