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Transport Will Produce Less Air Pollution in Future

By 2040, scientists anticipate a reduction in traffic-related emissions of nitrogen oxides by around 80 percent

Good news: by 2040, emissions of nitrogen oxides related to road and rail transport could be reduced by up to 80 percent – due to advances in exhaust gas purification and the introduction of new technologies, among other things. This is the conclusion of a study recently published by scientists from the Helmholtz-Zentrum Geesthacht – Centre for Materials and Coastal Research (HZG) and the German Aerospace Centre (DLR).


Photo: Unsplash/Denys Nevozhai

German motorways extend over a distance of 13,183 kilometres, according to the Federal Ministry of Transport and Digital Infrastructure's inventory of roads. This makes our motorway network one of the longest in the world. On top of that, there are also numerous federal, state, and district roads. But where exactly do most pollutant emissions from cars, lorries, and trains originate? And what will the situation be like in 20 years? Scientists from the HZG and the DLR have dedicated themselves to these questions.

Creating new networks

As part of the "Transport Development and Environment" project, scientists, led by atmospheric physicist Volker Matthias from the HZG, connected the emission models developed there with the DLR's transport and energy models for the first time. These models are based on work carried out by the DLR's Institutes for Transport Research, for Vehicle Concepts, and for Technical Thermodynamics. "The transport models simulate current and future traffic flows and thus deliver concrete statements about the distribution across the respective motorways and federal and district roads – all of this data can now be directly incorporated into our emissions models. This new model chain depicts plausible and realistic scenarios for the first time, with relevant representations that are much more precise," says Dr Volker Matthias, lead author of the study and head of the chemical transport modelling department at the HZG.

Emissions Matthias Graphic En Hzg

Trends in nitrogen oxide (NOx) and particulate matter (PM10) emissions between 2010 (base year) and the three scenarios "Reference", "Free Play", and "Regulated Shift" for 2040. Transport electricity refers to emissions from power plants that supply electricity for transport. Transport refinery refers to emissions from the crude oil refining process for transport fuels. The new model chain was verified by applying the simulations to the year 2010 and showing that the calculated values and trends are consistent with further calculations. Graphic: HZG/Volker Matthias

"Through the DLR Transport and Energy Institute studies we have outlined extensive possible paths for transport development up to 2040. In partnership with the HZG, emissions and their effects on air quality can now be depicted in high spatial resolution, allowing us to gain new insights," says project supervisor Stefan Seum from the DLR Institute for Transport Research.

The researchers simulated three scenarios for the development of transport in Germany up to 2040:

• Scenario 1 "Reference": this scenario assumed a continuation of current policies.
• Scenario 2 "Free Play" is based on strong market-based logic.
• Scenario 3 "Regulated Shift" includes stricter environmental regulations and laws.

The scenarios include various opportunities for development: how strongly will local public transport be promoted? To what extent will car traffic increase? Which vehicles, powered by which energy sources, are being driven? Which technological developments become apparent? What kind of political incentives exist? How are emissions standards developing? Alongside all of the aspects crucial to these scenarios, emission factors were also re-evaluated; for example the abrasion of tyres, brakes, and roads that contributes to particulate matter pollution.

Reduction of transport-related pollutant emissions

"In comparison with today, transport-related NOx emissions (nitrogen oxides) were reduced by around 80 percent in all of the simulated scenarios and particulate matter pollution was also reduced," concludes Volker Matthias. Nitrogen monoxide (NO) and health-endangering nitrogen dioxide (NO2) were grouped together as NOx. These are produced during combustion processes, especially in engines. The emissions in the sustainability-oriented scenario are about a third lower than in the other combustion engine-dominated scenarios. The scientists noted a particularly dramatic reduction in emissions in cities. "The modelling shows that particularly developments in technology and more stringent emissions standards make an enormous difference compared to 2010. Vehicles that produce a lot of emissions will no longer be on the roads. New propulsion technologies and exhaust gas purification technologies will be introduced in cars and lorries; for example, specialised catalytic converters. Rail transport is already largely electrified, and we are well on the way to achieving this thanks to the high proportion of wind and solar energy in the electricity mix." The study has been published in the professional journal Transportation Research Part D: Transport and Environment.

According to the Federal Environment Agency, harmful air pollutant emissions have been declining for several years (with the exception of ammonia) and the calculations by Volker Matthias and his team show that this trend looks set to continue. "We have now applied this new model chain to Germany for the first time – in future we hope to produce these kinds of simulations for Europe as well. In addition, we will now study the concrete effects on air quality using our chemical transport models," predicts Volker Matthias. "Now it is up to our society to focus on sustainable developments and decisions, and up to the economy to implement the appropriate technologies in order to continue improving air quality."

Original Publication


Dr. Volker Matthias Head of Department Chemistry Transport Modelling

Institute of Coastal Research

Phone: +49 (0)171 51 29 525

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Helmholtz-Zentrum Geesthacht

Gesa Seidel Public Relations

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