Efficient energy storage is crucial for the successful transition to a low-carbon, green economy. As we continue to adopt renewable energy sources, finding efficient methods to store and distribute this energy is essential, especially in ways that support net-zero greenhouse gas emissions.1
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Resource scarcity poses another challenge in advancing energy storage technology. The extraction of lithium and other materials for manufacturing traditional batteries significantly damages the ecosystem, underscoring the need to explore sustainable alternatives.
As renewable energy's share in the energy mix increases, challenges emerge within the national electricity grid.2 In this regard, naturally occurring compounds are proving to be an effective solution. Mycelium—the fungal filaments found beneath mushroom caps—is being researched and utilized for energy storage applications worldwide.
Exploring the Properties of Fungal Filaments
The applications of fungi have been a significant focus of research. Mycelium, composed of thin, thread-like structures called hyphae, has garnered considerable interest.3
Mycelium possesses distinctive and advantageous properties that make it an intriguing prospect for energy storage solutions. Its extensive network of thread-like fungal structures provides a large surface area for interaction with other materials, which could be crucial for energy storage applications.
Mycelium is naturally occurring and biodegradable, making it an environmentally friendly alternative that minimizes the release of harmful toxins. Certain fungi can also grow and form intricate structures, suggesting potential applications in the creation of biobatteries.
Sustainable Energy Storage Innovations
Mycelium-Based Superconductors: A Sustainable Energy Storage Source
Carbons are crucial in materials science as essential components of energy storage systems. Filamentous fungi show great potential as templates for producing carbon networks, although this area remains relatively unexplored.
Carbons derived from fungal mycelium demonstrate higher electrical conductivities compared to other types of carbonized fungal biomass.4 The cyclic voltammetry (CV) profiles of A. bisporus and P. eryngii carbons show intrinsic electrical resistance.
Despite their lower electrical conductivity, the carbons extracted from fungal filaments exhibit significantly higher specific capacitance than other carbons. The specific capacitance of P. eryngii and A. bisporus carbons is considered moderate for supercapacitor applications, surpassing values obtained for non-activated bacterial cellulose-derived carbon and even those associated with activated pyrolyzed bacterial cellulose.4
Applications of Fungal Filaments in Fuel Cells
Fungal fuel cells (FFCs) provide a versatile and innovative approach to tackling global challenges by meeting the growing need for alternative bioenergy production amidst population growth and expanding industrial activities.
FFCs utilize biodegradable waste materials to generate power during the treatment of contaminated surfaces. They function by harnessing oxidation-reduction reactions in anodic and cathodic regions, which occur through a network of microbial and electrochemical pathways.
Fungal mycelia grow either on the surface of the anode or within the anodic chamber, where they release their degradative and fermentative enzymes. Fungal degradation is well-known for its ability to treat water pollutants by consuming various substrates.
Yeast cells play a role in metabolizing hazardous compounds in water. When combined with fungi, algae are excellent for FCs to produce electricity. Protons move from yeast to algae and are transported through microporous tubes embedded in the active bleached earth, also known as the "ion exchange medium," to generate electricity.
How are Fungi Used in Batteries for Energy Storage?
Myceliotronics, the latest advancement in biodegradable electronic components, utilizes mushrooms to create battery parts. The mycelium skin from a tree fungus serves as a base layer for flexible circuit boards, as well as the casing and separator for a zinc-carbon battery.5
The mycelium skin is useful not only as a base for eco-friendly electronic circuits; thanks to its porous structure, it can absorb significant amounts of liquid, making it an excellent option for sustainable battery separators.
Currently, commercial Li-ion batteries typically rely on polyolefin polymer separators, which are derived from nonrenewable petroleum products and are costly and environmentally unfriendly.
Mycelium skin separators offer a greener alternative since they can be naturally grown and require minimal resources, even when compared to paper-based materials.6
Challenges and Future Prospects in Fungal Filament Energy Storage
Although scientists are exploring the integration of fungal filaments in energy storage applications, numerous challenges must be addressed to enhance the functionality and efficiency of this biotechnology.
Even the most advanced mycelium-based energy storage systems have a lower energy density than conventional lithium-ion batteries. Scaling up fungal growth for large-scale energy storage applications also requires extensive optimization of cultivation methods.
Consistency and control over growth patterns are essential for ensuring reliable performance. Integrating fungal filaments into existing battery designs on a large scale also poses significant technical challenges.
Further research is needed to understand how fungal materials interact with electrolytes and other components, which will facilitate their rapid commercialization. With advancements in sustainable manufacturing, fungal filaments are poised to become a significant part of modern energy storage systems.
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References and Further Reading
[1] Deloitte. (2024). Energy storage: Total supply chain Challenges and factors that influence investments. [Online] Deloitte. Available at: https://www2.deloitte.com/nl/nl/pages/energy-resources-industrials/articles/energy-storage-total-supply-chain.html (Accessed on 13 April 2024)
[2] Deloitte. (2024). Energy storage: Navigating challenges and opportunities - An overview of the energy storage landscape. [Online] Deloitte. Available at: https://www2.deloitte.com/nl/nl/pages/energy-resources-industrials/articles/energy-storage-overview.html (Accessed on 13 April 2024)
[3] Johnston, E., et al. (2023). Mycelium: Exploring the hidden dimension of fungi. [Online] Kew. Available at: https://www.kew.org/read-and-watch/fungi-hidden-dimension
(Accessed on 13 April 2024)
[4] Jones, M. et al. (2024). Fungal Carbon: A Cost‐Effective Tunable Network Template for Creating Supercapacitors. Global Challenges. doi.org/10.1002/gch2.202300315
[5] Kramer, K., et al. (2022). A recipe for biodegradable mushroom batteries. [Online] ChemistryWorld. Available at: https://www.chemistryworld.com/news/a-recipe-for-biodegradable-mushroom-batteries/4016529.article (Accessed on 14 April 2024)
[6] Danninger, D., et al. (2022). MycelioTronics: Fungal mycelium skin for sustainable electronics. Science Advances. doi.org/10.1126/sciadv.add7118
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