“Captura is one of a cadre of startups eyeing Earth’s oceans as a carbon sink ready to be harnessed. The bioengineering strategies it’s deploying aim to accelerate what the oceans already do: absorb carbon emissions on a massive scale. This natural process has helped keep atmospheric CO2 levels in check for millions of years, but it can’t keep up with present-day industrial emissions. Dozens of field trials and pilot projects have begun, and in 2025, Captura and several other companies will begin scaling up their facilities.

Their approaches are as diverse as they are bold. Some groups are growing kelp forests or microalgae in the sea. Others propose pumping seawater between shallow and deep layers to move carbon around. Two strategies caught IEEE Spectrum’s gaze—Captura’s ocean carbon dioxide removal approach, which sucks carbon out of the sea, and ocean alkalinity enhancement, which stores carbon in the sea. Both have inspired the engineering of novel, highly efficient electrochemical systems to treat copious amounts of seawater.

Big funding entities support these ideas. The finalists for both the US $100 million XPrize for Carbon Removal and the $35 million Carbon Dioxide Removal Purchase Pilot Prize from the U.S. Department of Energy include marine-based strategies, alongside atmospheric ones.”

From IEEE Spectrum.