Frequently asked questions

Seafields is a UK-based aquaculture business whose mission is to harness the ocean to grow huge amounts of biomass for carbon dioxide removal (CDR). Our aim is to alleviate the climate crisis, restore ocean health and rejuvenate the market for carbon removal. We plan to remove billions of tonnes of carbon dioxide from the atmosphere each year, and replace fossil fuel-based products, by growing and harvesting the floating seaweed Sargassum in the Atlantic Ocean.

Sargassum is a free-floating macroalgae that grows on the surface of the ocean and absorbs more carbon dioxide per square meter than land plants.

Seafields is developing offshore aquafarms to cultivate Sargassum at scale, contained in custom-designed barriers to prevent the seaweed from escaping while being fertilised by upwelling of nutrient-rich deep-sea waters.

Through this process we will harvest the Sargassum in situ, first to extract key nutrients and other components to be used in a variety of products, such as bioplastics, biofertilisers and biofuels. The rest of the biomass, along with its stored CO2, will be compressed, baled, and sunk to the ocean floor in specially-selected areas where it will remain stored, effectively removing CO2 from the atmosphere.

Our farms will be located in the South Atlantic and will grow modularly until they reach a size to enable us to sequester 1 gigatonne of carbon dioxide (Gt CO2) annually. This is one-tenth of what the UNFCCC says we must remove from the atmosphere each year, above and beyond the best case for emission reductions.

We anticipate that our aquafarms will also have the co-benefit of being a nursery, habitat and feeding ground for commercially important fish species and a potential habitat for commercially important shellfish. Our farms will offer a variety of opportunities and will create jobs for local communities, across various skill levels. We anticipate that our aquafarms will also have the co-benefit of being a nursery, habitat and feeding ground for commercially important fish species. These fisheries will provide food security for bordering communities.

Sargassum is a genus of seaweed, best known for its two floating species, Sargassum natans and Sargassum fluitans. Sargassum grows in large mats in the Sargasso Sea, in the north-west Atlantic Ocean. Unlike other species of seaweed, they are free floating during their entire lifecycle and never attach to the seafloor or other hard surfaces. They do not have holdfasts (akin to roots) and self-reproduce at a fast rate. It has small air-filled ‘bladders’ that allow it to float like islands in the sea. Carbon amounts for around 30% of the mass of dry Sargassum. In its natural distribution area, Sargassum is an important habitat for marine life such as shrimps, crabs and sea turtles, eels plus larger fish species such as tuna and marlin.

In 2011, Sargassum from the Sargasso Sea was transported to the equatorial region of the Atlantic Ocean, where it grew in nutrient-rich runoff from newly-established agriculture in the Amazon River basin. 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 Caribbean Sea all the way to the west coast of Africa.

Each year, starting around April, the seaweed blooms and travels on currents towards the Caribbean and Africa where it washes up on beaches in vast quantities, making it very difficult to manage. Without proper infrastructure and funding many beaches are engulfed in the algae, where it is often left to rot in shallow waters – damaging eco-systems, driving away tourists and releasing sulfuric fumes.

The original idea for the offshore aquafarm came from leading oceanographer and emeritus professor Victor Smetacek. Victor was former Head of the Pelagic Ecosystems Division of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Bremerhaven, Germany, and has published over 20 papers in Nature and Science. He shared his idea for an offshore aquafarm in an interview with The Sargassum Podcast, co-hosted by Dr. Franziska Elmer and Dr. Mar Fernández-Méndez.

Serial entrepreneur Sebastian Stephens, founder of SubSea Environmental Services came across this podcast episode while investigating sustainable fuel for a new airline for island nations. He immediately saw the potential of Victor´s vision and got in contact with him. Soon after, Sebastian assembled a team that included Victor and other experts passionate to bring this vision to life, including Dr. Mar Fernàndez-Méndez and Dr. Franziska Elmer. And so, Seafields was born.

The company’s executive team is composed of leading global scientific and business figures including John Auckland, an experienced entrepreneur who has helped more than 100 companies raise over £60m in investment funding; Randall Purcell, who managed the UN Food Programme’s largest climate adaptation programme and has 25 years' experience at the World Bank and the UN; and Erick Contag, a senior figure in the sub-sea business community.

Our farm will grow modularly until it reaches ~94,000 km². This is a bit bigger than Portugal - a mega-farm. It will be located in the South Atlantic Gyre. 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.

Seafields operations are led by science, though experienced scientists with diverse expertise that build the core strength of our team. Additionally, we seek the advice of an independent Science Advisory Board, comprising preeminent experts in the fields of marine chemistry, biology and ecosystems, from leading research organizations and universities, including the GEOMAR Research Institute at the University of Kiel, the German Centre for Marine Biodiversity Research at the Senckenberg Research Institute and the Alfred Wegener Institute for Polar and Marine Research.

At COP26, Seafields announced the establishment of the Seafields Foundation (incorporated in the United States) which, funded separately, will collaborate and support research all over the world to generate open-access science in order to quantify and monitor the carbon sequestered through growing and sinking seaweed, and the co-benefits and impacts of these activities on the ocean ecosystem. This will be closely coordinated with the Ocean Visions Seaweed Sinking Working Group and other scientists.

Seafields is part of a broad coalition of Ocean Carbon Dioxide Removal (CDR) researchers and practitioners that has come together under the guidance of Ocean Visions, a collaborative Ocean CDR incubator, that supports innovators competing for Elon Musk’s US $100 million XPRIZE. We are a member of the United Nations Global Compact Safe Seaweed Coalition and the industry sustainability-focused World Ocean Council.

We are a signatory to the United Nations Sustainable Ocean Principles and we are also working with a number of industry partners, including Carbonwave, the largest processor of Sargassum (in which Seafields owns a small stake), the engineering firm 2H Offshore, the large engineering construction firm NOV, and the chemical company BASF through a collaborative Sprin-D grant awarded by the German government. A number of informal Seafields advisors occupy high level positions in industry and policy circles.

We are also establishing a non-profit foundation to support long-term independent scientific monitoring and assessment of the potential ecosystem impacts of our operations both at the ocean’s surface and at the seafloor. It is imperative that we are science-led which will inform politics and the legal aspect of our marine activities. The scientific knowledge produced will be open source.

Seafields was named by globally popular British music band Coldplay as an associated organisation to support the band’s efforts to make its upcoming tour as sustainable and low-carbon as possible. Coldplay has stated that it will put 10 percent of everything it earns (touring, records, publishing, etc) into a good causes fund. These funds will be split between environmental and socially conscious projects and charities, which includes Seafields.

By cultivating Sargassum we will be reducing the CO2 concentration in the atmosphere. By processing, baling and sinking Sargassum to the deep-sea floor we will be sequestering carbon permanently. Throughout our work we will be researching, developing, monitoring and fine-tuning the best and most effective methods to sequester 1 Gt CO2 from the atmosphere each year without causing harm to the surrounding environment.

Yes. Whilst other businesses are also planning to operate in the open ocean, we are the only ones looking to simultaneously cultivate Sargassum and extract nutrients from the seaweed before sinking it. Seafields solution is also unique in using ‘Stommel pipes’ to provide a supply of fertilising nutrients to the Sargassum.

A Stommel pipe is a form of artificial upwelling, designed to draw up, or ‘upwell’, nutrient-rich water from the deep ocean to the sea surface. Stommel pipes are driven by buoyancy forces, generated by taking advantage of naturally occurring gradients in temperature and salinity which exist in the ocean (Stommel, Arons, and Blanchard, 1956). As they are driven by naturally occurring differences in temperature and salinity, Stommel pipes do not require a source of power to function, a major advantage over simply pumping water up from the deep ocean.

It’s difficult to visualise the scale of the problem of CO2 in the atmosphere. One gigatonne equals a billion metric tonnes. That is the equivalent to the CO2 emissions of Germany in 1990 or to the 276 million cars driven in the US, which release roughly 1.27 Gt CO2 per year. To return to pre-industrial CO2 levels in the atmosphere, about 1830 Gt CO2 needs to be removed, equivalent to the carbon in the entire biosphere.

Meeting the recent pathways laid out by the IPCC will require total cumulative net CO2 removals of 20-660 Gt CO2 by 2100, an endeavour that would need collaboration at a scale humanity has never seen before. The IPCC stated that “CDR is a key element in scenarios that limit warming to 2°C (>67%) or 1.5°C (>50%) by 2100 (high confidence)”.

In a study from 2019, an international research team found that we would need to plant 1.2 trillion trees (additional to the existing 3 trillion trees alive globally today) to take up the CO2 released in the last 10 years globally (Bastin et al 2019). The Land Gap Report found that the current climate pledges made by countries rely on an unrealistic amount of land-based carbon removals. Land for agriculture and other needs would have to go towards carbon sequestration, with negative impacts on livelihoods, land rights and ecosystems. The geopolitical challenge of this makes it practically unachievable. Lastly, trees take more time than seaweed to grow, and will be affected by droughts and fires.

The global ocean occupies more than 70% of the Earth’s surface, half of which is covered by the 5 subtropical gyres that are rotating lenses of nutrient-impoverished warm water. The Sargassum is retained by the closed circulation of the gyres. Additionally, Seafields is developing a floating barrier system to keep the Sargassum inside the farms.

By shifting activity away from the continental margins to the open ocean, we will be taking pressure off the biodiverse and unique coastal ecosystems, allowing them to recover. In contrast, the surface waters of the vast open ocean are comparatively homogeneous across large areas. Finally, the South Atlantic gyre is not crossed by major shipping routes or whale migration paths, and our farms will take up only a small fraction of the total area of the gyre.

The concern raised about the position of offshore seaweed farms and fertilisation is a valid concern. Seafields plans to start its operations in near-shore coastal waters and once our Sargassum aquafarming technology and personnel have been established and operations are successful, we will move into offshore farming with deep sea upwelling pipes for fertilization. The nutrient supply will come from a deeper water layer with ample concentrations of nitrogen and phosphorous at 400 metres depth. Moving offshore is important to reduce pressure on coastal areas where aquafarms would compete with other uses and space for scaling is limited, ensuring valuable and fragile ecosystems such as coral reefs, mangroves and seagrass meadows are not impacted.

The United Nations Intergovernmental Panel on Climate Change (IPCC) stated in its April 2022 report on mitigating climate change: “The deployment of carbon dioxide removals to counterbalance hard-to-abate residual emissions is unavoidable if net zero emissions are to be achieved.” Alongside using CDR methods to reach net zero, we need to scrub already existing historic CO2 emissions as well. This needs to be done quickly, to avoid reaching key climate tipping points. Current efforts are focused on cutting the 50 Gt CO2 we emit each year, but little thought is given to sequestering the ~1830 Gt CO2 post-industrialisation emissions that remain.

Aquaculture on the open ocean will open up a new sector for economic growth, generating revenue and healthy jobs from which the Global South will profit.

For certain types of seaweed, revenue from products is considerably higher than it would be from sinking it for CDR carbon credits. However, in the case of Sargassum, the products that currently exist are produced from its alginates and nutrients that must be extracted and leave behind carbon-rich biomass, which can then be sunk at the end of its value chain instead of disposing it in landfill sites. It is also important to note that unlike other types of seaweed, Sargassum cannot be used in food products for either humans or animals.

Furthermore, for nuisance algae such as pelagic Sargassum from the Great Atlantic Sargassum Belt, currently 99% of the biomass collected from beaches is disposed of in landfill sites and therefore not converted into products. The cost and impact of sinking the biomass to the deep sea should therefore be compared to the cost and impact of the biomass going to landfill rather than into products. A value chain that includes both products and sinking of the residual biomass after processing is win-win, as it will divert the Sargassum away from landfill and provide a revenue stream.

Carbon reduction or reducing carbon emissions is the process of avoiding greenhouse gas being put in the atmosphere or reducing the amount of output.

Carbon capture is a method which catch carbon dioxid emissions directly at the source of pollution like power plants or industrial factories. This captured carbon can either be stored in depots underground or be reused, thereby reducing the amount of carbon emissions that would go into the atmosphere.

Carbon removal is the process of actively removing the carbon already in the atmosphere (often called historic emissions) and storing it permanently. It goes one step further than carbon capture and is vital for tackling the climate crisis since we need to bring atmospheric carbon dioxide concentrations back down from currently 420 ppm to pre-industrial levels of 280 ppm. Seafields approach is do tackle these gigatonnes of carbon dioxide (1 ppm CO2 equals 2.12 gigatonne of CO2) by converting it into Sargassum biomass and store it on the deep-sea floor.

To reach 1 Gt of CO2 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 yearly peak). In order to harvest 14 million tonnes of Sargassum a day, we need to create a Sargassum stock that is about 300 million tonnes, of which we can harvest the daily growth.

The Sargassum in the Great Atlantic Sargassum Belt is dispersed over large areas and harvesting the parts that are not near a coast is costly and the fuel required to power the ocean vessels would emit a lot of CO2. While it is possible to determine the fate of Sargassum that is located near shore and only remove what would have landed on beaches and emitted greenhouse gasses, it is not possible to know what the fate of Sargassum far away from the coast would have been – whether it would have sunk naturally or beached – without the intervention.

Sargassum farms will provide a steady source of raw material for companies such as our partner, Carbonwave, for use in a range of products like bioplastic and fertilizer, to secure contracts for their products and employ more people. There are no other companies trying to farm Sargassum, we are therefore a pioneer filling an important niche.

Our barriers are the first to contain Sargassum and will keep the seaweed inside the farms. We recently tested the first barrier prototype off the coast of St. Vincent and are confident of its ability to contain Sargassum even in difficult seas. Our monitoring technologies (GPS and drones equipped with sensors) will make the tracking of our farms possible even under tough conditions.

Lastly, we will be operating in the South Atlantic gyre, which will act as a natural barrier in the unlikely event that any Sargassum escapes our barrier system.

From our initial trials we don't foresee adverse issues with large marine life entanglement since our structures are flexible, but we will monitor this with underwater cameras in the prototype farms. We are also working on systems to prevent any surface bycatch of smaller marine life.

Independent scientists will perform a thorough survey of the ocean floor for the environmental impact assessment before the first set of bales are deposited. We will not start commercial operations until these results are in and it has been shown cause minimal harm to the deep-sea.

As we will sink tightly compressed bales, the amount of space for bacterial remineralization will be significantly reduced. We also plan to remove nutrients before sinking, which will make the bales less attractive for bacteria and reduce remineralization.

Duarte et al, 2017 calculated that if all the seaweed grown in aquafarms in 2014 was used for CO2 removal, a total of 2.48 million tonnes of CO2 per year would be removed. That is about 0.4% of the 0.63 Gt CO2 per year that wild seaweed squesters (Krause-Jensen and Duarte, 2016). These numbers give a good overview of what would be possible with today's aquafarms and how much sequestration happens naturally.

It is difficult to give a clear number on the global potential this early on. Like anything produced at large scale, there could be challenges that come into play during scaling up. Anticipating these effects through careful monitoring and redirecting growth when needed is key to minimising undesirable impacts. We plan to work with Earth System modellers to determine how much space seaweed farms can take up while having the smallest possible impact on the surrounding ecosystem.

Along with other renowned actors in the Ocean Carbon Dioxide Removal (CDR) community, who are exploring carbon credit methodologies with carbon verification agencies, we too are starting that conversation. In this case, we are talking with Verra and Coastal Carbon Solutions around our CDR approach. They will review our unique carbon sequestration method and we will receive official certification. The certification process, while lengthy, helps ensure the scientific validity of the sequestration method and make the credits generated by the Seafields project more valuable and attractive.

The lion's share of revenues will be generated by selling carbon credits against the CO2 stored within the sunken algae. Once the bales are sunk to the sea floor, the carbon contained within the algae is essentially stored for at least the next 1000 years. Once the certification, design, and operational testing is complete and scientific partners are able to review and comment on the plans, the company is targeting the construction of a pilot farm in the Caribbean that can sequester 1000 metric tonnes of CO2 per year. If all goes well with the carbon credit certification process, the completed pilot farm will be able to sell certified credits against its sunk Sargassum bales by 2025.

As carbon is removed from the ocean, we will need to verify that this leads to carbon removal in the atmosphere. When there is a difference in CO2 concentration between the surface ocean and the atmosphere, this difference will be balanced out, however not instantly – it is a process that takes months to years. To estimate how much of the CO2 taken out of the ocean is then pulled from the atmosphere back into the ocean, we need detailed measurement of CO2 concentration in the water and air in our farms. This, paired with modelling of how long the water parcels leaving our farm stay in contact with the atmosphere, will tell us how much of the carbon sequestered by our aquafarms can be considered sequestered from the atmosphere.

Our science team has extensive experience in monitoring climate change impacts in the carbon and nutrient cycles in the open ocean. They are aware of the challenges that ocean CDR Measurement Reporting and Verification (MRV) pose (e.g. accuracy of partial pressure of carbon dioxide (pCO2) measurements, considering the dilution of the signal, etc.) and are planning to use international monitoring networks (e.g. Argo floats, sail drones and satellites) as well as developing novel tools to improve the monitoring resolution for large scale operations. Using a combination of water and air sensors, we will monitor the air-ocean CO2 influx in our farms and control sites.

Seaweed and kelp do not attach to soil, most attach to rocky substrates. The Sargassum natans and fluitans that we work with are free floating for their entire life cycle. Therefore, the above statement is a bit misleading and confusing.

While mangroves and seagrasses sequester carbon in the soil right below them, when their leaves or blades fall off, seaweed and kelp biomass is moved to either these same coastal soils and sequestered there or moved to the deep sea. While the infinite ability of the mangrove’s soils to sequester carbon is a huge advantage and makes these soils far superior to terrestrial soils, which have a maximum amount of carbon they can sequester, this does not disadvantage seaweed sequestration. Seaweed sequestration is done either in the same soils as mangrove and seagrass sequestration or in the deep sea where carbon is locked away for much longer and better protected against being dredged up.

Mangroves sequester about 7 tonnes CO2 per hectare per year (Alongi, 2020) while the Sargassum in our farms will sequester about 107 tonnes CO2 per hectare per year. Therefore, per unit area the fast-doubling rate of Sargassum is able to produce much more sequesterable biomass than mangroves. We plan to sink this biomass to the abyssal plain. In terms of permanence, deep sea sinking is highly advantageous compared to the soils of the mangrove forests, as sequestration rates for 1000 years can be guaranteed while mangrove soils have to be protected against being destroyed for other uses such as hotel, housing and shrimp farm construction.

Another advantage of working with Sargassum, as mentioned above, is that it is free-floating. As such, it does not need to attach to rocks, unlike other seaweeds, nor does it require soil to grow, unlike mangroves and seagrasses. This makes it possible for Sargassum to grow in the open ocean which covers a much bigger area than the shallow coastal waters suited for growth of mangroves, seagrasses and benthic seaweeds.

Each project using blue carbon plants has a vital part to play. We need mangrove and seagrass restoration and protection projects as well as seaweed farming. The colossal task of removing CO2 from the atmosphere needs all hands on deck.

We have conducted a Life Cycle Assessment and calculated how much it would cost to sequester a metric tonne of CO2. The Life Cycle Assessment of two farm setups showed that the equivalent of 8-10% of the sequestered carbon is emitted during the entire process, including the production and decommission of machinery used as well as the transport of materials. Currently the most cost-efficient way we can sequester carbon from Sargassum is a combination of preventing Sargassum from beaching and impacting local communities, economies and ecosystems and also growing it in stationary farms. This business model includes two other revenue streams: payment of hotels/beach owners for keeping their beaches clean of Sargassum and the extraction of biostimulants for agriculture.

Since part of the cost of our operations is covered by these two revenue streams we can offer the carbon credits at US $246 per metric tonne, which is a little bit less than the cost incurred by baling it, transporting it to the sinking site and monitoring, reporting and verification. As there is a lot of Sargassum beaching in the Caribbean and West Africa, this can become a substantial business and alongside it costs will likely fall, however we cannot reach gigatonne scale with this business model.

Our cost models show that our open ocean farms model is currently much more costly than the above mentioned US $246 per tonne and we are working on bringing down these costs by engaging with potential industrial partners who can help us bring down the costs of infrastructure used for upwelling.

Our aquafarms can impact the environment both at the surface of the ocean as well as at the abyssal plain where the biomass is stored. We are committed to conducting rigorous environmental impact assessments and are part of a broad coalition of partners supporting each other, learning and sharing information on Ocean CDR generally and biomass sinking in particular. Through our lead scientist, Dr. Mar Fernández-Méndez, we are part of the Ocean Visions Sinking Working Group and we are organising with others, as members of the World Ocean Council (WOC), a WOC research programme on Ocean CDR. As mentioned above, we are also members of the United Nations Global Compact Safe Seaweed Coalition and are a signatory to the United Nations Principles for Ocean Sustainability.

In addition to having our own scientists embedded in wider MRV efforts, we are commissioning independent scientists to deploy a new version of the low-cost cameras designed by Purser et al. (2020), as well as oxygen and pH sensors to monitor remineralisation rates on a longer time scale. And to monitor changes at the surface of the ocean, we will deploy pH, oxygen and nitrate sensors to monitor the Sargassum productivity and detect any changes in the marine ecosystem's productivity. We are also developing new aerial monitoring techniques using multispectral drones and using eDNA analysis to monitor the fauna attracted to the Sargassum.

We are currently partnering 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). This scientific study has a maximum of 500 kg of biomass deposited per site. 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.

We have developed a financial model that assesses the economic viability of our approach. The Seafields approach is unique as it combines services and products with CDR. Therefore, processing costs to make Sargassum negatively buoyant are offset by profits made on the products and services.

We fully agree that in-depth trials are needed to investigate the risks associated with sinking seaweeds, and we are therefore teaming 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.

One of the areas of concern is the impact on the deep sea environment, which currently is unknown. Due to Sargassum’s natural life cycle, in which it sinks at the end of its life span, 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. 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. While more studies like this will be needed, the SeaSINC study will contribute immensely to our knowledge on the environmental impact of sinking seaweed biomass to the deep sea.

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 of sinking 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 descend. In the highly unlikely event that the wrapping of a bale does become loose and some biomass escapes, due to processing prior to sinking, the Sargassum will no longer be alive and its aerocysts (air sacs) will be deflated, meaning that it will sink and stay at the bottom of the seafloor.

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 nation 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.

Compared to other sinking biomass approaches (e.g. phytoplankton or loose seaweed biomass), the amount of carbon sequestered in our bales is easy to monitor by weight and carbon content. The two main challenges are to estimate the amount of CO2 taken out of the atmosphere and the remineralization rate of our bales at the deep sea. To monitor atmospheric CO2 uptake at the ocean surface we will use pCO2 sensors. In addition, we will monitor temperature, salinity, pH, current speed, and oxygen in situ with our fully equipped CTD (Conductivity-Temperature-Depth Probe). The deep-sea depots will be equipped with cameras and oxygen sensors to assess macro and micro benthos consumption. All this will give us a precise indication of the fate of the biomass in the deep sea.

Our lab results show that Sargassum processed for nutrient recovery decomposes slower than fresh Sargassum, which will lead to less remineralization of our bales compared to Sargassum that sinks naturally. This, together with the fact that on tightly compressed bales the amount of space for bacterial remineralization will be significantly reduced, suggests there will be negligible remineralization rates of the carbon stored in the bales in the deep sea. Recent studies have shown that remineralization rates in the deep sea are much lower than previously reported (Amano et. al., 2022). Furthermore, on the Sargasso Sea floor, four times more Sargassum is found than at the surface (Baker et, al. 2018), indicating a long-term accumulation of biomass that is not consumed. The small percentage of remineralized CO2 that does occur, would take an average of 900 years to reach the surface of the ocean. Until then it is locked away (Siegel et. al., 2021).

Our sector would welcome this. We are delivering best practice and would want to support the Article 6 developments to ensure that they drive quality and integrity from the top down.

The first US $1.17m was financed by founding team members, friends, family and angel investors. We were also selected by the band Coldplay to be one of their 15 Good Causes for the recent Music of the Spheres world tour. On top of promoting us at each of their worldwide concerts, the band has also committed to donating 10% of their tour profits to the 15 Good Causes.

We are currently raising £7m in a mixture of grant funding and equity, and will need to raise £20m in Summer/Autumn of 2024 once we have achieved technical proof of concept. If we are successful with proving each of the technology elements, we will essentially be credit generating so will be able to advance sell credits (and be on your offtake track). However, we anticipate much of the £20m will be raised via an equity investment into Seafields Solutions Ltd, and have already had discussions with investors interested in investing at this stage.

In collaboration with international research institutions like AWI and our partner company Carbonwave, we have raised around US $0.6m to study the potential of Sargassum for Ocean CDR at a global scale (sea4soCiety-CDRmare project funded by the German Ministry of Education and Research) and to develop and test the first aquafarm prototype and the processing steps to ethanol for long-lived engineering plastics (C-CAUSE project funded by SPRIN-D).

We are also establishing a not-for-profit foundation to support the long-term independent scientific monitoring and assessment of the potential ecosystem impacts of our operations both at the ocean’s surface and at the seafloor. It is imperative that we are science led which will inform politics and the legal aspect of our marine activities. The scientific knowledge produced will be open source.

It is difficult to predict final costs, as we have not fully completed our techno-economic analysis. We’re operating in an entirely new field and with that comes new manufacturing processes. It could cost us anywhere between £100k and £2m per farm module and upwelling pipe. One of our jobs in the next 12-18 months is to refine that figure and ascertain if the model is financially viable.

The BBC:

https://www.bbc.com/news/science-environment-63200589

Forbes Magazine:

https://www.forbes.com/sites/erikkobayashisolomon/2022/06/07/seafields-an-innovative-ocean-based-nature-enhancing-solution-to-climate-change/?sh=1482657cd48eclimate-change/?sh=1482657cd48e