How SOS Carbon wants to rid the Caribbean of Sargassum tides

SOS Carbon developed a Sargassum harvesting and sinking solution that is low cost and easy to implement. Designed to create buy-in from fishermen, this allows for easy scalability.

SOS Carbon, short for Sargassum Ocean Sequestration Carbon, started in 2018 as a research project at Boston’s MIT University to address Sargassum tides in the Caribbean, and was spun off 2 years later in the Dominican Republic. Unlike purpose-built conveyor belt collector boats, SOS Carbon offers a plug-and-play system that can be installed on existing fishing boats. I talked to CEO Andrés Bisonó León and Operations Director Christopher Walker.

Can you tell a bit more about your Sargassum collector?

We started off with the realisation that small fishing boats are everywhere in the Caribbean, and that we could use them as a platform to build our collector on. This way, we could not only provide employment for an underprivileged group of people working informally, but it would also make it easy for us to scale our solution. So it has this dual purpose.

The LCM (Littoral Collection Module, red.) is basically a cost-efficient technology adaptable to fishing boats, that allows the pickup of Sargassum not only out in the ocean, but also close to the coast, where the large conveyor boats that are currently in use cannot reach.

We are now past the prototype stage, and we have been servicing the tourism industry, more specifically working with the largest tourism group in the Dominican Republic, Grupo Punta Cana, as well as servicing other hotels like Club Med. We have achieved days that we have collected more than 120 cubic metres with one LCM in just six hours of operation.

You have also prototyped a method to sink Sargassum in the open ocean. How does that work?

We evaluated a lot of different methodologies, like shredding, rolling, blasting the air blades before sending it down, et cetera. The one that we found consumed the least amount of energy, for the most value-add in terms of carbon sequestration, was a pumping system. Just sucking it in from one end and pumping it down on the other end until it reaches a critical depth where it keeps sinking by itself due to the ocean pressure and the air blades that Sargassum has.

In 2019, we did a full scale pilot with a navy vessel. We have a video of that pilot and we published a paper that covers the numbers of CO2 we can sequester. More work has to happen around the sinking of the seaweed, but the technology itself has been proven.

Why do you choose sinking instead of using the raw material for value-added products?

If other organizations develop value-added products that use Sargassum as a raw material in the same quantities that we will be pulling it out of the sea, then we can just work with them and we perhaps don’t need to sink at all.

However, we keep thinking that, at this point and in the future, the way to go will be to sink at least part of the Sargassum. Because the quantities are enormous, hundreds of thousands of tonnes, and as much as there will be other groups creating biostimulants or compost, building blocks, you name it, they will not be able to take all the Sargassum that invades the beaches. That’s why we are still pushing for the sinking, because we don’t see these groups able to take all of it.

The LCM at work near a Sargassum barrier in Dominican Republic

What is the next step for SOS Carbon to scale the business? Are you looking for investors?

Perhaps funds are not the crucial component here. We can just subcontract the boats as soon as we get a service contract, you don’t need to buy boats right off the bat.

What’s crucial is for those contracts to come in. In terms of the expansion plans, we are trying to structure license agreements, so that we can partner with stakeholders across the Caribbean. To maximize again, that win-win situation. We aim to keep developing our open ocean systems, not only with the interception component, but also to go and take Sargassum out to be sunk for carbon sequestration.

What is needed for the Caribbean to really make progress on tackling the problem of Sargassum tides?

The Caribbean at large needs to realize working together is the only way we will be effective at preventing the landfall. This means for instance hotels working together, instead of one getting the Sargassum removed and the other tagging along as a freerider.

Local governments and the tourism sector need to finally step in and realize that they will generate more economic value by preventing the seaweed from making landfall. Once you have those chains and management structures in place, those companies that use seaweed as raw material will emerge with bigger plans.

Are you seeing signs of that mind shift happening?

I think 2021 was a turning point for the Dominican Republic. Before, tourism organizations and governments were closing their eyes, saying that the problem is not here. But last year, some groups from the tourism sector publicly came out to say what they are doing to avoid the problem from affecting their properties. They changed their language.

Tourists know about the problem now, and the Caribbean doesn’t have the luxury anymore to ignore what’s really going on. Just like we take COVID seriously, we need to take Sargassum seriously here in the Caribbean, because it can have a massive effect on these countries that are absolutely dependent on tourism.

And tourism can pay for it. But what about the communities that don’t have the resources? There the government has to step in.

I left my full-time job in Philadelphia back in July 2020. Since then, we have met with a lot of people and we have been signing collaboration agreements with different organizations, both public and private sector. To some extent, we have received big support. But seen from a different angle, it is still very far off from the level that is needed to really face the problem.