Our oceans are critical carbon sinks, absorbing one-quarter of all carbon dioxide emissions. But what if the ocean’s natural carbon absorption was amplified? Direct ocean capture might turn that possibility into reality, and several companies are already working to implement such technology.
Carbon capture has gained popularity as an essential tool to fight climate change. Direct air capture removes carbon dioxide directly from the atmosphere to either store or use for industrial purposes. Although some companies have made progress in reducing costs, direct air capture can be expensive since carbon isn’t highly concentrated in the atmosphere, and it is more energy-intensive to try and capture it directly.
Direct ocean capture is conceptually similar to direct air capture but could be more cost-effective. The ocean contains 150 times more carbon than the atmosphere, making it a more efficient place to implement direct capture. Direct ocean capture processes vary from company to company, but they typically use an electrochemical process to dissolve carbon in seawater.
While direct ocean capture is still in its early stages, a few companies are working to scale the technology.
An Amsterdam-based startup, Brineworks, is developing a direct ocean capture technique that uses electrolysis (using an electric current to split water into hydrogen and oxygen molecules) as a starting point for carbon extraction. The company asserts that the co-generation of green hydrogen created by carbon extraction could be used in clean energy. Brineworks also predicts that the company’s technology will lead to more affordable carbon extraction, estimating that it will cost less than $100 per ton of carbon extracted when implemented at an industrial scale, less than half the cost of many direct air capture technologies.
Another company is Ebb Carbon. The company focuses on water being held and used in aquaculture farms, coastal industry plants, or desalination plants. Ebb uses an electric current to separate acidic and alkaline water solutions. Only the alkaline solutions are returned to the ocean, where they bind to carbon to form bicarbonate. Ebb argues that bicarbonate can store carbon for 10,000 years and that their process will help lower the ocean acidity that negatively impacts marine life.
Captura is another company in the ocean capture space that uses electrodialysis. Electrodialysis acidifies contained seawater to the point where carbon is separated for extraction, and then the water can be returned to the ocean. “Requiring no rare-Earth minerals and leaving no by-products behind, our streamlined process is designed for scale,” writes the company. “Captura systems capture a verifiable stream of CO2 to be permanently stored or reused.”
Whenever carbon is removed from the ocean, it opens up the ocean’s ability to draw down and lock up even more carbon from the atmosphere. Growing direct ocean capture technologies could allow governments and private actors worldwide to partner with the ocean in carbon capture, radically increasing capture without dramatic price tags. Unlocking greater potential for the ocean to capture carbon could significantly aid in the fight against climate change.
The views and opinions expressed are those of the author’s and do not necessarily reflect the official policy or position of C3.
