Many of us lace on a pair of running shoes with the intent of walking to a destination and thereby reducing our carbon footprint by a bit. But just one pair of running shoes generates 30 pounds of carbon dioxide emissions — the equivalent of keeping a 100-watt light bulb on for one week – scientists from MIT have found.
What’s more, most of that energy is expended in the manufacturing process, as the researchers learned after analyzing a pair of Chinese-made men’s size nine Asics gel Kayanos. The rest of the energy is generated from the processing of raw materials.
Billions and Billions of Synthetic Running Shoes are Bought Every Year
Some 25 billion running shoes were purchased around the world in 2010; Americans alone buy some 58 million pairs a year. Most are made in China, Cambodia and developing countries where environmental and human rights regulations are far less stringent than in the U.S. (as revealed by the calls for a global boycott of Nike over conditions in its factories in the 1990s). You can recycle your running shoes, but people tend not to.
Electronic devices require many parts and hundreds of steps to put together and a commensurate expenditure of energy. “Less advanced products” that do not contain any electronic components tend to require a far less complicated process to manufacture, but not so with synthetic running shoes. Made of plastic, polyester and other synthetic components, a typical running shoe contains about 65 discrete parts and needs more than 360 processing steps to put together — cutting, sewing sewing, injection molding, foaming, heating.
By highlighting the amount of carbon emissions produced in the making of one pair of shoes, the MIT researchers hope that manufacturers might figure out steps where reductions could be made. For instance, factories often throw out unused materials; what if they recycled the scraps? Researchers also noted that certain features could be printed, rather than separately added, onto a shoe, to lessen the number of steps in the manufacturing process.
Shoe Companies Say They’re Seeking to Make More Sustainable Shoes
Shoe companies including Nike, Adidas and Patagonia have said they are trying to develop more sustainable methods for manufacturing running shoes. Nike has sought to reduce waste with its “Flyknit” technology (in which the upper part of the shoe is one piece, reducing the amount of fabric wasted) and says that nearly 85 percent of its footwear manufacturing waste is not being sent to landfill or incinerators, but is recycled and otherwise disposed of. Patagonia and Timberland both make some types of shoes that, after use, are meant to be disassembled and recycled.
Another shoe company, Brooks, has been working with its suppliers in China to develop more eco-friendly methods of producing shoes. Most of the components of running shoes are made, as Runner’s World puts it, “exclusively from heavily processed crude oil.” But other materials could be used: sockliners could be made from bamboo; shoes could be assembled with glues that are less toxic; soles could be made from recycled materials and even rice husks. Shoes could also be packaged in boxes made of recycled materials.
Athletes, non-competitive runners, parents outfitting their children and anyone who wants to go for a walk to follow the doctor’s orders and exercise all have certain demands about their shoes. They must be sturdy, of course, comfortable and able to endure a few rounds in the washing machine — as Runner’s World notes, foam made from recycled materials does not perform as well; it rebounds faster and degrades at a faster rate. Some want their shoes colored and styled in certain ways. Some choose to replace their running shoes frequently.
Running shoes could be made with more sustainable methods and greener materials, but consumers need to realize that the finished product might not be what they are used to. Certainly, any one who is active needs shoes that fit and are durable. But the next time you reach for a new, “economically priced” pair of shoes, keep in mind that that it is 30 pounds of carbon dioxide emissions — quite a big carbon footprint! — you are swapping your old pair for.
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