Tyres, the polluter nobody talks about.

Wherever you go someone is going to talk about the mobility of the future and there is no shortage of concepts: Car-sharing, e-bikes, scooters, delivery services instead of shopping yourself, battery powered vehicles vs. fuel cells...

There is one environmental aspect that is not going to be affected by all these and this is the tyres all these vehicles roll on, regardless of what their power train looks like or who is driving or owning the vehicles in question.

So, what's happening in the world of tyres and what's happening to said tyres once they've reached their end-of-life?

Tyres come in all sizes but in they are all very similar.

They are essentially rubber-coated arrays of steel wires and textile fibres, but:

Interesting things are happening in the world of tyres.

One major aspect of the environmental impact of tyres is the rubber which is either made from oil or harvested from rubber tree plantations in the rainforests, causing a considerable transport footprint.

The German tyre manufacturer Continental, in collaboration with the Fraunhofer Institute for Molecular Biology and Applied Ecology, has developed a rubber from dandelions,[01, 02], yes, the pretty yellow flowers.

These flowers have the advantage of growing in European climates (the plantation next to the plant, as the marketing department of Continental put it).

Dandelions have the added advantage of growing on poor soil which would not be suitable for growing food, so the no-food-for-oil debate is elided.

Dandelion flower

The tyre company Goodyear, on the other hand, is working on a tyre which releases oxygen.

They do this by incorporating a moss into the rubber matrix of the tyre.

Continental dandelion truck tyres

This moss will then absorb CO2 and emit O2 by way of photosynthesis.[03]

Goodyear Oxygene Tyre

These are current research projects, the products are not on the market as yet.

Presumably even further into the future is the following, truly revolutionary development: Spherical tyres.

Apparently, Goodyear is working on spherical tyres in which magnets are embedded into the rubber matrix and electric coils are place around the spherical tyres.

Goodyear's spherical tire

The car will levitate on its tyres, and the nifty upshot of this is that you could park into the smallest of niches simply by moving sideways, have a look.[04]

Goodyear's spherical MagLev tyres

Fascinating and inspiring as all these (potential) developments are, the question of recycling run-down and worn-out tyres is pressing in the here and now already.

Unsurprisingly, given their intended use, the rubber is very resistant to wear and tear, there's the rub.[05]

Recycling tyres is very difficult.

In general, what happens to run-down tyres is that they are burnt (e.g. in cement kilns) or they are dumped in (legal or illegal) landfill sites.

Either way, the environmental balance is disastrous (although a very small number may find their way into kiddies' playgrounds).

A German company [06] has now found and commercialised a way to completely recycle old tyres. First, the tyres are shred.

The textile fibres obtained from the tyres are converted into thermal insulation materials for the building industry.

The steel from the steel wires are re-sold as well.

The remaining rubber is then subjected to pyrolysis, which yields three products:

  • A) Hydrocarbon gases,

  • B) carbon black (coke), and

  • C) oils.

The gas is then used to power the pyrolysis plant, whereas the coke and the oils are sold as commodities to various chemical industries, an interesting and salute-worthy example of a circular economy!

Whether in the future we will drive cars or bicycles, whether we will own or just use the vehicles, whether they will be powered by combustion engines, batteries, fuel cells or some other technology, the tyres for all these vehicles are already recyclable.

And that is very welcome news.

Institute of Scrap Recycling Industries

01) https://www.continental-tires.com/car/tires/tires-for-the-future/, last accessed 2021.04.14

02) https://www.ime.fraunhofer.de/en.html

03) https://www.tyrepress.com/2018/03/goodyear-faces-the-future-with-new-tyre-concepts/, last accessed 2021.04.14

04) https://www.youtube.com/watch?v=oSFYwDDVgac/, last accessed 2021.04.14

05) http://shakespearestudyguide.com/Hamlet%20Text.html, line 75, last accessed 2021.04.14

06) https://www.pyrum.net/en/for-a-cleaner-world/, last accessed 2021.04.14