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Would You Buy Sustainable Tires Made from Grass and Trees?

by Marguerite Darlington
March 21, 2017 | Our Future

If the answer wasn't an instant "Yes, that's so cool," you might not be 100 percent sold on sustainable anything.

Political agendas aside, "sustainable" is a much more practical concept than most people assume. In fact, you might use it to describe your car tires in a couple of years, thanks to new research from the University of Minnesota.

What exactly does sustainable mean?

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The term as it's used today has its origins in a 1987 World Commission on Environment and Development report, which first introduced the concept of "sustainable development." In this report, development was described as sustainable when it "meets the needs of the present without compromising the ability of future generations to meet their own needs."

Conventional car tires certainly don't fit this definition. From manufacturing to daily use, tires introduce potentially harmful chemicals and particles into the environment that could pose a threat to future generations. The U.S. Environmental Protection Agency has identified tire manufacturing as a major source of hazardous air pollutants (HAPs), and the small particles that break off  during normal use could contribute to both particle and near-roadway air pollution, which cause numerous health harms according to the EPA.

That's where the researchers come in: They've discovered a new technology that makes it possible to produce automobile tires from trees and grasses in a process that could shift the entire tire production industry toward using plant-based resources found in many people's backyards.

"Our team created a new chemical process to make isoprene, the key molecule in car tires, from natural products like trees, grasses or corn," said Paul Dauenhauer, a University of Minnesota associate professor of chemical engineering and materials science and lead researcher on the study.

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The problem with rubber

Today tires are viewed as environmentally unfriendly because they are predominately made from fossil fuels—but that wasn't always the case.

"Historically rubber came from the rubber tree in Southeast Asia," Dauenhauer said. "About twice a year, rubber trees were harvested. They would take out a liquid latex and then extract the rubber material, which includes isoprene. When rubber trees became scarce, we started making tires from petroleum."

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Catalytic conversion of biomass-derived chemicals to renewable polymers occurs in laboratory stirred-tank reactors. Photo courtesy of the University of Minnesota.

Currently, isoprene is produced by thermally breaking apart molecules in petroleum in a process called "cracking." The isoprene is then separated out of hundreds of products and purified. In the final step, the isoprene is reacted with itself to make a solid polymer, the major component in car tires.

Finding a new source of isoprene—especially one from natural materials—has been a major initiative of tire companies for the past decade. Most of the research focused on fermentation technology similar to ethanol production, but it wasn't until researchers from the U of M Center for Sustainable Polymers  combined biological fermentation using microbes with conventional catalytic refining (similar to petroleum-refining technology) that the breakthrough happened. The CSP is funded by the National Science Foundation.

The CSP's "charge is to make polymers more sustainably," Dauenhauer said. "We're interested in materials that can have an impact on society, and one is rubber. It's been an integral material for society for 100 years. Tire companies have been trying to crack it for a while."

Coming to a tire store near you?

The University of Minnesota, through its Office for Technology Commercialization, has applied for a patent on the renewable rubber technology and plans to license it to companies interested in commercializing the technology.

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"At the university, when we invent something, we file patents," Dauenhauer said. "Once we've filed the patents, then we go into early-stage development. Chemistry is figuring out how the molecules move, and chemical engineering is taking those molecules and figuring out how to make it into a big system. So we basically go from making something about the size of a pot of coffee to making something the size of a refrigerator to making something the size of a football stadium. At that point, we know how to mass-produce."

The car tires produced from trees and grasses would be identical to existing car tires, with the same chemical makeup, color, shape and performance.

So you're not going to find tires made from lawn clippings in an aisle at AutoZone next week, maybe not even next year. But it has the potential to disrupt not only the tire industry, but the production of other rubber-based products, like pacifiers.

"Economically bio-sourced isoprene has the potential to expand domestic production of car tires by using renewable, readily available resources instead of fossil fuels," said Frank Bates, polymer expert and University of Minnesota professor of chemical engineering and materials science.

Now I'll ask you: Would you buy sustainable tires made from grass and trees?

Marguerite Darlington
Marguerite Darlington has worked in digital marketing and media since 1999, supporting brands like The New York Times, The University of Chicago Booth School of Business, The University of Wisconsin–Madison’s Wisconsin School of Business, Jessica Simpson, ALDO Shoes and various independent entertainment properties. She joined Twin Cities Public Television as Rewire Director in June 2016.
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