Section 1: Climate Change
Why is it happening?
Industrial activities, from burning fossil fuels for heating and transport to large-scale farming, to building with concrete and steel, are releasing vast amounts of gasses that warm the atmosphere.
These gasses are called greenhouse gases (GHGs) because the way they warm the atmosphere is similar to the process of how a greenhouse warms the air within it.
The main GHGs are Carbon Dioxide (CO2), Methane (CH4), Nitrous Oxide (N2O) and Sulphur Hexafluoride (SF6).
The best way to understand how humans emitting GHGs are fuelling the climate crisis is to picture the Earth’s climate as a ship.
In this analogy, the ship represents the climate that we are currently experiencing.
Through releasing too many GHGs over the past 150 years, we have caused the ship to spring a leak, take on water and become unsteady.
The more unstable the ship, the more it rocks from side to side, causing increasingly extreme weather events and making it more difficult to navigate with.
The ship has some onboard stabilisers — the carbon removal capacity of our biosphere and oceans — but they can only provide so much stability until they become ineffectual.
As the instability increases, some parts of the ship become submerged and the incoming water forces people to move towards safer positions in the ship, which in turn creates other problems such as resource scarcity, social tensions and inequalities — this is an analogue for climate-driven migration and the pressures that creates.
To get back into a safe position, the leak must be stopped to prevent any additional water from flowing in — so we must stop releasing GHGs as quickly as possible.
However the ship will not properly stabilise until all of the water inside is pumped out — so as well as stopping the release of GHGs we must also remove GHGs from the atmosphere to bring us back into the safe zone.
If we carry on our current trajectory and the quantity of GHGs in our atmosphere gets so high that we pass through the critical threshold of 1.5°C of warming, the ship may become so unstable that it sinks altogether!
How do we stop it?
Containing and reversing climate change requires the long-term removal of atmospheric carbon.
Global greenhouse gas (GHG) emissions are now over 50 billion tonnes (Gt) per year.
Historical cumulative net carbon emissions from the industrial revolution in 1850 to 2019 were 2400 ± 240 GtCO2 (IPCC Sixth Assessment Report).
Rapidly reducing emissions by moving away from fossil fuels is a necessity, but not sufficient to return to pre-industrial levels.
We need to remove past emissions from the atmosphere to bring the concentration of GHGs back into the safe zone.
To return to the ship analogy, there are two ways that we can stop the ship from sinking as it fills with water:
Stop the flow of water into the ship (plug the leak); or
Increase the flow of water out of the ship (bail it out).
Net Zero, the goal of so many countries and a global target to come out of previous COP, will be achieved when the flow of water into the ship is the exact same rate as the flow of water out of the ship.
Section 2: Sargassum
What is Sargassum?
Sargassum is a genus of seaweed, best known for its two floating species, Sargassum natans and Sargassum fluitans
Seafields works with the two free-floating species Sargassum natans and Sargassum fluitans. When we use the word Sargassum, for the ease of reading, we are referring to these two species.
They are fast-growing and multiply by fragmentation, doubling their biomass as rapidly as every 1-3 weeks – this means that they can grow exponentially, and the ocean surface provides ample space in which to do so.
They have a very high average carbon-to-nitrogen ratio of 34:1, making them efficient at sequestering carbon per unit of nitrogen (Lapointe et al 2021).
Unlike many other species of seaweed, they are free-floating during their entire lifecycle and are not known to attach to the seafloor or other hard surfaces. Sargassum has small air bladders that enable it to float on the surface of the water forming island-like structures in the sea.
This creates enhanced economic opportunities compared to other types of seaweeds since they do not require hatcheries nor expensive infrastructure to grow on, like anchored ropes or frames.
Sargassum natans and Sargassum fluitans grow naturally in large floating surface mats that give the Sargasso Sea in the north-west Atlantic Ocean its name.
Floating Sargassum mats offer an important habitat for marine life such as sea turtles, shrimps, crabs and fish including larger fish species such as tuna and marlin.
Sargassum is also an important breeding ground and hatchery for freshwater eels and many other fish species such as the dolphin fish.
Analogous to a forest on land, the floating Sargassum mats are primarily a habitat for these marine organisms and not a food source.
What is also unique about Sargassum is that it grows in regions with warmer ocean surface temperatures, unlike kelp which requires colder water.
All of this means that Sargassum growth is not constrained by the availability of arable land, coastal space, or freshwater.
UNEP. (2021). Sargassum White Paper: Turning the crisis into an opportunity.
Properties of Sargassum
How Seafields Works
Seafields mission is to heal the climate and restore our oceans.
To do this we intercept Sargassum influxes from the Great Atlantic Sargassum Belt (GASB) to protect local marine environments.
Preventing the beaching of Sargassum has hugely beneficial impacts on local economies and ecosystems, and importantly avoids the release of large amounts of methane and hydrogen sulphide gas that is produced as the seaweed rots on beaches.
We then use the Sargassum as a valuable feedstock for industry.
The Sargassum is either immediately harvested and processed or it is transferred to our floating “AlgaePonix“ aquafarms.
Sargassum can be stored in the AlgaePonix farms for weeks to months, keeping it fresh and cultivating new growth for our industrial partners.
Once harvested, we process the Sargassum to separate the liquid component of the biomass from the solid, to extract the full intrinsic value of the seaweed.
The liquid component is filtered, bottled and sold as an agricultural biostimulant.
The remaining carbon-rich biomass is sold to industrial partners who will convert it into useful products, displacing the traditional fossil fuel-derived feedstocks and accelerating our transition away from them.
Seafields is the first company to successfully domesticate floating Sargassum, which means we can control it and leverage its amazing properties.
Near-Shore Catch and Grow Farms
Seafields is currently developing innovative “Catch and Grow” farms, which are designed to catch wild pelagic Sargassum from the Great Atlantic Sargassum Belt and contain it, while it naturally grows and increases in volume.
Our ‘Catch and Grow’ farms, located nearshore, enable us to test our innovative barrier technology while providing a consistent year-round feedstock of seaweed for industry.
Thus, we are flattening the curve for the supply and demand of Sargassum by storing and keeping fresh in water on high influx days and harvesting it on low influx days.
Open-Ocean Farms
To reach a scale where we are meaningfully mitigating climate change and sequestering over a billion tonnes of carbon per year, we need to enhance the natural process of large-scale carbon sequestration by Sargassum from the atmosphere.
To do this we will need to expand and create larger, open-ocean farms that are supplied with nutrients by artificial upwelling.
Any Sargassum not sold to industry will be shredded, baled and sunk to specially selected sites on the seafloor to lock away the carbon for geological timescales.
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It can be converted into a range of products including biochar, bioplastics, biofertiliser, emulsifiers and biofuels like bionaptha. It can even be turned into vegan leather!
We will be working with Carbonwave and MacroCarbon to process the Sargassum into these materials.
Sargassum – truly unique algae
Great Atlantic Sargassum Belt
Seafields will establish near-shore catch and grow farms in the Caribbean to catch and contain wild Sargassum from the Great Atlantic Sargassum Belt (GASB) that would otherwise be washed up on the shoreline.
The caught Sargassum will then naturally grow further and increases in volume inside the paddocks.
Adding value to Sargassum by manufacturing products with it and generating carbon credits from it will unlock its intrinsic value to provide a scalable solution to the problem of Sargassum beaching.
However, there are two main barriers for scaling up the processing of Sargassum:
Sargassum needs to be fresh for most products, and the time to collect it from the beach is very short.
The quantities of incoming Sargassum vary greatly per day and throughout the year.
Seafields’ Sargassum aquafarms offer a solution to store Sargassum fresh in the coastal ocean when large quantities arrive that exceed the processing capacity.
The aquafarms can also supply Sargassum in the few months when Sargassum does not arrive at all or only in small quantities, as it can grow in the aquafarms.
These two advantages enable scaling up of Sargassum products, such as plastics and biofuel as well as carbon credits, for which the market is much larger than the amount of Sargassum annually growing in the GASB.
In this way, Sargassum aquafarms help keep more Sargassum off the beaches and out of landfills.
In a later stage, we will expand into the South Atlantic gyre to build open-ocean farms with the goal to sequester 1 Gt of carbon from the atmosphere per year.
This large-scale sequestration is not possible with the biomass growing naturally in the GASB. To reach 1 Gt of carbon sequestered each year, we need to harvest 14 million tonnes of Sargassum a day, which is almost the entire biomass of the Great Atlantic Sargassum Belt (at its annual peak).
Sargassum concentrations in the Great Atlantic Sargassum Belt in 2023
In 2011, Sargassum from the Sargasso Sea was transported to the equatorial region of the Atlantic Ocean, where it grew in nutrient rich upwelled water in the middle of the tropical Atlantic, and in nutrient rich run off from Amazon, Congo and Orinoco rivers.
This created the perfect environment for Sargassum to proliferate exponentially, creating additional large mats in the tropical Atlantic.
Sargassum has now been established in The Great Atlantic Sargassum Belt, extending from the west coast of Africa all the way to the Caribbean Sea.
Each year the seaweed blooms in the tropical Atlantic and travels on currents towards the Caribbean and west Africa where it beaches in vast quantities, making it very difficult to manage.
Without proper infrastructure and funding, many beaches are inundated by the seaweed where it is often left to rot in shallow waters – damaging ecosystems, driving away tourists and releasing methane and sulfuric gases that are hazardous to human health.
Many countries are now resorting to collecting the Sargassum from beaches and transporting it to landfill sites.
This does not solve the problem but merely moves it from one location to another – effluent that comes off the Sargassum in landfill can pollute local freshwater sources, creating further issues.
The alternative is to make use of Sargassum biomass for which a steady supply, independent of seasonal and annual variations, is a prerequisite.
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How does the GASB impact people?
Livelihoods
The arrival of such vast amounts of Sargassum into the Caribbean region has caused severe impacts to many coastal communities.
Much of the region relies heavily on tourism as a primary source of income, and when the beaches are inundated with Sargassum, tourists look elsewhere for their holiday destinations.
Fisherfolk also struggle as their boats become entangled in the seaweed making it difficult to launch them.
In some countries that rely on flying fish as a primary product, the entire industry comes to a halt when Sargassum appears.
Human and environmental health
When large amounts of Sargassum are left to decompose on beaches, hydrogen sulphide, methane and other noxious gases are released which cause respiratory complications, headaches and nausea.
Sargassum brown tide (the water close to shore which has become inundated with rotting Sargassum) becomes an anoxic zone deprived of both oxygen and light killing off sea grass meadows, which normally provide stability to the coast during storms. The absence of seagrass has been directly correlated to coastal erosion often affecting entire villages.
Regions that lack the knowledge and/or infrastructure to effectively manage Sargassum inundations often use tractors to clear tourist beaches which results in sand removal (further contributing to coastal erosion).
This Sargassum is usually then transported inland to a site where it is dumped and left to decompose out of sight.
While this may provide a short-term solution, the biomass soon decomposes causing fluid to run off containing heavy metals which leach into the underground aquifer systems, contaminating what little fresh water is available.
Politics
Local and national level politics are now being shaped by policy on Sargassum management.
Very significant public spending is now being deployed on Sargassum management which could be spent elsewhere on schools, hospitals etc.
Social Inequality
As with many of the negative consequences of climate change, the people most affected are usually the ones who bear least responsibility.
Sargassum is no exception, in many areas, funds are used to keep the main tourist beaches clean, while others that are considered of secondary importance remain covered in rotting seaweed for most of the season.
Local people who cannot access the tourist beaches for social or economic reasons lose out.
How will Seafields help?
While the Sargassum problem may seem out of control, Seafields intends to establish its operations in some of the areas most affected.
Our regional teams will be made up of people recruited locally which will provide employment while also supporting our operations with local knowledge.
Section 3: The Science Behind our Farms
Barrier Technology
Seafields barrier technology provides a crucial piece of infrastructure for our carbon removal system.
Our proprietary barrier technology allows us to establish our Sargassum paddocks and farms, to store Sargassum and also cultivate it.
Operating in the ocean, these barriers need to be sturdy enough to withstand rough conditions frequently experienced at sea.
To perfect this technology, we have been conducting trials in the Caribbean, that test our barrier system, ensuring that it is both effective at retaining the Sargassum and also withstanding the powerful forces of the ocean.
Long-term we intend to make our infrastructure out of Sargassum-derived bioplastic. In fact, together with our partners Carbonwave and MacroCarbon, we won a €2m grant that aims to turn Sargassum into bionaphtha to be used as a feedstock for industrial grade HDPE.
From our initial trials we don't foresee adverse issues with large marine life entanglement since our structures are flexible.
We constantly monitor this with underwater cameras in our prototype farms. We are also working on systems to prevent any surface bycatch of smaller marine life.
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Open-Ocean Farming
To reach the scale of a gigatonne of carbon removal per year, we will need to expand our operations and establish a very large farm in the South Atlantic gyre.
The farm will grow modularly until it reaches ~94,000 km². This is a bit bigger than Portugal, so it will truly be a mega-farm. Although 94,000 km² sounds large, it is important to note that this will take up a tiny fraction of the ocean’s total surface.
This area of ocean is effectively a desert and installing upwelling pipes and associated infrastructure there will bring necessary nutrients to the surface for the Sargassum to prosper, creating oases in the ocean desert.
A significant advantage of operating in the South Atlantic gyre, one of the five subtropical gyres (STG) in the ocean, is that these high pressure zones experience the mildest weather conditions on the planet with damaging storms few and far between.
As well as being free-floating, the farm will also be modular and aggregated, thereby we would avoid occupying a large 'no-go' area in the ocean for ships or sailing vessels.
The farm itself will be well away from shipping lanes and marine life migratory routes.
To protect against the very small number of ships that may pass through, we will use warning lights and radar beacons to warn sailors away.
Leisure sailing traffic is likely to be low to non-existent, given the remoteness of where we will be operating.
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This diagram is indicative only. The farm itself will be modular and made up of lots of individual farms linked together, rather than one giant circle as shown.
Upwelling
Upwelling is a natural phenomenon in several regions of the oceans. Along the western continental margins and on the equator, impoverished surface water is pushed away by wind-driven currents and replaced by cold, nutrient-rich deep water rising to the surface. These upwelling systems support major fisheries.
The open-ocean aquafarms will be in the South Atlantic Gyre, where there is no natural upwelling.
Vertical upwelling pipes will fertilise these farms with nutrient-rich deep water, thus mimicking natural upwelling.
In order to reach our vision to sequester one gigatonne of carbon annually using Sargassum, we will need to use artificial upwelling pipes in our open-ocean farms, to bring deep-sea nutrients to the surface and successfully grow Sargassum in this area.
In contrast, our ‘Catch and Grow’ farms in the Caribbean region will operate without artificial upwelling.
Based on a refined version of the oceanographer Henry Stommel’s “perpetual salt fountain” principle (Stommel 1956, Maruyama et al. 2004 and 2011), Seafields’ pipes will combine up- and downwelling in a unique way.
The fundamental objective of our pipes is to draw up cold, low-salinity yet high-nutrient deep water from a depth of around 300-500 metres. A proprietary feeder system is then used to effectively channel this upwelled water into the floating Sargassum fields.
One key differentiating feature of our upwelling technique compared to other methods is that the water reaching the surface is pre-warmed, so we are avoiding water sinking again and the negative climate feedbacks of cold water reaching the surface (described in Oschlies et al 2010).
In addition, because we use a bidirectional counterflow pipe, the down-welled oxygen-rich waters will prevent the formation of oxygen-depleted areas below our farms.
Section 4: Carbon Removal
Biomass Utilisation
To reduce atmospheric carbon levels, we need to remove carbon from its fast cycle and sequester it in a safe storage.
To make sure that the carbon removed from the atmosphere by the Sargassum does not quickly return, we need to turn the Sargassum into long-life products, such as biopolymers, or prevent the Sargassum itself from being broken down.
Sargassum can be converted into biochar, which is a lightweight, black charcoal-like substance that is up to 80% elemental carbon.
Biochar can be used for long-term carbon removal and can generate high-quality carbon credits in the following two ways:
1. Biochar is applied to agricultural lands or in rewilding projects to grow healthier plants and trees, while also importantly locking away the embodied carbon in the soils, where it will remain for hundreds of years.
2. Alternatively, biochar can be added to construction materials, such as concrete, locking away the carbon stored in the seaweed’s biomass for geological timescales.
For any seaweed not used by industry, we may also potentially shred and bale the Sargassum, so that we can deposit the carbon-rich biomass on the deep-sea floor, locking the carbon stored in the Sargassum away for hundreds to thousands of years. The sunk carbon is sold as high-quality carbon removal credits.
The bales will be deposited at specially selected sites on the deep-sea floor at roughly 3000-5000 metres to lock away the carbon.
By processing and tightly compacting the Sargassum that we grow, we further reduce its already very low decomposition rate on the deep-sea floor. This will reduce the oxygen consumption on the deep-sea floor, preventing harm to the deep-sea ecosystem.
We work with leading independent scientists to confirm the minimal environmental impact of the Sargassum bales.
Biomass Sinking
FAQ
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As part of its life cycle, Sargassum naturally sinks at the end of its lifespan, so it is already found in large quantities on the deep sea floor. In places like the Sargasso Sea and the Gulf of Mexico, it is the most prominent biomass found in the deep sea and scientists have come across it naturally accumulating in hollows on the seafloor.
One of the areas of concern of biomass sinking is the impact on the deep sea environment, which currently is unknown. In-depth trials are needed to investigate the risks associated with sinking seaweed, so we therefore team up with leading research institutions to fill this knowledge gap. Our current trial is purely scientific and at a small scale (max. 500 kg of dry seaweed biomass per site).
However, once this trial comes back with results that are acceptable to the scientific community and local authorities, operational and commercial research should be allowed as a next step. This will still be conducted at small scale (e.g. 1,000 tonnes) and bear a very small risk for negative impacts, while providing a wealth of information for policy makers, scientists, investors and other stakeholders.
To learn more about what happens to Sargassum when it reaches the deep sea, the National Oceanographic Centre (NOC) and Integrated Environmental Solutions (INES), both lead by international experts on deep sea research, have designed a robust study that follows the recommendations made by an Ocean Visions working group consisting of 25 marine scientists. This study will use state of the art research vessels, Remotely Operated Vehicles (ROVs) and advanced research techniques.
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The London protocol regulates ocean dumping in international waters, regulations that were developed for fisheries and commercial shipping and are now being adapted for Marine CDR methods.
In Autumn 2023, scientific and technical committees published a potential amendment to the London protocol that would add regulations regarding seaweed sinking. Seafields and its partners immediately adopted these new and more cautionary regulations that may come into effect in 2025.
These regulations are not yet in place and not all countries are signatories to the London Regulatory Framework (e.g. the USA is not).
There are still legal challenges and uncertainties concerning sinking seaweed, especially in international waters. At the same time, one Caribbean island has been sinking thousands of tonnes of Sargassum in its waters, not for carbon credits but as a way of disposing the biomass to protect its beaches.
Likely, without sinking, this biomass would have been disposed of in landfill sites due a lack of other feasible options. Limited availability of space for safe disposal and the long-term negative consequences of disposing of Sargassum in landfill sites, such as contamination of freshwater with heavy metals caused by run-off from decomposing Sargassum, is now a reality for most Caribbean nations.
It is therefore critical that rigorous studies are conducted to test any potential impacts that sinking Sargassum could have on the deep sea, so that governments are as informed as possible before deciding to dispose of Sargassum in the deep sea.
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We have partnered with the National Oceanography Centre (NOC), Integrated Environmental Solutions (INES), and the University of the West Indies (UWI) to conduct a rigorous pilot study of the environmental impacts of sinking Sargassum to the deep sea (SeaSINC).
We are waiting for the results of this study before beginning a larger study that includes sinking biomass for carbon credits. As these studies take several years to complete, we believe that starting a commercial study in parallel, following the release of the first results of the scientific study, is prudent enough to minimise environmental harm yet fast enough to ensure the critical Carbon Dioxide Removal (CDR) goals set by the UNFCCC can be met.
It is very important to us that local stakeholders and governments are included in the project design and decisions from the start. SeaSINC, for example, includes professors from UWI and two local students from Barbados joined our first cruise. The coastal management unit that issued the permits for our project was grateful that through our work they were given access to detailed deep sea floor maps that can help them with spatial planning.
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A concern frequently raised is that not all the seaweed that is sunk will make it to the deep sea floor. While this is true for slow sinking biomass such as phytoplankton, it is not a problem for our Sargassum bales.
Seafields’ approach to sink tightly compressed bales, wrapped in hemp netting, has shown no biomass leakage over a filmed 4-hour journey to 4000 metres depth and back to the surface.
Our bales are negatively buoyant and sink to 4000 metres in about 7 hours, therefore, large distance dispersal is unlikely during the descent.
In the highly unlikely event that the wrapping of a bale does become loose and some biomass escapes, the Sargassum will no longer be alive and its aerocysts (air sacs) will be deflated, due to processing prior to sinking, meaning that it will sink and stay at the bottom of the seafloor.
What happens if we do nothing?
What we know for certain is that the best-case scenario of doing nothing, and letting climate change rapidly progress as it currently is, will be far, far worse than the worst-case scenario of any potential negative impacts from our solution materialising.
We are confident that the best-case scenario of our seaweed-farm solution will make an enormous global contribution to healing the climate and restoring the oceans.
We know which option is better for our future.
We cannot afford to do nothing.