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The carbon footprint of your running shoes

From the cradle to the grave, a typical pair of running shoes generates 30 pounds of carbon dioxide emissions. The biggest gas-emitting step might surprise you.
Written by Janet Fang, Contributor

A typical pair of running shoes comprises 65 discrete parts, requiring more than 360 processing steps to assemble. During its lifecycle, the pair will generate 30 pounds of carbon dioxide emissions -- that’s like keeping a 100-watt light bulb on for a week.

But where does the majority of that footprint come from? The results will help shoe companies identify ways to improve designs and reduce shoes’ social and environmental impact. MIT News reports.

Japan-based ASICS approached MIT’s Randolph Kirchain to perform a "lifecycle assessment" to break down the various steps involved with one pair of running shoes to identify hotspots of greenhouse-gas emissions.

The researchers divided the shoes’ lifecycle into five major stages: materials, manufacturing, usage, transportation, and demise (burned, landfilled, recycled). The last three stages contributed very little to the carbon footprint.

More than two-thirds of a running shoe’s carbon impact can come from manufacturing processes, with a smaller percentage arising from acquiring or extracting raw materials.

In particular, powering manufacturing plants located in China, where coal is the dominant source of electricity, contributes to a large part of the emissions. And, various manufacturing processes -- sewing and cutting, injection molding, foaming and heating -- are more energy-intensive for small, lightweight components, compared with materials such as polyester and polyurethane.

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 often the case.

The researchers spotted places where reductions could be made. For example, manufacturing facilities could recycle unused scraps or combine certain parts to eliminate cutting and welding. The findings may also help industries assess the carbon impact of similar consumer products.

The results were published in the Journal of Cleaner Production.

[Via MIT News]

Image: GrejGuide.dk via Flickr

This post was originally published on Smartplanet.com

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