From Trash To Treads: Turning Tomato Peels and Eggshells Into Tires

Scientists at Ohio State University are replacing the petroleum-based filler in tires with food waste


Back when she lived in California, Katrina Cornish found herself wondering about those open trucks she saw carrying big loads of ripe tomatoes. Why, she thought, weren’t the tomatoes on the bottom crushed into big red puddles.

The reason, she would later learn, is that the tomatoes were bred to have tough skins that allowed them to withstand all that weight from above.

That bit of knowledge would come to serve Cornish well after she moved to Ohio State University, where she is a biomaterials researcher. Recently, she and her research team discovered that not only those tough tomato peels, but also crushed eggshells, can be effective replacements for the petroleum-based filler used in car tires.

“What you want in a filler is something really tough and strong,” she says. “That was why we looked at the tomato peels.”

The filler of choice in tires and other rubber products has long been something called carbon black, a powdery carbon product that comprises 30 percent of most tires. In fact, it’s the reason many rubber products are black. Carbon black helps makes the rubber in tires more durable.

But it is in increasingly short supply as demand for cars is rising rapidly in developing countries. At the same time, carbon black production in the U.S. has dropped in recent years as the EPA cracked down on plants emitting excessive amounts of sulfur dioxide and nitrogen oxide.

That has made U.S. rubber manufacturers more dependent on overseas companies for a product that has always been susceptible to fluctuations in world oil prices.

The potential of food waste

So, being able to use food wastes to reduce the amount of carbon black needed could lower costs. It also could bring environmental benefits. “One reason these are such an asset is the whole sustainability issue,” says Cornish. “Carbon black is produced with petroleum. If you could start replacing some of this non-sustainable material with sustainable material, then you’re helping to wean us off petroleum.”

There’s clearly no shortage of food waste in America. Americans consume more than 30 pounds of tomatoes per person per year, according to the Department of Agriculture most of them canned or processed in some way, such as sauce on pizzas. Food companies peel and discard the tough skin. And, every American consumes, on average, close to 270 eggs a year, bringing the total in the country to about 86 billion. Roughly 40 percent of those eggs are used by food companies, which end up shipping tons of cracked shells to landfills. There they sit for a long time because they don’t break down very easily.

“We thought that using eggshells as filler would be a better fate than ending up in the landfill,” says Cornish. “And I was very pleasantly surprised when it turned out that they are a very effective reinforcing filler, and not a diluent filler.”

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