Tech Explained: Sustainable textiles

Innovators are turning to a variety of technologies in order to make textiles more sustainable, these include using recycled materials, plant-based fibres and bioengineered products.

Textile production is one of the least sustainable industries. Textile manufacturing produces an estimated 1.2 billion tonnes of CO2 equivalent per year – more than international flights and maritime shipping combined. And it does not stop there. Non-profit WRAP estimates that, globally, the fashion industry consumes around 79 billion cubic metres of fresh water annually. One kilogram of cotton – equivalent to the weight of a shirt and pair of jeans – can take as much as 10,000–20,000 litres of water to produce. From land use to chemical pollution from dyes, textiles need to become more sustainable. 

There is no one single method being used to manufacture more sustainable textiles. Rather, innovators are turning to a variety of technologies in order to use recycled materials, plant-based fibres and even bioengineered textiles grown using live organisms. So, how will sustainable textiles work?

Using recycled plastic

One eco-friendly option is to create textiles out of recycled materials. For example, PET plastic (like that used in water bottles) can be recycled into yarn that is then woven into a fabric. The plastic is first processed into flakes, then the flakes are melted and pulled into a yarn. The resulting fabric has a carbon footprint 50 per cent lower than organic cotton, 90 per cent lower than nylon and 75 per cent lower than polyester.

Another option is Econyl, which is made from post-consumer nylon waste such as abandoned fishing nets and carpets. The materials are sorted and shredded, then put through chemical reactors that break down the material and re-generate the polyamide 6. This is then processed into yarn.

Adidas uses a similar product to turn ocean plastic waste into a thread that is woven into its Adidas Parley clothing running shoes. Each pair of shoes uses around 11 plastic bottles and incorporates recycled plastic into the shoe’s laces, heel webbing, heel lining and sock liner covers.

Using sustainable plants

Many people think of cotton as a renewable resource, but it takes a huge amount of water to grow cotton. Cotton is also often mono-cropped, meaning fertilisers are needed, which can also be harmful to the environment. Innovators are working to find sustainable plant-based alternatives to cotton fibres.

One option is Tencel, which is made from eucalyptus trees grown in Australia and Indonesia. Eucalyptus trees don’t need any toxic pesticides and only require a little water. It also absorbs dye very well, meaning that manufacturers don’t need to use as much. Tencel can be used to make the same types of garments as rayon, as it has a similar look and feel.

Another option is provided by New York-based startup AlgiKnit, who have developed a way to create bio-degradable yarns from kelp. The aquatic plants contain bio-polymers that can be extracted and then extruded to form yarn. Kelp also has the advantage of being very fast-growing, making it rapidly renewable. It is also able to grow in adverse environments, such as in areas with sewer runoff. 

There is a rapidly growing list of other fibres made from plants such as bamboo, stinging nettles, pineapple and bananas. All are grown using less water and pesticides than cotton and have a high fibre content. In the case of bananas and pineapples, the fibres are made from material (peel) that is otherwise thrown away. Taiwanese textile company Singtex also uses food waste to make fibres – in this case, coffee grounds. The grounds are mixed with a  polymer to create a very durable fabric. In Myanmar, luxury fabric is being made using fibres extracted from lotus flowers. The fibres are then spun into a fabric similar to silk.

Bioengineered fabrics

Astonishingly, scientists are also working on ways to ‘grow’ fabrics in the lab using micro-organisms. They are even able to produce nearly-complete pieces of clothing, without the need for factory assembly. Materials manufactured in this way would be completely biodegradable into nontoxic substances. By being grown in moulds in the shape of, say, a T-shirt, they could also be manufactured using the precise amount of textile without generating excess waste material.

One such material is being created by a team of students at the Fashion Institute of Technology in New York City. The students have developed a method to use kelp. The team first extracts alginate, a sugar found in kelp. The alginate is dehydrated to form a powder, and water is added to create a gel. The gel is then extruded into a fibre. To dye the fibre, the team uses non-chemical pigments, such as crushed insect shells. Strong and flexible, the fibres are naturally fire-resistant and biodegrade faster than cotton. 

The leader of the project, assistant professor Theanne Schiros, has also explored using bacteria to grow clothing materials. Some of her students grew a baby-size pair of moccasins from a liquid culture made up of bacteria, fungi and compostable waste. The bacteria grew a fibrous ‘bio-leather’ that filled a shoe-shaped mould. The finishing stitching on the shoes used fibres taken from discarded pineapple tops. The dye was made using avocado seeds and indigo leaves.

Other researchers have used bacteria to create dyes. Research agency Faber Futures use naturally-pigmented bacteria to create textile dyes. The textiles are soaked in a liquid nutrient medium and then exposed to the bacteria, which grow on the textile, dyeing it. The fabrics are then sterilised to kill the bacteria and washed to remove the medium. Although the process uses less water and chemicals than conventional dyes, it is far more expensive.

Cost is just one of the challenges to using more types of sustainable textiles. The materials also need to be able to stand up to normal wear and tear and to be manufactured in large quantities. However, if these hurdles can be overcome, the textile industry could move to a more sustainable model.