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EU Invites Comments on Draft Euro VI Scenarios for Heavy-Duty Vehicles

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
  A B C D
PM 0.01 0.01 0.02 0.02 0.015 0.02 0.015 0.01
NOx 0.4 0.4 0.2 2.0 1.0 2.0 0.5 1.0
THC 0.16 0.66 0.55 1.05 0.55 1.05 0.55 1.05
CO 4.0 4.0 4.0 3.0 4.0 3.0 4.0 3.0
NH3 10 ppm 10 ppm 10 ppm 10 ppm 10 ppm 10 ppm 10 ppm 10 ppm
Increased CO2 2-3% 5-6% Neutral Neutral

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.



Rafael Seidl

For reference, here are the values for HDVs corresponding to those levels in g/kWh. Note that N2 (HDV) emissions are tested using the EDC cycle on an engine dynamometer.

Euro 4 HDV (initial registration 2005-2008):
CO 1.5
NOx 3.5
THC 0.46
PM 0.02

Euro 5 HDV (initial registration 2009-2012):
CO 1.5 (unchanged)
NOx 2.0
THC 0.46 (unchanged)
PM 0.02 (unchanged)


Euro 6 will affect HDVs starting in 2013. The proposed split into compression and positive ignition engines is new. Apparently, the EU commission would like HDV operators to consider switching to CNG/LNG or LPG. This may have more to do with managing the future demand mix for fuels than with clean air considerations. To satisfy demand for diesel, many European refineries already have to produce surplus gasoline and export it to the US.

Note that in all four options, the proposed limits for PI engines are actually less severe than those for diesel. This is consistent with stratified combustion strategies that would make such vehicles more competitive in terms of fuel cost per kWh. The fuel tank systems for CNG and especially, LNG, are a lot more expensive than those for diesel. LPG retrofits are cheap but the fuel is expensive as it is also used as a feedstock by the chemical industry.

Option D sounds like a sensible compromise.

Cameron Dell

I always wondered why trucks have rear ends with hypo-gears and not trans axles. A lot of buses have trans axles in them. By reversing this configuration and using it in a semi a 25% fuel saving and power increase could be achieved. I think there has to be a lot of incremental changes to get the average person off the couch. As long as they has beer, potatoes chips and hockey there will be no riots. When most people are sending less than 3% of there income on auto fuel its only a faint blimp on the radar screen but 10 to 15% maybe. The only other thing to do is to fight the vested interested heavy energy use brainwashing. Hummers and hypo-gears be gone. I don't see the need for them on the scale that we are producing them. Subaru just an announced they will be producing a flat four diesel. Mount that in the back of a van transferrally and that would be my dream vehicle. A diesel pusher van with no rear end.

Rafael Seidl

@ Cameron Dell -

(a) Subaru's design is the first flat diesel ever and it's intended for cars, not trucks.

(b) installing the engine near the rear axle would save weight but also reduce ground clearance and/or increase load height - even with a flat engine. On an 18-wheeler, the vertical location of the trailer coupling is standardized.

(c) rear mounted engines still need to be cooled and fed fresh air.

(d) mounting the engine near the rear axle of a tractor rig would greatly increase noise emissions, which are limited by law in Europe.

(e) trucks are designed to haul loads. For safe handling, you want to make sure you have enough weight on the front axle to maintain control, even in rough terrain.

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