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19.01.2011
Estimating the carbon footprint of a fabric


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.

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. 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

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.  By contrast, a person in Haiti produced a total of only 0.21 tons of total carbon emissions in 2006.

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.

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 5.89
hemp, conventional 1.90 2.15 4.10
cotton, organic, India 2.00 1.80 3.75
cotton, organic, USA 0.90 1.45  

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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  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  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.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. 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.

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. 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. 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. 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.  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. 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.


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