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Climate Tech

The Startup Sinking Seaweed to Capture Carbon

September 11, 2023
x min read

United Kingdom based startup Seafields has completed the world’s first ever test on sinking seaweed to the bottom of the ocean to reduce carbon emissions.

And the implications for the future could be groundbreaking.

The big idea:

  • Sargassum naturally absorbs CO2, with carbon dioxide actually representing about a third of its dried mass
  • Seafields develops offshore aqua farms to cultivate Sargassum at scale
  • Once cultivation is complete, they then extract key nutrients from the Sargassum that have a variety of potential uses, including bioplastics and biofuels
  • The remaining Sargassum mass is then compressed, baled and eventually will be sunk to the bottom of the ocean
  • By sinking the bales the aim is that it can safely store away carbon indefinitely while not making a negative long term impact on the ocean floor

Why it matters:

  • Finding innovative and sustainable ways to remove carbon from the atmosphere is essential to achieving net zero
  • This first-of-its-kind long term study of the effects on the ocean floor from sinking Sargassum could unlock meaningful insights around how scaleable this is for the future
  • Sargassum has incredible potential to absorb carbon, with Seafields projecting it can sequester 107 tonnes of CO2 per hectare of their aqua farms each year
  • By comparison, mangroves sequester about 7 tonnes of carbon per hectare each year

The intrigue:

  • Popular band Coldplay was so captivated by what Seafields is doing they made them one of their ’15 Good Causes’ that will receive a portion of their recent tour profits


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