The ocean has absorbed more than 525 billion tons of human-made CO2 since the start of industrialization. The result: seawater is now 30 percent more acidic than in the pre-industrial era, increasingly threatening corals, shellfish, and fish larvae. Dutch startup SeaO₂ has developed a method that uses electrochemistry to decarbonize seawater, transforming it into a carbon sink. Since this year, the company has been testing the first independent continuous operation of its pilot system in the port of Scheveningen.
How Electricity Strips CO2 from the Ocean
The crucial difference from other approaches: SeaO₂ requires no external chemicals. The system sends electrical current through a membrane, electrochemically separating a portion of the seawater. The resulting difference between acid and alkaline solutions releases dissolved CO2 as a gas, similar to carbonation rising from a bottle of soda. The gas is captured and either permanently stored in geological formations or bound in mineralized concrete. The decarbonized water then flows back into the ocean, where it can absorb CO2 from the atmosphere again.
Founded in 2021 as a spin-off from Delft University of Technology, the twelve-member team led by CEO Ruben Brands and electrochemist Rezvan Sharifian, who completed her dissertation on this technology in 2022, has been working on an initial pilot system since 2023. "Carbon removal as a whole is growing. We are leading in direct ocean carbon capture," said founding associate Zamin Syed, according to the European Commission in February 2026.
In 2023, the team achieved its first success with Project Ripple, removing CO2 from seawater and permanently binding it through mineralization. The pilot system Project Swell followed at the Afsluitdijk in the Netherlands: a container-sized device with a capacity of 25 tons of CO2 per year. In 2025, the system ran for the first time under real field conditions with actual North Sea water.
Scheveningen 2026: First Independent Continuous Operation
2026 is a decisive step: Project Swell is moving from the Afsluitdijk to the port of Scheveningen. There, the system is to run for the first time completely autonomously, without experimental supervision, in continuous operation. SeaO₂ calls this Europe's first commercially developed independent field trial for direct ocean carbon removal. The CIEIF funding program has approved 75,000 US dollars for this step, covering environmental impact assessment and community engagement.
For 2028, the company is planning Project Breaker: the entry into commercial operation with the sale of verified CO2 credits. The fintech company Klarna has already pre-ordered initial credits. A growth financing round of around 12 million euros is planned for early 2027. In the medium term, SeaO₂ aims for one megaton of CO2 per year by 2030, and one gigaton by 2045.
Ebb Carbon and Planetary: The Field Grows Internationally
SeaO₂ is not alone. US competitor Ebb Carbon pursues a similar electrochemical approach but integrates it into existing seawater desalination systems. Microsoft has signed a contract with Ebb Carbon for up to 350,000 tons of CO2 removal over ten years, and Google also signed an initial agreement in December 2025.
Canadian company Planetary Technologies takes a mineral-based approach: it increases seawater alkalinity through mineral additives rather than electrolysis. In August 2025, the Frontier Coalition, backed by technology companies like Stripe and Alphabet, secured Planetary a purchase agreement worth 31.3 million dollars. Starting in 2026, this will deliver 115,211 tons of verified CO2 credits.
The scientific framework for this technology group is provided by the EU research project SEAO2-CDR: a Horizon Europe-funded consortium with 13 participating organizations, coordinated by Uniresearch and running from 2023 to 2027. It investigates mechanisms, impacts, and feasibility of ocean-based carbon removal.
What Researchers Point Out
The scientific community assesses this technology group with mixed findings. A 2025 analysis published in the journal Biogeosciences shows that increasing seawater alkalinity, even with 80 percent technical efficiency, only produces modest and time-limited increases in surface pH. The reason: atmospheric feedback. When the ocean removes CO2, atmospheric CO2 concentration drops slightly. This reduces the ocean's natural uptake capacity, offsetting part of the theoretical benefit. Another analysis from the same group showed that interactions between atmosphere, ocean, and land biosphere significantly reduce efficiency compared to simplified models.
Another open problem: previous research has focused primarily on plankton response. Public interest centers more on what happens to commercially exploited sea animals like mussels, oysters, and crustaceans. A research article in Environmental Science and Technology explicitly urged in 2023 better research on effects on commercially and culturally important species. The Carbon to Sea Initiative therefore issued new research calls in 2025 and 2026 to close this knowledge gap.
From 25 Tons to a Gigaton: What Must Work
For the bigger climate picture, current numbers remain tiny. Scheveningen 2026: 25 tons of CO2 per year. Global climate scenarios require that new technologies together remove at least one gigaton per year by 2050. That is a factor of 40 million compared to today's pilot level.
SeaO₂ itself names 2045 as the target date for one gigaton. This requires three conditions: that the technology scales reliably, that international permits are granted for large-scale seawater treatment in national and international waters, and that CO2 credit markets offer stable prices to sustain operations. Project Breaker in 2028 will be the first real test.