Explaining vehicle emissions

A new report by the European Environment Agency (EEA) provides a non-technical guide that describes why, for certain pollutants, vehicles can emit substantially higher emissions on the road than official emissions tested in laboratories. It gives a simplified explanation of the often complex information available on road transport emissions as well as the technologies to reduce them.

Standardised measurements are made in laboratories to check that vehicles meet the official requirements for exhaust emissions. However, the testing procedures currently used in the EU are not representative of real driving conditions. For example, emissions of nitrogen oxides (NOx) from new diesel cars can be more than seven times higher in real driving conditions than in official tests. Moreover, new vehicles can emit up to 40 per cent more carbon dioxide (CO₂) than official measurements would indicate. And this gap has increased in recent years.

The report outlines three main reasons for these discrepancies:

The EU is using an outdated test procedure that does not reflect real driving conditions;
Car manufacturers exploit the permitted flexibilities in the current test procedure to “optimise” certain testing conditions, thereby achieving lower fuel consumption and emission values;
Various in-use factors which are driver-dependent (e.g. driving style) or independent (e.g. environmental conditions).

Work is ongoing in the EU to improve future consistency between official vehicle emissions and real driving performance. This includes changing the outdated official test procedure to one that is more representative of real driving emissions, and introducing a procedure for measuring the real driving emissions of vehicles on the road.

The European Commission is planning to introduce a new test cycle (known as the WLTP) in the EU with a focus on improving CO₂ emissions testing – the timing of this is still to be agreed.

A new real driving (RDE) procedure will measure emissions of NOx, and later also particle numbers, using portable emission measurement systems (PEMS) attached to the car. The new protocol will require the real driving emissions from cars to be lower than the legal limits multiplied by a “conformity factor”. This factor expresses the ratio of on-road PEMS emissions to the legal limits. The NOx conformity factor has been set at 2.1 (i.e. 110% above the Euro 6 limit) from 1 September 2017 for new models and two years later for all new vehicles. In a second step, it will be reduced to 1.5 (i.e. 50% above the Euro 6 limit) from 1 January 2020 for new models and one year later for all new vehicles.

The report “TERM 2015, Evaluating 15 years of transport and environmental policy integration” (Dec. 2015) can be downloaded at: http://www.eea.europa.eu/publications/term-report-2015

In this issue

A 1.5 target is needed to save the Baltic Sea

Effects of global temperature increases on the biodiversity of the Baltic Sea.

CCS in Norway – still a long way from the goal

The CCS project at Mongstad in western Norway was finally cancelled in 2013, causing sarcastic comments about “The Moon landing that failed”.

How to account for emissions of greenhouse gases from imported goods?

Carbon emissions have dropped in many rich countries, Sweden among them. Or is it just that the emitting industries have moved to China? A technical discussion is getting intensely political.

Member states opt for weakening air pollution targets

Compared to the Commission’s proposal, the relaxed targets agreed by member states could result in an additional 130,000 premature deaths by 2030.

The EU should phase out fossil gas

AirClim has published a new report (1) about the need to phase out the use of fossil gas as soon as possible in order to meet the climate targets agreed at the UN Paris Climate Conference in December 2015.

Sanctions missing for ship sulphur sinners

In the first year of stricter standards in the Sulphur Emission Control Areas (SECA) of the Baltic Sea, the North Sea and the English Channel, Swedish authorities took 441 ship fuel oil samples. They discovered 15 violations of the sulphur limit, but none of these resulted in fines or other types of sanctions.

New rules on emissions from medium combustion plants adopted

Despite a widespread agreement on the urgent need to cut emissions to improve air quality, existing installations are given very generous transition periods.

Cutting meat and dairy intake is beneficial for health, the environment and climate

Halving the consumption of meat and dairy in the EU would cut agricultural nitrogen losses by more than 40 per cent and GHG emissions by 25–40 per cent.

Sector targets for aviation and shipping wanted

In the absence of additional action, international shipping and aviation will be responsible for close to 40 per cent of global CO2 emissions by 2050.

Europeans still exposed to harmful air pollution

A new report by the European Environment Agency estimates that air pollution continues to be responsible for more than 430 000 premature deaths in Europe.

A new era for the debate on coal phase-out in Germany

2015 was not only the year of the groundbreaking climate agreement in Paris. It also marked a new era in political efforts on a more actively managed phase-out of power generation from coal and lignite mining in Germany.