The Great Sargassum Belt in the central Atlantic has been increasing since 2009, resulting in ecological damage along the shores and shallow waters where it accumulates.
Seaweed Generation, a UK start up that sinks Sargassum into the deep ocean for CO₂ removal and coastal cleanup, has raised US$1M from AeraVC and Graph Ventures to scale its carbon removal technology. The company plans to develop its AlgaRay (patent pending) technology, which intercepts and sinks invasive Sargassum into the deep ocean, before it can reach coasts.
Seaweed Generation CEO, Paddy Estridge, describes the AlgaRay as, “PacMan meets a Roomba — the AlgaRay eats the Sargassum, then deposits it in the deep ocean.”
By using Seaweed Generation’s novel collecting device, Sargassum is scooped up at the sea surface, preventing it from coming ashore and damaging the environment. Once AlgaRay has a full payload the device moves down to deeper waters where the seaweed is released, before returning to the surface to collect more.
The AlgaRay drops Sargassum over waters with 2000m of depth or greater. It reaches this depth within a few hours, where the carbon it contains will remain for hundreds to thousands of years.
Each full sized AlgaRay will be able to sink the equivalent of two tons of CO₂ per drop and make four drops an hour. Each unit will be able to remove around 8,000 tons of CO₂ per year.
There are around 24 million tons of Sargassum passing through the Caribbean region each year, representing at least four million tons of carbon dioxide absorption.
Seaweed Generation’s Chief Science Officer, Professor Mike Allen of Exeter University has been working with Sargassum for six years. “When we talk about carbon removal with seaweed, most people think we need to cultivate the algae first. But driven by climate change and nutrient run-off from land, unwanted Sargassum has increased explosively over the last decade. When these invasive Sargassum rafts come ashore they impact coastal ecologies and can lead to significant negative economic consequences.
“The best thing about what we’re doing is that it has a dual benefit — we can reduce Sargassum beaching and remove carbon dioxide at the same time. And we can do it in a way that is incredibly well documented to show its benefits and uphold high environmental standards.”
Seaweed Generation is working with countries in the Caribbean, where rising sea levels and more extreme weather events are compounded by the millions of tons of Sargassum seaweed hitting their shores every year, devastating local tourism and ecologies.
“We are in a pretty serious time crunch when it comes to climate change,” said Ms. Estridge, “but we also need to make sure that we do things right. Carbon removal with seaweed could really scale, and we can do that with cultivation, but there are questions that need to be answered first. Sargassum gives us an amazing opportunity to solve a known problem, whilst conducting the monitoring, reporting and verification that we know carbon removal needs.”
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