Maine company with big plans for using seaweed to soak up carbon draws scrutiny

Adam Baske, business development manager for Portland's Running Tide Technologies, holds a tube wrapped in early-stage kelp in 2020. Entwined with biodegradable rope, the kelp will grow in the sea off Scarborough and once full-grown, sunk to the ocean bottom. (Fred Bever/Maine Public)
Adam Baske, business development manager for Portland's Running Tide Technologies, holds a tube wrapped in early-stage kelp in 2020. Entwined with biodegradable rope, the kelp will grow in the sea off Scarborough and once full-grown, sunk to the ocean bottom. (Fred Bever/Maine Public)

A Portland startup that aims to remove millions of tons of planet-warming carbon from the air and store it deep in the ocean is going international. Running Tide is expanding its footprint to Iceland, but its ambitious plans are also drawing scrutiny.

Running Tide founder Marty Odlin has a big idea about how to fight climate change: millions of seaweed farms. Little ones, suspended from biodegradable buoys floating free in the north Atlantic.

He's testing out baseball-size buoys in the company's waterfront headquarters, where they bob around in a wave machine.

"It's a wave pool that accelerates wave action that we would see in the open ocean," he says.

The wood-fiber buoys are coated with limestone dust that could help the ocean safely absorb more carbon-dioxide. And they'd carry small rafts of seaweed that would grow and photosynthesize, absorbing more carbon.

Over time these "microfarms" would sink to the deepest ocean floor, to stay there for millennia.

Outside, Odlin points to a jumbo jet flying overhead.

"That's an industry built around releasing carbon into the atmosphere. If we want to bring that carbon back down, we need to operate at that scale," he says.

Big-name investors have committed to buying carbon-dioxide removal credits from the company, whose value one venture-capital tracker pegs at $14 million. Its plans have received positive attention from CNN and The Atlantic. But an article published last month in the MIT Technology Review was more critical. Some scientists are also skeptical.

"We've never tried to have an invasion of near-shore marine life into the open ocean. So we need to think carefully about this," says Philip Boyd, a professor of Marine Biogeochemistry at the University of Tasmania.

Boyd and other scientists say that while each microfarm Running Tide floats might be small, an enormous number would be required to make a real dent in climate change — with complex and potentially harmful effects on ocean ecosystems.

Boyd questions whether the seaweed rafts might compete with open-ocean plankton for nutrients, introduce harmful microbes or filter the light available for deep-sea life.

"And you know, our conclusions are not saying 'don't do it'; our conclusions are saying, 'this looks like it's more complex than you're probably currently envisaging.' So you need to be extra diligent,'" says Boyd.

CEO Marty Odlin says his staff of more than 60 is determined to get it right, gradually deploying larger and larger sets of rafts — responding to the data and analyses with each iteration. They're also working with a panel of outside scientific advisers from a research collective called "Ocean Visions."

Those include Jim Barry, a deep-sea ecologist at the Monterey Bay Aquarium Research Institute.

"You know, they're trying to do something that's difficult, in general," Barry says.

Barry says Running Tide has been responsive to the group's concerns about upending ocean ecosystems. With novel carbon-removal companies springing up around the world, he says there are tough choices ahead over how to balance environmental degradation against the threat of global warming.

"I think we need to think about these things and Running Tide is doing that. Maybe I'm not sure if their approach is the best one but at least they're moving ahead with it," Barry says.

And even sympathetic observers like Barry worry that the financing needed to design and deploy the new technologies could become a distraction.

"The carbon market for this is going to happen. I worry that groups like Running Tide might be, in a sense, chained to their funding source and they're conflicted because they want to do the right thing but at the same time they're trying to make money off of it. There's some difficult choices there," Barry says.

Nan Ransohoff is Head of Climate at Stripe, a software company which so far has committed a half million dollars to Running Tide. She's also the leader of a $925 million carbon-removal initiative funded by her company and other dot-com heavyweights.

"There are open questions for Running Tide and for most of the other companies that we are funding, and that is what we expect," she says.

"I think we should expect rapid iteration, especially for companies that are in their infancy ... We're pretty risk-tolerant at the beginning when there's small scale."

She says Stripe will buy another half million dollars worth of Running Tide credits only if it can produce data on ecosystem effects and verifiable CO2 removal.

Odlin says Running Tide has already engineered unique data recorders that will provide the real-world information on ecosystem effects and carbon removal that scientists and funders alike want to see.

"We were the first people to grow kelp in the open ocean and measure it. It was a tremendous amount of computing power to put into something so small and operating remote thousands of miles from shore," Odlin says.

The Icelandic government likes what it's seeing so far. This month it granted Running Tide a four-year permit to release up to 50,000 tons of biodegradable rafts off Iceland's coast, with the understanding that up to 450,000 tons more could be released in international waters. The permit requires the company to share its data with the government.

This story is a production of New England News Collaborative. It was originally published by Maine Public.



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