The tire has been around for approximately 200 years — not as long as the wheel, though even that mechanical marvel has been around for only about five to six thousand years. Even so, the tire has had several tweaks and design variations over the years. Now, as the number of used tires pile up, scientists are working to develop more sustainable tires to protect our vehicle’s wheels and the surface of the road.
A New Spin on Tires
An ambitious approach to the problem of making tires green is going beyond the figurative use of the word “green.” During the 2018 Geneva International Motor Show, Goodyear revealed the design for their Oxygene concept tire. The design incorporates live moss inside the tire, which picks up moisture from the road via its tread structure and has a clear panel to allow photosynthesis to occur. This process lets the moss process CO2 from the air into oxygen.
In addition, an energy generation system built into the tire draws electricity from the process of photosynthesis to power light strips in the wheel structures. These lights can be used for signaling direction changes or breaking.
The rubber portion of the wheel is 3D printed using rubber from recycled tires, with a structural design meant to increase grip and tire durability. The design is still a concept, with no date of implementation released, but it does aim high with its goals.
Another, more imminent, eco-friendly tire improvement in the works: creating processes to make renewable rubber. A team of researchers at the University of Minnesota discovered a method by which the rubber-making industries could use renewable carbon resources (such as grasses or corn) instead of the fossil fuels currently used in the process.
With current methods, the production of a single tire requires seven gallons of oil, with five of those gallons used as feedstock to generate the main compound used in rubber — isoprene. The new process transforms plant-sourced glucose from renewable biomass processes into isoprene, allowing the fabrication of synthetic tires without oil. With this process, rubber could be generated from a more sustainable source than rubber tree farms that have been supplanting rainforest environments.
Renewable rubber research is ongoing, with new studies finding that a second biomass-based process for generating butadiene (a monomer used in producing synthetic rubber) is approximately 58% carbon efficient. The study also specifies the process of refining this compound from biomass input, with specific economic and technical factors identified for the best implementation of such a system in the future.
Retreading Old Material
While there are always new ways to approach the design of tires, we still must attend to the remains of older models. Although tire recycling already allows us to reclaim the rubber for reuse, scientists are improving this process.
A rubber additive made by the German company Evonik enables more efficient processing of the rubber. The additive, “VESTENAMER,” is cost-efficient and allows waste rubber to be reworked into a durable enough material for widespread applications, from durable equipment to floor mats to road barriers and even the roads themselves. This helps reduce the carbon footprint of millions of scrapped tires by allowing the rubber to be recovered and reworked into new products.
Also, numerous companies — including Liberty Tire and Genan Incorporated — accept tires for use in industrial processes. These companies will break down scrap tires to rework the materials into different forms of usable scrap rubber — from crumb rubber to rubberized asphalt.
We look forward to future innovations in tire technology that bring us closer to a truly sustainable tire.