Agricultural waste is a largely unused resource that could be turned into fibres for textiles, if the cellulose from the plant residues can be extracted in a cost-competitive manner. The challenge is identifying, collecting and refining crop residues into raw materials that can be made into fibres or dyestuffs.

Few of us ever take a moment to think about the waste generated by the rice we eat, the orange juice we drink or the thyme we sprinkle over a dish we prepare. While the fashion industry is often criticised for the waste it generates, agriculture, and the food industry, may have an even worse track record. One solution would be to turn these unused cellulose-rich resources into new textiles.

The Laudes Foundation (formerly the C&A Foundation) took a close look at the possibility of using agricultural residues to make textile fibres in a report, “Spinning future threads”, that it published in June 2021. It believes that innovation in this field “offers strong potential to decrease extensive crop burning and its associated negative environmental and climate impacts; generate new, additive low-cost revenue streams for low-income agricultural communities in South and Southeast Asia; and activate a scalable and more environmentally sustainable source of fibre for the fashion industry”.

The report identifies husk and straw from rice and wheat, empty fruit bunches from oil palm, sugarcane bagasse and banana plantain waste as having potential in textiles, as either new agricultural fibres or a source of cellulose pulp for manmade cellulose fibres (MMCFs). These biomass conversion pathways do not require increasing land under cultivation or crop volumes, which the Foundation rules out.

New natural fibres

Not all agricultural waste can be used to make textile fibres, but a number of start-ups have identified unused cellulose-rich resources. Circular Systems, a sustainable textile start-up founded in 2017 and based in Los Angeles, has successfully developed several fibres from fibrous crop residues, such as the stalks of flax grown for its oil seed and hemp, cannabidiol (CBD) hemp, and generally all forms of industrial hemp, Isaac Nichelson, company co-founder and CEO, tells Inside Denim. “In North America alone, one million acres of oil seed flax is planted. This is amazing biomass that is going to waste.” The company is currently making its Agraloop BioFibre from oil seed hemp grown in the Champagne region of France and flax crop waste in Belgium. It plans to launch early-stage pilot processing of banana and pineapple waste soon.

The Agraloop pre-processing phase, in which the fibre is roughly decorticated, is conducted as close to the farm as possible, then shipped to a centralised biorefinery. The company’s wet processing technique uses a “bio-appropriate chemical”, says Mr Nichelson, that purifies the cellulose of stems and leaves into fibre bundles that can be spun into yarns. The result is a natural fibre yarn, he says, not a MMCF, and could be labelled linen or hemp on garments.

“The yarns drawn from hemp crop waste are coarser than cotton,” he says, but 30 single yarns containing 30% Agraloop BioFibre have been produced. The company has made a 100% Agraloop BioFibre fabric, “a heavy canvas for denims and bottoms,” but he believes the yarn will most often be used in blends with organic or recycled cotton. Denim mills are currently testing the yarns, including Crescent Bahuman (CBL), Arvind, Artistic Milliners and Ananta Group (Bangladesh), which is also an investor in the company. Mr Nichelson expects to see denim Agraloop BioFibre fabrics on the market in 2022.

Zurich-based sustainable accessories brand Qwstion has found a new resource for textiles in a banana genus crop waste. It first identified abaca, Musa Textilis, in 2015 in the Philippines. With the help of a Taiwanese textile company, it developed Bananatex. To make the fabric, the fibrous raw material is first transformed into sheets of paper, then cut into fine filaments that are spun and woven into fabric, a process similar to Japanese washi fabrics.

The company is now making Bananatex available to other brands in a move to scale up production and reduce costs. “We look to partner with brands having values similar to ours,” says Stephanie Walter, in charge of brand development, who says H&M used Bananatex to make sneakers. A prototype parka cut from a lighter weight fabric, weighing 250 gsm, was on display on the company’s booth at Premiere Vision last month. Apparel applications are just beginning to be explored, but the fabric is not washable, as the company has yet to stabilise shrinkage, she says.

Tree-free cellulosic fibres

MMCF producers are quick to emphasise the natural origin of their viscose, lyocell, modal or acetate, as these are made from wood. But pressure to reduce the risk of deforestation is pushing key companies to seek out alternative sources of cellulose, ideally from biomass waste.

This is exactly what Austrian MMCF producer Lenzing has achieved through its partnership with Orange Fiber. This Italian company has patented a pulp production process for citrus by-products. A first production run of four tonnes of the fibre have been produced by Lenzing, in a ratio of 80% wood pulp and 20% citrus pulp. The collaboration is part of what Lenzing is calling its Tencel Limited Edition initiative, and the company says it is open to experimentation with other biomass resources.

“Together, we have successfully incorporated an unconventional waste material with Lenzing’s sustainably sourced wood to produce a new fibre, without compromising on quality or technical properties,” Gert Kroner, Lenzing’s vice-president for global research and development, said to Inside Denim’s sister publication WSA. The concept remains a limited edition, says Florian Heubrandner, Lenzing’s VP of textiles, due to the limited availability and added cost of citrus pulp compared to conventional wood pulp. Orange Fiber is overseeing sales of the new fibre, and the first fabric sample kit will be presented this October. Earlier, some will remember, Orange Fiber had presented an acetate yarn made from citrus pulp.

Many MMCF producers are investigating non-wood sources of pulp. These currently make up 7% of the world’s virgin cellulose pulp, as cited in the “Spinning Future Threads” report. Birla Cellulose, an Aditya Birla Group company, is involved in several such projects. These include a research programme with Nanollose, that is developing a MMCF made from coconut waste, and a biomass research project with Fashion For Good and the Laudes Foundation. “We are looking to identify three or four possible sources of biomass, to see what applications they could have, what machinery is needed and in what blends the fibre could be used,” says Mukul Agrawal, the company’s head of sustainability. He insists on the importance of finding a solution that is scalable and provides yarn that can be used in all types of fabrics.

Hurd Co, a sustainable textile start-up based in Los Angeles, seeks to make cellulose pulp from hemp agricultural waste, which would be used to make lyocell or viscose fibres. Its Agrilose process is said to be zero waste and to require half the water and 350 times less energy than conventional fibre pulp. “Hemp is a high yield plant that contains a lot of cellulose,” says co-founder Taylor Heisley-Cook. Still in the early stages of its development, it is seeking further funding to scale up its R&D facility.

Alternative biosynthetics 

Other projects under way seek to use biomass resources to produce biosynthetic materials. Kintra Fibers, a start-up based in Brooklyn and Los Angeles, is working on the development of a bio-based and biodegradable polymer known as polybutylene succinate (PBS). “It is used mainly in packaging and hasn’t yet been optimised for textile applications,” says company co-founder and COO Alissa Baier-Lentz. She says most commercial PBS is only 50% biobased, and the first iteration of Kintra’s version is 56% plant based, but its goal is to reach 100% renewable content. Like standard biosynthetics and bioplastics, the feedstock used to make Kintra fibre is sugar syrup, sucrose or glucose. The fibre in development has a cotton-like, even cashmere hand feel, she says. At lab scale, the company is producing 1kg batches. The advantage, she points out, is that once the process is optimised, the polymer will be “a direct fit for industrial extrusion and spinning”. Pangaia, a company investor, will be releasing the first garments made in the fibre.

Fashion for Good has identified another biodegradable biopolymer with possible textile applications and set up a research programme known as the Renewable Carbon Textiles Project last June to investigate polyhydroxyalkanoates (PHA) polymer fibres. The consortium includes Bestseller and PVH Corp, with technological solutions provided by Bio Craft Innovation (formerly Biomize), Full Cycle Bioplastics and Newlight Technologies, and funding by the Laudes Foundation.

PHA, like PBS, is a form of polyester that is considered biodegradable; these new biosynthetic yarns would therefore not contribute to microfibre pollution, and both have been used in plastics, not textiles. Feedstocks under study in the Fashion For Good project include inedible food waste, bamboo production biomass and carbon capture. The critical stage is fibre melt-spinning, it says in the project announcement.

Agro-industry dyestuffs 

Fibres are not the only materials that can be drawn from agricultural waste, as Archroma has proven in its EarthColors dyestuffs, launched in 2014. These are made from an array of crop leftovers including almond shells, orange peels and rosemary leaves. “EarthColors is a journey, we are continually seeking new unused resources as alternative raw materials,” says Nuria Estape, head of global marketing. The available colours are limited to those found in nature, and developing a full palette has proven to be a challenge, despite the company’s efforts. Achieving bright colours is another challenge, but she says research is ongoing.

“In recent months, we’ve seen a change in outlook from major fashion brands,” she says, noting that Primark is the latest to adopt the dyes. “It is not the first company to use EarthColors, but it is the first to use it to such an extent,” she says, adding that the retailer has embraced the concept to the point of printing EarthColors branding directly on the clothes.

Colorau, a range of natural dyestuffs developed by Portuguese textile manufacturer Tintex, also uses food and wood industry waste when possible. To expand the available palette, the company also continually seeks new unused resources, “but we want to use materials that are as sustainable as possible and preferably available in our region,” says Pedro Magalhães, R&D manager. Colorau includes thyme waste from a local herbal tea maker, and the chestnut and gambier are wood industry by-products sourced in Europe, he says. The company has set up a research programme with a local university to identify other possible local resources and improve extraction methods using only water as a solvent.

Tintex is also busy developing a patent-pending textile alternative to leather made from vegetal waste, including grape residue from vineyards in the north of Portugal. The biopolymers are combined with a water-based polyurethane and coated on a cotton substrate. “The coating can have anywhere from 10% to 30% biobased content, and with the cotton ground, we can achieve a total of 60% in the finished composite,” says Mr Magalhães.

The possibilities of transforming crop waste into new materials and chemicals are far from having been fully explored, as seen in the diversity of the projects under way. Admittedly, the new fibres in development have yet to reach full commercial scale. But demand is high, and the appeal of bio- and plant-based textiles ever growing, if the success of Candiani’s natural rubber stretch fibre is anything to go by. Turning leftovers from agriculture into viable industrial resources would further boost the appeal of this new crop of biofibres.

Primark has introduced garments dyed using Archroma EarthColors, derived from agro-industry waste.  

Photo: Primark 

Share this story: