Tyre abrasion is now a major problem for electric cars, especially when it comes to heavy cars. The heavier the vehicle, the greater the abrasion. Thus, although electric cars emit fewer and fewer pollutants, the fine dust from the tyres ends up in the air and on the road.
Anyone who rides the metro in Paris or Montreal knows the constant smell of rubber in the shafts and tunnels. The smell comes from the rubber tyres of old underground cars, which are supposed to make the ride feel less bumpy. But what was once considered progress is now a problem. Because the abrasion is very harmful to health. That is why the French environmental organisation "respire" has sued the metro operator RATP, because the underground air that passengers breathe in is three times higher than above ground, with 100 micrograms of fine dust per cubic metre. The French company Tallano has developed a technical solution that directly extracts the abrasion at the source. When the brakes are applied, negative pressure is generated, which extracts up to 85 percent of the fine particles that are abraded. A prototype is already equipped with this technology on the Paris RER suburban railway.
However, the filter system is not only suitable for railways, but also for cars, buses and commercial vehicles. And that is important, because in the meantime less fine dust comes from the exhausts of modern cars than from the tyres and the road surface. Only twelve percent of particulate matter still comes from the exhaust. It can be assumed that the development of a new Euronorm 7 from 2025 will also include this type of pollution. Unfortunately, retrofitting cars with the technology is difficult because there is no storage space. The situation is different with trains, where there is usually more space for retrofitting.
A similar product is also being developed by the German filter manufacturer Mann + Hummel. The biggest difference, however, is that the system does not actively extract the particles but collects them passively. With this system, too, up to 80 per cent of the abrasion can be collected. With both systems, it is important that the braking process is not negatively affected. Bosch is trying a different approach: it is developing brake discs with a coating of tungsten carbide, which is extremely abrasion-resistant. Machine manufacturer HPL Technologies, on the other hand, is using a process in which the coating fuses with the brake pad, thus preventing 90 per cent of fine dust.
Time is pressing: Even though the fine dust limit has not been exceeded in Germany in recent years, it is to be expected that the much stricter WHO limits will be adopted across Europe sooner or later. In the worst case, this could lead to stricter environmental zones and further driving bans in Europe.