The fashion industry is rapidly developing new solutions to move from being a polluting industry to one that is regenerative. An incredible new category of fibre derived from agricultural and food waste is one such solution.
The role of agricultural waste in sustainable fashion
Food crop agriculture creates a tremendous volume of waste from the parts of the plants that are not consumed or utilised (i.e. leaves, barks and fruit skins etc.). On average, each kilo of food harvested corresponds to 1.5 kilo of residue, and 270 million tons of waste are created from banana crop alone. Often these waste residues are burned or left to rot, causing severe damage to the environment as the decomposition of crop by-products generates significant amount of greenhouse gasses, which contributes to climate change.
If this waste is burnt to clear land the result is air pollution in the form of greenhouse gases and soot particles, also endangering human health. Additional impacts of crop residue burning are: loss of active soil beneficial bacteria, soil nutrients and fertility, soil hardening and erosion. This impacts negatively upon plant nutrients and biodiversity, leading to the loss of flora and fauna.
Plant biomass (i.e. waste residues) contains renewable sources of diverse biopolymers such as cellulose, lignin and pectin, which can be turned into fibres for textiles. Converting food and agricultural waste into usable fibres not only optimises the use of neglected resources and reverts fashion industry’s extractive pattern that consumes finite resources at a damaging pace, it also helps to build a more regenerative system by reducing the environmental impact and land/water overuse from agriculture.
An increasingly well-known feedstock source is fruit peel. One can now find leather alternatives, such as the bio based materials created from apple skin and grape musc, or the silk-like material made from orange peel. Frumat is created by extracting cellulose from apple pectin, which is then dried, ground into powder, mixed with binder and spread out onto a backing canvas until it turns into a leather-like material. In contrast, VEGEA material is produced from bio-oil extracted from dried grape residues collected from the wine industry, which is then polymerised to create a material with similar hand-feel and texture like leather. Note that these materials still have PU added to increase strength. Then there is Orange Fiber, which extracts citrus cellulose from juice production by-products, to create a polymer that is then spun into soft, lightweight and silk-like yarn that can be blended with other materials.
Seed oil and plant stalks
Seed oil, plant leaves and stalks are also a major source of feedstock. The most notable bio innovation supplier working with these types of feedstock is Agraloop™, who focus on five agriculture crops: hemp seed oil, flaxseed oil, pineapple leaves, banana trees and sugarcane bark. Using their proprietary Agraloop system, plant-based chemistry is applied to transform waste into natural fibres called BioFibre. According to Circular Systems™, waste materials from these five crops could generate up to 250 million tonnes of fibre each year, more than 2.5 times the current global fibre demand.
Leading Italian yarn manufacturer Radici Group has also developed a technology to produce bio-based nylon yarn synthesised from castor oil plant seeds at commercial scale. Fabrics made from castor oil based nylon yarn can be sourced from suppliers such as Olmetex. Other suppliers specialised in under-explored cellulose fibres include Torcetex who utilises the usually unwanted and discarded husk from cotton cultivation to produce beautiful textile suitable for home furnishing.
The final major type of agricultural waste feedstock is biogas, derived from the decomposition process of organic waste. This process produces PHA’s (polyhydroxyalkanoates), which are melt-processable thermoplastics produced from microorganisms by fermentation of renewable carbohydrate feedstocks. PHAs are 100% bio-based and biocompatible. There are large established chemical companies such as BASF, as well as young material science start-ups like Mango Materials who are active in this innovation space.
BASF uses a proprietary method called the mass balance approach to replace 100% of fossil feedstock required for the chemical process to produce polyamide fibre with certified renewable material from biogas, creating a high-performance bio-nylon fibre called Ultramid that saves at least 35% greenhouse gas emissions vs. virgin nylon. Tawainese mill Flying Tex is one of the mills that produces fabrics made from Ultramid. Mango Materials uses waste methane to feed bacteria, which then produce the PHA polymer that can then be spun into yarn.
Potential concerns of agricultural waste based fabrics
Alongside the potential upsides and benefits associated with materials created from agricultural waste, there are a number of considerations to be taken into account.
First, it’s important to distinguish between bio-based (i.e. first generation crop) from biomass (i.e. waste-based) feedstocks. There are big differences in terms of their potential impact, as bio-based generally corresponds to commodity crops that compete for arable land and severe the states of deforestation and loss of biodiversity. Feedstocks from waste on the other hand, will most likely be more environmentally preferred and more efficient, as they generally don’t require new production of crops and if not re-used would end up discarded.
Second, the recycling and disposal of material created from biomass could be a problem. For example, while bio-based polyester can be recycled in existing PET recycling infrastructures, most recycling technologies cannot yet distinguish between different types of plastic. The end-of-use concerns need to be addressed so that the potential benefits from biopolymer material are maximised without impeding their commercial viability.
Third, biodegradability of these materials is also of significant importance. There is a misconception that all biopolymers are by default biodegradable, but this is not the case, and some can actually off-gas detrimentally if not properly processed. Additionally, clothing products are often developed from mixed material sources, such as cotton and polyester blended together, so composting is only an option if the materials have been separated first. Last but not least, unless the product being composted can return nutrients to the soil, the higher value option would be to recycle or up-cycle products at the end of their intended life.
With the right business models and infrastructures that enable the scaling of the technologies and proper end-of-use treatment, agricultural-waste based materials might become one critical piece of the puzzle to accelerate this industry transformation.