Like it or not, cars have an impact on the environment before they even hit the road. So, it’s no surprise that manufacturers are looking at ways to make vehicle production more sustainable through the use recycled materials. However, we’re guessing making tyres from food waste isn’t something you’ve considered before.
It’s what researchers at Ohio State University have been up to, in a fascinating project that could revolutionise tyre manufacture. Katrina Cornish - the university’s Research Scholar and Endowed Chair in Biomaterials - has developed a patent-pending procedure to turn eggshells and tomato peels into a material that could replace carbon black.
Carbon black is a not particularly pleasant, petroleum-based product that’s used as a filler in tyre construction, making up about 30 per cent of your typical hoop. It’s what makes the natural rubber more durable, makes the tyre appear black, and is a material that’s in short supply, says Cornish.
Replacing it with something more durable is a damn good idea, especially when you consider 100 billion eggs are consumed in the USA alone every year. Half of those are cracked open in food factories, leaving an extraordinary amount of waste which has a habit of sticking around for some time. Reducing the waste while providing a more sustainable replacement for carbon black sounds like a win win scenario, and then some.
It’s the same situation with tomato peels. 13 million tonnes of tomatoes are eaten in the USA each year, with a big chunk of those - again - going through food factories. There the peels are frequently discarded to make products like tomato sauce and tinned tomatoes.
It gets particularly interesting when you learn that these part-recycled boots might actually perform better than the rubber we use now. Cindy Barrera, a postdoctoral researcher from Cornish’s team, said: “Fillers generally make rubber stronger, but they also make it less flexible…We found that replacing different portions of carbon black with ground eggshells and tomato peels caused synergistic effects - for instance, enabling strong rubber to retain flexibility”.
It’s down to the “porous microstructures” of the shells giving a “larger surface area for contact with the rubber,” and as a bonus, tomato peels are apparently “highly stable” at high temperatures.
But if carbon black gives tyres the aesthetic they currently have, what kind of colour is this part-recycled tyre rubber? A “reddish brown” apparently, varying slightly depending on the amounts of each food waste used. But tyre manufacturers do consider aesthetics quite carefully, so don’t worry - if this is the future of tyre construction, I’m sure there’ll be artificial ways to make them black again…