Estimating the carbon footprint of a fabric

19 01 2011

We published this blog almost two years ago, but the concepts haven’t changed and we think it’s very important.   So here it is again:

Although most of the current focus on lightening our carbon footprint revolves around transportation and heating issues, the modest little fabric all around you turns out to be from an industry with a gigantic carbon footprint. The textile industry, according to the U.S. Energy Information Administration, is the 5th largest contributor to CO2 emissions in the United States, after primary metals, nonmetallic mineral products, petroleum and chemicals.[1]

The textile industry is huge, and it is a huge producer of greenhouse gasses.  Today’s textile industry is one of the largest sources of greenhouse gasses (GHG’s) on Earth, due to its huge size.[2] In 2008,  annual global textile production was estimated at  60 billion kilograms (KG) of fabric.  The estimated energy and water needed to produce that amount of fabric boggles the mind:

  • 1,074 billion kWh of electricity  or 132 million metric tons of coal and
  • between 6 – 9 trillion liters of water[3]

Fabrics are the elephant in the room.  They’re all around us  but no one is thinking about them.  We simply overlook fabrics, maybe because they are almost always used as a component in a final product that seems rather innocuous:  sheets, blankets, sofas, curtains, and of course clothing.  Textiles, including clothing,  accounted for about one ton of the 19.8 tons of total CO2 emissions produced by each person in the U.S. in 2006. [4] By contrast, a person in Haiti produced a total of only 0.21 tons of total carbon emissions in 2006.[5]

Your textile choices do make a difference, so it’s vitally important to look beyond thread counts, color and abrasion results.

How do you evaluate the carbon footprint in any fabric?  Look at the “embodied energy’ in the fabric – that is, all of the energy used at each step of the process needed to create that fabric.  To estimate the embodied energy in any fabric it’s necessary to add the energy required in two separate fabric production steps:

(1)  Find out what the fabric is made from, because the type of fiber tells you a lot about the energy needed to make the fibers used in the yarn.  The carbon footprint of various fibers varies a lot, so start with the energy required to produce the fiber.

(2) Next, add the energy used to weave those yarns into fabric.  Once any material becomes a “yarn” or “filament”, the amount of energy and conversion process to weave that yarn into a textile is pretty consistent, whether the yarn is wool, cotton, nylon or polyester.[6]

Let’s look at #1 first: the energy needed to make the fibers and create the yarn. For ease of comparison we’ll divide the fiber types into “natural” (from plants, animals and less commonly, minerals) and “synthetic” (man made).

For natural fibers you must look at field preparation, planting and field operations (mechanized irrigation, weed control, pest control and fertilizers (manure vs. synthetic chemicals)), harvesting and yields.  Synthetic fertilizer use is a major component of the high cost of conventional agriculture:  making just one ton of nitrogen fertilizer emits nearly 7 tons of CO2 equivalent greenhouse gases.

For synthetics, a crucial fact is that the fibers are made from fossil fuels.   Very high amounts of energy are used in extracting the oil from the ground as well as in the production of the polymers.

A study done by the Stockholm Environment Institute on behalf of the BioRegional Development Group  concludes that the energy used (and therefore the CO2 emitted) to create 1 ton of spun fiber is much higher for synthetics than for hemp or cotton:

KG of CO2 emissions per ton of spun fiber:
crop cultivation fiber production TOTAL
polyester USA 0.00 9.52 9.52
cotton, conventional, USA 4.20 1.70 5.90
hemp, conventional 1.90 2.15 4.05
cotton, organic, India 2.00 1.80 3.80
cotton, organic, USA 0.90 1.45 2.35

The table above only gives results for polyester; other synthetics have more of an impact:  acrylic is 30% more energy intensive in its production than polyester [7] and nylon is even higher than that.

Not only is the quantity of GHG emissions of concern regarding synthetics, so too are the kinds of gasses produced during production of synthetic fibers.  Nylon, for example, creates emissions of N2O, which is 300 times more damaging than CO2 [8] and which, because of its long life (120 years) can reach the upper atmosphere and deplete the layer of stratospheric ozone, which is an important filter of UV radiation.  In fact, during the 1990s, N2O emissions from a single nylon plant in the UK were thought to have a global warming impact equivalent to more than 3% of the UK’s entire CO2 emissions.[9] A study done for the New Zealand Merino Wool Association shows how much less total energy is required for the production of natural fibers than synthetics:

Embodied Energy used in production of various fibers:
energy use in MJ per KG of fiber:
flax fibre (MAT) 10
cotton 55
wool 63
Viscose 100
Polypropylene 115
Polyester 125
acrylic 175
Nylon 250

SOURCE:  “LCA: New Zealand Merino Wool Total Energy Use”, Barber and Pellow,      http://www.tech.plym.ac.uk/sme/mats324/mats324A9%20NFETE.htm

Natural fibers, in addition to having a smaller carbon footprint in the production of the spun fiber, have many additional  benefits:

  1. being able to be degraded by micro-organisms and composted (improving soil structure); in this way the fixed CO2 in the fiber will be released and the cycle closed.   Synthetics do not decompose: in landfills they release heavy metals and other additives into soil and groundwater.  Recycling requires costly separation, while incineration produces pollutants – in the case of high density polyethylene, 3 tons of CO2 emissions are produced for ever 1 ton of material burnt.[10] Left in the environment, synthetic fibers contribute, for example, to the estimated 640,000 tons of abandoned fishing nets in the world’s oceans.
  2. sequestering carbon.  Sequestering carbon is the process through which CO2 from the atmosphere is absorbed by plants through photosynthesis and stored as carbon in biomass (leaves, stems, branches, roots, etc.) and soils.  Jute, for example, absorbs 2.4 tons of carbon per ton of dry fiber.[11]

Substituting organic fibers for conventionally grown fibers is not just a little better – but lots better in all respects:  uses less energy for production, emits fewer greenhouse gases and supports organic farming (which has myriad environmental, social and health benefits).  A study published by Innovations Agronomiques (2009) found that 43% less GHG are emitted per unit area under organic agriculture than under conventional agriculture.[12] A study done by Dr. David Pimentel of Cornell University found that organic farming systems used just 63% of the energy required by conventional farming systems, largely because of the massive amounts of energy requirements needed to synthesize nitrogen fertilizers. Further it was found in controlled long term trials that organic farming adds between 100-400kg of carbon per hectare to the soil each year, compared to non-organic farming.  When this stored carbon is included in the carbon footprint, it reduces the total GHG even further.[13] The key lies in the handling of organic matter (OM): because soil organic matter is primarily carbon, increases in soil OM levels will be directly correlated with carbon sequestration. While conventional farming typically depletes soil OM, organic farming builds it through the use of composted animal manures and cover crops.

Taking it one step further beyond the energy inputs we’re looking at, which help to mitigate climate change, organic farming helps to ensure other environmental and social goals:

  • eliminates the use of synthetic fertilizers, pesticides and genetically modified organisims (GMOs) which is  an improvement in human health and agrobiodiversity
  • conserves water (making the soil more friable so rainwater is absorbed better – lessening irrigation requirements and erosion)
  • ensures sustained biodiversity
  • and compared to forests, agricultural soils may be a more secure sink for atmospheric carbon, since they are not vulnerable to logging and wildfire.

Organic agriculture is an undervalued and underestimated climate change tool that could be one of the most powerful strategies in the fight against global warming, according to Paul Hepperly, Rodale Institute Research Manager. The Rodale Institute Farming Systems Trial (FST) soil carbon data (which covers 30 years)  provides convincing evidence that improved global terrestrial stewardship–specifically including regenerative organic agricultural practices–can be the most effective currently available strategy for mitigating CO2 emissions.

At the fiber level it is clear that synthetics have a much bigger footprint than does any natural fiber, including wool or conventionally produced cotton.   So in terms of the carbon footprint at the fiber level, any natural fiber beats any synthetic – at this point in time.   Best of all is an organic natural fiber.

And next let’s look at #2, the energy needed to weave those yarns into fabric.

There is no dramatic difference in the amount of energy needed to weave fibers into fabric depending on fiber type.[14] The processing is generally the same whether the fiber is nylon, cotton, hemp, wool or polyester:   thermal energy required per meter of cloth is 4,500-5,500 Kcal and electrical energy required per meter of cloth is 0.45-0.55 kwh. [15] This translates into huge quantities of fossil fuels  –  both to create energy directly needed to power the mills, produce heat and steam, and power air conditioners, as well as indirectly to create the many chemicals used in production.  In addition, the textile industry has one of the lowest efficiencies in energy utilization because it is largely antiquated.

But there is an additional dimension to consider during processing:  environmental pollution.  Conventional textile processing is highly polluting:

  • Up to 2000 chemicals are used in textile processing, many of them known to be harmful to human (and animal) health.   Some of these chemicals evaporate, some are dissolved in treatment water which is discharged to our environment, and some are residual in the fabric, to be brought into our homes (where, with use, tiny bits abrade and you ingest or otherwise breathe them in).  A whole list of the most commonly used chemicals in fabric production are linked to human health problems that vary from annoying to profound.
  • The application of these chemicals uses copious amounts of water. In fact, the textile industry is the #1 industrial polluter of fresh water on the planet.[16] These wastewaters are discharged (largely untreated) into our groundwater with a high pH and temperature as well as chemical load.

Concerns in the United States continue to mount about the safety of textiles and apparel products used by U.S. consumers.  Philadelphia University has formed a new Institute for Textile and Apparel Product Safety, where they are busy analyzing clothing and textiles for a variety of toxins.  Currently, there are few regulatory standards for clothing and textiles in the United States.  Many European countries,  as well as Japan and Australia, have much stricter restrictions on the use of chemicals in textiles and apparel than does the United States, and these world regulations will certainly impact world production.

There is a bright spot in all of this:  an alternative to conventional textile processing does exist.  The new Global Organic Textile Standard (GOTS) is a  tool for an international common understanding of environmentally friendly production systems and social accountability in the textile sector; it covers the production, processing, manufacturing, packaging, labeling, exportation, importation and distribution of all natural fibers; that means, specifically, for example:  use of certified organic fibers, prohibition of all GMOs and their derivatives; and prohibition of a long list of synthetic chemicals (for example: formaldehyde and aromatic solvents are prohibited; dyestuffs must meet strict requirements (such as threshold limits for heavy metals, no  AZO colorants or aromatic amines) and PVC cannot be used for packaging).

A fabric which is produced to the GOTS standards is more than just the fabric:

It’s a promise to keep our air and water pure and our soils renewed; it’s a fabric which will not cause harm to you or your descendants.  Even though a synthetic fiber cannot be certified to  GOTS, the synthetic mill could adopt the same production standards and apply them.   So for step #2, the weaving of the fiber into a fabric, the best choice is to buy a GOTS certified fabric or to apply as nearly as possible the GOTS parameters.

At this point in time, given the technology we have now, an organic fiber fabric, processed to GOTS standards, is (without a doubt) the safest, most responsible choice possible in terms of both stewardship of the earth, preserving health and limiting toxicity load to humans and animals, and reducing carbon footprint – and emphasizing rudimentary social justice issues such as no child labor.

And that would be the end of our argument, if it were not for this sad fact:  there are no natural fiber fabrics made in the United States which are certified to the Global Organic Textile Standard (GOTS).  The industry has, we feel, been flat footed in applying these new GOTS standards.  With the specter of the collapse of the U.S. auto industry looming large, it seems that the U.S. textile industry would do well to heed what seems to be the global tide of public opinion that better production methods, certified by third parties, are the way to market fabrics in the 21st Century.


[1] Source: Energy Information Administration, Form EIA:848, “2002 Manufacturing Energy Consumption Survey,” Form EIA-810, “Monthly Refinery Report” (for 2002) and Documentatioin for Emissions of Greenhouse Gases in the United States 2003 (May 2005). http://www.eia.doe.gov/emeu/aer/txt/ptb1204.html

[2] Dev, Vivek, “Carbon Footprint of Textiles”, April 3, 2009, http://www.domain-b.com/environment/20090403_carbon_footprint.html

[3] Rupp, Jurg, “Ecology and Economy in Textile Finishing”,  Textile World,  Nov/Dec 2008

[4] Rose, Coral, “CO2 Comes Out of the Closet”,  GreenBiz.com, September 24, 2007

[5] U.S. Energy Information Administration, “International Energy Annual 2006”, posted Dec 8, 2008.

[6] Many discussions of energy used to produce fabrics or final products made from fabrics (such as clothing) take the “use” phase of the article into consideration when evaluating the carbon footprint.  The argument goes that laundering the blouse (or whatever) adds considerably to the final energy tally for natural fibers, while synthetics don’t need as much water to wash nor as many launderings.  We do not take this component into consideration because

  • it applies only to clothing; even sheets aren’t washed as often as clothing while upholstery is seldom cleaned.
  • is biodegradeable detergent used?
  • Is the washing machine used a new low water machine?  Is the water treated by a municipal facility?
  • Synthetics begin to smell if not treated with antimicrobials, raising the energy score.

Indeed, it’s important to evaluate the sponsors of any published studies, because the studies done which evaluate the energy used to manufacture fabrics are often sponsored by organizations which might have an interest in the outcome.  Additionally, the data varies quite a bit so we have adopted the values which seem to be agreed upon by most studies.

[7] Ibid.

[8] “Tesco carbon footprint study confirms organic farming is energy efficient, but excludes key climate benefit of organic farming, soil carbon”, Prism Webcast News, April 30, 2008, http://prismwebcastnews.com/2008/04/30/tesco-carbon-footprint-study-confirms-organic-farming%E2%80%99s-energy-efficiency-but-excludes-key-climate-benefit-of-organic-farming-%E2%80%93-soil-carbon/

[9] Fletcher, Kate, Sustainable Fashion and Textiles,  Earthscan, 2008,  Page 13

[10] “Why Natural Fibers”, FAO, 2009: http://www.naturalfibres2009.org/en/iynf/sustainable.html

[11] Ibid.

[12] Aubert, C. et al.,  (2009) Organic farming and climate change: major conclusions of the Clermont-Ferrand seminar (2008) [Agriculture biologique et changement climatique : principales conclusions du colloque de Clermont-Ferrand (2008)]. Carrefours de l’Innovation Agronomique 4. Online at <http://www.inra.fr/ciag/revue_innovations_agronomiques/volume_4_janvier_2009>

[13] International Trade Centre UNCTAD/WTO and Research Institute of Organic Agriculture (FiBL);    Organic Farming and Climate Change; Geneva: ITC, 2007.

[14] 24th session of the FAO Committee on Commodity Problems IGG on Hard Fibers of the United Nations

[15] “Improving profits with energy-efficiency enhancements”, December 2008,  Journal for Asia on Textile and Apparel,  http://textile.2456.com/eng/epub/n_details.asp?epubiid=4&id=3296

[16] Cooper, Peter, “Clearer Communication,” Ecotextile News, May 2007.

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How to get rid of chemicals in fabrics. (Hint: trick question.)

10 11 2010

Can you wash or otherwise clean conventional fabrics to remove all the toxic residues so that you’d end up with  a fabric that’s as safe as  an organic fabric?  It seems a reasonable question, and sure would be an easy fix if the answer was yes, wouldn’t it?  But let’s explore this question, because it’s really interesting.

Let’s start by looking at one common type of fabric: a lightweight, 4 ounce cotton printed quilting fabric.  In this case the answer is no (and as you’ll find out, our answers will always be no, but read on to see why).

The toxic chemicals in conventionally produced (versus “organically” produced)  cotton fabric that cannot be washed out come from both:

1.      the pesticides and herbicides applied to the crops when growing the cotton and

2.      from the dyes and printing inks and other chemicals used to turn the fibers into fabric.

Let’s first look at the pesticides used during growing of the fiber.

Conventional cotton cultivation uses copious amounts of chemical inputs.  These pesticides are absorbed by the leaves and the roots of the plants. Most pesticides applied to plants have a half life of less than 4 days before degredation.(1)   So pesticides can be found in the plants, but over time the chemicals are degraded so the amount to be found in any bale of cotton fiber is highly depending on time of harvest and how recently the crop had been sprayed.  

Gas chromatography easily shows that  common pesticides used on cotton crops are found in the fibers, such as:  Hexachlorobenzene,  Aldrin, Dieldrin, DDT and DDT. (2)   Look up the toxicity profiles  of those chemicals if you want encouragement to keep even tiny amounts of them out of your house.   With time, as the cotton fibers degrade, these residual chemicals are released.

We could find no studies which looked at the fibers themselves to see if pesticides could be removed by washing, but we did find a study of laundering pesticide-soiled clothing to see if the pesticide could be removed.  Remember, this study (and others like it) was done only on protective clothing worn by workers who are applying the pesticides – so the pesticides are on the outside of the fibers  –   NOT on the fibers themselves during growth.  The study found that, after six washings in a home washing machine, the percent of pesticide remaining in a textile substrate (cotton)  ranged from 1% to 42%.  (3)

If you’re trying to avoid pesticides which are applied to cotton crops, you’d do better to avoid cottonseed oil than the fiber (if processed conventionally) because we eat more of the cotton crop than we wear.  Most of the damage done by the use of pesticides is to our environment – our groundwater and soils.

Before we go further,  let’s do away with the notion that organic cotton, woven conventionally, is safe to use.  Not so.  There are so many chemicals used during the processing phase of fabric production, including detergents, brighteners, bleaches, softeners, and many others that the final fabric is a chemical smorgasbord, and is by weight at least 10% synthetic chemicals (4), many of which have been proven to cause harm to humans.

The chemicals used in conventionally processed organic cotton fabrics make the concerns about  pesticides used in growing the crop pale in comparison:  If we use the new lower chemical inputs that GMO cotton has introduced, it’s now possible to produce 1 lb. of conventionally grown cotton, using just  2.85 oz of chemical pesticides – that’s down from over 4.5 oz used during the 1990’s – a 58% decrease.   So to produce enough cotton fiber to make 25 lbs of cloth,  it would require  just 4.45 lbs of chemical pesticides, fertilizers and insecticides.  Processing that fiber into cloth, however, requires between 2.5 – 25 lbs. of chemicals.  If we take the midpoint, that’s 12.5 lbs of processing chemicals – almost three times what it took to produce the fiber!

There are over 2,000 different kinds of chemicals regularly used in textile production, many of them so toxic that they’re outlawed in other products.  And this toxic bath is used on both organic fibers as well as non-organic fibers – the fibers are just the first step in the weaving and finishing of a fabric. (Make sure you buy organic fibers that are also organically processed  or you do not have an organic fabric.   An organic fabric is one that is  third party certified  to the Global Organic Textile Standard. )      Fabrics – even those made with  organic fibers like organic cotton IF they are conventionally produced and not produced according to GOTS –  contain chemicals such as formaldehyde, azo dyes, dioxin, and heavy metals.  Some of the chemicals  are there as residues from the production, others are added to give certain characteristics to the fabrics such as color, softness, crispness, wrinkle resistance, etc.    And these chemicals are designed to do a job, and do it well. They are designed to NOT wash out.  The dyes, for instance, are called “fiber reactive” dyes because they chemically bind with the fiber molecules in order to remain color fast.   The chemical components of your fabric dye is there as long as the color is there. Many dyes contain a whole host of toxic chemicals.  The heavy metals are common components of fabric dyes.  They are part of the dye and part of the fabric fiber as long as the color remains.

And these chemicals are found in the fabrics we live with.  Studies have shown that the chemicals are available to our bodies:  dioxins (such as the 75 polychlorinated dibenzo-p-dioxins (PCDDs) and 135 polychlorinated dibenzofurans (PCDFs)) were found in new clothing in concentrations ranging from low pg/g to high 300 ng/g in several studies. (5)

 

How do these chemicals get into our bodies from the textiles?  Your skin is the largest organ of your body, and it’s highly permeable.  So skin absorption is one route; another is through inhalation of the chemicals (if they are the type that evaporate – and if they do evaporate, each chemical has a different rate of evaporation, from minutes or hours to weeks or years) and a third route:  Think of microscopic particles of fabric that abrade each time we use a towel, sit on a sofa, put on our clothes.  These microscopic particles fly into the air and then we breathe them in or ingest them.  Or they  fall into the dust of our homes, where people and pets, especially crawling children and pets, continue to breathe or ingest them.

In the United States, often the standards for exposure to these toxins is limited to  workplace standards (based on limits in water or air) or they’re product specific: the FDA sets a maximum limit of cadmium in bottled water to be 0.005 mg/L for example.  So that leaves lots of avenues for continued contamination!

The bad news is that existing legislation on chemicals fails to prohibit the use of hazardous chemicals in consumer products -–and the textile industry, in particular, has no organized voice to advocate for change.  It’s a complex, highly fragmented industry, and it’s up to consumers to demand companies change their policies.  In the United States we’re waking up to the dangers of industrial chemicals, but rather than banning a certain chemical in ALL products, the United States is taking a piece meal approach:  for example,  certain azo dyes (like Red 2G) are prohibited in foods – but only in foods, not fabrics.  But just because the product is not meant to be eaten doesn’t mean we’re not absorbing that Red 2G.  Phthalates are outlawed in California and Washington state in children’s toys – but not in their clothing or bedding.  A Greenpeace study of a Walt Disney PVC Winne the Pooh raincoat found that it contained an astounding 320,000 mg/kg of total phthalates in the coat – or 32% of the weight of the raincoat! (6)

Concerns continue to mount about the safety of textiles and apparel products used by U.S. consumers.  As reports of potential health threats continue to come to light, “we are quite concerned about potentially toxic materials that U.S. consumers are exposed to everyday in textiles and apparel available in this country,” said David Brookstein, Sc.D., dean of the School of Engineering and Textile and director of Philadelphia University’s Institute for Textile and Apparel Product Safety (ITAPS).

The good news is that there are fabrics that have been produced without resorting to these hazardous chemicals.  Look for GOTS!  Demand safe fabrics!

(1)  “Degradation of Pesiticides on Plant Surfaces amd It’s prediction – a case study of tea leaves”, Zongmao, C and Haibin, W., Tea Research Institute, Chinese Academy of Agricultural Sciences, Zhejiang, China.   http://www.springerlink.com/content/vg5w5467743r5p41/

(2) “Extraction of Residual Chlorinated Pesticides from Cotton Matrix, El-Nagar, Schantz et.al, Journal of Textile and Apparel, Technology and management,  Vol 4, Issue 2, Fall 2004

(3)  Archives of Environmental Contamination and Toxicology 1992  (23, 85-90)

(4) Laucasse and Baumann,  Textile Chemicals: Environmental Data and Facts, Springer, New York, 2004, page 609.

(5) “Dioxins and Dioxin-Like Persistent Organic Pollutants in Textiles” Krizanec, B and Le marechal, Al, Faculty of Mechanical Engineering, Smetanova 17, SI-2000, Maribor, Slovenia, 2006; hrcak.srce.hr/file/6721

(6)   http://www.greenpeace.org/raw/content/greece/137368/toxic-childrensware-by-disney.pdf