Sargassum uses: Housing, fuel, textiles, and the next wave of sustainability.

Sargassum: From coastal menace to natural resource

For years, sargassum has been branded a disaster for Caribbean nations and coastal communities worldwide. Beaches once prized for tourism are now often buried beneath thick, foul-smelling mats of this brown seaweed. Fisherfolk, hoteliers, and environmentalists have sounded alarms as it suffocates coral reefs, traps marine life, and drives visitors away.

Yet, emerging science and entrepreneurship are revealing a different narrative. Instead of a liability, sargassum is proving to be a versatile, renewable resource with applications ranging from construction and clean energy to cosmetics and high-performance materials.

This article explores how sargassum shifted from a contained ecological phenomenon in the Atlantic to an annual crisis since 2011, and more importantly, how innovators are transforming it into a global resource.

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How sargassum became a global problem

Sargassum is not a new species or an alien invader. It is a floating seaweed that has thrived for centuries in the Sargasso Sea, a region of the Atlantic encircled by looping ocean currents. Unlike other seaweeds, it never anchors to the seabed. Its small gas-filled bladders keep it afloat, enabling massive mats to drift freely. This mobility, combined with its ability to regenerate from broken fragments, makes it highly efficient at reproduction.

Historically, this was a balanced system. The Sargasso Sea provided a nursery for marine life, and the seaweed stayed contained within the Atlantic’s circular currents. That equilibrium ended in 2010 when an unusual weather event disrupted ocean patterns. Currents carried large masses of sargassum out of its traditional range, dispersing it across the Atlantic and into the Caribbean. By 2011, unprecedented blooms began arriving on tropical shores.

The phenomenon has intensified annually. In May 2025 alone, an estimated 38 million tonnes washed ashore. Caribbean resorts reported sharp declines in tourism, schools shut down due to the unbearable hydrogen sulphide odour from decomposing sargassum, and vital ecosystems such as coral reefs and seagrass beds suffered suffocation. Governments, including the US Virgin Islands, declared states of emergency. Clearing even one kilometre of beach can cost US$70,000 per month, straining budgets and filling landfills.

What was once a biological curiosity has become a recurring natural disaster. But with the right perspective, this floating biomass is being redefined as opportunity.

Sargassum as a construction material

One of the most practical uses of sargassum is in construction. In Mexico’s Yucatán Peninsula, entrepreneur Omar Vázquez pioneered a technique to produce durable bricks made with 40% sargassum. Each house built with these bricks locks away up to 20 tonnes of seaweed, transforming a disposal problem into housing solutions.

The first prototype home, built in 2018, has already withstood five hurricanes. Beyond resilience, residents report that the homes remain cooler in tropical heat compared with conventional buildings. The production process is also cheaper than making standard bricks, meaning that sargassum-based housing is not only sustainable but also affordable for communities in need.

Turning seaweed into clean energy

Decomposing sargassum naturally releases methane, a greenhouse gas. Instead of letting this escape into the atmosphere, innovators are capturing and converting it into useful energy. In Grenada, the company SarGas has developed biodigesters that combine sargassum with food waste and pig manure. Microbes break down the mixture, releasing methane, which is then harnessed to fuel bakery ovens.

With government support, SarGas is scaling up to produce electricity. A facility processing 5,000 to 8,000 tonnes of sargassum annually could generate 150 kW of power the equivalent of 1,500 home solar panels. While this only covers a fraction of demand, for small islands dependent on imported fuel, it represents both cost savings and a step towards energy independence.

In Barbados, researchers have taken the concept further. By fermenting sargassum with wastewater from rum distilleries and sheep manure, they have produced methane capable of powering vehicles. With a retrofit costing around US$2,500, a standard petrol engine can be converted to run on biogas. This innovation points toward a future where taxis and buses in the Caribbean could operate on locally sourced, renewable fuel.

High-value products from sargassum

Beyond bricks and biogas, sargassum contains compounds of significant economic value. Biorefineries are extracting alginate, fucoidan, and nanocellulose from the seaweed materials that have uses in pharmaceuticals, cosmetics, textiles, and advanced composites.

Cosmetics and skincare

Companies like Origin by Ocean are refining Caribbean sargassum in Finland to extract natural thickeners and moisturisers. These ingredients are already used in premium skincare, sunscreens, and personal care products. Ironically, the same seaweed that tourists flee from on beaches is being applied to soothe sunburn.

Textiles and packaging

In St Lucia, entrepreneur Johanan Dujon founded Alt-Fibr, which transforms sargassum fibres into paper, food packaging, and even fabric. Working with universities in the United States, the company is developing lightweight, durable fibres that could replace tree-based pulp in the paper industry.

Bioplastics

Start-ups are creating compostable straws, garment bags, and packaging materials from seaweed-derived polymers. Unlike corn-based plastics, these require no farmland or fertiliser, making them environmentally superior.

Nanocellulose composites

In Florida, Soarce extracts nanocellulose from sargassum, creating a material as strong as steel for its weight. Potential applications range from vehicle components to aircraft panels, delivering lightweight strength for industries dependent on advanced materials.

Scientific frontiers: Fuels and critical metals

Research institutions are also advancing sargassum utilisation at a molecular level. At UCLA, scientists are developing a process to extract hydrogen fuel by heating sargassum with sodium hydroxide and a nickel catalyst. The result is 90% pure hydrogen, a critical fuel for clean energy transitions.

Other studies are exploring sargassum as a potential source of critical metals used in batteries and electronics. By employing molten salt electrolysis, researchers are investigating whether metals absorbed by the seaweed can be safely recovered and used in manufacturing. Such methods could reduce dependency on destructive mining operations.

Additionally, experiments are under way to transform by-products of hydrogen production into carbon nanotubes nanostructures valued for their strength and electrical properties.

Overcoming challenges

While the potential is vast, challenges remain. Sargassum often absorbs heavy metals such as arsenic, which must be removed before it can be safely used in food, packaging, or cosmetics. Processing methods are improving, but scaling them efficiently remains a key focus of international research.

Another challenge is logistics. Collecting sargassum at sea before it decomposes on beaches is costly, yet it is essential to prevent ecological damage to coastal ecosystems. Developing affordable collection technologies, combined with efficient processing systems, will determine how quickly sargassum can shift from burden to resource on a global scale.

From disaster to opportunity

The transformation of sargassum from ecological nuisance to economic asset is a powerful example of rethinking natural challenges. In 2025 alone, tens of millions of tonnes will wash ashore in the Caribbean and Gulf of Mexico. Left unmanaged, this biomass represents a crisis. Managed effectively, it represents a renewable, versatile, and valuable natural resource.

From bricks that withstand hurricanes to renewable energy that reduces diesel imports, from skincare to nanotechnology, sargassum is demonstrating that innovation can turn environmental disruption into sustainable opportunity. With coordinated scientific, entrepreneurial, and policy support, what was once branded as a natural disaster can become a foundation for a new bio-based economy.

The story of sargassum is still unfolding. Its future will depend on how societies respond to its abundance. By embracing it as a resource rather than fearing it as a menace, communities stand to gain both economically and environmentally.

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