Car tyres are a major global waste problem. Collectively we drive 1.5 billion tyres to the end of their useful lives every year. They can be retread and reused up to a point, but not endlessly. And at the end of their usefulness you have a conundrum. End of life tyres (or ELTs) are difficult to process for any kind of recycling, because they’re a complex mix of materials – natural and synthetic rubber, fibre and wire, all in a heavy and unwieldy package. They’re not biodegradeable, so tyres don’t rot down naturally. And every year we use more of them.
This has been an issue in developed nations for a while, and a variety of strategies have emerged to deal with them. The , and 100% of tyres are processed in some way in continental Europe. Some countries levy a tax on tyres and then the government takes charge of them. Most EU countries have made the tyre companies responsible for taking them back at the end of their lives. Britain has a free market for end of use tyres, which manages to deal with 95% of them.
Elsewhere, the growth in car ownership is often outstripping legislation to deal with waste tyres. Billions of them are now stockpiled around the world. So what do we do with them all?
The easiest and worst thing to do with ELTs is to put them in landfill. Here’s a , where tyres are piled up in their millions and then buried in the sand. We used to do this in Britain too, but it’s now illegal under EU waste directives. The trouble with tyres in landfill is that they leach toxins into soil and water. In tropical countries they fill with water and become a paradise for breeding mosquitoes, making them a serious health risk. Even if you’re tempted to ignore both of these issues – because you’re dumping them in the desert, say – they’re also dangerous. Tyre dumps are a fire risk, and burning tyres are notoriously hard to deal with. A valley full of 10 million tyres caught fire near Knighton in Wales in 1989. It took months to put the fire out, and then it smouldered until 2004 – an impressive 15 years.
So landfill is a bad idea. Besides, dumping them loses the materials and energy they contain. But since they burn, maybe that gives us an obvious solution – incinerate them to generate electricity, or for heat in steelworks or cement kilns. This is known as ‘energy recovery’, and that is the fate of about half of Europe’s tyres. They’re quite a good fuel, as it happens. They are as energy-dense as coal, and they don’t produce nitrous oxides. Where they displace coal, tyres could arguably be considered a greener option. But they do produce other pollutants, some of which are a health risk. The exact environmental impact of energy recovery depends on how they are burned and what sort of scrubbing technologies are used, but we’re talking about the lesser of two evils here. It’s better than landfill, but we’re only capturing some of the energy in tyres, and the materials are still lost.
There are a number of ways to reuse the materials in tyres, and since the EU banned sending tyres to landfill, a whole lot of research and development has gone into it. Lots of new businesses have emerged that treat end of life tyres as a resource. One of the more common is the rubberised surfaces used in playgrounds and running tracks. There are only so many of these in the world though. With mountains of ELTs to get through, we need large scale uses – like road building. Ground up tyres are now regularly used in asphalt, and there are several advantages. Roads with rubber in them have better grip, and they’re 50% quieter. They last three times longer than normal tarmac, and don’t need as much maintenance.
Another potential customer is the railways. Recycled rubber pads can be fitted under railway or tram tracks to reduce noise and vibration. Switzerland has been doing this since the 70s. An Italian company called goes one further and has developed a sleeper made from ELTs. This reduces demand for concrete and ballast, and they run quieter too. 35 tonnes of used tyres would go into each kilometer of track using Greenrail sleepers.
In the hierarchy of waste strategies, recycling come after reuse, and many tyres are already retread and sold on. Retreading has been possible for a while, and the technology to do it is better than ever. Unfortunately, public perception of remanufacturing is a problem. 90% of buses and trucks have retread tyres. Taxis and commercial fleets use them. The general public are more sceptical. That’s something that needs to change, as keeping tyres in circulation for longer is one of the simplest ways to reduce the waste mountain. Regulation varies around the world, and nobody wants to drive on inferior tyres, but in Britain retreads have to meet exactly the same standards as new tyres. They should be more common.
Even with all these techniques in play, we have an underlying sustainability problem. Natural rubber is still a key ingredient in tyres, and that means we’re still relying on forests to supply our raw materials. As more people drive, the demand for natural rubber is increasing, and the risk to forests and biodiversity increases too. In the long term, we’re going to need more radical alternatives. And that’s going to have to be another post.
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