A pioneering project designed to extract carbon from the ocean has officially begun operations on England’s south coast.

Known as SeaCURE, this small-scale pilot scheme is funded by the UK government as part of a broader initiative to develop innovative technologies to combat climate change.

While cutting greenhouse gas emissions remains the top priority for tackling global warming, many climate scientists agree that some form of carbon removal will also be necessary. Most carbon capture efforts have so far focused on either trapping emissions at their source or pulling carbon directly from the air. What sets SeaCURE apart is its attempt to remove carbon from seawater, where concentrations of carbon are higher than in the atmosphere.

The project is tucked behind the Weymouth Sealife Centre, past a warning sign about biting moray eels. A pipe runs beneath the stony beach and out into the English Channel, drawing seawater inland to begin the carbon removal process.

Professor Tom Bell of Plymouth Marine Laboratory, who guided the first broadcast journalists to visit the site, explained the basic process. Some of the seawater is first treated to make it more acidic. This triggers the dissolved carbon to shift into a gas form, releasing it as CO₂.

“This is the seawater stripper” Prof Bell says with a smile as we turn a corner.

The “stripper,” a large stainless steel tank, maximises the contact between the acidic water and the air, encouraging the CO₂ to escape.

“When you open a fizzy drink it froths, that’s the CO2 coming out.” Prof Bell says. “What we’re doing by spreading the seawater on a large surface area. It’s a bit like pouring a drink on the floor and allowing the CO2 to come out of the seawater really quickly.”

The emerging carbon dioxide is then captured and concentrated using filters made from charred coconut husks, preparing it for long-term storage. Meanwhile, the seawater—now low in carbon—has an alkali added to neutralise the earlier acid treatment before being pumped back into a nearby stream that flows into the sea. Once returned to the ocean, this water immediately begins absorbing more carbon dioxide from the atmosphere, helping to reduce greenhouse gases.

Currently, SeaCURE’s carbon removal capacity is modest—at most 100 metric tonnes of CO₂ per year, which is less than the emissions from a single commercial flight across the Atlantic.

Nevertheless, project lead Dr. Paul Halloran believes the method has enormous potential.

“Seawater has got loads of carbon in it compared to the air, about 150 times more,” says Dr Halloran.

“But it has got different challenges, the energy requirements to generate the products that we require to do this from seawater are huge.”

The team estimates that if 1% of the world’s ocean surface water were processed this way, it could theoretically remove up to 14 billion tonnes of CO₂ annually.

Scaling up to that level would require the entire process to be powered by renewable energy, likely using floating solar panel installations at sea.

“Carbon removal is necessary. If you want to reach net zero emissions and net zero emissions is needed to halt further warming,” says Dr Oliver Geden who’s part of the Intergovernmental Panel on Climate Change and an expert in carbon capture.

“Capturing directly from seawater is one of the options. Directly capturing it from the air is another one. There are basically 15 to 20 options, and in the end the question of what to use, of course, will depend on the cost.”

SeaCURE has secured £3 million in government funding and is among 15 pilot projects aimed at developing technologies for carbon capture and storage.

“Removing greenhouse gases from the atmosphere is essential in helping us achieve net zero,” says energy minister Kerry McCarthy. “Innovative projects like SeaCURE at the University of Exeter play an important role in creating the green technologies needed to make this happen, while supporting skilled jobs and boosting growth.”

However, questions remain about the environmental impacts of widespread deployment.

In Weymouth, the amount of low-carbon water released back into the sea is small and unlikely to affect local ecosystems. But researchers are keen to understand the potential consequences at a larger scale.

Guy Hooper, a PhD student at Exeter University, is studying the effects by exposing marine organisms to low-carbon water in laboratory settings.

“Marine organisms rely on carbon to do certain things,” he says. “So phytoplankton use carbon to photosynthesize while things like mussels also use carbon to build their shells.”

His early findings suggest that, if scaled up massively, the introduction of large volumes of low-carbon water could have measurable impacts on marine life.

“It might be damaging but there might be ways to mitigate that – for example through pre-diluting the low-carbon water. It’s important this is included in the discussion early on.”

Despite the challenges ahead, SeaCURE’s team believes their approach could play a valuable role in the broader effort to remove carbon from the atmosphere and slow the pace of climate change.

 

 

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