The European Union is in the process of drafting future Euro VI emissions standards for heavy-duty vehicles, which it hopes to bring forward by the end of 2007. The EU is now inviting stakeholders to comment on the future limit values. The Commission says that it will take into account the feedback received in the consultation when drafting the final proposal.
The EU recently went through a similar process on developing the Euro 5 and 6 standards for light-duty vehicles.
The draft Euro VI proposal will establish common EU rules on heavy-duty motor vehicles with regard mainly to their emissions of ozone precursors (nitrogen oxides—NOx—and hydrocarbons—HC) and particulate matter (PM).
The EU developed four scenarios combining different levels of PM, NOx and HC emissions for compression ignition engines (CI) and positive (spark) ignition (PI) engines fueled with gas (natural gas or liquefied petroleum gas) with different levels of stringency. In order to converge to uniform limit values in different parts of the world, two of the scenarios are similar to the future US standards. The EU is also requesting comment on the influence of the different scenarios on fuel consumption and CO2 emissions.
Since gas-fueled buses currently represent around 1% of the buses on the EU market and gas-fueled trucks represent less than 0.5% of the trucks on the EU market, in practice the emission limits for compression ignition (CI) engines (i.e., diesel), will have the most significant impact on air quality.
|Euro VI Scenarios for Heavy-Duty Vehicles|
|NH3||10 ppm||10 ppm||10 ppm||10 ppm||10 ppm||10 ppm||10 ppm||10 ppm|
Limit values in scenario A are considered to be equivalent to the future US standards. Compliance with the emission limits of this scenario would require a higher rate of cooled exhaust gas recirculation (EGR) (in addition to the use of a more efficient selective catalytic reduction (SCR) system). The higher rate of cooled EGR would lead to a higher fuel consumption and hence to higher CO2 emissions in the range of 2% to 3%.
Scenario D could also be considered, to a certain extent, as equivalent to the US standards. Higher fuel consumption with higher CO2 emissions is not foreseen in this case.
Scenario B is stricter than scenario A in terms of NOx for diesel engines but less stringent in terms of PM. This scenario requires a rate of cooled EGR that is considerably higher than that of scenario A. In order to achieve such a high ratio of EGR, scenario B requires an improved cooling system. As a result, higher fuel consumption and thus higher CO2 emissions of around 5% to 6% are anticipated.
Scenario C is the least stringent in terms of NOx emissions; no negative impact is anticipated in terms of fuel consumption/CO2.