Creating new kicks from old soles: How a Dutch recycling company is tackling footwear waste

By Michelle Cohan, CNN

(CNN) — For runners, footwear is one of the most important – and often most expensive – pieces of gear. Experts say the typical lifespan of a traditional running sneaker falls between 500 to 700 kilometers (310 to 435 miles), or about four to six months, depending on usage. With some shoes costing hundreds of dollars, it can certainly add up.

The shoe industry also comes at a great cost to the environment: from production to end-of-life, it generates about 700 million tons of carbon dioxide per year, according to research by Quantis, an environmental sustainability consultancy.

“We are standing on the problem, and nobody sees it,” says Danny Pormes, an avid runner and owner of an athletic shoe store in the Netherlands, who started looking into the industry’s impact on the planet a decade ago.

What he discovered would lead him and his wife, Erna, who’s also his business partner, to develop FastFeetGrinded, a shoe-recycling solution to tackle footwear’s waste problem.

The carbon footprint of shoes

Twenty-three billion pairs of shoes are produced globally every year, with any given pair containing up to 60 different materials, says Yuly Fuentes-Medel, an MIT researcher of fiber technologies, and founder of The Footwear Collective, a non-profit dedicated to driving circularity in the shoe industry.

While footwear generates a significant carbon footprint throughout its lifecycle, from creating the raw materials to manufacturing, what happens at the end of its life is also of concern.

Widely used materials, such as polyester and ethylene vinyl acetate (EVA), can take a long time to break down. According to a 2022 report by MIT, some shoes can take hundreds of years to decompose.

Fuentes-Medel said that with rates of shoe disposal growing in the US, landfills will become increasingly full unless something is done.

Recycling footwear

Footwear is notoriously hard to recycle because it can contain dozens of different materials that need to be processed separately. But the Pormeses decided to try and find a way to recycle shoes in their entirety.

“Everybody told us, ‘it’s not going to work, it’s impossible,’” Danny Pormes recalls. But after months of experimenting in their kitchen – which involved microwaving and boiling shoes, along with a few disasters – they finally came up with a proof of concept. From there, they partnered with a machine manufacturing company, Heilig Group, which helped bring their shoe recycling factory FastFeetGrinded to life.

The process begins by sorting the footwear. From there the different components that make up a shoe – like rubber, foam and plastic – are separated by machines using heat and friction. Those materials are then shredded into small pieces, before being separated out by type, and then refined into recycled materials ready for reuse.

The foam, rubber and textile granules are then sold to manufacturers to be made back into items such as shoe parts, yoga mats, or flooring for playgrounds and outdoor sports centers.

The factory receives unwanted shoes from store collection boxes across Europe, and defective or unreleased sneakers from shoe companies. Pormes says they accept all types of footwear – from slippers, to hefty construction shoes, to flip flops.

Pormes says FastFeetGrinded currently processes about 3,000 shoes per hour – and up to about three million per year.

Driven by EU sustainability goals, other European companies are also leading the way in shoe recycling, like Italy’s Eso Recycling, which collects, processes and creates new materials from end-of-life gear.

“[Recycling] is one piece of the solution that will allow us to reduce the volumes [of shoes] that are circulating,” Fuentes-Mendel says of FastFeedGrinded, but she believes the industry needs advancements in technology and automation for footwear recycling to scale up.

Making shoes from shoes

A shoe made of fully recycled FastFeetGrinded material has yet to hit the market, but brands are making strides to reuse materials. Nike’s “Reuse-A-Shoe” program grinds old shoes into new materials for repurposing. Adidas has used plastic waste collected from the sea in some of its shoe uppers.

Asics is also trying to tackle the issue. “More than 60% of the environmental impact of footwear is coming from manufacturing and the materials that go into the product, so addressing those is something that as an industry, we really need to tackle,” said Romy Miltenberg, manager of sustainability for the EMEA region for Asics.

FastFeetGrinded is the brand’s largest footwear recycling partner in Europe; it takes Asics factory floor rejects, as well as used shoes returned in stores. Miltenberg says the rubber outsoles of the shoes are turned into rubber particles, the midsoles are turned into foam particles, and the uppers are recycled back into textile fibers.

“Right now, we are exploring what we can do with the outcome of those materials,” Miltenberg says, “seeing, can we actually make shoes from shoes again?”

Textile-to-textile recycling can be a challenge, she adds, due to the high-performance standards of the company’s sneakers.

“More than 90% of all new running shoes of Asics contain recycled materials in their uppers, but finding solutions for the midsoles, it’s much more complicated,” she says.

Fuentes-Mendel acknowledges the difficulty of true circularity. “Companies that are in the athletic space have to work in the triangular challenge – sustainability, performance, and style,” she says. “It takes a lot of research and testing to make shoes that potentially can be brought back in a singular cycle.”

She says R&D companies are experimenting with new materials that could one day serve both in the performance and reuse spaces, adding that investments in technology and science will allow the industry to recover value from recycled parts by putting them back into shoes, ideally with the same performance level as virgin materials.

A collective problem

But Fuentes-Mendel believes the problem requires an approach that goes beyond manufacturers. “I wouldn’t say, ‘the brand needs to fix this,’ because it’s not only their responsibility; governments, private entities, silicon suppliers, the FastFeetGrindeds of the world and innovators need to collaborate,” she said.

Consumers also have a part to play. Fuentes-Medel is interested to see how people can be incentivized to care more about their individual impact – whether that’s brands providing tools to extend the life of their shoes or giving gift cards in exchange for used shoes.

Second-hand stores and online thrift retailers also offer a solution to prolonging footwear’s lifespan, as well as non-profits like Soles4Souls that divert shoes headed to landfill and distribute them to those in need.

For its part, FastFeetGrinded has plans to take its operations international.

“The problem is everywhere, so it’s very important to have recycling factories all over the world,” Pormes says.

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