Phykos Testing Robotic Seaweed Farms

A startup named Phykos is on a mission to sequester one gigaton of carbon per year safely in the deep ocean — for generations to come. As reported by Adele Peters in Fast Company, a prototype of a small, solar-powered robotic vessel recently started sailing in the Pacific Ocean, pulling an underwater rack filled with seaweed. Phykos says each platform holding the fast-growing kelp may be able to capture as much CO2 as 250 trees — and though the approach still needs to be proven, the company thinks that it could be a viable way to quickly sequester carbon by sinking the seaweed to the ocean floor.

The tech is modular: with the units that float on the surface, each the size of a small boat, and the lines of kelp underneath roughly the size of a single-family house. After seaweed “starts” from nurseries are planted on the lines, the vessels navigate out to the open ocean. Software on each vessel is designed to steer toward the best areas for growth, moving throughout the year, and automatically avoid areas like shipping lanes. Then it will harvest itself. “The seaweeds will grow and periodically get a haircut, so to speak, with an integrated harvest clipper mechanism,” says Nico Julian, who co-founded Phykos with Jeff Zerger.

Unlike some types of kelp that float — picture the seaweed along California coastlines, which has small, round air-filled pockets to keep it near the surface — the company plans to work with species that naturally sink. A scale built into the platform will weigh the seaweed after each harvest to help calculate how much carbon has been captured.

Seaweed farming near the shore isn’t new, but the startup’s approach is different. “It’s a really challenging robotics problem,” says Marius Wiggert, a PhD researcher at the University of California, Berkeley, who is one of a team of researchers collaborating with the company. The device has to be able to navigate through unpredictable waves and wind and to operate on its own for multiple years. Because it’s becoming harder for seaweed to grow as the ocean warms, it will have to be able to navigate to cooler areas. (The system may be able to help make up some of the gap in sequestration that has occurred as naturally-grown seaweed has been declining.) The vessels can also navigate to particular areas to deposit the seaweed underwater.

The company, which just completed a stint at the tech accelerator Y Combinator, is still developing the technology. But they expect that the cost will be “probably on the lower end of the cost spectrum,” compared to other carbon removal technology, Mr. Julian says.