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What’s Needed for Biosynthetics to Replace Petrochemical Fibers

Fashion brands are scrambling to hit their ambitious climate targets as the planet heats up. Substituting fossil-fuel-based synthetics with materials derived from plants and agricultural waste could help.

“We at Textile Exchange view biosynthetics as an important material within the synthetic fiber category,” Kate Riley, the sustainability think tank’s synthetic fibers and materials strategy lead, told Sourcing Journal. “When managed responsibly, we believe that these materials can not only help lead the transition away from the extraction of virgin fossil-based resources but [also] play an active role in a regenerative and circular future for the industry.”

Virgin petrochemical-based fibers such as polyester and nylon account for the majority of global fiber production and its attendant greenhouse-gas emissions, Textile Exchange noted in a report published last month. If the fashion industry wants to stick to the 1.5-degree Celsius pathway as laid out in the Paris Agreement, it must also pivot away from fossil-fuel extraction and toward “holistically assessing” available alternatives, whether existing preferred materials such as recycled synthetics or biosynthetics made from corn, sugar beet, sugarcane, wheat and other natural, renewable sources.

The catch—and it’s a big one—is that the commercial share of biosynthetics is still very low. Infinitesimally so, in fact. Bio-based polyester, to name an example, made up 0.03 percent of all polyester fiber produced globally in 2020. Bio-based polyamide, or nylon, had a market slice of 0.4 percent. For those numbers to increase, companies need to ramp up their collaboration and knowledge sharing, Riley said.

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Not all biosynthetics are created equal, which means they must be treated with “care and nuance.” When it comes to inputs, there is no one perfect source. Assessing the impacts of corn versus sugar beet versus agricultural residues therefore requires an individualized approach based on region, production methods and technological application.

A traditional life-cycle assessment approach may also not cut it, Textile Exchange said. Sussing out the ramifications of a biosynthetic material requires going beyond greenhouse-gas emissions and examining factors such as water, soil health, biodiversity and livelihoods. Crucially, the Higg Material Sustainability Index of a specific supplier’s biosynthetic should not be used as a general assessment of all biosynthetics of its ilk. In any case, both the availability and quality of data for biosynthetics are currently limited, the report said.

Another nuance: Biosynthetic doesn’t always mean biodegradable. A bio-based material uses a feedstock that is renewable rather than fossil-fuel-based. A biodegradable one, on the other hand, can be broken down by microorganisms into carbon dioxide and biomass. So far, only a few bio-based synthetics are also biodegradable, which can be an advantage when it comes to fiber and material leakage into the environment, such as with microfibers. Design for durability and recyclability should still be the first choice, however, the report said.

Riley said brands don’t have to choose between biosynthetics and recycled polyester. (Some environmental campaigners disagree.) For the industry to reach its goal, “every tool in our tool kit” is necessary. This could eventually require the development of recycled biosynthetics to help close the loop, too. Further collaborative action is needed to overcome the challenges of the climate crisis, she added.

“With the publication of this guide, we hope to further drive the industry toward developing, scaling and implementing solutions,” Riley said. “It is important that we have material choices available which are 100 percent bio-based, as well as contributing to solving the climate challenges we face.”