In late January, Elon Musk tweeted that he planned to give $100 million to promising carbon removal technologies, stirring the hopes of researchers and entrepreneurs.

A few weeks later, Arin Crumley, a filmmaker who went on to develop electric skateboards, announced that a team was forming on Clubhouse, the audio app popular in Silicon Valley, to compete for a share of the Musk-funded XPrize.

A group of artists, designers, and engineers assembled there and discussed a variety of possible natural and technical means of sucking carbon dioxide out of the atmosphere. As the conversations continued and a core team coalesced, they formed a company, Pull To Refresh, and eventually settled on growing giant bladder kelp in the ocean.

So far, the venture’s main efforts include growing the seaweed in a tank and testing their control systems on a small fishing boat on a Northern California lake. But it’s already encouraging companies to “get in touch” if they’re interested in purchasing tons of sequestered CO2, as a way to balance out their greenhouse-gas emissions.

Crumley says that huge fleets of semi-autonomous vessels growing kelp could suck up around a trillion tons of carbon dioxide and store it away in the depths of the sea, effectively reversing climate change. “With a small amount of open ocean,” he says, “we can get back to preindustrial levels” of atmospheric carbon dioxide.

‘No one knows’

Numerous studies show the world may need to remove billions of tons of carbon dioxide a year from the atmosphere by midcentury to prevent dangerous levels of warming or bring the planet back from them. In addition, more and more corporations are scouring the market for carbon credits that allow them to offset their emissions and claim progress toward the goal of carbon neutrality.

All of that has spurred a growing number of companies, investors, and research groups to explore carbon removal approaches that range from planting trees to grinding up minerals to building giant C02-sucking factories.

Kelp has become an especially active area of inquiry and investment because there’s already an industry that cultivates it on a large scale—and the theoretical carbon removal potential is significant. An expert panel assembled by the Energy Futures Initiative estimated that kelp has the capacity to pull down about 1 billion to 10 billion tons of carbon dioxide per year.

But scientists are still grappling with fundamental questions about this approach. How much kelp can we grow? What will it take to ensure that most of the seaweed sinks to the bottom of the ocean? And how much of the carbon will stay there long enough to really help the climate?

In addition, no one knows what the ecological impact of depositing billions of tons of dead biomass on sea floor would be.

“We just have zero experience with perturbing the bottom of the ocean with that amount of carbon,” says Steven Davis, an associate professor at the University of California, Irvine, who is analyzing the economics of various uses of kelp. “I don’t think anybody has a great idea what it will mean to actively intervene in the system at that scale.”

The scientific unknowns, however, haven’t prevented some ventures from rushing ahead, making bold promises and aiming to sell carbon credits. If the practice doesn’t sequester as much carbon as claimed it could slow or overstate progress on climate change, as the companies buying those credits carry on emitting on the false promise that the oceans are balancing out that pollution, ton for ton.

“For the field as a whole, I think, having this research done by universities in partnership with government scientists and national labs would go a long way toward establishing a basic level of trust before we’re commercializing some of this stuff,” says Holly Buck, an assistant professor at the University at Buffalo, who is studying the social implications of ocean-based carbon removal.

The lure of the ocean

Swaying columns of giant kelp line the rocky shores of California’s Monterey Bay, providing habitat and hunting grounds for rockfish, sea otters, and urchins. The brown macroalgae draws on sunlight, carbon dioxide, and nutrients in the cool coastal waters to grow up to two feet a day. The forests continually shed their blades and fronds, and the seaweed can be knocked loose entirely by waves and storms.

In the late 1980s, researchers at the Monterey Bay Aquarium began a series of experiments to determine where all that seaweed ends up. They attached radio transmitters to large floating rafts of kelp and scanned the ocean depths with remote-operated submarines.

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By: James Temple
Title: Companies hoping to grow carbon-sucking kelp may be rushing ahead of the science
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Published Date: Sun, 19 Sep 2021 09:00:00 +0000