Waste seaweed finds use as insulation


March 8, 2013

Washed up dead seaweed known as Neptune balls is being converted into building insulation

Washed up dead seaweed known as Neptune balls is being converted into building insulation

If you live near the Mediterranean Sea, you might be familiar with little balls of seaweed that regularly wash up on the beach. These come from the Posidonia oceanica plant (better known as Neptune grass), and are generally thought of as a nuisance. Now, however, Germany’s Fraunhofer Institute for Chemical Technology is involved in a project that’s converting the little balls into high-quality building insulation.

Besides being plentiful, renewable and not wanted for anything else, the dead seaweed is reportedly mold-resistant, almost completely non-flammable, won’t rot, and doesn’t require the addition of any other compounds – good news for people who are chemically-sensitive. It can also absorb water vapor and release it again, without compromising its own insulation value.

Converting the “Neptune balls” into a more easily-applicable form of insulation proved to be challenging, however. In its rolled-up form, the seaweed harbors a lot of sand, and its fibers tend to catch on things, causing the balls to clump together.

Mechanically shaking the seaweed seems to do the trick. It causes the clumped-together balls to separate, and the sand to fall out. After being shaken, the Neptune balls travel down a conveyor belt and are cut up. As a result, the seaweed is no longer in ball form, but instead consists of loose non-clumping 1.5- to 2-centimeter (0.6 to 0.8-inch) long fibers. The whole process is said to require relatively little energy.

The fibers can be stored and transported in plastic bags, and then blown and/or hand-packed into attics or walls like other types of insulation. The loose material has an energy value of 2.502 joules per kilogram kelvin, which Fraunhofer claims is 20 percent higher than that of wood-based insulation. There are also plans to make it available in sheet form.

The Neptune balls are currently being harvested by hand and imported to Germany from Tunisia and Albania. The insulation is being produced and marketed under the name of NeptuTherm, by a company of the same name.

Source: Fraunhofer

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Finally, a feedback loop that works in mankind's favor.

Humans burning carbon to heat houses -> seaweeds grow like crazy clogging up the oceans -> humans use seaweeds to insulate houses, until -> no more carbon is needed to heat houses!


Can anybody figure out what the R value per inch is?


Hi there, here in Ibiza this has been used in traditional houses since many years, and as the island is full of artist, is also used by them, an example of one of the artist living in Ibiza:

Ibizart Guide

From a marine biologist's perspective, just a technical point, Posidonia is a sea grass not a seaweed. Sea grass beds in many parts of the world are a threatened habitat. I'm not sure this makes any real ecological sense.


Seaweed has been used in houses as insulation here in Nova Scotia for at least 100 years.

Colin Fox

Let's hope that neptune grass is not habitat for some organism that an endangered species eats. :-) I wonder if some sand-cleaning machines I have seen on the beach in the USA could be modified to harvest the neptune grass.

Bruce H. Anderson

The Posidonia Oceanica oxygenates water, protects the beaches from erosion and is habitat for lots and lots of organisms! It grew up very very slowly. Please do not harvest them!!!! And worst, with some industrial cleaning machines.

Anne de Harlez

Make use of natural products, is almost never an ecological attitude.


More jobs & income for Greece, Italy & Spain for sure & Turkey.

Stephen Russell

As shrimpfish pointed out, Posidonia is a seagrass, not seaweed. There's a big difference!

About seaweeds... Only a few species of seaweeds (more correctly called macroalgae) are in fact weeds and work in the way that BeWalt describes - clogging up the ocean and resulting in adverse ecological and human health consequences. Seaweeds are integral components of marine ecosystems, and underpin coastal (and even abyssal!) marine foodwebs.

Seagrasses on the other hands are true plants, like land plants - i.e. they are angiosperms. They also form part of marine food webs, but are not always as readily consumed as the macroalgae for various reasons (some megaherbivores do graze them directly, however). Species like Posidonia are very important for habitat creation, providing a substratum for colonisation of algal epiphytes, and enabling the consolidation of marine sediments.

Sorry to get fussy about seaweeds vs. seagrasses, but from ecological and evolutionary perspectives they are vastly different.

Those "neptune balls" form because of lignin and cellulose fibres, a characteristic of seagrasses (and other angiosperms) but not of seaweeds.

Kind regards! AJ (Cynical phycologist)


How well does this stuff burn? Would a house insulated with it go up like a torch?

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