Tires Made of Eggshells and Tomato Skins Now a Reality

Tire manufacturing at its current state is quite harmful to the environment. To make tires more durable, manufacturers use a filler called carbon black, a material made from petroleum byproducts. Unfortunately, carbon black production contributes to dangerous emissions. If the automotive world is serious about sustainability, then such products must be replaced with eco-friendlier versions.

Researchers at Ohio State University (OSU) claim to have found the ideal replacement: eggshells and tomato skins.

Katrina Cornish, OSU Research Scholar and Endowed Chair in Biomaterials, recently patented a procedure that allows for the development of eggshells and tomato peels into a suitable tire filler substance. Both materials offer practical advantages in tire manufacture. Tomato skins offer high-temperature stability, while the porousness of eggshells enable it to bond well with rubber.

With tomato skins and eggshells, tires become stronger and more flexible, the researchers say. Together, they exceed industrial standards for performance, which means it may soon see other applications for rubber.

The case for the eggshell and tomato skin tire filler

Carbon black comprises approximately 30 percent of a tire’s entire structure. Aside from providing stability to rubber, it’s what also gives tires their black color.

The growing demand for tires has led to a significant shortage of the material. Add that to the fact that tire makers import carbon black from oil-producing countries, then we could be looking at more expensive tires in the future if the trend continues.

“The tire industry is growing very quickly, and we don’t just need more natural rubber, we need more filler, too,” Cornish said. “The number of tires being produced worldwide is going up all the time, so countries are using all the carbon black they can make. There's no longer a surplus. At the same time, we need to have more sustainability.”

“We can't just buy some from Russia to make up the difference like we used to,” she adds.

A more than suitable replacement

As carbon black supply dwindles, eggshells and tomato skins abound. America alone consumes almost 100 billion eggs and 13 million tons of tomatoes annually, with their shells and skins going to landfills. Cornish expects the food factories that dispose of these items to become the go-to source for new filler material.

Cornish explains that the technology has the potential to address three problems: allow more sustainable tire manufacturing process, reduce the tire industry's dependence on foreign oil, and keep waste out of landfills.

Reddish brown is the new black

One downside to using eggshells and tomato skins as filler is that instead of black, it produces a reddish brown color. With doctoral student Tony Ren and postdoctoral researcher Cindy Barrera, Cornish is now testing different eggshell and tomato skin percentage combinations and looking to introduce color to the materials.

According to phys.org, the technology for these biowaste-based tires has been licensed to a company called EnergyEne, which Prof. Cornish is the owner of, for further development.