Building with Mushrooms
We've heard all about how fungi work in their natural environment but one company, Ecovative Design have worked out how to use mushroom roots in packaging, building insulation and even surfboards. Hannah Critchlow spoke to Ecovative co-founder, Gavin McIntyre.
Hannah - So Gavin, plastic foam is used all over the world in packaging and so forth, but why do we need to come up with an alternative? What's the problem with using it?
Gavin - Well, the protective packaging foam that's used today which is predominantly made out of expanded polystyrene is a product that has a very short duration in terms of its use. But then when it comes to its disposal, has a life expectancy that'll exceed centuries. So, what we have done is we've generated a drop in replacement with a grown material that is 100% home compostable. It can be put in the backyard and passively return to the Earth.
Hannah - And I believe you've used mushrooms to help solve this problem with plastic packaging.
Gavin - That's correct because when you look at the ecosystem, mushrooms truly are nature's recyclers. But what we're really interested in is what's known as fungal mycelium which as you called earlier is similar to mushroom roots and this is what we leverage as a natural glue or adhesive in our process.
Hannah - We don't usually associate fungi with building materials, so what properties do mushrooms have that make them good for using in this kind of thing?
Gavin - The core characteristics that make our material fantastic for the construction industry is that first, they're class A firewalls. You can hit these materials with blowtorch and they really won't burn, unlike foam which will quickly proliferate a fire. They have the same insulation value, better water resistance actually because fungi, their construct is chitin, the same biopolymer you find in crab shells for example. And of course, they're incredibly strong which most of our products today are actually more durable and tougher than traditional plastic foams.
Hannah - But how are you then converting this and manufacturing it into the foam?
Gavin - So today, all of our raw materials are locally sourced agricultural by-products. Rather than being dependent upon finite resources such as fossil fuels, we source all of our raw materials from within 50 miles of our manufacturing facility. So, we're taking waste streams from farms, things like plant stocks, seed husks and seed hulls, and providing that in our process as a nutrition source for the fungus as well as basically a bulking agent.
Hannah - So, why does the fungus actually make this material stick together in this way?
Gavin - The way that the adhesion characteristic works with the fungus is that if you were to look at a microscopic scale, a lot of these plant materials do have some pores and the fungus itself in terms of its diameter, because these are small little filaments or fibres, individually known as hyphae, they can penetrate into the little pores of the plant material and actually bind it together. So, it's digesting part of the plant product. While actually, adhering or sticking itself to it and it's very similar to basically finding its way through a little maze and that maze is comprised entirely of farm waste.
Hannah - So, you're basically generating this big mushroom fungi farm in your local area. And then how do you kind of make this into the foam?
Gavin - We grow these materials to the final shape. We have these small growth enclosures where we mix a concoction of the farm waste and fungal mycelium tissue and it's very similar to concrete. We pour it into the tool and over the period of just 2 to 3 days, the fungal mycelium will grow, digest some of the farm waste, and bind the rest of it together. And the resultant product has the final shape of the original geometry that you want it. And of course, our final process is the drying or inactivation phase where we kill the fungus before it goes out the door. So, by the end of the process, you don't have to worry about it growing again and it's safe for shipment all around the world.
Hannah - How do you make sure that the mushrooms are definitely dead because we wouldn't want the mushroom to kind of spring to life again?
Gavin - Of course, and that's really critical, not as we ship domestically here in the United States, but as we ship internationally. We put our materials into a drying process that allows us to remove the water initially because this is a wet process, turgor pressure drives growth, similar to that of plants. So, if the materials are too dry, they won't grow. So first, we remove the remaining water and then we hit it with a very high temperature to ensure that the entire cross section of the product is thoroughly dead and we take measurements on petri dishes before our products go out the door to make sure they're no longer viable.
Hannah - And then once it's been used as packaging, how long does it take to actually then degrade this material? Are we then left with a problem that it's going to be around on the planet for a very long time?
Gavin - The product's final degradation is really dependent upon its environment. The only time the product will break down is if you put it in the soil. It has to be exposed to soil biota. So, other fungi or bacteria that are prevalent and found in the soil, produce the enzymes that are necessary to break down our material. But for example, if you were to leave it in a house, it can well withstand 30 plus years of use. And similarly, if this product were to be placed in the ocean, it will also degrade in about 90 days and that's because the fungus is comprised of chitin and chitin is very prevalent in crustaceans and other organisms that are found within the ocean.