The present wording of implementing the regulation for
type-approval of motor vehicles and engines with respect to
emissions from heavy-duty vehicles (e.g., Euro VI requirements)
describes the procedure to determine gaseous emissions from on-road
measurements using Portable Emissions Measurement Systems (PEMS).
Emissions to be measured according to the PEMS protocol are carbon
monoxide (CO), total hydrocarbons (HC) nitrogen oxides
(NOx) and carbon dioxide (CO₂). Measurement methods of
particles will be included in the Euro VI requirements.
Emission results from on-road testing can be used for In Service
Conformity (ISC) pass/fail criteria but also for establishing
emission factors for specific routes and verification of the fuel
impact on the emissions. During onboard measurement, emission
sampling, measurement of the exhaust parameters and recording of
the engine parameters as well as ambient data shall continue
throughout the normal in-use operation of the vehicle, i.e.,
driving conditions that are mostly used by the operator or fleet
owner of the particular vehicle type.
During the past years a PEMS pilot study has been carried out in
Sweden, supported by The Swedish Transport Agency, in order to
verify the emissions from different types of heavy-duty vehicles
and fuels.
This paper presents some of these results with focus on
evaluating the impact on emissions measured with a PEMS instrument
with regard to different alternative fuels such as Fatty-Acid
Methyl Ester (FAME), Dimethyl Ether (DME), Ethanol and Compressed
Natural Gas (CNG) when the vehicles are driven on the road during a
normal working day. The results are compared with emissions from a
diesel vehicle.