Producers of wood-based fibres, a group of materials spanning viscose, lyocell and acetate, are quick to promote their plant- or bio-based raw materials. But these manmade cellulosic fibres face two key challenges. They need to prove they play no role in deforestation and they need to provide guarantees with regards to the chemicals used in the process of turning a hard yet fibrous material, namely wood, into a smooth and silky, drapeable fibre

Plant-based is the catchword of the day in sustainable apparel. Along with wood-based, these terms are used to describe manmade cellulosic fibres (MMCFs) to play up their renewable raw material origin. Behind the appealing wording, this industry faces a challenging task: as demand grows for these fibres, so does pressure to address the sustainability of sourcing and manufacturing processes. Behind the hangtags that glibly indicate the wood- or plant-based origins of a garment made from a viscose, modal, lyocell or acetate fabric, the reality is not so fetching.

Reports exposing the negative impacts of the MMCF industry come in steady streams and    from a wide array of organisations exposing unsustainable practices related to forestry and chemicals, and spanning biodiversity to working conditions. The four main hot-spots viewed as problematic are, in a nutshell, the opaque nature of the logging industry, the production of dissolving pulp, operations at MMCF mills, and the use of sodium hydroxide and sulfuric acid to make the fibres. Since 2017, The Changing Markets Foundation has released “Dirty Fashion” reports every year. Fashion for Good and Greenpeace have recently added their own tomes to the topic.

An industry under scrutiny 

Canopy, based in Vancouver, Canada, has been monitoring this sector since 2013, publishing its first CanopyStyle report in 2014. The organisation founded and headed by Nicole Rycroft has arguably had the most impact on the industry, not only by shining a spotlight on its dark underside but also by rallying major brands and retailers to mobilise manufacturers and instigate change. Its annual Hot Button Ranking monitors progress made, and progress is being made. In the 2020 report, eight major MMCF producers, Eastman, ENKA, Formosa, Jilin, Kelheim, Tangshan Sanyou, Xinxiang Chemical Fiber (Bailu), and Yibin Grace earned what it calls ‘green shirt’ designations. Two, Birla Cellulose and Lenzing, obtained the first-ever ‘dark green shirt’ ranking. The organisation estimates that 52% of global MMCF production is now made from wood pulp whose sourcing has been assessed as being of low or no known risk. This is a great achievement, says Ms Rycroft, but she points out that this still means 48% of the MMCF fibres produced yearly do not provide the same guarantees.

“Plant-based is being marketed as the holy grail,” she says. And this is, in part, fair as wood is a renewable resource. But Canopy estimates that 30% of viscose is currently sourced from ancient and endangered forests. “Those are not a renewable resource,” she says. “It takes hundreds of years to develop the functions and qualities of a mature forest.” She also stresses that maintaining forests has been identified by climate scientists as the fastest, cheapest and most effective way to address climate change. Forests are furthermore believed to provide habitat to an estimated 80% of the world’s terrestrial biodiversity.

The threat to these natural ecosystems remains high. Production of MMCFs increased twofold between 2013 and 2020 and is expected to double again in the next eight to ten years, says Canopy. 

Chemicals of concern

In addition to the issue of logging, the making of wood pulp and manufacture of viscose filaments and their kin involve heavy-duty chemistry. To drive change at this stage of the manufacturing process, which is not Canopy’s field of expertise, it reached out to the ZDHC Foundation, which has now added MMCFs to its Roadmap to Zero Programme. “Fibres are an important part of the value chain and global viscose production has been growing fast,” says programme director, Scott Echols. Within the production process for MMCFs, he says the most critical impacts come from chemicals that can be released into the air, water and soil. The organisation released MMCF Guidelines for wastewater and air emissions last year and expects to publish guidelines for filament MMCF production and dissolving pulp processes in the near future.

As Canopy’s Hot Button Ranking indicates, the main producers of MMCF have taken action. It helps that this industry is highly concentrated, with a handful of companies (11 to be precise) controlling 75% of global viscose production, as indicated in the Changing Market’s 2018 report. The manmade cellulosic fibre family represented 6.4% of total fibre production by volume in 2019, some 7.1 million tonnes, according to the Textile Exchange’s Preferred Fibre Material Benchmark Market Report for 2020. Viscose accounts for the greater part of this market (79%), followed by acetate (13%), lyocell (4.3%), modal (2.8%) and cupro (>1%). This last MMCF is not made from wood pulp but from cotton linters; Japanese producer Asahi Kasei is the only producer of this type of fibre. 

Action on the ground

Austrian producer Lenzing and India-based Birla Cellulose are the two companies that have made the most effort to abide by Canopy’s recommendations. “More than 99% of wood and dissolving wood pulp used by the Lenzing Group is either certified by FSC and PEFC or inspected in line with these standards,” says Lenzing’s head of corporate sustainability, Peter Bartsch. The company produces much of its own pulp, 62.4% coming from its own operations in 2020. It plans to increase its wood pulp dissolving capacity to cover 75% of its fibre production needs by 2024, in part the result of a new pulp production facility in Brazil.

Birla Cellulose, which is part of the Indian conglomerate Aditya Birla Group, says it sources 100% of its wood pulp from suppliers complying with FSC, SFI or PEFC standards. “We source our wood pulp from mature countries and avoid regions where deforestation is a risk,” Mukul Agrawal, the company’s head of sustainability, tells WSA. To address the issue of chemicals management, he says Birla Cellulose has invested $175 million to set up closed-loop processes, complying with the EU’s best available technologies emission limits (EU-BAT), which also complies with ZDHC recommendations. “We aim to recover over 90% of the sulfuric acid used in all of our sites by 2022, and we are already halfway there,” he says.

German viscose producer Kelheim has chosen to abide by the guidelines of the Eco Management and Audit Scheme (EMAS), a standardised certification system set up by the European Union, which it says offers greater transparency and covers all of the company’s operations. “We exclusively use wood pulp sources from suppliers with FSC or PEFC certification,” says Kelheim sustainability manager, Timo Thunitgut.

Sateri, a producer of MMC fibres based in Shanghai, has also committed to better policies with regard to sourcing and chemicals management. In 2020, some 96% of the wood pulp it sourced was from certified or controlled sources and it aims to achieve 100%, says Sateri’s vice-president for sustainability, Sharon Chong. “The average total sulfur recovery rate for our viscose mills is over 95%, one of the highest in the industry,” she adds. The company intends to make its viscose mills comply with the emission limits of the EU-BAT by 2030. It does, however, also plan to increase production. Sateri announced in March that it will expand its (closed-loop) lyocell production from an annual capacity of 25,000 tonnes to 500,000 tonnes by 2025.

US acetate manufacturer Eastman imposes high standards for its pulp sourcing and shares the names and mill locations of its three main pulp suppliers on its website and company documents. “Canopy’s work is very relevant to the industry, as many brands will only source from Green Shirt suppliers,” says Ruth Farrell, Eastman marketing director, adding that Eastman is the very first acetate manufacturer to have joined the ZDHC Foundation.

Late last year, Eastman launched Naia Renew, a new version of its branded acetate yarn, sourced from 40% recycled content. Wood pulp accounts for 60% of the raw material to make the fibre, and the acetic acid, which makes up the remaining 40%, is now derived from recycled plastics. The company has developed a chemical recycling process it calls Carbon Renewal Technology (CRT) that breaks down a wide array of difficult-to-process plastics to their molecular units. The proportion of recycled input is based on a mass balance system, certified by ISCC, a global sustainaility certification system, which monitors that inputs match outputs, she says.

Not only wood

The next step for Eastman, as well as for other makers of manmade cellulose fibres, is to replace pulp made from wood with other natural resources that have a high cellulose content. In its 2020 sustainability report, Eastman revealed plans to launch a non-wood-based fibre in late 2021. “We are looking at all types of alternative feedstocks to develop a fibre that would be indistinguishable from the yarns we currently make from wood pulp,” says Ms Farrell.

Many major MMCF producers have begun to invest in and develop fibres that can be made from non wood-based pulp. Lenzing launched Refibra technology lyocell in 2017, which incorporates recycled cotton fabrics and has steadily increased its recycled content. Up to 10% of the recycled raw material can now contain post-consumer cotton waste. Its next stated goal is to increase recycled content to 40% by 2023.

The recycled content used to make these next-generation MMCF fibres is, for the most part, drawn from post-industrial waste, unused fabric provided by garment manufacturers. At Birla Cellulose, Liva Reviva is made from 20% pre-consumer cotton fabric waste. Here again, the company says it takes care to source the fabric from reliable and respected suppliers, says Mr Agrawal. Production has been scaled up by 700% he says, as demand for this fibre is high. The company plans to increase the percentage of waste that can be incorporated into the fibre, whilst keeping its cost within an acceptable market range. “Good-quality waste is expensive, if we pushed to reach 100% recycled content, it would be too expensive. We have come to an agreement with our brand partners to supply Liva Reviva in large volumes and without sacrificing quality or price,” says Mr Agrawal.

Birla Cellulose is working with several textile start-ups seeking to scale up alternatives to wood-based pulp. These include Nanollose, which uses food waste to produce a pulp suitable for lyocell production, Re:newcell, which recycles waste fabric and used clothing into pulp, and a project to extract cellulose from agricultural biomass with Fashion For Good. “In this programme, 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 Mr Agrawal. He insists on the importance of finding a solution that is scalable and provides yarns that can be used in all types of fabrics. The company is also a partner in a research programme funded by the Laudes Foundation to develop a fibre made from agricultural waste.

Making viscose fibres from pre- and post-consumer textile waste is also on Sateri’s agenda. Its Finex branded viscose is made with pulp from recycled cotton fabrics supplied by Södra (OnceMore) and Re:newcell (Circulose). It has achieved Recycled Claim Standard (RCS) certification for these fibres which can include up to 20% recycled content, says Ms Chong. Chinese manufacturer Tangshan Sanyou’s Revisco staple fibre, launched in 2019, is also made from 50% post-consumer recycled content with pulp supplied by Re:newcell.

Reducing wood and textile waste 

The transition to next-generation fibres is a key focus for Canopy. Its research has revealed that 4.5 tonnes of trees are needed to make one tonne of viscose whereas the alternative raw materials in development, such as Re:newcell’s, can turn one tonne of used cotton clothing into nearly one tonne of fibre, says Nicole Rycroft. Canopy is working to identify the most promising candidates among these new woodless MMCF ventures and build up demand from the 340-plus brands that adhere to its CanopyStyle programme. The organisation has asked brands to commit to these next-generation fibres with letters of intention to purchase, indicating specific volumes, to support research and investment.

While Re:newcell, Sodra and Infinited Fiber are turning fabric waste into pulp, a number of start-ups seek to extract cellulose pulp from agricultural waste. California-based The Hurd Co is developing what it says is a “gentle” chemical process, requiring less water and energy to dissolve hemp waste into its Agrilose pulp. “Hemp is a high-yield plant that contains a lot of cellulose,” says company co-founder, Taylor Heisley-Cook. Still in the early stages of development, it plans to set up an R&D facility this summer before seeking further funding.

Circular Systems, based in Los Angeles, is also working on a method to manufacture a manmade cellulosic fibre it is calling Agraloop from hemp and flax agricultural waste. Hempcell is yet another such venture, co-developed by German textile research institutes and Berlin-based eco-brand Kind of blau.

Others still are focusing on introducing new chemistry for MMCF production, as is Swedish textile start-up TreeToTextile. It is working on a process, protected by several patents, which replaces carbon disulfide with what it describes as a “cold alkaline solution”. “Our objective is to make a more sustainable fibre that can be scaled to address the needs of high-volume markets,” says TreeToTextile CEO, Sigrid Barnekow. The company has received €35 million from its backers, which include H&M, IKEA and Stora Enso, to build a demonstration plant located at Stora Enso’s Nymölla mill in Sweden.

Major manufacturers and new players are actively seeking to develop these new-generation manmade cellulosic fibres that are not based on wood pulp, but pulp made from used clothing or agricultural waste. This would help reduce pressure on the world’s forest resources. It could also provide a solution for the waste generated both by agriculture and fashion.

Tencel lyocell fibres, made by Austrian producer Lenzing, are considered among the more eco-friendly of the MMCFs thanks to their closed loop NMMO-based chemistry. In 2020, the company invested some €34 million in an R&D programme exploring different plant-based materials as a source of cellulose, including hemp, straw, and bamboo.
Credit: Lenzing AG

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