Seaweed: The New Ethanol?

Caroline Delbert
Photo credit: Richard Green

From Popular Mechanics

  • Remote seaweed farms with autonomous drones for workers could be the future of bioenergy.
  • Algae and seaweed are plentiful, already grown on farms, and almost ready for their energy moment.
  • Seaweed is the vernacular word for the largest kinds of algae, known as macroalgae.

Is seaweed the next energy frontier on which humans can rely? The Advanced Research Projects Agency—Energy (ARPA-E) and a program called Macroalgae Research Inspiring Novel Energy Resources (MARINER) are exploring how giant seaweed farms could make biomass for renewable energy.

The concept has a long way to go before it’s real, but proponents say it could be a better, cleaner, and larger-scale replacement for resource-intensive ethanol and other existing biomass sources.

What would an ocean dotted with massive seaweed farms look like? Well, scientists and engineers would have a tough task to design structurally sound and practical farms that could be sustained in the remote, faraway parts of the oceans. Without a good solution for facilities where workers could live, these giant farms would have to be as independent or even autonomous as possible.

Seaweed farms go back hundreds of years and include the kind used for sushi along with many others. Scientists discovered iodine while processing seaweed. And seaweed is really just an extremely large alga—in fact, seaweeds are also called macroalgae. Until now, seaweed farms have been smaller, closer to shore, and almost exclusively for food.

The overall goal of huge offshore seaweed farms is to provide biomass to be used to generate bioenergy. Scientific American says these farms will cycle huge pallets of seaweed from the surface to underwater and back each day to make sure the seaweed is getting enough nutrients. This alone requires a new kind of farm machinery that could be made into an autonomous drone.

The seaweed farms would also be responsive to weather threats and other hazards, like a living thing retreating underwater for protection from the tumultuous surface. The MARINER program in particular is made of dozens of different organizations and private companies making different parts of the entire idea of giant seaweed farms, from the autonomous farm drones to the way they’ll be attached to the ocean floor.

Indeed, rather than building the farms themselves, MARINER is making the best tools with which to start building the farms. With larger scale and more remote farms, all the current uses for seaweed could expand to make up a much larger portion of each of those markets. And those uses go way beyond just renewable biomass energy: “Presently, macroalgae, or seaweed, is primarily used as food for human consumption, but there is a growing opportunity for the production of macroalgae for use as feedstock for fuels and chemicals, as well as animal feed,” MARINER’s site explains.

Instead of water-hogging, fertilizer-drenched land biofuel crops, the future of biomass could be under the sea. And while the long-term goals include far-out farms with few human touches, in the short term, farmers everywhere from Alaska down to the Gulf Coast could join a growing group that farms seaweed just off U.S. coasts. The only remaining obstacle is, well, developing the best way to turn the seaweed into usable fuels.

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