Whenever I fly, I always pay the extra $ for what the airline I usually use call ‘carbon offsets’. As I travel a lot (probably too much), it gives me the warm fuzzies known I have done something to reduce the carbon footprint of my travel. During the last few weeks I was a parent helper at my daughters school trip to a sustainability center and have worked with them on a school project that they had to do. So my interest picked up when this morning, there was a press release in my alerts for a study on the carbon footprint from running shoes. Here is the study that the press release was talking about:
Manufacturing-focused emissions reductions in footwear production Original Research Article
Lynette Cheah, Natalia Duque Ciceri, Elsa Olivetti, Seiko Matsumura, Dai Forterre, Richard Roth, Randolph Kirchain
Journal of Cleaner Production, Volume 44, April 2013, Pages 18-29
What is the burden upon your feet? With sales of running and jogging shoes in the world averaging a nontrivial 25 billion shoes per year, or 34 million per day, the impact of the footwear industry represents a significant portion of the apparel sector’s environmental burden. A single shoe can contain 65 discrete parts that require 360 processing steps for assembly. While brand name companies dictate product design and material specifications, the actual manufacturing of footwear is typically contracted to manufacturers based in emerging economies. Using life cycle assessment methodology in accordance with the ISO 14040/14044 standards, this effort quantifies the life cycle greenhouse gas emissions, often referred to as a carbon footprint, of a pair of running shoes. Furthermore, mitigation strategies are proposed focusing on high leverage aspects of the life cycle.
Using this approach, it is estimated that the carbon footprint of a typical pair of running shoes made of synthetic materials is 14 ± 2.7 kg CO2-equivalent. The vast majority of this impact is incurred during the materials processing and manufacturing stages, which make up around 29% and 68% of the total impact, respectively. Other similar studies in the apparel industry have reported carbon footprints of running shoes ranging between 18 and 41 kg CO2-equivalent/pair.
For consumer products not requiring electricity during use, the intensity of emissions in the manufacturing phase is atypical; most commonly, materials make up the biggest percentage of impact. This distinction highlights the importance of identifying mitigation strategies within the manufacturing process, and the need to evaluate the emissions reduction efficacy of each potential strategy. By suggesting a few of the causes of manufacturing dominance in the global warming potential assessment of this product, this study hypothesizes the characteristics of a product that could lead to high manufacturing impact. Some of these characteristics include the source of energy in manufacturing and the form of manufacturing, in other words the complexity of processes used and the area over which these process are performed (particularly when a product involves numerous parts and light materials). Thereby, the work provides an example when relying solely on the bill of materials information for product greenhouse gas emissions assessment may underestimate life cycle burden and ignore potentially high impact mitigation strategies.
Here are some snippets from the press release:
But what’s surprising to researchers isn’t the size of a shoe’s carbon footprint, but where the majority of that footprint comes from.
The researchers found that 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. 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.
In 2010, nearly 25 billion shoes were purchased around the world, the majority of them manufactured in China and other developing countries. As Kirchain and his co-authors write in their paper, “An industry of that scale and geographic footprint has come under great pressure regarding its social and environmental impact.”
In response, companies have started to take account of their products’ greenhouse-gas contributions, in part by measuring the amount of carbon dioxide associated with every process throughout a product’s lifecycle. One such company, ASICS, an athletic equipment company based in Japan, approached Kirchain to perform a lifecycle assessment for a running shoe manufactured in China.
The team took a “cradle-to-grave” approach, breaking down every possible greenhouse gas-emitting step: from the point at which the shoes’ raw materials are extracted to the shoes’ demise, whether burned, landfilled or recycled.
In tallying the carbon emissions from every part of a running shoe’s lifecycle, the researchers were also able to spot places where reductions might be made. For example, they observed that manufacturing facilities tend to throw out unused material. Instead, Kirchain and his colleagues suggest recycling these scraps, as well as combining certain parts of the shoe to eliminate cutting and welding steps. Printing certain features onto a shoe, instead of affixing them as separate fabrics, would also streamline the assembly process.
How much is barefoot running reducing the carbon footprint from running shoes?
Cheah, L., Ciceri, N., Olivetti, E., Matsumura, S., Forterre, D., Roth, R., & Kirchain, R. (2013). Manufacturing-focused emissions reductions in footwear production Journal of Cleaner Production, 44, 18-29 DOI: 10.1016/j.jclepro.2012.11.037