Science

To Fight Climate Change: Grow a Floating Forest, Then Sink It

I’m Teresa Carey, and this is Scientific American’s 60-Second Science.

“In a few weeks, these tanks will be full of little baby oysters, the size of a piece of quinoa. But right now, they’re still in the larval stage.”

Adam Baske strolls through a warehouse on the coast of Harpswell, Maine. Surrounding him are trays of oysters with water circulating between them in small tubes. In another room stands rows of eight-foot-tall tanks of algae growing at different stages. The algae will be food for the oysters. If you’ve never seen a shellfish hatchery, this one looks pretty typical. But it’s not. This year, they’re planning to harvest something new—atmospheric carbon.

His company, called Running Tide Technologies, plans to grow vast quantities of seaweed in drifting ocean mini-farms—farms that the company plans to sink to the bottom of the ocean.

“So this is basically taking the emissions of our fossil-fuel burning, locking them back up into the structure of the kelp and sending it back to the bottom of the ocean, where, you know, it’s at least locked up for hundreds to thousands of years because of the great pressure and the slow movement of the water in the deep ocean.”

Kelp, like other plants, uses photosynthesis to extract carbon dioxide from the atmosphere. Colette Feehan, a marine ecologist at Montclair State University, who does not work with Running Tide Technologies, says that kelp is a no-brainer when it comes to carbon sequestration. 

“The productivity of kelp forests has been found to be comparable to tropical rain forests, meaning that they put on a great deal of biomass, and that biomass is stored carbon.”

It can do this because it grows fast (about a foot per month). It also quickly sinks to the seafloor. Once there, it degrades very slowly.

Trees, on the other hand, store carbon but ultimately release it back to the atmosphere when they die and decompose. Kelp can stay effectively buried, its carbon entombed by the crushing pressure and lack of oxygen, for hundreds, maybe thousands of years. 

“As a climate change mitigation strategy, there’s mounting evidence that this is a good approach. These forests aren’t taking up land that would otherwise be used for agriculture or housing. So there’s really no negative side to growing kelp forests.”

How it works is that Running Tide Technologies hangs a kelp mini-farm tube from a biodegradable buoy, which they set adrift in the ocean currents. Over several months, the kelp absorbs carbon, growing longer and heavier until it sinks to the bottom, taking the stored carbon with it. They are still experimenting with buoy’s material—trying out glass, cellulose and other materials.

Baske is Running Tide Technologies head of business development. He says the project is still in its early stages, with about 1,600 buoys. This year they are focused on assessing the project’s impact—looking for problems like whale entanglement and evaluating the feasibility with sensors and trackers. In the future, they are aiming for millions of micro-farms, sponging up billions of tons of carbon, which they plan to sell in the carbon offset market.

“Some of the biggest companies in the world already have net-zero commitments—are hungry for permanent, verifiable carbon offsets. And that doesn’t mean they have net-zero emissions. It means they’re offsetting their emissions while they’re also reducing their emissions.”

Shopify, an e-commerce company for online stores, will be one of the first companies to buy carbon offsets from Running Tide Technologies.

“This can be one of the many solutions we need to employ to have a chance in this fight. You know, we need to mobilize the troops for this war. And if we don’t build the infrastructure and the knowledge base to give us a fighting chance, then we might as well give up now.”

Running Tide Technologies is drawing from the strong fishing tradition on the Maine coast—and casting a net for carbon.

“Very few people on the planet have an appreciation for the scale of our oceans: 70 percent of our planet. It’s just such an incomprehensible number, I think, for a lot of people. The opportunity to put that surface area to work in helping us solve the biggest challenge facing humanity—I can’t think of a more inspiring or motivating mission.”

Thanks for listening. For Scientific American’s 60-Second Science, I’m Teresa Carey.

—Teresa L, Carey

[The above text is a transcript of this podcast.]
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