Off the coast of Catalina Island near Los Angeles, a prototype of a new “kelp elevator”–a long tube with seaweed growing on it that can be moved up and down in the water to access sunlight and nutrients–will soon begin tests.
If the study works as hoped, the startup behind it, Marine BioEnergy, wants to use similar technology, driven by robotic submarines, to begin farming large tracts of the open ocean between California and Hawaii. Then it plans to harvest the kelp and convert it into carbon-neutral biocrude that could be used to make gasoline or jet fuel.
“In order to grow that much kelp, you really have to move outside the normal range of where kelp is found, which is along the coast.” [Photo: David Ginsburg]“We think we can make fuel at a price that’s competitive with the fossil fuel that’s in use today,” says Cindy Wilcox, who cofounded Marine BioEnergy with her husband Brian Wilcox, who manages space robotics technology in his day job at NASA’s Jet Propulsion Laboratory at California Institute of Technology.
Other biofuels, such as ethanol made from plant waste on corn fields, have struggled to become commercially viable, particularly after oil prices crashed. Solazyme, a company that planned to make biofuel from algae (and predicted in 2009 that it would be cost-competitive with fossil fuels within two or three years), ended up pivoting to make food products under the name TerraVia, and has now declared bankruptcy.
“You’re going to need a lot of kelp in order to make it cost-competitive with something like coal, fossil fuels, or natural gas.” [Image: Evan Ackerman/IEEE Spectrum]Kelp might have a chance of faring better. Unlike plants on land, it has little lignin or cellulose, fibers that make processing more difficult and expensive. In the right conditions, it can grow more than a foot a day, without the need for the irrigation or pesticides that might be used on land.
A key to the company’s concept is farming in the open ocean, where there is room to grow vast quantities of kelp. “You’re going to need a lot of kelp in order to make it cost-competitive with something like coal, fossil fuels, or natural gas,” says Diane Kim, a scientist at the University of Southern California’s Wrigley Institute for Environmental Studies, which is helping run the proof-of-concept study of Marine BioEnergy’s technology at Catalina. “In order to grow that much kelp, you really have to move outside the normal range of where kelp is found, which is along the coast.”
Kelp doesn’t typically grow in the open ocean since it needs both sunlight found near the surface of the water and nutrients that are found near the ocean floor (it also needs to anchor itself to something). In the 1970s, during the oil embargo, the U.S. Navy began investigating the possibility of farming kelp in the open ocean, pumping deep ocean water filled with nutrients to kelp anchored near the surface. But anchors often failed in ocean currents, and after the embargo ended, government interest faded.
“Here’s the right feedstock, and we just aren’t using it.” [Image: Evan Ackerman/IEEE Spectrum]In shallow coastal waters, where kelp naturally has access to both sunlight and nutrients, it’s a challenge to grow the seaweed at scale. Attempts to cultivate kelp gardens for food only have succeeded in relatively small areas.
But Brian Wilcox, who happens to be the son of the researcher who led the early work with the Navy, believed that kelp farming in the open ocean still might be possible. “My husband just kept thinking about this–here’s the right feedstock, and we just aren’t using it,” says Cindy Wilcox. He began considering a new approach: moving kelp up and down in a process he calls depth cycling, which gives the kelp access to both the nutrient-rich deep water and the light near the surface.
In 2015, Marine BioEnergy got a grant from the U.S. Department of Energy’s ARPA-E to test the proof of concept that is now in early stages with the Wrigley Institute researchers. Long lines stretch in a net-like pattern in the water, with kelp attached; the the kelp can be raised in a saltwater nursery on land where it is seeded into twine, and then later can be tied to the floating farm. At the end of the farm, underwater drones can pull the whole system up and down, both to maximize growth and to avoid ship traffic or storms near the surface. When the kelp is ready for harvest, the drones can tow the farm to a nearby ship.
The startup is also working with Pacific Northwest National Laboratory, which has developed a process to convert kelp to biocrude. The team is evaluating whether it’s more economic to make the crude on a ship–the processing center could fit on a container ship, powered by the processes’ own fuel–or to bring the harvested kelp back to land.
The resulting fuel should be carbon neutral, because the carbon dioxide released when the fuel is burned will equal the carbon dioxide taken in by the kelp as it grows. Still, some argue that biofuels are not an ideal choice for powering transportation. Mark Jacobson, a Stanford University professor who has calculated that it’s feasible to get all energy needs from wind, hydropower, and solar, says that a car running on renewable electricity makes more sense than a car running on biofuel.
“I believe liquid biofuels for transportation (or any other combustion purpose) are a bad idea because they still require combustion, resulting in air pollution, which using electricity generated from clean, renewable sources for transportation avoids,” Jacobson says.
But air transportation is unlikely to run on electricity anytime soon, and–despite some predictions about the rapid demise of gas cars–biofuel could serve a practical purpose in the near term. The kelp biocrude, which could be processed at existing refineries, could also be used to make plastics that are typically made from fossil fuels.
The first step is proving that the kelp can grow and thrive as it’s pulled up and down. “Part of this project for the next two years is to really figure out, using the depth cycling strategy, if it works at all, and what are the parameters,” says Kim. “Theoretically, it should work.”
If the proof of concept is successful, Marine BioEnergy wants to go big: To cover 10% of the transportation fuel needs in the U.S., they’ll have to have enough kelp farms to cover an area of the Pacific roughly the size of Utah.
