The Plan to Turn the Caribbean’s Glut of Sargassum Into Biofuel

by Edith Gonzalez Cruz (Wired) With record-breaking quantities of the seaweed set to hit Mexico’s beaches, experts propose converting it into biogas and construction materials, as well as using it to underwrite carbon credits. -- In the Caribbean, summer is supposed to be the season of sun, sand, and crystal clear waters—for decades, Mexican vacation destinations like Cancun, Cozumel, and Tulum have been synonymous with paradise. But then the sargassum began to arrive. For the past 15 years, large quantities of this brownish-colored seaweed have been invading beaches around the Gulf of Mexico every summer, its arrival from the open seas coinciding with high tourism seasons. READ MORE

Excerpt from Latin American Post: The floating mass at sea is even more staggering: after peaking at 22 million metric tons in 2018, monitoring this spring showed 37.5 million tons in May and a projected 50 million by June, according to Esteban Amaro of the Quintana Roo Sargassum Monitoring Network, speaking to Wired.

Once on land, the seaweed quickly becomes toxic. Decomposing sargassum releases hydrogen sulfide, methane, and carbon dioxide, along with leaching heavy metals into the sand and nearshore waters. For tourism-driven towns, that means a health hazard, a stench that clears hotel zones, and a cleanup bill that runs into the millions during high season.

To some, the answer is obvious: stop treating sargassum as waste and start treating it as biomass. Miguel Ángel Aké Madera, founder of Nopalimex and a veteran of cactus-to-energy projects, told Wired that every ton of processed seaweed can yield a cubic meter of biogas—roughly the same energy as a liter of gasoline.

He’s done the math. Processing 500 tons a day could produce 20,000 cubic meters of biogas, matching the daily fuel sales of a standard Mexican gas station. And he says that’s just a start: “At 2,500 or 3,000 tons a day, you’d see a real difference within a year.”

Amaro agrees. With sargassum’s tendency to release heavy metals and greenhouse gases as it decays, he warns against turning it into consumer products that could pose health risks. “Sargassum’s vocation is to produce energy,” he said. In his view, biogas and biofuels offer the safest, most scalable way to turn a public nuisance into a renewable asset.

Not all roads lead to gas. At UNAM’s Center for Applied Physics and Advanced Technology, researchers have developed Sargapanel, a building material made from 60 to 70 kilos of wet seaweed per panel. According to project lead Miriam Estévez González, the panels are stronger, more flexible, and naturally fire-resistant compared to conventional versions—and they can be recycled at the end of their life.

The benefits aren’t only structural. “Every five tons of wet sargassum equals one carbon credit, valued between 10 and 30 dollars,” Estévez González told Wired. By her estimate, processing 4,000 tons of dried sargassum could earn $80,000 to $240,000 a year in credits while removing the equivalent of 8,000 tons of CO₂ from the atmosphere—like taking 1,000 cars off the road.

In off-season months, when the tide thins, biogas plants could co-digest wastewater sludge to keep output steady.

Mexico’s fisheries research institute proposed classifying it as a fishery product—opening the way for regulated harvesting and sale.

Aké Madera believes that clarity could unlock investment. He’s already proved the concept at his Michoacán plant, hauling in 50 tons from Quintana Roo to test alongside tequila vinasse and cactus waste. “It’s an ideal biomass for biogas,” he said.

Elsewhere in the Caribbean—Dominican Republic, Jamaica, Guadeloupe, Martinique, Dominica—small biodigesters are being tested, but eyes are on Mexico to prove it can be done at scale. Interest is coming from Spain, the Netherlands, Germany, the United States, and France. Two sites near Cancún are under consideration while project plans are finalized. READ MORE