• Lululemon has started to sell shirts that are made with nylon manufactured with ingredients from plant-based sources, instead of raw materials that come from the petrochemical industry.
• The shirts are the result of a partnership born from Lululemon's equity investment in the biotech company Geno.
• Geno uses microorganisms operating in fermentation reactors to convert sugar molecules into a specific product, instead of using fossil fuels.

Lululemon has started to sell shirts that are made partly with nylon created from plant-based sources, instead of raw materials that come from the petrochemical industry, according to an announcement on Tuesday.

The shirts are the result of a 2021 partnership born from Lululemon's equity investment in biotechnology company Geno.

The short-sleeved shirts are made from at least 50% biologically sourced nylon, at least 40% recycled polyester and 3% elastane (itself made with 30% plant-based content). The shirts cost the same as the conventionally sourced version: $78 for the men's version, and $68 for the women's.

As part of a goal to make 100% of its products with sustainable materials by 2030, Lululemon has partnerships with other companies that make materials in novel and sustainable ways. For example, in February 2022, Lululemon launched two products — a meditation and yoga mat bag and the Lululemon barrel duffel bag — made out of the mycelium-based leather from Mylo.

Conventionally, nylon is mostly made from ingredients sourced from fossil fuels like coal, natural gas or crude oil.

The petrochemicals used to make nylon are adipic acid and hexamethylene diamine, and the climate impact of making adipic acid is particularly damaging, Stephen Wallace, a professor of biotechnology at the University of Edinburgh, told CNBC.

Conventional adipic acid manufacturing processes releases nitrous oxide, a greenhouse gas that is as much as 200 times more potent than carbon dioxide, Wallace told CNBC. "It's been estimated that 8 to 10 percent of all human-associated nitrous oxide emissions come from this single industrial process" to make adipic acid, Wallace told CNBC.

To make the nylon precursor used in the Lululemon shirts, Geno uses biological organisms instead of chemicals from fossil fuels.

"As with all of the products that are produced with Geno technologies, we utilize biotechnology to convert plant-based sugars into the products we target," Christophe Schilling, the CEO and founder of Geno, told CNBC.

"Plants take up CO2 from the air, and with sunlight providing energy, convert that into sugars, which can be collected and then fed into a Geno process." That biomanufacturing process uses fermentation to create the same nylon precursor ingredient, Schilling said.

A preliminary life cycle analysis suggests that the bio-nylon will offer at least a 50% reduction in carbon emissions, said Sasha Calder, the head of Impact at Geno.

'A big push' to reinvent plastics

Remaking supply chains that have depended on fossil fuel-based ingredients is generally a hot topic right now, according to Christopher Reddy, an environmental chemist and a senior scientist at the Woods Hole Oceanographic Institution who studies how plastics break down in the environment.

Many of the synthetic products used in modern, everyday life, including nylon, are made from the leftovers at an oil refinery after a product is made.

"Most of the plastics are made up of carbon and some small other elements," Reddy told CNBC in a phone conversation on Friday. "So the big push right now is: Can we use another source of carbon — like from plants or kelp or food waste — and can we use that as the starting material and maybe still keep making nylon?"

(Reddy was speaking about plastics supply chains more broadly, as the Lululemon-Geno product announcement was not public yet.)

"Because nylon, like it or not, has a lot of good value," Reddy told CNBC. "There's lots of reasons why plastics are bad to the environment, but at the end of the day, plastics, nylons are part of our everyday life."

There's already a long history of making plastics from petrochemicals — nylon itself was invented in the 1930s — and so reimagining those infrastructures takes both time and money, Reddy said.

An effective replacement product has to work well and be cost-effective, too. "Look at those first-generation replacement straws — they didn't work, and everybody's annoyed," Reddy told CNBC. "So, when you go and make these changes for a cleaner, better environment, you better make sure they work."

Geno is acutely aware of these challenges.

"Across our portfolio, we review each technology before it goes to market to ensure that the carbon profile offers significant sustainability benefits, while also being cost-competitive and of similar or better performance as the incumbent source it's replacing," Geno's Schilling told CNBC.