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Ocean carbon removal draws backers

Illustration of a shoreline on a beach washing away the word CO2 while a seagull looks on

Illustration: Sarah Grillo/Axios

There's growing interest from investors and governments to back startups removing carbon dioxide from the oceans in various ways.

Why it matters: Oceans could emerge as an efficient and low-cost means for carbon removal if companies can successfully commercialize technologies.

Yes, but: The sector is at an early stage, even earlier than the direct air capture market.

Driving the news: Marine carbon removal startup Banyu Carbon closed a seed round of $6.5 million led by Australian VCs ReGen Ventures and including backing by United Airline Ventures, ocean-focused investors Propeller, and Grantham Foundation, among others.

  • Banyu Carbon was founded in 2022 by Alex Gagnon and Julian Sachs, two professors of chemical oceanography at the University of Washington who are also Activate fellows.
  • Gagnon says the Seattle-based startup plans to use the funds to build a pilot plant this summer in the waters of the San Juan Islands off the coast of Washington state. The pilot project will be able to remove a ton of carbon dioxide per year.

How it works: Banyu Carbon uses sunlight to power a chemical reaction that causes carbon dioxide to be released from seawater.

  • The company uses light-sensitive molecules called photoacids, which become more acidic when light is shined on them. The acid converts the dissolved carbon in the seawater into CO2 gas, which can be more easily captured.
  • Banyu Carbon says the process is a lot more efficient, low energy and low cost compared to other removal processes.
  • The company also has a contract with carbon removal fund Frontier to remove 360 metric tons of CO2 by the end of 2026.

State of play: A swell of marine carbon removal companies has emerged over the past few years, many with funding from VCs.

  • Last month startup Captura closed a $21.5 million round to commercialize its technology from the VC arms of shipping giant Maersk and energy companies Eni and EDP.
  • Last week, Planetary Technologies told Axios it's raising a $10 million or so Series A round to add antacids made from industrial byproducts into the Earth's oceans.
  • Ocean tech investor Propeller has supported a whopping eight startups developing technologies around ocean carbon capture, including Ebb Carbon, which uses electrochemistry to remove CO2 from seawater; Canadian river carbon removal startup CarbonRun; and Cambridge, Mass.-based Aquatic Labs, which makes ocean sensor tech.

Big picture: It's still early days for so-called "marine carbon dioxide removal."

  • Banyu Carbon is still in the lab phase and hasn't yet demonstrated its tech through a pilot.
  • One of the more established startups, Captura, is just now trying to move into a more commercial phase of the company.
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