Podcast’s Essential Bites:
[1:17] JR: "The world's oceans already do some serious heavy lifting when it comes to pulling carbon dioxide out of the air. Sea water and the life forms that live within it suck up about a quarter of the CO2 we put into the atmosphere annually. Land-based plants and forests account for another quarter. Now a private company plans to earn carbon credits by giving nature a nudge, boosting the oceans capacity to capture even more carbon by cultivating vast fields of seaweed hundreds of miles from land, and it plans to do it on a truly epic scale."
[2:02] JA: "Seafields is developing a hyperscale seaweed farm that it's going to be placed in the South Atlantic to grow the brown seaweed sargassum for the principal reason to sink in to the bottom of the ocean for carbon sequestration. [...] The eventual size of the farm is intended to be about 55,000 square kilometers, [...] about the same sort of size as Croatia. [...] That's the size we need to get to we believe to do a gigaton [of carbon sequestration] per annum."
[6:50] JR: "Success depends on the unique properties of the seaweed sargassum. [...] Most seaweed anchors itself to the sea floor so it can stay in the shallows close to the light, which it uses for energy. Sargassum is different. It floats on the surface forming a giant raft. It looks like greeny, brown, hairy carpet, and has little air bladders to keep it buoyant. It pulls CO2 from the air and uses light to make sugars to grow. This is why locating the farm within the ocean gyres is so important. Seafields believe it will act like a giant whirlpool, keeping the floating sargassum within its limit."
[7:41] JA: "The gyre just stops the sargassum from escaping, so we can control it. Because the unique property of sargassum in particular is that it's free floating. So as long as we create the right conditions for it, it will grow. And it will only grow there. So if any escapes from our farm, it will just die off or just fail to continue growing. And all of the farm infrastructure can also be free floating."
[8:11] VS: "[Seaweeds] have enormous growth rates. They double their biomass every 10 days. And then at the fringes of the farm, we will be collecting the seaweed, compressing it into bales, treating it so that it becomes compact, solid seaweed. And these blocks could then be stored in the deep sea floor, which [...] is the largest area of the planet."
[8:32] JR: "This is how the carbon is eventually sequestered. The idea is the tightly wrapped bales of seaweed sink deep to the inert sea floor, where there's so little oxygen, they won't rot and where there are a few animals to nibble at it. But the seaweed will only get to its final resting place if the entire system works. If the pipes aren't willing nutrients from the deep function at scale. If the floating harvesters work. If the sargassum can weather Atlantic storms and remain within the confines of the slowly rotating gyres. That is a lot of ifs."
[9:46] JA: "Our belief is that the voluntary carbon market is going to explode over the next few years as more companies commit to going carbon neutral or some will even go as far as Microsoft and say we're going to scrub our past submissions as well. There's not many projects out there. There's only so much land to plant trees. And the technological solutions to things like direct air capture are so far away and so prohibitively expensive at the moment. We fail to see many solutions that can operate this sort of scale and produce this many carbon credits to meet the coming demand."