Rolling car tires into the global circular economy

Addressing the Challenge of Tire Pollution through Circular Economy Solutions

A Toxic Conundrum

Tires typically start their life’s journey in the tropics, with rubber produced predominantly by smallholder farmers on monocrop plantations. Current production methods risk ongoing deforestation and harm to biodiversity, along with uncertain livelihoods for farmers. Some 70% of the world’s natural rubber ends up in car tires with most coming from tropical countries such as Thailand, Indonesia and Malaysia.

But natural rubber is just one component found in a modern tire. Like the cars they’re fitted to, tires are composite products, made of steel and hundreds of chemicals and compounds that give them durability and strength.

Unpacking tire environmental impacts is complicated, say experts, partly due to that complexity, and also due to the lack of publicly available data on tire ingredients.

What is known is that tire impacts are spread far and wide: Rolling on roads wears them down, releasing microplastic particulates everywhere — making them one of the most common pollutants in Earth’s oceans today, according to research.

“We know enough to say that it is possibly the biggest, and possibly the least well understood, environmental problem related to transportation,” says Nick Molden, CEO of Emissions Analytics, a company that conducts research into tire wear.

Some tire waste kills. A tire additive known as 6PPD, for example, has been identified as particularly alarming. The mass die-off of coho salmon in the U.S. Pacific Northwest has been linked to tire wear via chemical pollution in the form of this antioxidant.

As it protects tires, 6PPD transforms into 6PPD-quinone, a highly toxic chemical. Edward Kolodziej, who led the team that made the discovery and a researcher at the University of Washington Tacoma, describes 6PPD-quinone as possibly one of the most toxic substances known to aquatic species.

Since its discovery, researchers have found 6PPD and 6PPD-quinone in fresh- and saltwater, ocean sediments, air, soil, and human urine; yet its overall ecological and health impacts remain unknown. Many other tire chemicals lack sufficient study as to risk.

Chemical-laden tires at the end of their life pose a serious waste management headache. Landfilling them is no solution; no matter where they’re dumped, heaps of aging tires become a pollution source as they break down, leaching toxins into soils and aquifers. Burning tires, another common practice, merely transfers that toxic burden from soils and waters to the sky. Research shows that open burning can emit carbon monoxide, nitrogen dioxide, sulfur dioxide, particulate matter, and other compounds at potentially harmful levels, posing a risk to human health.

Circling the Tire Economy

At its core, the circular economy seeks to reduce, reuse and recycle materials in closed loops, with zero waste as the ultimate goal. Tires are prime circularity candidates, say analysts, because when discarded they retain a wealth of useful materials. But getting at those materials, processing them, and making a profit doing so is a major challenge.

“Successful ELT [end-of-life tire] management systems … foster circular flows of materials … and avoid the unregulated dumping of tires,” says Gavin Whitmore, senior communications manager at the Tire Industry Project (TIP), a group that includes some of the world’s major tire manufacturers.

But ELT recovery is woefully inadequate today. A 2019 TIP report noted that in 45 countries surveyed, just 42% of end-of-life tires were used in material recovery and 15% in energy recovery. Some common management options include shredding tires into small rubber pellets for use as construction filler, in rubber-modified asphalt, or in artificial sports pitches.

Millions of waste tires become alternative energy, dubbed tire-derived fuel, burned in kilns for the production of cement, steel, pulp and paper. This market is only set to grow in coming years, say analysts, due to its low cost and reported reduced carbon emissions. Some argue that tire-derived fuel could even lessen the heavy environmental footprint of the cement and paper industries, while helping dispose of tire waste.

TIP notes that “energy recovery can be a particularly efficient way to deal with high volumes of ELT and eliminate long-standing stockpiles because it is generally technically straightforward to implement” while “the use of ELT as an alternative fuel is also encouraged to reduce CO₂ emissions.”

But some experts argue that these common disposal routes — grinding down tires or burning them — amount to little more than downcycling, failing to maximize the full potential for material reuse of waste tires.

Not surprisingly, some of these trumpeted solutions are also plagued by their own environmental issues.

Researchers in Ireland, for example, found that the spreading of rubber crumb on artificial sports pitches is a source of microplastics and may pose health concerns due to the toxic chemicals locked up in the materials. The European Union is aiming to ban this widespread practice, potentially leaving a backlog of tires to be disposed of properly.

Making Old Tires New Again: Reusing and Recycling

Two other solutions tipped to deal with tire waste on a large scale offer the promise of circularity: devulcanization and pyrolysis, both of which could ultimately make new tires out of old, according to analysts.

“The most important part of the circular economy for tires is getting the original product back into its intended application,” says Jon Visaisouk, chief operating officer of Tyromer. His company produces dev

SDGs, Targets, and Indicators

SDGs Addressed:

• SDG 12: Responsible Consumption and Production
• SDG 13: Climate Action
• SDG 15: Life on Land

Targets Identified:

• Target 12.5: By 2030, substantially reduce waste generation through prevention, reduction, recycling, and reuse.
• Target 13.3: Improve education, awareness-raising, and human and institutional capacity on climate change mitigation, adaptation, impact reduction, and early warning.
• Target 15.2: By 2020, promote the implementation of sustainable management of all types of forests, halt deforestation, restore degraded forests, and substantially increase afforestation and reforestation globally.

Indicators Identified:

• Indicator 12.5.1: National recycling rate, tons of material recycled.
• Indicator 13.3.1: Number of countries that have integrated mitigation, adaptation, impact reduction, and early warning measures into national policies, strategies, and planning.
• Indicator 15.2.1: Progress towards sustainable forest management.

Analysis:

The issues highlighted in the article are connected to several Sustainable Development Goals (SDGs). The main SDGs addressed are SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 15 (Life on Land).

Under SDG 12, the article discusses the need for circular economy solutions to reduce waste and promote responsible production and consumption. It emphasizes the importance of reducing, reusing, and recycling materials in closed loops to address the tire pollution problem.

SDG 13 is relevant because tire wear releases microplastic pollution and contributes to climate change through carbon emissions. The article highlights the need for sustainable solutions to reduce tire-associated environmental impacts and mitigate climate change.

SDG 15 is connected to the article’s discussion on the environmental harm caused by tire production and disposal. It emphasizes the need to address deforestation risks and protect biodiversity in rubber supply chains.

Based on the article’s content, specific targets that can be identified are Target 12.5 (reduce waste generation), Target 13.3 (improve education and awareness on climate change), and Target 15.2 (promote sustainable forest management).

The article mentions or implies several indicators that can be used to measure progress towards the identified targets. For Target 12.5, the indicator could be the national recycling rate, measured in tons of material recycled (Indicator 12.5.1). For Target 13.3, the indicator could be the number of countries that have integrated climate change measures into national policies and planning (Indicator 13.3.1). For Target 15.2, the indicator could be the progress towards sustainable forest management (Indicator 15.2.1).

Table: SDGs, Targets, and Indicators

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Source: news.mongabay.com

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