Fungal future: a review of mycelium biocomposites as an ecological alternative insulation material

Abstract

Reducing the use of non-renewable resources is a key strategy for transition to circular economy. Mycelium is the vegetative part of fungus which can cement particulate substrate and can be formed into any shape if grown in a mould. Mycelium biocomposites (MBs) are rapidly being seen as green alternative for many hydrocarbon-based products, including Expanded Polystyrene (EPS) used for insulation in the construction industry. This is largely due to its comparable acoustic/insulative properties, superior fire safety and minimal environmental impact. Furthermore, as MBs can utilize low cost readily available commercial waste products such as wheat husks as a composite substrate, a clear value chain upscaling can be envisioned. Throughout its linear lifecycle, EPS insulation pose numerus environmental issues, including high resource use and challenges in its end of life disposal. Even if disposed correctly it can take thousands of years to degrade, evidently making it extremely difficult to properly contain. This has resulted in bioaccumulation of toxic chemicals in food webs across the planet. Conversely, MBs are biodegradable and importantly can be used as raw material for the production of more MBs. When comparing life cycle assessment (LCA) and production, MBs are estimated to hold clear advantages in terms of reduced CO2 out put and costs. It is thus clear it holds the potential to become an ideal candidate for a “cradle to cradle” economy, in this sector. Despite these attributes, MB insulation still have evident disadvantages when compared to their hydrocarbon counterparts and could hinder its adoption on a commercial scale. These include higher density and issues with water uptake. Furthermore, there can be wide variability in material performance on the basis of which substrate composition fungal strain, incubation conditions and manufacturing techniques are used. This coupled with the relatively sparse research in this field makes full assessments and comparisons between studies more difficult. New design approaches will also have to be considered when producing MB due to the additional factors of working with growing organisms. MB offers new degrees of freedom to the designer to create shapes and internal geometries yet only seen when using 3d-printing but at a price which potentially is suited for mass production low price products such as advanced packaging products and composite sandwich structures with tailor-made porous internal stiffening elements. Fully commercialised MB products have however begun to emerge. These still largely rely on costly labour-intensive manufacturing practices but present as an ideal target for optimization through factory atomisation. Integrating other emerging technologies such as 3D printing and computerised optimizations could also allow for controlled growth of internal structures of MBs. This would enable the creation of novel green materials with greatly improved performance characteristics which can be tailors to specific requirements. Ultimately furthering their viability as a green option to traditional EPS insulation.