Cotton vs. Polyester......

Originally posted here on UD Journal: FIBER

by Gail Baugh 

Cotton is the “green” fiber! Polyester is bad for the environment! Simple, right? Our choices are not so simple anymore. With broadened awareness of fiber and textile innovations and of human impact on our environment, we must consider our choices with new enlightenment. Is it possible that polyester fiber is more eco-friendly than cotton fiber?

I did a consulting project last fall comparing the environmental impact of cotton and polyester fiber production with surprising results. I concluded recycled polyester fiber, produced from existing polyester products, is more sustainable than cotton fiber.

Since the mid-1980s, cotton and polyester fiber production have grown dramatically, so that today, these two fibers account for more than 80% of all fiber production worldwide. The quantity of production of these two fibers is nearly equal. Future production of these fibers will confront new problems. Petroleum production will continue to decline, and arable  land for fiber production may also be reduced, as the demand for biofuel and food production take priority over fiber.

There are ongoing innovations in fiber and textiles. For the past 15+ years, plastic bottles have been recycled into low-grade polyester fiber. The big news is that it is now possible to recycle polyester fiber, yarn, fabric, and garments into new, high-quality polyester fiber. Cotton fiber can also be recycled into new yarn and fabric, but the quality of the fiber is reduced, so the res ulting product is not as high quality as the original fiber. For both fibers, it is a new concept that it is now possible to recycle and create new fiber and products from existing fiber.

Let’s clarify some of the terms the press and the fashion industry are using to tell customers how they can help prevent pollution. There are no standard industry definitions to describe the ecology of the fashion business. The result is confusion regarding the complex nature of fiber, fabric, and garment production and the impact each has on the environment and resources.

• First, banish the terms “eco,” “eco-friendly,” and “green.” I’ve used them above to make a point. To another generation, these were defining words, but they do not currently describe what we are      facing in climate change, resource depletion, or full landfills.
• Second, use terms that describe “methods” or “practices” that can be implemented to sustain resources and protect our nvironment. These terms will give the industry choices to act      responsibly. I use the term “sustainable practices” to define choices we can make instead of using terms like “green.”

As I compared cotton with polyester fiber, I developed a set of questions to determine which fiber used more sustainable practices:

• Is the fiber easily renewable?
• For natural fiber, is the use of water and land appropriate for the quantity and cost of the fiber produced?
• For manufactured fiber, is the raw material for production easily available and renewable?
• Is the fiber produced using nonpolluting methods?
• For natural fiber, is it grown/raised using nontoxic substances in the air, land, and water?
• For manufactured fiber, is it produced using nontoxic methods or materials that may end up in the air, land, and water?
• Can the products be recycled into new fiber production? Is the recycled fiber the same quality as the original fiber?

In my consulting project last fall, I compared the production of cotton fiber (both conventionally and organically grown) to virgin polyester and recycled polyester fiber production. Using three questions above to compare the environmental impact of each fiber, I concluded recycled polyester fiber involved more sustainable practices than any cotton fiber. Here’s why:

Is the fiber easily renewable?

Cotton Summary — Water and energy use are high, and the useable fiber is one-third of the total harvest volume.

Water use: Both conventionally and organically grown cotton fiber require large quantities of water for a consistent crop yield. Estimates range from 1,400–3,400 gallons per pound of fiber. (1 lb of fiber = about two t-shirts.)

Fiber yield per acre: About two-thirds of an acre’s harvest volume is discarded, leaving one-third of the harvest volume available for textile production.

Energy use: About 8.6–9.4 Kwh per pound of fiber for both types of cotton. However, energy used to move water for irrigation (organic and conventional cotton) and to produce synthetic fertilizers (mostly petroleum-based products — conventional cotton only) is not considered in this figure. By adding in this additional energy use, conventional cotton fiber energy consumption is estimated to be nearly the same as virgin polyester energy consumption.

Recycled Polyester Fiber Summary — Low water use. Energy use is high, though one-third less than virgin fiber. Very little waste in fiber production.

Water use: Water used in recycled fiber production is almost nil. Even in virgin fiber production, water is used as a coolant, in very small amounts.

Fiber yield: Compared to raw materials used, which must be measured by weight. There was some weight loss, but nothing close to the two-thirds lost in the cotton harvest.

Energy use: About 13.8 Kwh per pound of fiber. Energy used to produce the original virgin fiber was about 18.3 Kwh per pound of fiber.

Is the fiber produced using nonpolluting methods?

Cotton Summary — Synthetic chemicals used continue to pose significant water, soil, and air pollution threats.

Use of chemicals: Conventionally grown cotton uses synthetic fertilizers and pesticides (mostly petroleum-based). Pesticides have been greatly reduced due to genetically modified seed. However, these same GM seeds seem to require specific synthetic fertilizers and irrigation to have better yields than other seed. The use of these synthetic fertilizers has polluted the soil, ground water, nearby streams/lakes, and potential human water supplies. Emissions from spraying also contaminate surfaces and endanger nearby human habitation. Mono-crop cultivation reduces the future soil enrichment. Cotton does not return nutrients to the soil as other fiber crops do naturally. Organically grown fiber does not use GM seeds, synthetic fertilizers, or pesticides.

Recycled Polyester Fiber Summary — Chemicals used for recycled polyester fiber production are recycled back to produce more fiber.

Use of chemicals: Most or all of the chemicals used to recreate polyester fiber from the recycled material are then recycled back into more recycled fiber production — it’s a closed-loop production system. It’s unlikely that toxic chemicals enter the water supply. There are some emissions but less exposure to the population than in cotton aerial spraying. In virgin polyester production, there are more emissions than in recycled fiber production. However, if this closed-loop system becomes marketable, there may not be as much need to produce virgin polyester.

Is the fiber recyclable?

Cotton Summary — Recycled cotton fiber is lower quality than the original fiber.

The physics of breaking down a cotton fabric into fiber, called “opening,” breaks the cotton fiber into shorter fibers. When spinning the fiber into yarn, these short fibers create weak, low-quality yarns. There are on-going experiments to improve the yarn quality by introducing other fibers. So far, the perfect blend hasn’t been developed. But the fact remains that recycling cotton products back into fiber and new products is possible and is ongoing now. Of course, the idea of using existing cotton fabrics as a resource to create recycled yarn and fabric is a new concept. The issue remains that cotton fiber quality is reduced when recycled. Therefore, the recycled fiber may need other nontextile uses to stay out of the landfill.

I suggest that there be new research efforts to recycle cotton fiber into new fabrics. There has been extensive research for growing new fiber more efficiently. I suggest that this same energy also focus on how to use the existing cotton fiber supply. Also, perhaps there can be new ways to evaluate cotton fiber. For example, organically grown, the least available fiber, should be used for the highest quality items; transitional cotton (chemical-free production) for most production; and finally, recycled cotton fiber in low-quality items.

Recycled Polyester Fiber Summary — Recycled polyester fiber is the same quality as the original fiber.

This fiber, produced from existing polyester textile products, meets or exceeds the quality of virgin polyester. Continuously recycling the enormous quantity of existing polyester productions into new polyester fiber does not reduce the quality of the new fiber. Is it possible to nearly eliminate the production of virgin polyester?

I suggest that we review Patagonia’s example of collection and recycling of their products, particularly their partnerships with Teijin and Toray and other suppliers. In my conversations with my industry colleagues, it is clear that recycling polyester into new fiber is very costly. However, with the petroleum supply continuing to decline, it seems this innovation will be become more necessary and cost effective.

My study led me to conclude that recycled polyester fiber, produced from existing polyester fabrics, either post-industrial or post-consumer products, is more sustainable than conventional or organic cotton fiber. Cotton fiber research has concentrated on genetic modification to control pests and reduce water use for new fiber production. The polyester fiber mills, recognizing the shrinking petroleum supply and the environmental problems of virgin polyester fiber production, have eclipsed the cotton fiber innovation effort.

We find ourselves in a world where climate change and oil supplies will force the textile industry to make different choices. It must reevaluate its raw material sources and the environmental impact of its production methods. With over 80% of all fiber production in polyester and cotton fibers, fiber and fabric producers must diversify raw materials (incorporating existing fiber stock as a raw material source), lower water and energy consumption, improve soil restoration, and reduce pollutants in production while maintaining the fiber and fabric supply we had come to assume was unlimited.

*Please note the findings in this article may be contrary to findings posted by other organizations and studies~Coral Rose