Turning harmful seaweed blooms into sustainable building materials.
By Nick Owens
The world’s addiction to plastic means we now produce 430 million tons of it each year. Half of this – designed for single use – is discarded almost immediately. Unsurprisingly, the vast majority of this plastic never reaches recycling facilities. Instead, it ends up in landfills, unregulated waste sites, or polluting our oceans and ecosystems.
Simultaneously, nutrient runoff from industrial agriculture—particularly nitrogen and phosphorus—has fuelled massive seaweed blooms across the Atlantic. These vast mats of Sargassum now form what’s known as the Great Atlantic Sargassum Belt, visible from space and estimated to weigh 24.2 million tons – the same as the entire human populations of the United States and Mexico combined!
On land, Sargassum piles up on beaches without warning, where it rots, releasing hydrogen sulphide—a gas with an unpleasant odour and potential health risks like headaches and eye irritation. In the ocean, it entangles with plastic debris and disrupts coastal ecosystems: blocking sunlight, harming marine life, and preventing sea turtle hatchlings from reaching the water. It can also interfere with infrastructure and tourism, particularly in regions like the Caribbean where seasonal income is vital.
So—what can be done with all this plastic and invasive seaweed?
Looking to address both problems at once, father-daughter team Andrés de Antonio Simancas and Raquel de Antonio Crespo founded Sargassum Eco Lumber. Based in Miami, where Sargassum cleanup costs the city an estimated $4–6 million annually, the duo set out to turn the nuisance into something useful. They began experimenting with ways to repurpose Sargassum and eventually developed a method to convert it—together with discarded plastic—into a viable building material.
After multiple iterations, they created Sargassum Eco Lumber: a durable blend of processed seaweed and plastic that forms robust planks and panels. To make it, Sargassum is collected from beaches or the sea using trucks, shovels, and tractors. It’s then dried at high temperatures and ground down. Meanwhile, plastic waste—such as shopping bags and packaging—is densified and shredded. The two materials are combined and moulded into synthetic wood sheets. This new material is strong, durable, and resistant to rot, termites, and rust.
Sargassum Eco Lumber is still in its early production phase and currently raising funds to scale. Despite this, their innovative panels—already shown to outperform traditional plywood in strength—have drawn interest from logistics and pallet companies committed to reaching carbon neutrality.
Sargassum Eco Lumber isn’t a silver bullet for the wider environmental crises we face. Solving the root cause of the Sargassum blooms will ultimately require a global reduction in synthetic fertiliser use and more sustainable agricultural practices. And while there’s a valid concern about building a business model around an invasive species, the current scale of the issue means this isn’t a manufactured demand—it’s an urgent clean-up need. Crucially, by removing Sargassum and the plastic waste entangled within it, this initiative tackles two major waste streams at once. As long as its founders remain mindful of the ecological dynamics at play, Sargassum Eco Lumber offers a smart, circular approach to turning pollution into potential.