Diesel debate: fine dust instead of nitrogen oxides??

Diesel debate: fine dust instead of nitrogen oxides?

Inversion weather situation in the Black Forest. Photo: Mummelteich. License: CC BY-SA 3.0

The traffic scientist Matthias Klingner points out that "a large part of the measured particulate matter emissions is naturally caused and influenced by the diurnal variation of the sun"

Matthias Klingner is head of the Fraunhofer Institute for Transportation and Infrastructure Systems (IVI). In the Dresdner Neueste Nachrichten (DNN) he draws attention to a phenomenon that was or still is unknown not only to many readers of this local newspaper: that by far the largest part of the particulate matter in the air does not come from the exhaust gases of cars, but has quite natural causes, which even after a total ban of vehicles with combustion engines may well ensure that the limit value is exceeded.

To prevent this, it was also necessary to prohibit the laws of physics – or the sun, which, by warming the ground, causes warm air to rise and sink again when it has cooled down. This 200 to 2000 meter thick "roller" from rising and sinking air swirls up dirt that is invisible to the human eye, but regularly accounts for up to 40 micrograms of particulate matter, the limit of which is 50 micrograms per cubic meter. In winter, when the cold layers of air above the rollers cause them to condense, the natural levels of particulate matter can reach as high as 140 micrograms. Especially when it does not rain for a long time.

Of the five to eight micrograms of particulate matter contributed by cars, only two to four micrograms come from their exhaust fumes – the rest is caused by vehicles kicking up dust. Dust that electric vehicles also kick up. Or horse-drawn vehicles, which environmental extremists like Niko Paech propagate. Even a "complete closure of the traffic" was therefore "in fact not reduce the peak load at all."

Antagonistic contradiction

Nitrogen oxides, on the other hand, do come from internal combustion engines to a relevant extent. Especially when these engines burn their fuel at very high temperatures that ensure little particulate matter is formed. This combustion at high temperatures, demanded by eco-politicians, has the side effect that it also burns the nitrogen contained in the air. The nitrogen monoxide (NO) that is formed during such combustion at high temperatures later oxidizes in the air to nitrogen dioxide (NO2).

Because, according to Klingner "an antagonistic contradiction" is, "to reduce particulate matter and nitrogen oxide levels at the same time through clever engine management", in his opinion, one should concentrate on the factor whose proportion can really be reduced in a relevant way, and the in his opinion "nonsensical" particulate matter limits "should be made less stringent" or abolish them again. Then engineers could develop engines that co-fire as little nitrogen as possible.

"Utopian wishful thinking"

According to Llarena, a complete replacement of internal combustion engines by electric motors, as envisioned by the Grunens, is utopian wishful thinking "utopian wishful thinking", because the batteries of electric vehicles still store far too little energy, take up too much space and take too long to recharge. "If you fill up your diesel in two minutes", according to the traffic scientist in an illustrative comparison, then "you would need three rough windmills to charge the battery of an electric car in the same amount of time" – and "no battery can currently withstand such high charging currents." Also the "environmental balance of the electric car" and "and batteries in particular" is, in his words "not as brilliant as it is often portrayed (cf" (cf. Study: Electric cars in China more harmful to the environment than gasoline-powered cars). Therefore, he said, one should continue to research this intensively, but not overthrow anything.

In Klingner’s opinion, public transport, which already hardly functions in Munich due to overcrowding at rush hour and would be extremely uneconomical in rural areas, is not a patent invention either. "The philosophy of the 70’s, I only have to hinder the traffic enough, then everyone will switch to buses and trains", has, according to his impression "nowhere true", which is why he advocates a "sensible transportation mix" that can be discussed "be discussed free of ideology" should.

However, the Fraunhofer Institute director is rather pessimistic about the chances of such an ideology-free discussion coming to fruition. In view of the real diesel debates, which are partly led by people whose scientific knowledge is not sufficient to distinguish between gases and solid particles, this pessimism is probably also realistic. The question he poses as to why truths and illusions that are openly exposed in the diesel debate are so seldom openly expressed may also have something to do with actors whose warning behavior was scrutinized by the Frankfurter Allgemeine Zeitung (FAZ) in an article published yesterday.

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