Choosing Between Organic Cotton and Tencel

Which has the lighter environmental impact?

Photo: Lane Becker

Comfort is king when it comes to choosing the fabric of our clothing and eco-friendly fibers generally perform well, providing soft, breathable textiles that often feel better on your skin than synthetics. But what else should you consider in choosing sustainable fabrics and what counts when, say comparing a fiber with well established credentials like organic cotton to synthetic fiber derived from wood, such as Tencel? Are there ways that a man-made fiber can be better for the environment than an organic fiber?

Organic Cotton

Organic cotton is grown without synthetic pesticides or fertilizers, which reduces worries about poisoning workers, contaminating water supplies or depleting soil nutrients. And if you buy GOTS-certified organic cotton (see “Green Fashion”), you can be assured that it has been dyed and processed in an earth-friendly way, too.

But cotton’s biggest environmental impact worldwide is water use, and growing cotton organically doesn’t always save water. In California, for example, organic cotton can actually use more water than conventional cotton, over 780 gallons per pound of fiber—enough to make a single t-shirt. However, a rain-fed organic cotton farm in India could use about 528.3 gallons of irrigation water to grow a pound of fiber. Organic cotton grown in Brazil is almost entirely rain-fed, and would use only about 10.6 gallons to make a t-shirt. Some manufacturers include a rain-fed claim to help you find low-water cotton.

Most of the world’s organic cotton is grown in developing nations. Shipping it around the globe for processing and manufacturing and then on to consumers in the West racks up global warming emissions. Patagonia estimates that the carbon footprint of its organic cotton t-shirt is 3.5 pounds.

As far as land use, organic cotton is also pretty intensive. On a global average, it takes about 2.5 acres of land to produce a ton of conventional cotton—and organic cotton needs anywhere from 20 to 50 percent more land to produce the same amount of useable fiber.

Tencel

Tencel is part of the rayon family of man-made fibers made from renewable plant materials. This sets them apart from petroleum-derived synthetic fibers such as polyester. Tencel, made by the Austrian company Lenzing, is manufactured from eucalyptus trees, which grow fast and thick on low-grade land. According to Lenzing, it takes just half an acre to grow enough trees for a ton of Tencel fiber. Cotton needs at least 5 times as much land, and good quality farmland at that.

Some of the eucalyptus wood pulp is sourced from forests certified by the highly regarded Forest Stewardship Council. However, wood pulp is also sourced from forests certified by bodies accredited by the PEFC (Programme for the Endorsement of Forest Certification), an umbrella organization which allows for clear cutting and holds harvesters to lower standards than FSC.

As for water, eucalyptus trees don’t need irrigation, but Lenzing does need water to process the pulp and turn it into Tencel fiber. The company estimates its water use at 154.7 gallons per pound of fiber—considerably more than Brazilian rain-fed cotton, but much less than irrigated organic cotton from California.

Like most man-made fibers, Tencel takes more energy to produce than a natural fiber. However, Lenzing uses primarily low-carbon biofuels and only 14 percent fossil fuels to keep their carbon emissions down. Tencel’s carbon footprint, according to a company-sponsored study, is less than a pound of CO2 for each pound of fiber. That figure, however, doesn’t include shipping impacts. Tencel is made in Austria, the UK, and the United States, but Lenzing sources eucalyptus from South Africa (along with beech from Europe and pine from North America) so shipping would add to this impact.

The manufacturing process is usually the ugly side of plant-based fibers. While the plants can grow chemical-free, turning them into textile fibers usually requires some nasty chemicals. (This is often the case with bamboo.) According to Lenzing, however, their “closed loop” manufacturing process uses a nontoxic solvent—N-Methylmorpholine N-oxide—and 99.7 percent of it is recycled and pushed back into the system, instead of being flushed out as waste water. Moreover, Tencel has been certified by the European eco-label Oeko Tex 100 as containing low levels of manufacturing chemicals and byproducts.

How They Stack Up

Bearing in mind that the figures below include wide room for variation that makes any strict head-to-head comparison impossible, we can distill the discussion down to some basics:

	Organic Cotton	Tencel
Synthetic pesticides and fertilizers	Not allowed	None used
Water use	As low as about 10.6 gallons/lb for rain-fed from Brazil and as high as 782 gallons/lb for CA organic cotton	154.7 gallons/lb fiber
Land use	3.5 acres/ton	.52 acres/ton
Heat-trapping gases	3.5 pounds/lb	Less than 1 lb/lb fiber
3rd party certification	USDA organic, GOTS in some cases	Oeko Tex 100, FSC, PEFC-accredited certifiers

As the numbers suggest, the different ways in which organic cotton is grown around the world result in very different impacts. This is just as true within a single country such as India, the world’s leading organic cotton producer, where water usage varies remarkably from one cotton producer to another. Tencel, manufactured by one company, is much easier to pin down.

In the end, no process is without impact. When comparing how eco-friendly products are, we have to consider the positives and negatives of the full life cycle of a product rather than just a single factor. The aim is to reduce impacts to the greatest extent possible, recognizing that a failing in one area such as water use isn't the whole story. In this case, both the organic cotton farmers and the Lenzing corporation are aware of the lifecycle issues and have made significant advances, which puts them in a category way ahead of conventional fibers. So choose for long-lasting durability along with efforts to minimize social, health and environmental impacts.