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.
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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.