Debris continues to collect on the U.S. Pacific coast from last year’s Japanese tsunami. Onlookers are surprised by the amount of Styrofoam and foam insulation. In fact, these materials accounted for over half (by volume) of the 2 tons of tsunami detritus collected along 2 miles of Alaskan coastline.
This wave of pollution illustrates why there is widespread interest in biodegradable alternatives to petroleum- based plastics. One recent development in this area is a material called EcoCradle. Developed by Ecovative Design LLC, Green Island, N.Y., the material replaces synthetic, petroleum-based foams such as expanded polypropylene (EPP), expanded polyethylene (EPE), and expanded polystyrene (EPS). Containing fungus rather than petroleum, EcoCradle isn’t so much manufactured as it is grown.
Start at the root
EcoCradle begins as a combination of living fungi and agriculture waste. The fungi — called mycelium, or mushroom roots — is mixed with inedible and unusable agricultural by-products such as seed hulls or seed husks from staples like rice or oats.
Ecovative grows and forms the material by first cleaning the agricultural waste, mixing it with mycelium, and pouring it into plastic molds. Over the course of five days and without light or water, the mycelium digests some of the waste particles and binds to the others. Every cubic inch of the mixture contains a matrix of 8 miles of mycelial fibers. These tiny fibers let the mixture grow in tight corners of the mold.
After material is released from the mold, it gets dehydrated and steam-heat treated to stop it from growing and to eliminate the formation of spores. (A spore is a reproductive structure of fungus which can continue growing and cause allergens.) The result is a brownish-white piece of material that works like polystyrene.
Ecovative modifies the weight, density, texture, and strength of EcoCradle simply by blending different ratios and types of agricultural waste. The company has fine-tuned the mixture to yield a material that weighs around 2.5 lb/ft3. Traditional synthetic foams weigh between 1 to 3 lb/ft3.
Mushrooms sound expensive
The cost of EcoCradle is competitive with the cost of synthetic expanded foams and can even be less expensive at times. Synthetic foams depend on finite resources like petroleum. EcoCradle can be made from different types of agriculture waste which lets the company switch out ingredients. For example, oat hull will work if there is a price constraint on rice hull.The growing and forming of EcoCradle entails no complex machinery and requires less energy than manufacturing synthetic foams. In fact, its fabrication process consumes one-tenth the energy used to make foam packaging.
Ecovative is trying to improve that number to one-fortieth by working on a new energy-efficient sterilization treatment to replace steam-heating. The treatment is said to use natural oils from cinnamon bark, thyme, oregano, and lemongrass.
EcoCradle can be composted, mulched, or simply thrown away because the material is 100% biodegradable. Depending on temperature, moisture, and biological activity, the material breaks down over the course of four to 12 weeks in a healthy, active compost. The material breaks down faster when broken into smaller pieces and thrown in a compost heap ranging from 100 to 140°F.
Though you can eat the material, Ecovative believes its technology is better suited for applications other than food. The material can replace parts of furniture such as the structural cores found in tabletops. Or, it can serve as a sustainable alternative to seating foams. The material is inherently fire retardant, which alone is a breakthrough in the seating-foam industry as concern continues to build over the use of toxic fire retardants.
Ecovative has used the material as insulation in a number of commercial and residential buildings. The company is also developing a mushroom material capable of absorbing and dissipating energy for use in vehicle door panels and bumpers.
This summer, packaging giant Sealed Air Corp., Elmwood Park, N.J., licensed the technology for protective applications in North America. Sealed Air is known for its packaging brands such as Bubble Wrap cushioning and Cryovac food packaging. The company is already seeing widespread use for the material. Sealed Air Product Manager Tim McInerney says, “Thus far, we have seen a demand in white goods, automotive, and lighting. Additionally, electronics, such as computerdisplay monitors, are a perfect fit due to the antistatic properties of the packaging.”
The future of mushrooms
When mushrooms are grown with conductive copper solution, the mushroom works like a circuit.In an effort to reduce the toxic waste associated with the disposal of electronics, Ecovative plans to use its expertise with living fungus to create reusable circuits. In a recent TEDx talk, Ecovative cofounder Gavin McIntyre describes studying the natural formation of mushrooms around toxins as a way to develop a reusable circuit.
Research started with an abandoned open-pit copper mine in Montana called the Berkeley Pit, which spans one mile long by half a mile wide. A natural spring lls the pit with about 900 of water laden with heavy metals and dangerous chemicals that leach from rock. Mushrooms form around the Berkeley Pit because fungi grow naturally around metal toxins. They grow around metal toxins because the mycelium within the fungi contain complex proteins that bind to surrounding materials and store toxins within their cell walls. When fungi grow on materials without the presence of a metallic solution, toxins are stored outside their cell walls, producing excess spores.
To replicate the model of storing toxins within cell walls, Ecovative grew fungi on potato media in a solution with a heightened concentration of copper. The fungi did not produce spores, but more importantly, 80% of the metal ions in the solution were absorbed and stored within the cell walls. This amount of metal within the cell walls makes the fungi highly conductive.
Standard mycelium is composed of chitin, a biopolymer found in fungi and on arthropods like crabs. Chitin acts as a natural electrical insulator. An electric charge cannot travel across this insulative material by itself, thus copper solution is introduced to create conductivity. The combination of the insulative and conductive properties within the fungi combine to make a biological circuit.
Ecovative creates biological circuits by mimicking and scaling this discovery. The team makes a copperfilled solution and mixes mycelium with agricultural waste. The waste serves as the nutrition source to grow the conductive fungal tissue. Scientists and chemists dry out the tissue and use proprietary methods to make the brittle tissue more elastic. Elasticity is needed so the tissue can be cut and etched to make a circuit pattern. The etched tissue can now connect to an LED and a battery pack to make the first mushroom ashlight.
Circuits at the end of their life can reenter Ecovative’s fermentation process. The mycelium becomes nutrition for more mycelium and the copper passes along to become the conductive agent in a new circuit.