Tyres: the secret polluter

Automotive emissions are a hot topic, but increased regulation coupled with industry-wide innovation is driving consumers towards greener alternatives. More effective particulate filters mean that even combustion engine exhaust gases, although still laden with CO2, are now particulate-ly clean. In any case, electric or hydrogen powered vehicles would appear to be the final solution to automotive pollution.

However, recent national winners of the 2020 James Dyson Award, The Tyre Collective, are looking beyond traditional exhaust emissions to address a little known polluter - tyres.

Beyond the Exhaust

Tyres are thought to be the second largest source of micro-plastic particulates. As a tyre turns, its surface abrades against the road, loosening tiny particles of surface rubber which are jettisoned into the air and deposited onto the road. Indeed, the worn-down tread has to go somewhere.

Comparing the particulates found in exhaust gases, which average a mere 4.5 milligrams per km, tyre originating particulates are released at a rate of 5.8 grams per km - over 1000 time higher. What’s more, emissions increase with vehicle weight, so heavy, battery laden electrical vehicles tend to produce more tyre-born particulates. Combined with the rise in mileage and speed expected to brought about by autonomous vehicles (see our blog The future of tyres in the driverless age), tyres are fast becoming the primary source of automotive particulate emissions.

Most tyre particulates end up in water systems, and ultimately in the ocean. They are now thought to make up 10% of total ocean micro-plastics. However, tyre dust also contributes around 3 to 7 % of the particulate matter in city air, which the Netherlands Open University estimates has contributed to between 130,000 and 300,000 deaths globally.

The Tyre Collective

Recognising the magnitude of ‘in use’ tyre pollution, The Tyre Collective, a group of graduates from Imperial College London and the Royal College of Art, have developed an innovative way to capture tyre particulates at the source.

As tyres rub against the road, electrons are lost from the tyre thus giving it a slight positive charge. The Tyre Collective’s system leverages this charge difference, by using an electrostatic array to attract and capture the positively charged tyre particulates.

The award-winning design also takes into consideration the complex aerodynamics of a spinning wheel and tyre. The system cradles the tyre and is positioned close to the road so airflow is directed past the charged array - initial testing shows that the system captures around 60% of airborne tyre particulates.

Ultimately, the captured tyre dust can be retrieved and re-used in the manufacture of new tyres, making for a truly circular process (see our blog Circular tyres: a new challenge for the circular economy).

James Dyson Award

Innovation focussed competitions like the James Dyson Award encourage teams from across the world to recognise esoteric problems and bring them into the mainstream. Off the back of the James Dyson Award, the tyre particulate problem has received a huge publicity boost, and is beginning to attract attention across the industry.

With this in mind, The Tyre Collective are seeking patent protection for their seminal electrostatic system, to secure an early foothold in a relatively unexplored sector. It will certainly be interesting to see how The Tyre Collective maintain momentum as big names in the automotive industry, and new start-ups alike, begin to ramp up innovation in this space.