New ocean carbon capture projects aim to remove thousands of tons of CO2

Over the next year, two companies plan to use the ocean to capture thousands of tons of carbon dioxide from the atmosphere.

Earlier this month, carbon removal company Captura began operations at its new Hawaii-based carbon capture plant, which will remove 1,000 tons of carbon annually. Additionally, carbon removal company Gigablue announced last month that it will sequester a whopping 200,000 tons of carbon over the next four years through a new deal with SkiesFifty, an aviation sustainability investment firm.

Though both companies sequester carbon using the ocean, their methods are different. Captura uses direct ocean capture (DOC), meaning it removes carbon from the water through electrodialysis and gas extraction. The company says it uses DOC on the “upper ocean” to enhance water’s “natural ability to absorb additional CO2 from the atmosphere.” The CO2 gas captured by Captura’s Hawaii plant will be given to local industries in need of carbon for their own operations.

Gigablue, on the other hand, uses marine carbon fixation and sequestration, which uses phytoplankton: The phytoplankton consume carbon while living on a nutrient-dense substrate the company provides. Once there are enough phytoplankton on the substrate, it sinks to the bottom of the ocean, where the carbon is then stored permanently.

“We are harnessing the basic building blocks of life on Earth—water and sunlight—to create a financially sustainable carbon removal solution,” Ori Shaashua, Gigablue’s co-founder and CCO, said in a press release. The company claims its deal with SkiesFifty is “the largest marine carbon dioxide removal offtake agreement to date.”

Captura’s Kona, Hawaii, plant is also a milestone for the company. CEO Steve Oldham said once the pilot facility is up and running, the company is one step closer to “widespread commercial deployment of DOC technology.”

“[The plant’s] rapid installation and commissioning in just over two months demonstrates how our simple, modular design is ready to be scaled quickly to help address the urgent climate and energy challenge,” Oldham said in a press release.