As the climate crisis is one of the highest concerns for people around the world, many strategies have been developed by scientists to improve the health of the climate.
When the climate crisis comes to mind, we think of curbing carbon emissions to eliminate this greatest threat to the Earth. For a long time, it has been known that reducing emissions is the only way to address the climate crisis. However, we have hardly witnessed any progress in this regard, as there is no record of global carbon emissions being lower than the previous year. This calls for thinking beyond the horizon.
As part of these efforts, scientists have discovered the carbon capture method—a process that involves capturing carbon dioxide (CO₂) emissions from sources like power plants, industrial facilities, or even directly from the air, before the CO₂ enters the atmosphere.
Though carbon capture offers some hope in the colossal fight against climate change, it remains a topic of debate. Critics claim it is expensive, not yet fully scalable, and risks shifting focus away from reducing emissions at their source. Still, the field is expanding quickly. The Global CCS Institute reports that over 628 carbon capture and storage initiatives are now underway worldwide—a 60% rise from the previous year. As noted by Fortune Business Insights, the market was valued at slightly more than $3.5 billion in 2024 and is anticipated to reach $14.5 billion by 2032.
Among the most ambitious and costly approaches is the extraction of carbon dioxide (CO₂) directly from the atmosphere. Despite its potential, only a limited number of direct air capture (DAC) plants are currently operational. Some researchers propose an alternative strategy: removing CO₂ from seawater instead. Since oceans absorb roughly a quarter of global CO₂ emissions, this method could offer a more efficient and promising solution.
In the United Kingdom, where the government committed up to £20 billion ($26.7 billion) in 2023 to advance carbon capture technologies, a promising experimental project has emerged along the English Channel. Named SeaCURE, the project seeks to determine whether extracting carbon dioxide from seawater can be a practical and cost-efficient alternative to capturing it from the air.
“Seawater holds a significant amount of carbon because, when CO₂ dissolves in it, nearly 99% converts into various dissolved carbon compounds that don’t easily return to the atmosphere,” says Paul Halloran, a professor of Ocean and Climate Science at the University of Exeter and the project’s lead researcher.
“This property also makes it relatively simple to draw the carbon back out,” he adds.
Roughly a year ago, SeaCURE began assembling a pilot plant at the Weymouth Sea Life Centre, located on the southern coast of England. Now operational for several months, the facility is engineered to treat up to 3,000 liters of seawater per minute, with the capacity to extract around 100 tons of CO₂ annually.
“Our intention was to evaluate the system under actual environmental conditions, using genuine seawater to discover any potential technical challenges,” explains Halloran. He notes that setting up the plant at a public aquarium made sense due to its existing infrastructure for drawing and discharging seawater.
The system functions by slightly lowering the pH level of the seawater, which causes the carbon to revert into gaseous CO₂. The water is then dispersed over a wide surface while air flows over it, prompting the CO₂ to be released. “This technique enables us to capture more than 90% of the carbon present in the water,” Halloran states.
Once extracted, the CO₂ is purified using activated carbon made from charred coconut husks, preparing it for permanent storage, ideally in underground geological formations. Before the seawater is released back into the ocean, its acidity is restored to normal, allowing it to take in more carbon dioxide from the air.
“With most of its carbon content removed, the water becomes ‘hungry’ for CO₂, effectively pulling it from the atmosphere,” Halloran explains. “Think of it as squeezing a sponge dry and then letting it absorb again.”
While the early results are encouraging, Halloran admits the method doesn’t yet surpass direct air capture (DAC) in terms of energy efficiency. He also points out other obstacles, including the need to eliminate impurities before discharging the water and evaluating its potential environmental impact. However, he emphasizes a major benefit: seawater has a much higher carbon content than air, which could make future systems more cost-effective to build and operate.
