Giant seaweed farm in the middle of the ocean aims to be a global carbon sink

The mid-Atlantic “golden rainforest” is expected to capture one gigatonne of carbon dioxide each year.

Data overwhelmingly confirms that rising greenhouse gas emissions are locking us into a scenario of destructive climate chaos, which is motivating scientists and companies to invent ambitious carbon capture solutions.

One concept from Seafields Solutions looks to utilize some unlikely real estate by developing a giant seaweed farm in the middle of the Atlantic Ocean capable of capturing a gigatonne of carbon dioxide annually.

This England-founded company aims to be on the frontlines of the “ocean-based agricultural revolution” by scaling the farm to 94,000-square-kilometres within the North Atlantic gyre, where it will swirl around and largely stay in place.

The planned location for the giant seaweed farm. (Seafield Solutions)

The planned location for the giant seaweed farm. (Seafield Solutions)

In an interview with The Weather Network, John Auckland, Director and Co-Founder of Seafields Solutions, explained that not only is removing carbon from the atmosphere an urgent issue to mitigate severe impacts from climate change, but the seaweed can be used to create sustainable products like biofuel and bioplastic.

Sargassum is a type of seaweed that was chosen by the company based on its high capacity to store carbon in its biomass, free-floating nature, and ability to double in size every two weeks.

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Once the sargassum is grown to a certain size it will be harvested and compressed into bales that are destined for the bottom of the ocean. Seafields Solutions refers to these bales as “carbon batteries” because once they are sunk, the carbon that is trapped within them will remain at the bottom of the ocean and out of the atmosphere for thousands of years.

The compressed Sargassum becomes a "carbon battery" and sinks to the bottom of the ocean. (Seafield Solutions)

The compressed Sargassum becomes a "carbon battery" and sinks to the bottom of the ocean. (Seafield Solutions)

Offshore testing is ongoing in St. Vincent to see if the company can be the first to domesticate Sargassum. After the company has proven that the seaweed can grow within the offshore barrier, the next phases will involve testing the bailing and sinking methods and providing evidence that leaving the bales at the bottom of the ocean has no environmental impact.

“The bales sink from the surface down to a depth of 4,000 metres in seven hours. That means it's moving so quickly that it's very difficult for an animal to eat it on his way down, and that's also quite important,” explained Auckland.

A mat of wild Sargassum growing in the ocean. (Seafield Solutions)

A mat of wild sargassum growing in the ocean. (Seafield Solutions)

The team is also designing “pipes” that will transport cold, low salinity, high nutrient water from a depth of 350 metres to the surface where it can be used by the growing seaweed. This water transport does not need any energy input, but Auckland notes that even though the pipe technology has been around for several decades, they still have to be tested and scaled in an economically viable way.

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The seaweed farm will not be an autonomous operation — approximately 2,000 onsite staff will work in three-month cycles while living in “terrestrial, city-standard facilities and homes.”

“It's like building the International Space Station in the middle of the ocean,” said Auckland. The company hopes that this employment opportunity could appeal to those in the offshore oil and gas industry that are interested in the sustainability sector.

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Given the novelty of such an expansive carbon sink, Auckland said that there are hopes for potential tourism.

“Victor Smetacek, our visionary founder talks about the ‘Republic of Sargassum’ being a tourist destination. People will want to come and see this golden rainforest that stretches as far as the eye can see. It's going to be beautiful and really quite a meaningful tourism [opportunity],” said Auckland.

Auckland says that the Sargassum can be used to make sustainable alternatives to fossil fuel-based products, such as biofuel, bioplastics, and emulsifiers.

“The cosmetics industry is absolutely dependent on oil because they need emulsifiers, which make oil mix with water. It’s absolutely essential in a lot of cosmetic products and our food,” Auckland explained.

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“Our partners, CarbonWave, managed to create an emulsifier from Sargassum, the first potentially commercially viable alternative to a fossil fuel-based emulsifier. So we can soon start supplying that to the cosmetics industry.”

Dr. Mar Fernández-Méndez, lead scientist, analyzing the growth rates of Sargassum samples. (Seafield Solutions)

Dr. Mar Fernández-Méndez, lead scientist, analyzing the growth rates of Sargassum samples. (Seafield Solutions)

As with any initiative that is in the developmental stages, Auckland acknowledges that headwinds lie ahead.

“We could be blocked from doing it. There could be regulation that comes in that stops us from being able to operate in the mid-ocean international waters. There's currently no regulation that legally stops us, but there are some frameworks within international policies that we would have to adhere to,” said Auckland.

Other potential hurdles could be the perceived environmental impact of a giant 94,000-square-kilometre seaweed farm. Although the company’s research indicates that the project would have very little negative impacts, there are neighbouring ecosystems that will require environmental assessments and monitoring.

The commercial viability is also a top priority, which Auckland say carries “incredibly low” risk because all aspects of this initiative integrate proven concepts and technologies.

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The company has a goal of raising £5 million in seed round funding by early 2023 and then another £20 million to reach a stage where the seaweed farm is functioning and available for carbon credit investments. Auckland estimates that it will take about a decade before the seaweed farm is operating at the scale of capturing one gigatonne of carbon annually.

“What we're finding is that of investors really understand that the open ocean has a huge amount of space and potential. So that conviction is really quite strong and carries us quite far,” concluded Auckland.

Thumbnail image: Diver tends to a mat of sargassum growing in the ocean. (Seafield Solutions)