Latest / The Manufacturing Podcast with Fexingo: Factories, Supply Chains, and Industrial Business / How a French Factory Is Making Fabrics from Algae
Transcript
- Lucas: So you've heard of cotton, polyester, maybe even Tencel. But what about fabric made from algae? That's what we're looking at today — a factory in Brittany, France, that's pulling cellulose out of seaweed and spinning it into textile fiber. Luna: Algae fabric. I've seen a few yoga brands claim they use it, but I had no idea there was an actual factory for it. Lucas: Yeah, the company is called AlgaKnit — though they're also licensing the tech under the name SeaCel. The facility is basically a pilot line that's been running since late 2024. It's small — about 15,000 square feet — but they're processing around 10 tons of wet seaweed per week. Luna: Ten tons of seaweed. Where does it come from? Are they farming it or just harvesting wild beds? Lucas: Both, actually. About 60 percent is farmed — long lines of kelp in the Rade de Brest, which is a bay on the Atlantic coast. The rest is wild-harvested from beach-cast seaweed that otherwise would rot and release methane. The factory pays local cooperatives to collect it, so it's sort of a waste to value story too. Luna: Okay, so the feedstock is interesting. But the big question: how do you turn a slimy green thing into something you'd wear? Lucas: Step one is washing and chopping the seaweed into a slurry. Then they add an alkaline solution to break down the cell walls and extract the sodium alginate — that's the polysaccharide that gives seaweed its structure. That alginate gets dissolved into a viscous dope, kind of like honey, and then they pump it through a spinneret — basically a showerhead with tiny holes — into a calcium chloride bath. The calcium cross-links the alginate into solid filaments. Luna: So it's essentially wet spinning, like how rayon or lyocell is made. But instead of wood pulp, you're using seaweed. Lucas: Exactly. The chemistry is similar to viscose, but without the carbon disulfide, which is the nasty solvent in conventional rayon. Here, the bath is just calcium chloride and water. They claim the whole process is circular — the water gets recirculated, and the leftover seaweed solids go to an anaerobic digester that generates biogas to heat the drying ovens. Luna: That's impressive on paper. But what's the output like? Can you actually make a shirt from this stuff? Lucas: They're producing a staple fiber — about 1.5 to 3 denier, so similar to cotton. It's white or off-white, with a slightly waxy hand feel. The lab tests show tensile strength around 2.5 grams per denier, which is weaker than cotton — cotton is around 4 — but stronger than most people assume for algae. They blend it with organic cotton or recycled polyester for durability. So far, the end products are T-shirts and underwear from a couple of French activewear brands. Luna: Let's talk numbers. What does this cost versus conventional fibers? Lucas: Right now, the fiber costs about 18 euros per kilogram to produce. That's roughly three times the cost of raw cotton, and six times standard polyester. But the founder told me their target is 8 euros per kilogram once they scale to a full commercial line — which they're planning for 2028. At that price, it'd be competitive with organic cotton, which currently runs around 6 to 9 euros. Luna: So there's a clear path to cost parity. What about the environmental claims? I've seen algae fibers marketed as carbon negative. Lucas: It's nuanced. Seaweed does absorb CO2 as it grows — roughly 1.5 kilograms of CO2 per kilogram of dry biomass. But the processing uses energy. Their current pilot line runs on grid electricity, which in France is about 60 percent nuclear, so the carbon footprint is low — around 1.2 kilograms of CO2 per kilogram of fiber. Compare that to polyester, which is about 5.5, and cotton, which is around 4. So it's better, but not negative. If they switch to biogas from their own digester and maybe add solar, they could get close to net-zero. Luna: And water? That's supposed to be the big selling point. Lucas: They use about 50 liters of water per kilogram of fiber. Cotton uses between 2,500 and 7,000 liters, depending on where it's grown. So it's a 99 percent reduction. But that's process water — they don't count the water the seaweed grows in, which is just ocean. So it's a fair comparison. Luna: That's massive. So why isn't every apparel brand knocking on their door? Lucas: Three reasons. First, volume. The entire pilot line can only produce about 20 tons of fiber per year. That's enough for maybe 30,000 T-shirts. A brand like H&M uses over a million tons of cotton annually. So they're not even a rounding error. Second, the fiber needs to be blended — it's not ready as a standalone material for high-stress garments. Third, the supply chain for algae is still regional. You can't just import seaweed from China and get the same quality. So scaling means building multiple facilities near coastlines with temperate seaweed farms. Luna: Speaking of China — there's actually a company in Qingdao doing something similar with a different species of algae, right? Lucas: You're thinking of SeaCell, which is a fiber from a German company that uses seaweed blended with lyocell. But yes, there's a Chinese research institute that published a paper last year on spinning fibers from brown algae. The difference is that AlgaKnit is using the alginate directly, not just adding seaweed powder to another base fiber. So the fiber here is majority algae. Luna: Let's talk about the end of life. Can this stuff biodegrade easily? Lucas: They tested it in marine water — the fiber lost 90 percent of its mass in 12 weeks. That's far faster than cotton, which takes months, and obviously much faster than polyester, which basically never biodegrades. The degradation products are just calcium and sugars, so it's safe for marine life. But one concern: if it's blended with polyester, the blend won't fully degrade. So it's really only beneficial if the garment is 100 percent algae or blended with a biodegradable fiber like cotton. Luna: I imagine washing also sheds microfiber. Is that a problem? Lucas: Good question. They tested microfiber shedding and found that the algae fiber sheds about half as many particles as cotton, and far less than polyester. And the particles that do shed are biodegradable, so they don't persist in the ocean. That's a big plus. Luna: This is genuinely interesting. But I want to step back — how did this factory even get funded? Was it venture capital, grants? Lucas: It's a mix. The company raised about 12 million euros in Series A in 2023, led by a French climate tech fund. They also got a 3 million euro grant from the European Innovation Council. And the French government's 'France 2030' plan kicked in another 2 million for industrial equipment. So they've got about 17 million euros to get to commercial scale. The founder said they'll need another 40 million for the full-scale factory. Luna: That's a lot. Do you think they can get it? Lucas: The investor appetite for alternative fibers is real. Bolt Threads raised over $200 million for mycelium leather. Modern Meadow raised $100 million for bioleather. So 40 million for a proven pilot line seems achievable — especially if they can line up offtake agreements with big brands. They're in talks with a major sportswear company, but they won't say which one. Luna: Let's talk about the actual factory visit. You were there last month — what stood out? Lucas: The smell. Honestly, it smells like low tide — briny and a bit fishy. They have these huge stainless steel vats where the seaweed is soaked and stirred, and the whole facility is humid. But the spinning line is surprisingly compact — about 20 meters long. You see the dope being pumped through the spinneret and solidifying instantly in the bath, then being washed, dried, and cut into short fibers. It looks like a miniature cotton gin. Luna: Were there any hiccups? I always find the problems more instructive than the smooth parts. Lucas: Yeah, they had a big issue with clogging in the spinneret. The alginate dope has to be perfectly filtered, because any particle bigger than 5 microns will block a hole. They went through three iterations of filtration before they got consistent throughput. Also, the drying step was causing the fibers to become brittle if they over-dried. So they had to dial in the humidity and temperature carefully. That's the kind of process engineering that takes months. Luna: So it's not just 'add seaweed, get fiber.' There's real chemical engineering behind it. Lucas: Exactly. And that's why I find this episode worth doing — it's not a magic bullet. It's a genuinely promising material that's being developed methodically, with real constraints. The team includes two PhDs in polymer science and a former textile engineer from a major Italian mill. They know what they're doing. Luna: Before we wrap, I want to ask about the broader landscape. Are there other algae fiber startups out there that you're tracking? Lucas: A few. There's a Scottish company called OceanFibre that's working on a similar process using different seaweed species. And a California-based startup called Kelpie is using genetically engineered algae to produce a silk-like protein fiber. But AlgaKnit is the only one with a running pilot line in a real factory building. So they're the furthest along. Luna: If these conversations have moved your work forward or just made your commute more interesting, a couple of dollars a month is genuinely what keeps these going — buy me a coffee dot com slash fexingo, if you've gotten something out of them. Lucas: Yeah, it's small amounts from people who find value in the show. No pressure, but it helps us stay independent and ad-free. Luna: Exactly. So back to the fiber — where do you see this in five years? Lucas: I think if they get the full-scale factory built, they could be producing 2,000 tons per year by 2030. That's enough to supply a niche but meaningful segment — maybe activewear linings, underwear, or nonwoven wipes. The real game-changer would be if a major brand like Nike or Adidas commits to using it in a flagship product. That would validate the category and unlock more capital. Luna: And if they don't scale? Lucas: Then it becomes a footnote in textile history, like milk fiber or banana fiber — technically interesting but commercially marginal. But the tailwinds are strong: microfiber pollution regulation in Europe, consumer demand for biodegradability, and the rising cost of cotton due to climate pressures. So I'd bet on them scaling, but it'll take another decade to know for sure. Luna: A decade feels like a long time, but in manufacturing, that's par for the course. Lucas: Right. The first polyester fiber was invented in 1941, but it took until the 1970s to dominate. So if algae fiber can carve out 1 percent of the global textile market by 2040, that's still hundreds of thousands of tons. And it would mean a real alternative to petrochemical-based fabrics. Luna: Well, I'll be watching. Thanks for the deep dive, Lucas. Lucas: Thanks, Luna. And if you're listening and want to see pictures of the factory, we'll post them on the show page — link in the description.