While we enjoy the convenience brought by automobiles, a significant environmental challenge—"black pollution"—is quietly accumulating. Over 1 billion scrap tires are generated globally each year, resembling a black tide continuously flooding into landfills or open dumping sites. They not only occupy valuable land resources but are also highly prone to triggering hard-to-extinguish fires (releasing toxic smoke) and serve as breeding grounds for mosquitoes, becoming a persistent global dilemma. As environmental regulations tighten, simple and crude methods like landfilling and dumping are no longer viable options. How to find a sustainable destination for these durable black rings has become a critical challenge for both technological innovation and environmental responsibility.

I. Traditional Treatment Methods and Their Limitations

Despite the urgent need for recycling, traditional treatment methods often have significant drawbacks:

Direct Landfilling and Dumping: Over 1 billion tires are discarded annually after use, but most end up in landfills or storage sites, sometimes even causing fires. This approach not only occupies land and damages soil structure but also poses fire hazards and long-term environmental risks.

Incineration for Energy Recovery: Energy recovery is a common method, involving burning tires in incinerators to generate electricity or using them as auxiliary fuel for cement kilns and other industrial processes. However, this exacerbates pollution.

While this method can generate electricity or provide heat for cement kilns, the combustion process releases highly toxic pollutants such as polycyclic aromatic hydrocarbons and produces large amounts of greenhouse gases. Essentially, it trades environmental pollution for energy, making it an less-than-ideal green solution.

Therefore, some companies have begun exploring alternative approaches. Since tires are primarily composed of hydrocarbons, it should be possible to convert old tires into low-carbon fuels to power the vehicles they once supported.

Wastefront, a company from Norway, uses pyrolysis technology to transform 80 million old tires into new products. These include 25,000 tons of a viscous black liquid known as tire-derived oil (TDO).

II. Key Steps of Pyrolysis Technology

Tires are broken down into three components: steel (primarily used to support the tire structure and easily recyclable), carbon black (a powdered coal that enhances tire durability), and rubber (a mix of natural and synthetic rubber).

First, the steel support structure of the tire is removed. The remaining material then undergoes a process called pyrolysis, where it is exposed to high temperatures in the absence of air.

This causes the rubber to decompose into a mixture of hydrocarbon gases. Once these gases are extracted, what remains is pure carbon black.

After the extracted gases cool down, a portion of them liquefies into TDO. The remaining gases, including methane, are recirculated and burned to fuel the reactor.

This creates a zero-emission closed-loop system. The total output of this process includes 40% TDO, 30% carbon black, 20% steel, and 10% gas.

III. Utilization Directions

The carbon black can be reused to manufacture new tires. Tire manufacturers are particularly interested in this, as it contributes to achieving carbon neutrality. Producing carbon black from scratch requires partially burning heavy oil residues or coal, leading to significant greenhouse gas emissions.

The recycled tire-derived oil is similar to crude oil freshly extracted from the ground and is highly suitable for producing diesel. To this end, Wastefront is collaborating with Vitol, a Swiss company and one of the world's largest independent oil traders, which operates multiple refineries globally.

IV. Application Prospects

Although the entire process is not carbon-neutral, diesel produced from tire-derived oil reduces CO2 emissions by 80–90% compared to traditional fuels.

While electric vehicles are the ultimate direction for the future, internal combustion engine vehicles (especially heavy-duty transportation like trucks, ships, and construction machinery) will remain prevalent for the next two to three decades. Their demand for diesel will remain substantial. The future clean energy market is likely to remain considerable.

Trucks are harder to electrify and consume large amounts of diesel. Trains and ships also rely on these fuels. During the long transition period from oil to gas, any technology that helps reduce overall emissions is valuable, especially those that address waste issues.

From being a troublesome "black pollution" to a potential "urban mineral," the transformation journey of scrap tires demonstrates the immense power of technology-enabled environmental protection. While pyrolysis technology is not a perfect ultimate solution (its own energy consumption and the comprehensive application of rCB still require ongoing optimization), it is one of the most practical and sustainable paths available today.