More renewable textile fibres, please!

In my recent think piece “Textile Waste – Mind the Dark Matter” I showed how surprisingly little textile fibre consumption in general, and synthetic fibre consumption in particular, is related to fashion consumption in the developed countries of the so-called Global North. I highlighted the role of technical textiles and nonwovens and how their growth on a global scale will require a broad strategy for reducing the textile industry’s impact on global resource footprint, CO2 emissions and pollution. Just reining in fast fashion will not do the job. I concluded:

“If your primary goal is to fight total textile carbon footprint, fossil-based (plastic) material use, total textile waste generation or microplastics pollution of land and seas, don’t overlook the producers and end users of nonwovens and other technical textiles. But also understand that many of these products do not serve frivolous consumption, but rather fulfil vital and optimised functions for safety and quality of life that billions of consumers in the Global South are also in the process of adopting. Therefore ensuring that we can make those increasingly needed fibres out of non-fossil feedstocks (including captured CO2) is as important, as becoming better at recycling them.”

Today I want to take a closer look at potential sources of more sustainable textile fibres that are needed to feed the growing global demand for textiles and fibre-based materials.

As a first step we need to develop a better understanding of the scale of the challenge, namely the realistically expectable amount of textile fibre consumption at a given point in the future – I use 2050 as target year – as well as the average annual growth rate to get there from today. The best way to figure out the future evolution of a complex, but not totally chaotic system is to describe as clearly as possible the current situation and to understand the past evolution and its underlying drivers.

Global fibre production in 2021 was pegged at 113 million metric tonnes by The Textile Exchange or 127 million metric tonnes by The Fibre Year the latter of which also includes spunlaid nonwovens, which go from polymer via filament to nonwoven in one integrated production process and are therefore not captured in many fibre statistics. I will work with the larger figure, as in my opinion all nonwovens are textile fibre based materials and should therefore be included in the sector’s material footprint statistics. Final figures for 2022 are not yet published, but it seems not much growth was seen compared to 2021, so I will stick with the 127 m.t. figure of 2021.

Over the last 50+ years, global textile fibre production has quintupled from 25 m.t. in 1970 to about 125 m.t. today for a compound annual growth rate (CAGR) of approximately 3%. What are the underlying drivers of this growth and what will they tell us about the future of textile fibre production and consumption?

Like for all materials and products that are used by people every day, the most fundamental underlying demand driver for textiles is global population growth. When comparing population growth and textile fibre consumption growth as K. Niinim?ki et al, Aalto University did, one sees clearly a correlation, although interestingly while global population growth rates started to decline in the early 1990s, fibre consumption growth rates around the same time started to accelerate.

What can explain this disconnect? And is it likely to persist as global population growth rates slowly but surely march towards zero (and likely into negative territory at some point later this century)?

K. Niinim?ki (and many others in this debate) point to fast fashion as the main culprit. And there is certainly something to this argument as the rise of the business model of ever faster changing fashion cycles and collection rhythms indeed coincides somewhat with the upward turn of fibre consumption growth rates in the 1990s. In my opinion, the engineered higher speed of the fashion cycle including faster obsolescence only explains a small part of this growth. The other very decisive element is the much greater affordability of clothing today due to massive cost reductions realised through automation and economies of scale in production of man-made fibres and all subsequent textile processing steps as well as the lowering of garment making costs through offshoring of production to the lowest labour cost countries in the world. In this way, most clothing (apart from the volume-wise irrelevant luxury segment) has seen virtually no price inflation and in many cases deflation over decades, enabling consumers to buy more. It is therefore more correct to say that cheap rather than fast fashion has been a demand driver for more fibre production. But to me, this is the smallest of 4 significant growth trends.

Also since the 1990s accelerated economic growth and prosperity gains have been achieved in the worlds most populous countries such as China, India, Brazil, Mexico, Turkey, Indonesia and other Southeast-Asian countries. If more than 50% of the world's population newly joins the global consumer class, we sure would expect to see an impact on demand for apparel products that are so fundamental to comfort, safety and self-expression. And this for me was, is and will remain by far the number one driver of global textile fibre consumption growth.

Thirdly, the type of products and applications for which we use textile fibres also keep growing incessantly. With greater prosperity comes increased consumption of many products that contain textile materials; from larger more comfortable homes, to cars, to sports and leisure goods. More free time and disposable incomes lead to consumption of more services which need textiles to function from hotels and restaurants, to transportation services, to entertainment and wellness. More prosperous societies have higher expectations for health care services, especially during the later years of our growing lifespans and there is a lot of textile use in hospitals, elderly homes and other health care facilities.

Finally, fibres are also increasingly used for materials that many people don’t intuitively link to textiles, namely nonwovens and composites. Nonwovens production is a highly efficient process at large scale and has driven substitution of other materials (including reusable textiles) for cheap disposable nonwovens. In hygiene and medical markets in the form of diapers, wipes, protective masks and gowns. For filtration and insulation in construction, automotive and many other industrial markets, for protection in agriculture and packaging and so forth. About one-sixth of all textile fibres are becoming nonwovens these days. Fibre-based composites are another area of rapidly growing fibre demand. From conventional synthetics, to glass and carbon fibres, to even some cellulosics and natural fibres such as hemp; many textile fibres find their way into cars, ships, trains, airplanes, buildings, protective equipment, sporting goods, windmill blades etc. Those fibre-reinforced composites provide exceptional performance, stability and durability at light weight and affordable cost, contributing to resource savings and lower CO2 impact.

Taking all these factors together, I predict that global fibre consumption growth will remain on its 2-3% growth trajectory over the next 25+ years, even if global population growth slows and fashion consumption in the Global North gets somewhat reined in by sustainability concerns. This growth will not be evenly distributed across the world. Europe may not see any volume growth in textile fibre consumption at all due to almost no population growth and a rapidly ageing society in which shrinking fibre consumption for clothing and interiors may be barely compensated by fibre demand growth for hygiene and medical nonwovens, technical textiles and composites. North America with somewhat healthier demographics, but also an increasingly ageing society will likely see slower than historic fibre consumption growth. The newly developed countries on the other hand will continue to play consumption catch-up and modernise cities, infrastructures and services, all of which will consume increasing fibre amounts even if population growth rates slow or may even turn negative (e.g. China). If the countries with the fastest population growth, mostly in Africa, will also improve political stability and economic prosperity another 1-2 billion consumers can give a further boost to global textile fibre consumption over the coming decades.

To summarise, global textile fibre consumption stagnation or even decline is not in the cards anytime soon. A 2% CAGR from today's fibre production level will take us to approximately 215 million tonnes of global fibre production and consumption in 2050, a 3% growth rate will result in 275 million tonnes. So where will these additional 100 to 150 million tonnes of fibres come from, meaning from what feedstocks are they going to be made?

When looking at fibre production trends over the last 20-30 years, it seems there is not an awful lot of potential in natural fibres, especially cotton. The reasons are manifold. Some such as soil degradation, water shortages or urban sprawl, maybe be difficult to reverse, others such as low yield and poor cotton farming economics especially in small-holder dominated growing regions (India, Sub-Saharan Africa) may be improved over time. Still, seeing global cotton production double by 2050 seems very unlikely. Other natural fibres such as wool, flax, hemp, silk etc. are so small in the overall picture and have various factors that seriously constrain meaningful growth. Hemp may have the best prospects, but developing farming practices, industrial processing capacities plus know-how and end market demand at the same time is a complex, costly and time-consuming undertaking.

Man-made fibre production on the other hand is very easy to scale and this is the reason why we have seen man-made fibres become so dominant over the last 25-30 years. Their main drawback however is the fact that most of them are made of non-renewable fossil resources, which the world tries to wean itself off in its effort to fight climate change. Other problems are related to their properties – most people still prefer cotton especially for the comfort layer of clothing that is in contact with the skin – and issues related to very slow degradation of most synthetic fibres when they end up in increasing quantities in the form of microplastics in our environment.

An interesting intermediate between fossil-based synthetics and natural fibres are man-made cellulosic fibres (MMCF). Like natural fibres, they are made of a biobased renewable feedstock, typically wood, but in principle any cellulose-rich feedstock can do, even cotton textile waste. And like synthetics, they are made in an industrial process that produces a very regular fibre output at easily scalable industrial efficiency and low cost. Potential drawbacks include the sustainability of the feedstock sources (e.g. deforestation) and the footprint and pollution risk of the chemical-heavy production process, especially when the conventional viscose process is applied. These drawbacks however can be overcome and therefore MMCF are perhaps the highest and most immediate potential fibre type to fill the global demand gap for sustainable textile fibres, especially when in additional to process improvements also fibre properties can ?be further enhanced and diversified to better match the fibres they seek to substitute incl. cotton.

Beyond man-made cellulosics, many other biopolymer based fibres from various feedstocks are under development or partially already in some industrial use such as fibres made of polylactic acid (PLA) or biobased PET or PA. These developments are needed and should be sped up, because a broader range of biobased fibres with a wide range of properties and from diverse feedstocks are needed if we want to have any chance of replacing 100% of fossil-based fibres at some future point in time. Like in the case of hemp, these developments are lengthy and risky because feedstock supply, processing and end market challenges need to be successfully tackled at the same time and the costs of fibres produced initially at smaller scale are not competitive with established commodity fibres. The European Environmental Agency has recently published a good overview report on the potential for biobased textile fibres, looking in detail at the various alternatives. However, like in the EU Textile Strategy the critical need of a broad biobased fibre development strategy to meet the material sustainability challenges of the global textile sector is not addressed. The EEA report sounds quite unexplainably doubtful and dismissive of biobased fibre potential, perhaps inspired by the misguided belief that fashion consumption reduction alone can bring about a fibre demand decline.

Beyond biobased feedstocks, there are two more principal ways of making textile fibres renewable. The first and currently very much focussed – perhaps even hyped one – is recycling. The problem is that current fibre-to-fibre recycling rates are ridiculously small. The latest estimate from Textile Exchange pegs the amount of post-consumer textile-to-textile recycling at 0.6% of total fibre use, which translates into post-consumer content making up just 4% of all recycled fibres used by the apparel industry, while the vast majority today is composed of rPET (from recycled PET bottles) plus some recycled industrial and pre-consumer materials. The true global rate of post-consumer textile-to-textile recycling is certainly much lower as the figure reported by Textile Exchange is limited to their members which are skewed towards the more sustainability-engaged European and American brands. Significant efforts funded by industry and a wide range of public and private donors are underway, but the runway to large-scale adoption of fibre-to-fibre recycling is long and littered with challenges from collection and sorting of post-consumer waste, to technical and economic hurdles to an uncertain regulatory environment. By 2050 textile-to-textile recycling will surely be a significant contributor to the required renewable fibre supply, but in my opinion neither the dominant nor the most sustainable source.

The 3rd and currently still mostly theoretical source of renewable textile fibres is the transformation of captured CO2 into monomers and polymers from which one can make all types of commonly known and used synthetic fibres. CO2 capture and feedstock use is pursued by many in the chemical and other processing industries and is likely to eventually contribute to the range of options to make carbon-based materials including textile fibres renewable. But again, the road to large scale adoption is long, technological and economical challenges especially the cost and environmental footprint of the energy employed will have to be overcome. The advantage is that the fibres produced are well known and established, which limits end use problems. What percentage CO2-based fibres will contribute by 2050 is today completely speculative, but that they can play a meaningful role is entirely plausible.

The Renewable Carbon Initiative does a great job in mapping out the transformation from a fossil to a renewable material based industry and society. As for all other carbon-based material sectors, the textile sector should tap into all 3 main sources of renewable feedstocks – the biosphere in the form of natural and biopolymer-based fibres, the technosphere for recycled post-consumer materials and the atmosphere for CO2-based fibre feedstocks. If I had to guess a likely distribution of a fully renewable fibre supply by 2050, I would give biobased fibres a 50-60% share (equally split between natural fibres, MMCF and other biopolymers), recycled fibres a 20-30% and CO2-based fibres a 10-20% share. This means ?biobased fibres would have to grow about 5-fold from todays 30 m.t. to about 150 m.t. Recycled and CO2-based fibres would have to jump from basically zero today to 50-60 m.t. and 25-30 m.t. respectively.

This cannot happen without a massive global innovation and upscaling effort to make those biobased, recycled and CO2-based fibres at quantities, properties and cost that allow the fossil to renewable material transition to happen without shortages, price spikes, industry and end market disruption. If we do not succeed on this path, the petrol-based synthetic fibre production capacities being built today in China, India or the Middle East may well keep running far beyond 2050.

No, the growing global need for textile materials will not go away even if we manage to curb some of its current excesses and inefficiencies of overproduction and overconsumption of cheap and cheerful fashion. And we will never be able to recycle our textile material stock over and over again without injecting a significant percentage of virgin fibre material from sustainable sources. What happens when these materials all of a sudden aren’t available in the needed quantities and qualities at affordable prices we all experienced during the first wave of the COVID pandemic, when face masks made of synthetic fibre nonwovens were in dramatically short supply.?