Oceans have long been seen as part of the solution to rising greenhouse gas emissions. With over 30% of CO2 absorbed in them, as well as 90% of excess heat, ocean carbon removal has recently emerged as another branch of the carbon industry with the promise of sparing us some of the impacts of global warming.
The last few years have seen a number of startups emerge, either adopting their own new technologies or spinning off from universities after announcing promising research. The number of pilot projects and new funding has swelled in 2023.
A bit of clarification before we go into the list. We use the blanket term “ocean carbon removal” to refer to all seven approaches according to non-profit Ocean Visions: Artificial Downwelling, Deep Sea Storage, Electrochemical Ocean Carbon Dioxide Removal, Macroalgal Cultivation, Marine Ecosystem Restoration, Microalgae Cultivation and Ocean Alkalinity Enhancement.
We’ve arranged the companies alphabetically and selected them based on their adoption of either one or multiple approaches. In any case, we feel they are the ones that have generated the most excitement and attention in the last year.
But with great promise come great risks. We’ve also provided some background about the dangers these approaches pose, as well as the efforts to create policies for regulating the industry.
Brilliant Planet is a UK-based startup that has set out to fight rising global temperatures with microalgae. The company specializes in growing microalgae in coastal deserts and outdoor ponds with the intention of pulling carbon dioxide from the atmosphere.
The approach is not surprising, as algae’s capability to draw CO2 from the air has long been known to surpass that of land vegetation, such as trees and plants. But the issue with lab-grown microalgae has always been its strong sensitivity to even minor changes in water quality. Hence, maintaining these populations has so far been a struggle, resulting in higher costs.
However, Brilliant Planet has managed to come up with an innovative process that in fact has brought those costs down to only a fraction, thus paving the way towards scalability and potentially removing CO2 from the atmosphere by the gigaton in the near future.
The UK startup has already successfully demonstrated the efficiency of its technology in Morocco and is currently working together with global engineering and management consultancy Mott MacDonald, on deploying the world’s largest algae production facility, set to become operational in 2024.
A spin-out from Caltech, Captura was founded in 2021 by two of the university’s professors – CX Xiang and Harry Atwater. The company attracted a lot of attention at the start of this year with an impressive Series A round of $12 million.
Its visualization of a full-scale carbon removal facility also triggered the imagination of those hoping that ocean carbon removal can have a substantial impact.
Relying on a new variation of electrodialysis, the company’s approach utilizes Henry’s law by taking CO2 from the ocean, creating an imbalance, causing the ocean to draw down carbon dioxide from the atmosphere to compensate for the one it lost.
CEO Steve Oldham has been leading the company since April 2023 and has a wealth of experience in carbon removal. His previous position was as CEO of Carbon Engineering, one of the most prominent direct air capture companies.
In an interview with Carbon Herald he shared that “Direct air capture is a perfectly good solution, but it’s quite expensive … Fundamentally Captura’s approach is taking CO2 out of the ocean, so that the ocean draws down the same amount of CO2 from the atmosphere. If you can do that in a way that doesn’t harm the ocean, you have a very cost-effective and highly scalable way to take CO2 out of the atmosphere.”
The company’s first pilot was launched in August 2022 and in May 2023 they made the next step by deploying a 100-ton system together at the Port of Los Angeles.
Ebb Carbon was established in 2021 by co-founders Matt Eisaman, Dave Hegeman and Ben Tarbell. CTO Eisaman has been working on Ebb’s ocean carbonate system for a decade, perfecting an electrochemical process that can not only remove CO2 but also reduce ocean acidity.
CEO Ben Tarbell is a mechanical engineer and served as VP of products for SolarCity before joining Google X as climate tech research lead. Dave Hegeman completes the leadership team as VP of Engineering.
The main example of where and how the system can work is at a desalination plant. It utilizes the salt water flows there by pulling acid out from the brine flow (generating acid can then be sold as a product). The treated seawater is then returned to the ocean with slightly higher alkaline levels, where it reacts with atmospheric carbon dioxide to form bicarbonate, while simultaneously decreasing water acidity.
Ebb Carbon points out that their tech is modular and can be fitted onto a wide variety of coastal industry plants.
The company raised a substantial Series A round of $20 million in April 2023, indicating a solid degree of trust in the approach from investors. And with an expected price of less than $100 per tonne of removed CO2, this could be one of the flagship ocean carbon removal projects in the near future.
Equatic is a carbon removal startup that recently spun out from the UCLA Samueli School of Engineering’s Institute for Carbon Management.
Equatic’s unique approach utilizes the ocean’s natural ability to sequester carbon dioxide and speeds it up using a single process that in the end not only results in permanent CO2 removal, but also produces carbon-negative hydrogen.
The company has two pilot plants in Singapore and its hometown of Los Angeles, both of which are operational and busy removing CO2 from the atmosphere.
All of the carbon dioxide currently removed by the LA-based startup has already been pre-sold, including via pre-purchase agreements with major clients like payment provider Stripe and, most recently, aerospace giant Boeing. In fact, the latter just signed a purchase agreement with Equatic for the removal of 62,000 metric tons of CO2, as well as for 2,100 metric tons of carbon-negative hydrogen.
The company plans to remove as much as 100,000 tons of carbon dioxide from the air annually by 2026 and then ramp up its operations to reach millions of tons by 2028, which is expected to bring down the cost to under $100 per ton of CO2.
Ocean-Based Climate Solutions
Ocean-Based Climate Solutions Inc. is among the pioneers of ocean CDR, having embarked on this journey back in 2005. At the core of its operations is cutting-edge technology that not only helps remove planet-warming carbon dioxide emissions from the atmosphere, but it also boosts fish populations.
The way Ocean-Based’s approach works is it pulls CO2 from the air and converts into ocean fish food, while sinking the carbon dioxide to the seafloor.
Namely, the technology involves upwell pumps that bring water, which is rich in nutrients, up from the deep sea and to the sunlit surface, where excess CO2 is naturally converted into phytoplankton.
The Santa Fe-based company has tested its technology in different parts of the world, including the US, Bermuda and Peru. Thanks to this global effort, Ocean-Based Climate Solutions can now get clear estimates of the new fish grown every year by each one of the company’s upwelling pumps. A further advantage of this technology is that it is powered exclusively by renewable wave and solar energy.
Planetary Technologies has set on with the ambitious goal of capturing 1 billion tons of carbon dioxide from the atmosphere by 2045. The startup was one of 15 teams to receive the $1 million XPRIZE Carbon Removal award in April 2022, which it plans on using to bring its technology to a full-scale demonstration.
Planetary Technologies’ approach kills four birds with one stone: it removes CO2 from the air, restores the ocean’s natural acidity and purifies mine waste, turning it into nontoxic antacid. In turn, the antacid is released into the ocean, where it restores the seawater’s pH levels, thus accelerating the ocean’s natural ability to pull carbon dioxide from the air.
Finally, the process results in the production of green hydrogen, which many consider to be the fuel of the future and allows hard-to-abate sectors to rely less on the use of fossil fuels.
To scale its technology, the company has already made arrangements to open its first plants in Canada and the UK. And to ensure that its solution is scientifically sound, it also works closely together with academic institutions, such as Plymouth Marine Lab and the University of Miami Basico2 project.
Established in 2017, Running Tide is one of the most experienced companies in the ocean carbon removal space. It’s led by CEO Marty Odlin, an experienced systems engineer who ran the Columbia University Center for Sustainable Engineering and is a fourth-generation member of a commercial fishing family.
The company’s approach is a combination of photosynthesis and alkalinity enhancements that allow carbon dioxide to be moved from the fast carbon cycle (which involves both atmosphere and biosphere) to the slow carbon cycle in the deep ocean. By growing macroalgae and shellfish and then sinking them to the bottom, Running Tide harnesses the geological processes that allow CO2 to be stored for prolonged periods.
The company has placed scientific principles at the center of its efforts. It has been working with Ocean Visions since 2021 on the different iterations of its approach and published a framework protocol intended for the Voluntary Carbon Market that provides guidance for the quality and measurement of removed carbon.
The latest funding round for the company was a Series B in February 2022 (for an undisclosed amount). And it seems the funds have been put to good use.
On the technological side Running Tide deployed two constellations of ocean observing platforms off the coast of Iceland. They will be used to provide insights into the ocean’s biochemistry and help with modeling the optimal path for scaling its approach.
Seafields is a science-based company from the UK, which offers sargassum as a solution for the climate crisis. Sargassum is a type of brown macroalgae or seaweed that is naturally found throughout the temperate and tropical oceans of the world.
The company’s approach suggests that growing sargassum and sinking it to the depths of the ocean can act as a way to remove and store away vast quantities of CO2 for millenia.
Part of the advantages of sargassum is that it is free-floating and contains a high amount of carbon compared to nutrients. Furthermore, the seaweed grows very rapidly and doubles in size every two weeks, making this solution incredibly easy to scale.
Seafields claims to be the first to ever domesticate sargassum, which in the future will also be beneficial to ocean biodiversity and productivity, while enabling the extraction of valuable resources that can be used to replace fossil fuels in the manufacturing of different products.
Despite its recent launch this year, Seafields quickly earned the trust of the public and was able to raise more than $330,000 in just 24 hours from a crowdfunding campaign.
The aptly named Dutch startup SeaO2 was founded in 2021 with the ambitious goal of removing 1 gigaton of carbon dioxide by 2035.
Founders Ruben Brands, Rose Sharifian and David Vermaas are working on developing a technology that first emerged in Delft University of Technology (where Sharifian is a Researcher PhD Candidate and Vermaas an associate professor) and Wetsus laboratories.
SeaO2’s approach uses the flow of ocean water through a capture plant, taking seawater at 50-100 depth and subjecting it to an electrochemical reaction that separates CO2 in a gaseous form. After the process the treated water is returned to the ocean’s surface, where it can again absorb CO2.
The company says the technology can be retrofitted to existing industrial installations and that the compressed CO2 it generates can be directed towards storage or utilization.
Project Vesta offers the world a very promising approach to ocean CDR in that its solution revolves around a material that is already available in abundance – sand. The solution is what is referred to as enhanced coastal weathering. Namely, the company found that adding small amounts of the finely ground mineral olivine to regular beach sound can help pull more CO2 from the air and even restore eroding coastlines.
To demonstrate this concept, Vesta launched its first demonstration project in Southampton together with NSBC Beach Erosion Control District (NSBC-BECD) in the summer of 2022.
The company has also been working together with the public and private sector to provide the necessary knowledge on the implementation of its approach in coastal regions.
As olivine is one of the most common minerals in the world, Vesta’s climate solution is not only scalable, but can potentially be more cost-effective than many other alternatives. Furthermore, Vesta is also working towards understanding how its CDR approach can positively influence policy efforts.
While the world’s oceans have the unrivaled potential to remove CO2 from the air at gigaton scale, the many different ocean CDR solutions developed by scientists and companies may still pose certain risks to the environment. Ocean experts warn that ocean-based climate interventions (OCBIs) are likely to have an immense impact on entire ecosystems
According to a paper published in Science, over 90% of the world’s habitable space is in the deep ocean, making it the largest realm on the planet. Not only that, but meddling with the ocean’s CO2 or its acidity can affect the natural carbon cycle and have dire consequences.
Burying carbon dioxide directly below the ocean’s surface could potentially suffocate the local flora and fauna. Finally, humanity is also very dependent on the ocean for food and medicine supply, which can also be negatively affected by the use of ocean CDR solutions and other OCBIs.
The world is still in need of robust policies and legal frameworks to advance scientific developments in the field of ocean CDR to make sure new solutions can effectively mitigate the climate crisis, while preventing any harm from coming to the environment. Environmental organizations are drawing attention to this issue and are working towards developing frameworks and recommendations for policymakers and legislators.
For instance, in its latest white paper, Carbon180 addresses the known knowledge gaps and talks about how these gaps can be filled with the help of policy. Earlier this year, the Sabin Center, which specialized in the development of legal techniques to address the climate crisis, published its model federal legislation for ocean CDR in the US.
The proposed framework is intended to support the safe and responsible research in the emerging sector and focuses on creating an efficient and comprehensive permitting procedure, which includes multiple safeguards.
Ocean carbon removal is at the very beginning of its journey. With the planet’s climate moving towards several tipping points and symptoms like heat domes appearing more frequently, the importance of the ocean can’t be overstated.
It has already helped us by absorbing almost all of the warming in the last several decades but natural capacity seems to be reaching its limit. Proponents of ocean carbon removal believe we can create extra capacity or speed up some of the natural processes, and they clearly have backing from public and private capital.
But all efforts need to be done in sync with the existing balance of the complex ecosystems this new crop of companies will be operating in. Intervention with good intentions doesn’t magically reduce risks.
Conservation of both marine life and the health and safety of coastal communities should be a priority, so that the potential positive outcome of reducing atmospheric CO2 is achieved without damage elsewhere. If done right, these companies will have one of the most crucial roles in reducing global warming.