Rubber tyres have supported over a century of safe and comfortable motoring.
But disposing of used tyres presents problems.
Most tyres are made of rubber, followed by large sections of black carbon and silica, and then metal. Small amounts of hazardous materials, including copper, zinc, cadmium, and lead can also be part of their mix.
In the United States, over 242 million scrap tyres are generated each year. This is in addition to about 2 billion waste tyres.
On the Mexican border, there are more than 42 tyre mountains. The largest contains more than 4.5 million tyres.
In New Zealand, as many as 4 million tyres are retired each year.
Of these, about 3 million are sent to landfill, 700,000 are used for purposes like farm silage covers, while 300,000 are illegally disposed of.
When casually stored or landfilled, old tyres represent a large risk of being burned, causing pollution.
Above ground, old tyres can also become ideal breeding places for vermin and undesirable insects, such as mosquitoes. When the tyres are encased in the earth and removed from the elements, they may take thousands of years to decompose. Under certain conditions, they can disintegrate and may leach some of their hazardous materials. Because of such problems, a number of countries decided to try to export the problem away to poorer nations. However, even the poorer countries have increasingly realised they are not open to a trade that seeks to only dump this waste.
Most countries have begun to try to manage this problem. First, they have extended the lifetimes of once-used tyres, by having them either regrooved or retreated, which can save up to 80 per cent of the materials and energy needed to make a new tyre.
When the reused tyre can no longer meet safety standards, then it is recycled for another use.
Such recycling accounts for the fate of about 30 per cent of all tyres in Europe. Tyres can be reused for coastal protection, or for building materials.
They can be shredded, granulated, or chemically taken apart, so that the valuable parts, such as the rubber, can be reclaimed and fed into virgin compounds or used for over 100 different products.
In the US, ground rubber from 12 million scrap tyres a year is used for highways.
Tyres can also be used for energy. Very broadly, a tonne of tyres is the equivalent to a tonne of good-quality coal, or 0.7 tonne of fuel oil. Energy recovery through incineration is the leading recovery for scrap tyres in most OECD countries. In France, Germany and Sweden, up to 65 per cent of the total quantity of used tyres is incinerated in cement kilns. New Zealand has a number of cement kilns where such processes could probably be copied, but this is at present not the case.
New Zealand has not developed an active market in recycling tyres or using them for energy production because it is both legal, and cheaper, to landfill them. We have no law on end-of-use tyres. Rather, we have followed the Australian example where each region develops its own standards. South Australia, Tasmania, Victoria, Western Australia and the Sydney metropolitan area landfills have all banned disposal of whole tyres.
In New Zealand, while some landfills will no longer accept whole tyres, many still do, for between $1 to $4.
Even those which do not accept full tyres are often willing to accept those which have been shredded or quartered. This approach is the opposite of best practice overseas.
Between reuse, recycling and use for energy, the European target is that by 2015, 95 per cent of their waste tyres will be accounted for.
In the US, 49 out of 50 states have now addressed scrap-tyre management. Just under 50 per cent of their end-of-use tyres are being used for energy, five times higher than it was at the beginning of the 1990s, and a further 15 per cent are being recycled.
Although banning the landfilling of tyres largely solves the problem of creating a steady supply of the raw material needed for those who wish to invest in this area, additional regulatory measures are needed.
To ensure compliance it is also necessary to effectively ensure people do not dispose of their waste tyres illegally. While the maximum penalty for an individual for dumping a tyre as litter in New Zealand is up to $500, or $2000 for a corporate, in Britain the fine is up to £20,000 ($38,700). Active engagement in terms of extended producer responsibility of tyre makers is essential. It is only when all of these factors work in unison that public and market confidence for the solutions will eventuate, and this problem will be solved.
Alexander Gillespie is a professor of law at University of Waikato.
Dialogue Contributions are welcome and should be 600-800 words. Send your submission to email@example.com. Text may be edited and used in digital formats as well as on paper.By Alexander Gillespie