Home compostable plastic made of spirulina

Researchers at the University of Washington, US, developed a new type of biodegradable plastics made of spirulina that can be composted in your backyard.

Biobased plastics are becoming more common, but they are not all compostable, certainly not in backyard composting conditions, or even biodegradable (read more here).

The new plastic was designed to degrade on the same timescale as a banana peel in a backyard compost bin. The bioplastic is made entirely from powdered blue-green cyanobacteria cells, otherwise known as spirulina. The team used heat and pressure to form the spirulina powder into various shapes, the same processing technique used to create conventional plastics. The bioplastics have mechanical properties that are comparable to single-use, petroleum-derived plastics.

Spirulina is commonly available as it is used in various food and cosmetics products. In addition, the spirulina cells sequester carbon as they grow, so the plastic is carbon neutral or even carbon negative. Finally, spirulina has unique fire resistant properties, as it instantly self-extinguishes when it comes into contact with fire, unlike traditional plastics that combust or melt.

For now, the team still has to tweak the recipe a bit, as the material is fairly brittle, if strong, and sensitive to water.

Photos: Mark Stone/University of Washington