Tread Lightly: New Life for Worn-Out Shoes

When your favorite pair of sneakers wears out, will they end up in the trash, or be transformed into the surface of a playground? Every year, two billion pairs of shoes are sent to landfills, but there are options for giving shoes life as something new.

Nike has a long history of recycling athletic shoes through their Reuse-a-Shoe program; rubber from outsoles is turned into playgrounds, running tracks, gym tiles, and, sometimes, new shoes. Midsoles and uppers become cushioning for basketball and tennis courts. But the company doesn't work with boots, heels, sandals, or any other kind of non-athletic footwear.

Researchers at Loughborough University in England are working on solving the problem of recycling all types of shoes. It's not easy, since most shoes are made from a complex mix of materials that are hard to separate. There also isn't a large financial incentive to recycle footwear, unlike products like cellphones, which contain valuable components.

But the researchers think they're close to an answer. They've created a machine that shreds an entire shoe into tiny particles, and then automatically separates the materials by weight. The resulting mixes can be turned into surfaces or flooring, as in the Reuse-a-Shoe program, or insulation, or even bonded leather.

The system doesn't work perfectly yet, in part because the problem also needs to be addressed at the beginning, with the shoe's design. If designers understand the issues at the end of the shoe's life, they can design with that in mind, choosing materials that are easier to recycle, and possibly avoiding extras, like metal decorations, that make the process difficult.

Eventually, perhaps more designers can reach the holy grail of a cradle-to-cradle process for shoes, where instead of grinding up shoes into a "downcycled" material that's less valuable, shoes can be recycled in a continuous loop without a loss in quality. Nike and a few others are headed in this direction, and perhaps other designers will follow.

Shoe image from Shutterstock