Warm Seaweed

December 3, 2023
By Damond Benningfield

701023_Warm Seaweed_360 px width.jpg

Alginate, which is derived from brown seaweeds like the one seen here, has been used to form beads that are very efficient at storing heat. Credit: Jonathan Wilkins, CC BY-SA 3.0.

Seaweed is useful stuff. Among other things, it provides habitat for fish, turtles, and other creatures.

It’s also used in a lot of products in the human realm: food, fertilizers, animal feed, medicines, thickeners for everything from toothpaste to ice cream, and many more. And there’s one new possible use: providing heat.

There are many varieties of seaweed. They can be up to hundreds of feet long. All of them are types of algae. They don’t grow in the ground. Instead, they anchor themselves to the sea floor, or they float in the water. They take their nutrients directly from the seawater.

Scientists in Great Britain recently developed a way to use seaweed to store heat: They formed it into beads just a fraction of an inch across.

The beads are made from a material called “alginate”—sugars extracted from some varieties of seaweed. It’s cheap, there’s a lot of it, and it’s non-toxic, so it’s easy to work with. And the beads wouldn’t contribute greenhouse gases to the air.

The scientists tested a couple of ways to process the alginate. Both methods yielded beads that are about four times more efficient at storing heat than similar beads made from other materials. The beads would absorb heat from the Sun or from industry, then release the heat when needed. They can store the heat indefinitely, so there’s no time limit.

The scientists were scheduled to test the beads at a steel mill in 2023—seeing if they’ve really found another application for useful seaweed.