By Daisy Donnelly
A study conducted by the Massachusetts Institute of Technology found that a typical pair of running shoes generates 30lbs of greenhouse gases, the equivalent of keeping a 100 watt lightbulb burning for an entire week.
This is a sizeable environmental impact for a product that does not use electricity or require sophisticated components.
The paper, which was published in the Journal of Cleaner Production, notes, “For consumer products not requiring electricity during use, the intensity of emissions is atypical.”
But what’s even more surprising than the size of a shoe’s carbon footprint is where the bulk of that footprint comes from.
Researchers found that more than two thirds stem from manufacturing processes, with a smaller percentage arising from acquiring or extracting raw materials.
This breakdown is expected for more complex products such as electronics, where the energy that goes into manufacturing fine, integrated circuits can outweigh the energy expended in processing raw materials. But for “less-advanced” products – particularly those that don’t require electronic components – the opposite is usually true.
The study found that much of the carbon impact came from powering manufacturing plants, a significant portion of which are located in China where coal is the dominant source of electricity.
It also found that the many tiny components that go into making a typical pair of running shoes – 65 discrete parts requiring more than 360 processing steps to assemble, from sewing and cutting to injection moulding, foaming and heating – were energy- and therefore carbon-intensive.
“It’s the many small parts – the making it, the manufacturing – cutting out the pieces, injection-molding the rubber, sewing it together,” says Elsa Olivetti, co-author of the paper. “Everything happens in Asia, and that means the shoe has a relatively high burden compared to the extraction of raw materials.”
Nearly 25 billion shoes are purchased around the world every year, with the majority of them manufactured in China and other developing countries. As the paper notes, “An industry of that scale and geographic footprint has come under great pressure regarding its social and environmental impact.”
The challenge for the industry now is streamlining the manufacturing process – and importantly cutting the number of stages within that – without compromising design.
The study had a few pointers for where reductions could be made. It observed that facilities tend to throw out unused material and suggests recycling these scraps, as well as combining certain parts of the shoe to eliminate cutting and welding. Printing certain features onto a shoe, instead of affixing them as separate fabrics, would also streamline the assembly process.
Principal researcher Randolph Kirchain said he hopes the study’s findings will help shoe designers identify ways to streamline the process and cut emissions. Many companies are already evaluating their production methods and even multinationals like footwear giant Asics, which approached MIT about performing the lifecycle assessment, are taking steps towards reducing their carbon footprints.
One company, OAT has already launched a biodegradable sneaker. Read more HERE.
As a footwear designer/manufacturer, have you thought about the environmental impact of your manufacturing process? As a buyer/retailer, does this impact how you buy?
We’d love to hear from you.
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