Environment and Climate

Exhaust emissions

Since the start of the nineties, the introduction of the standard European exhaust emissions regulations has meant that vehicle emissions in the EU are measured on the basis of a standard driving cycle.

Exhaust emissions legislation in Europe

Conventional vehicles still determine the look of our roads – and with good reason. Modern vehicles are extremely clean, use the energy of their fuel frugally and convert raw energy into the necessary propulsive power in extremely efficient ways. The Euro VI standard has been binding on heavy commercial vehicles since 2014 for reducing exhaust emissions. From September 2015 onwards, the Euro 6 exhaust emissions standard will be binding on all newly registered cars. This means pollution emissions can be reduced by about 95 percent compared to Euro 0. NOx and particulate emissions have been reduced particularly markedly over recent years: 80 percent NOx reduction and 50 percent particulate reduction from trucks in the last level alone (i.e., compared to Euro V). As far as cars are concerned, the 80 percent particulate reduction has already been implemented with Euro V. In Euro 6, it is now the NOx emissions above all that are being reduced by a further 56 percent.

Even if no new exhaust emissions level is currently under discussion – the exhaust emissions legislation in the EU and the UNECE continues to develop further. The Euro VI c level has been mandatory on heavy commercial vehicle since 2014, and imposes tighter OBD limits (on-board diagnosis). For cars and light commercial vehicles, the EU is planning to introduce what it calls RDE legislation as part of a new Euro 6 level c.

Euro exhaust emissions limits are closely linked to the underlying New European Driving Cycle, NEDC for short. In future, the WLTP (Worldwide Harmonized Light Vehicles Test Procedures) will form the legal basis for Euro exhaust emissions legislation. The RDE legislation (Real Driving Emissions) is an addition to Euro exhaust emissions legislation directed towards areas of driving and parameters that lie outside the type test procedure. RDE regulates any kind of driving under any conditions.

The proposal of the EU Commission is for additional possible driving and ambient boundary conditions, extreme weather, environmental conditions and driving conditions to be included. Pollution emissions will be measured using a mobile measuring device (PEMS, portable emission measurement system) attached to the vehicle being measured. As a result of the physics of combustion, pollution emissions from internal combustion engines increase under extreme driving and ambient conditions. NOx emissions-reducing exhaust gas recirculation is restricted under harsh ambient boundary conditions. Exhaust post-treatment can limit this effect of increasing emissions, but not eliminate it. As a result, other limit values will have to be defined for harsh driving and ambient conditions rather than those for the strictly defined measurement conditions in the type test based on the NEDC.

The automotive industry is tackling this challenge of reducing exhaust emissions by developing new exhaust post-treatment systems. The VDA assumes that the RDE legislation will mean that the majority of diesel vehicles will have to be equipped with additional NOx post-treatment technology in future. The EU Commission is planning to introduce legislation for new vehicle types from September 2017 onwards, and for all new vehicles from September 2018. The RDE law is expected to be approved at the end of 2015. As a result, the automotive industry does not have adequate time to prepare for the technical implementation and retrofitting additional exhaust post-treatmenttechnologies to ongoing series production. As a result, the planned date of introduction for ongoing series production in September 2018 must be regarded as particularly critical. The planned introduction of RDE legislation at the present time must be reconsidered under the aspect of a cost-benefit ratio instead. Consequently, the VDA proposes that the regulation should be introduced from September 2017 onwards with a higher limit value (conformity factor), and that this factor should be tightened up five years after publication of the law.

The introduction of RDE legislation is justified by the difficult situation of enabling compliance with air-quality limits in future, even at the measuring points in Europe that are exposed to severe pollution. Euro-6 technology can solve the remaining airquality problems. A precondition is that vehicles equipped with this particularly clean technology achieve rapid market penetration. The automotive industry has presented a proposal to permit rapid introduction of RDE at the same time as drastically reducing real emissions in road transport.

Air-quality simulations carried out by the independent AVISO Institute show that the regulatory approach proposed by the industry will enable the number of violations of air-quality limits in Germany to be reduced by almost two thirds over the next ten years. In the long term, it will even be possible to avoid air-quality violations in Germany almost entirely. As a result, the automotive industry is calling for the regulatory approach that it has proposed to be discussed seriously. Regulatory requirements set far beyond this cannot be achieved either technically or economically, and would lead to a scarcely measurable environmental benefit.

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Key positions of the VDA with regard to RDE

1. The law must be complete and applicable.
Only if the law is complete and robustly applicable will the automotive industry work on its technical and administrative implementation.

2. The law must be introduced with a two-stage approach.
The lead-up time for introduction of the complete regulation by September 2017 is too short. Consequently, the VDA proposes that the regulation should be introduced from September 2017 onwards with a higher conformity factor for new vehicle types. This factor should be tightened up five years after publication of the law, and apply to all new vehicles one year later.

3. The difference between cycle and urban driving must be taken into account when setting the conformity factors.
It is the intention of the EU Commission that these conformity factors should only compensate for tolerances in the measuring sequence; differences between driving on public roads and driving in the NEDC should not be applied. The VDA is calling for realistic conformity factors to be defined that are oriented towards the available vehicle technology, the established ambient and driving conditions as well as the physical qualities of internal combustion engines.

4. Limitation of dynamic band reconditions.
Extreme driving and statistically irrelevant driving conditions can falsify the emissions result and, as a result, it is essential for them to be limited to sensible and statistically relevant parameters in advance so that unnatural driving simply with the intention of increasing emissions will be avoided (e.g., driving only in first gear, pumping the accelerator pedal).

Dr. Jakob Seiler Consultant

Tel: +49-30-897842-285 Fax: +49-30-897842-606
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