This Is CDR is an ongoing series of online events to explore the range of carbon dioxide removal solutions that are currently in development. Last week, we talked to Kelly Erhart and Tom Green of Project Vesta about using carbon-negative sand to sequester carbon dioxide in the ocean. This week, we’re going deeper – literally! – with Marty Odlin of Running Tide.
Where Project Vesta aims to do their work on the coasts, Running Tide will look further out in the ocean, using aquaculture to grow carbon-removing kelp microforests.
The process is quite elegant: cultivate kelp, which, like trees on land, absorbs atmospheric carbon dioxide as it grows. This kelp grows at the surface of the sea, where carbon dioxide is in equilibrium with the atmosphere. But when the kelp dies, it sinks to the bottom. Below 1,000 meters, the ocean’s horizontal layers don’t mix much. So if Running Tide can aim their kelp in the right place, it can drop to a quiet place on the bottom of the ocean and take its payload of carbon dioxide with it, where it will stay for 800 years.
Filling the oceans with kelp may sound like a disruptive operation, but Marty notes that the status quo only looks like the safe option. In fact, doing nothing will have massively disruptive results on human civilization and global ecosystems. Even a 1.5°C increase in global temperature will have disastrous effects all over the world, and on our current trajectory we’ll substantially exceed that. In Marty’s words, we need to reverse 150 years of fossil fuel use in 25 years. Even a “natural” solution will need to be deployed on an industrial scale.
But, urgency of the need aside, there’s also good news about the process itself: kelp forests have suffered terribly from human activity already, and ocean ecosystems need them badly. So Running Tide’s process would be feeding two birds at once, so to speak.
Running Tide’s plan also has an advantage over some other CDR solutions in that it could be very efficient. Any given CDR approach needs to balance the energy used with the carbon removed. Enhanced rock weathering needs energy to grind up rocks and transport them to the ocean; direct air capture needs energy to create chemical solvents and blow air across them. If we capture some CO2, but burn enough fossil fuel to release more in the process, we’re moving backwards. With kelp forestation, most of the required energy is provided by the sun and the sea, so it could be a very low-impact way to go.
That said, we shouldn’t make it sound too easy; Running Tide is doing a lot of data analysis on ocean currents to figure out the best places to grow kelp. And while the company waits for carbon markets to mature, it’s also building up knowledge, infrastructure, and funding in a surprising way. Let’s just say you can help fund future carbon removal and enjoy a tasty snack bar at the same time. Watch the video to find out more, and be sure to check back next week for more This Is CDR. Find the whole series on our resources page.