In 2023, the apparel sector generated 944 million tons of global greenhouse gas emissions, almost 2% of the global carbon footprint (Apparel Impact Institute, 2025). Consumer desire is increasing for sustainable fashion that reduces waste and uses low-carbon alternatives to conventional fibers such as cotton and polyester. Seaweed-based fabrics could be part of the solution. In addition to potentially reducing emissions if substituting for conventional fabrics, they can also potentially reduce pressures on the use of  water and arable land. Seaweed-based alginate and cellulose fibers have desirable properties for fabrics, are currently used in medical applications such as wound dressings and are gaining attention in garment and furniture fabrics, hygiene products, and more.

This chapter covers the state of science, policies, and markets underpinning seaweed-based fiber production for use in fabrics, covering process steps after seaweed biomass is harvest and before the fiber is woven into a fabric. For seaweed cultivation and dewatering/drying, refer to the “Cultivation and Dewatering/Drying” chapter. Figure 1 summarizes the lifecycle elements discussed below.

Cleaned, dewatered, and dried seaweed is milled into a fine powder to increase surface area, then soaked to break down cell walls and remove compounds like fats and proteins that can weaken fiber quality. The pre-treated material is then refined into either alginate or cellulose intermediates: sodium alginate is extracted and formed into a spinnable solution, while cellulose is isolated and regenerated into filaments. Alginate routes typically spin the alginate into filaments (or mold it into sheets for bio-leather). Cellulose routes wet-spin regenerated cellulose into fibers similar to plant-derived cellulose, which are the most common fibers used for “seaweed fabrics” in medical, home, and fashion contexts.

Pre-processing

After being cleaned, dewatered, and dried, fresh seaweed is milled into a fine powder to increase surface area for subsequent soaking treatments. This can range from simple integration into existing soaks (e.g., cellulose) to complex acid or alkaline chemical baths (e.g., alginate). The goal is to dissolve cell walls and remove compounds that can degrade fiber quality (e.g., fats, proteins; Saji et al., 2022).

Processing

The processing stage is where pre-treated seaweed powder is refined to generate desired alginate/cellulose filaments or gels which are then spun into fibers or molded into sheets, respectively.

Alginate fibers/gels

Alginate fibers are created by spinning extracted sodium alginate into filaments; sodium alginate can also be molded into sheets to make bio-leather. Alginate fibers are very good at soaking up liquid and turning into a soft gel, which makes them well-suited for one-time use products like medical bandages or paper towels. However, this quality limits their use in everyday clothes and water-resistant use-cases (Qin, 2008; World Bank, 2023).

Cellulose fibers

Seaweed-based cellulose fibers are made by isolating glucose-based cellulose and regenerating it into filaments, then wet-spinning into fibers. The fibers are similar to those found in terrestrial plants, and are used to produce the “seaweed fabrics” seen today (Gregersen, 2019; Baghel et al., 2021).

Post-processing

Seaweed-based fibers are then blended with other fibers for further manufacturing into fabrics for different use-cases (e.g., medical, home, fashion; see Figure 1) and scale (e.g., personal use, fashion brand, commercial-scale).

Species Selection, Cultivation and Harvesting

Species Selection

There are over 10,000 species of seaweed that vary substantially in their life cycles, impacting the concentration of compounds suitable for fiber production. Given the emerging exploration of seaweed-based fibers, seaweed species selected for production have been limited to regional seaweed supply. Species high in cellulose or alginate are desirable because the fibers produced are similar in chemical composition, mechanical performance, and tactile properties to conventional fibers (e.g., cellulose), or are already extracted in high volumes for other industries (e.g., alginates) (Felgueiras et al., 2021). Common products using seaweed-based cellulose have <10% inclusion, but with alginates it can increase to as much as 100%. Table 1 summarizes how seaweed-based fibers are commonly used and by what companies.

Alginate & Cellulose AdditiveAlginate

Table 1. Examples of species used in fiber production, use cases, and associated companies/institutions with publicly available records of seaweed inclusion in the product.

Cultivation

For more information on the cultivation approaches, see the “Cultivation and Drying Considerations” chapter.

Harvesting

Currently the most common fibers made with seaweed (e.g., SeaCell) are sourced from wild harvests, which can produce variable quality. This is also seen in studies with cultivated seaweed species – for example, Ocean Rainforest has shown that the concentrations of alginates and cellulose can vary with seasonality (Gregersen, 2019).

Processing information is proprietary in most cases, but general processing methods and active R&D are detailed below for alginate and cellulose-based fiber production (summarized in Figure 3).

Processing and Post-processing

Alginate

Following preprocessing, seaweed is added to a tank with an alkaline solution (e.g., sodium carbonate). Consistent heating (e.g., 40°C for three hours) then converts the seaweed’s alginic acid to sodium alginate, the desired material. After conversion, the mixture is filtered to separate the solid fraction (containing materials like cellulose, fucoidan, laminarin) from the liquid fraction containing sodium alginate. Ethanol-induced precipitation purifies the sodium alginate for downstream processing (Gregersen, 2019; Managò, 2022; World Bank, 2023; Figure 2A).

Downstream Processing: Alginate fiber

Wet spinning mixes sodium alginate powder with water and soluble additives. The solution is passed through a spinneret or nozzle within a coagulation bath filled with a salt solution to link the polymer chains, producing fiber. Multiple rounds of washing, stretching, and drying occur to shape the fibers before they are cut to size for further processing into yarn and fabrics (Bojorges et al., 2023).

Downstream Processing: Alginate leather

Sodium alginate powder is poured and set into a plasticizer (made of cardboard and/or faux leather) shaped to mimic a leather finish. Once the plaster is completely dried, a pigment-containing hydrogel is poured into the mold cavity and then compressed. Applying calcium chloride then nebulizes the hydrogel, curing the alginate without cracking the material; it also provides a protective patina to the exterior, which can give the material water and microbial resistance (Managò, 2022).

Novel alginate extraction methods

More novel methods (e.g., ultrasound-, microwave, or enzyme-assisted extractions; MAE, UAE, EAE, respectively) are also being explored to extract sodium alginate for higher quality and efficiency (Saji et al., 2022; Bojorges et al., 2023). MAE, UAE, and EAE are desirable for industry-scale use due to their specificity in targeting desirable compounds, higher yields compared to traditional methods, and lower environmental impact compared to current commercial methods. Table 2 below summarizes the novel extraction methods and their current readiness.

Table 2. Emerging extraction techniques for seaweed-based fiber production, claimed benefits, and technological readiness/status. Sources: Saji et al., (2022), Bojorges et al. (2023)

Cellulose

Cellulose fiber production occurs primarily through viscose, modal, and lyocell processes and with tree-based feedstock (e.g., eucalyptus, oak, birch; Varnaitė-Žuravliova and Baltušnikaitė-Guzaitienė, 2024). None of the current manufacturing methods incorporates raw seaweed as the dominant material in production. The lyocell process has been most commonly used in producing seaweed-based fibers given the lower environmental impacts of its production (Guo et al., 2021).

Lyocell Process

Dried and ground seaweed is suspended in an amine oxide (surfactants used as stabilizers, thickeners etc.) solution with wood pulp at constant heat. The seaweed suspension is then added to another wood pulp suspension in doses. Dosing occurs at the wood pulp treatment, subsequent cellulose suspension, and at the spinning and filtration stages. The mixture is then filtered, spun, washed, and dried, producing a fiber with approximately 4% seaweed for yarn and fabric manufacturing (Gregersen, 2019).

If seaweed cellulose by-product is used following a prior product extraction process (e.g., after alginate extraction), it can be separated and characterized by whether its chemical composition (e.g., moisture, ash content, viscosity, dissolvability in lyocell solvents) enables further refinement into cellulose fibers (Figure 2B). If so, the by-product is processed using the lyocell method referenced above to purify the cellulose at levels suitable for fiber manufacture, sometimes in multiple rounds after chemical characterization.

The diluted amine oxide can be recycled for future processing batches by purifying and evaporating the water. Research is ongoing to valorize seaweed residues from the hydrocolloid industry as a primary feedstock for cellulose; while the research is being developed for producing films, it could apply to fiber production for fabrics (Jiang et al., 2025).

Table 3 below summarizes the Technology Readiness Level (TRL) of fibers with seaweed inclusion. Companies that incorporate seaweed as a minor additive into fiber blends are generally commercialized but niche (TRL 7–9), while those that seek to make seaweed the dominant feedstock are in the emerging research levels (TRL 2-4; Gregersen, 2019; World Bank, 2023).

Table 3. Fiber product, process, commercial examples, TRL, percentage of seaweed inclusion and tradeoffs. Sources: Gregersen (2019), World Bank Report (2023)

Buyers interested in seaweed-based fibers compare them to the durability, water resistance, tensile strength, and feel found in conventional petroleum- and cotton-based products. Currently, seaweed-based fibers have limited inclusion in garments and furniture due to concerns over material integrity (Gregersen, 2019; SEACELL, 2025; World Bank, 2023). For example, laundry is one of the most energy-intensive processes in a garment’s life, a challenge for alginate-based fibers  with high absorbency (World Bank, 2023). In certain cases, seaweed-based fibers’ have a performance advantage; for example, seaweed-based dressings specialized for wounds that need moist environments (e.g., burns, ulcers, sores), or hygiene products like Vyld’s tampon (“kelpon”), to absorb blood and other bodily fluids.

Table 3. State of the Market of global fibers, grouped into polyester and natural fibers; and biosynthetic textiles. The market of seaweed-based fibers is currently too small to be quantified. *Growth rate used is from global fiber market. Sources: Grand View Research (2026), Textile Exchange (2024) World Bank (2023)

Fashion and clothing segment makes up 52.8% of the textile fiber market in 2024, and consumer habits/preferences are shifting in favor of greener, sustainable products that promote circular economies and zero waste (Todeschini et al., 2017; Grand View Research, 2026). Notable examples have already been seen by fast fashion giants like C&A’s 2014 program and H&M’s commitment to manufacture goods from 100% circular and sustainably sourced materials by 2030 (H&M, 2025). Seaweed-based fibers can speak to the circular economy and zero waste desires of consumers, but only if its durability, design, and price is competitive with conventional materials. Current small-scale production is not economically viable, and more techno-economic studies are needed to evaluate costs at scale.

Context

According to the Apparel Impact Institute (2025), more than a quarter of global greenhouse gas (GHG) emissions from the apparel sector is generated from raw material extraction (22%, 209 million tons CO₂e) and processing (15%, 139 million tons CO₂e). In 2023, the apparel sector produced 944 million tons of GHG emissions, representing approximately 1.8% of the global carbon footprint (Apparel Impact Institute, 2025). More than 720 million tons stem from fossil-fuel-based (polyester) and cotton fiber production (see Figure 3).

Emissions Reduction Potential

Evidence Base

We use LCA data from raw material extraction and the Lyocell fiber production method to estimate what the global warming potential of seaweed-based fibers would be. Combining the global warming potential of refined sodium alginate extraction with commercial scale lyocell production yields an estimated climate impact of 3.36 kg CO₂e/kg fiber, in contrast to 5.09 kg CO₂e/kg fiber and 7.47 kg CO₂e/kg fiber produced by polyester and cotton methods, respectively (Gonzalez et al., 2023; Ayala et al., 2024; Agarwal and Sethi, 2026).

Calculation Chain

Step 1 — Displacement factor derivation

The functional unit is kg CO₂e per kg of finished fiber (cradle-to-fiber-gate). This is the boundary used by the primary LCA sources. It excludes weaving, dyeing, garment manufacture, consumer use, and end-of-life — meaning all estimates are upper bounds on the full lifecycle benefit.

Step 2 — WB 2030 central market scenario

Step 3- 2050 Scenario

Co-Benefits

• Seaweed-based fiber production will require less arable/forest land, freshwater, fertilizers, and/or pesticides to grow compared to conventional fibers such as cotton and wood-based cellulose. It can also help in bioremediation efforts like ocean acidification mitigation, depending on the site of production (World Bank, 2023; Baghel et al., 2021)

Risks

• Chemical reagents used to process seaweed-based fibers using conventional approaches can pollute adjacent ecosystems, if not properly managed and disposed of (Baghel et al., 2021; Bojorges et al., 2023; Guo et al., 2021; Quaratesi et al., 2024)
• Conventional alginate extractions have a high water footprint (Saji et al., 2022)

Co-Benefits

• Seaweed fibers’ blendability with other fibers allow for better integration into existing workstreams like cotton, ensuring minimal disruption to livelihoods
• Seaweed alginate fibers have been shown to have beneficial properties for wound dressings and hygiene products, including improve absorbency, blood clotting, and cell regeneration (Dhiman & Chakraborty, 2015; Gregersen, 2019; Qin, 2008)
• Seaweed-based fiber scale-up can create coastal jobs via local processing, biorefineries, and manufacturing; convert residues into income (“waste-to-wealth”); diversify communities’ livelihoods; and expand women’s leadership and employment (Madukhar et al., 2023; Jiang et al., 2025)
• Seaweed-based fiber production can relieve pressure on land-use for global food security, fulfilling Sustainable Development Goals (SDG, Madukhar et al., 2023):
  • SDG 2: Zero Hunger
  • SDG 12: Responsible Consumption and Production

Risks

• The industrial processes used to refine materials into fabric-grade fiber can be chemically toxic, introducing occupational hazards and job inequities. (Bojorges et al., 2023

The seaweed fabric industry is nascent, with most activity at the pilot and experimental stage. Although early adopters describe seaweed as a vibrant, living material, the sector must cross the “valley of death” between lab innovation and commercial scale to establish long-term credibility (World Bank, 2023; Franzo et al., 2024). Seaweed’s environmental advantages in reduced land, freshwater, and pesticide use can strengthen its social license within coastal communities (Ayala et al., 2024). That trust is further supported by the potential for restorative ecosystem services and inclusive value chains that benefit marginalized groups. Sustaining this positive perception, however, will require closing awareness gaps and addressing consumer skepticism about product durability and supply-chain traceability, as well as the risks of associated industrial processes to convert the seaweed into a textile/fabric (World Bank, 2023).

There is currently limited inclusion of seaweed-based fibers in governance and policy frameworks. To promote the scaling of seaweed-based fibers in the fabric industry, certain policies and regulations could provide market support and incentives for scaling the industry. However, some of the certifications that could promote more market support exclude parts of the workstream that are in certain regions (e.g., Fairtrade certification only applies to textiles produced in developing countries). Table 5 summarizes current policies and regulations that would apply to seaweed-based fibers.

Table 5. Example policies and regulations relevant to seaweed-based fibers.