A curious thing happens when you enter your 40s. Once the main signs were an increase of grey hairs and wrinkles, the inability to hear sounds above 15,000 hertz, and making involuntary noises when standing up. Now, thanks to the wonders of targeted advertising, I am reminded that I have entered a different demographic by a marked change in what social media is trying to sell me.
All of a sudden, I am too old for body weight fitness, mindfulness apps, and sports betting. Instead, I am apparently the target market for artisan olive oil (I suppose someone has to be), magazine subscriptions for kids, and, for some reason, fungi.
It started with mushroom powder, promising focus, concentration, and a slew of other questionable benefits that I would more readily associate with prescription medicine. Then came mushroom brew, threatening to take all of the enjoyment out of tea and coffee and, worse still, all of the caffeine.
But one product that did catch my eye was artificial leather. This is something I’ve long been interested in; I have wallets and belts made from cork, for instance. I discovered that last year, lifelong vegetarian Stella McCartney launched a new bag made from mycelium leather. Mycelium is the underground network of threads that make up most of a fungus body, and so the visible mushroom is essentially fruit to the mycelium’s tree.
Because of its physical characteristics, mycelium can be used to bind a filler. In this case, a fungus derived from hot springs in Yellowstone is mixed with sugar cane waste to make a flexible, durable leather substitute. Other products have seen mycelium mixed with agricultural waste to form insulation panels, bricks, and even walls.
The technical case is credible. Mycelium composites can be lightweight, fire-resistant and naturally insulating. Since fungi will grow on almost anything, they can be produced using low energy inputs and degrade without leaving microplastics.
The difficulty has always been the scale demanded by industry. Construction materials must meet strict building standards and be available in large and consistent volumes. Given the defective block crisis, we are understandably cautious in certifying new building fabrics. Producing large amounts of mycelium at the uniformity required for structural use remains challenging. This means that the impressive architectural pieces like the Sunflower Sound System at Glastonbury, a mycelium-insulated dance tent, are still proofs of concept rather than commercially ready solutions.
Even if it isn’t quite ready for the construction industry, mycelium does offer a promising opportunity at a smaller scale. The properties that make it excellent for producing insulation panels mimic those of expanded or extruded polystyrene, and so it can potentially replace it in packaging. Polystyrene is lightweight, cheap, but extremely difficult to recycle economically, making it one of the most persistent forms of plastic waste.
In Ireland, only about 30 per cent of plastic packaging waste was recycled in 2023, leaving 250,000 tonnes unrecycled and triggering €200 million in EU Plastics Own Resource levies. That is the equivalent of filling 100 Olympic-sized swimming pools with discarded plastic packaging each year.
Protective packaging needs to be mouldable, shock absorbent, and light. Polystyrene obviously meets those needs, but so can mycelium. A start-up based in Cork, Ecoroots, grows mycelium on agricultural byproducts such as spent grain from whiskey distilleries. The fungus binds the organic substrate into a rigid, mouldable bio-foam that can replace expanded polystyrene in protective packaging for sectors such as cosmetics, beverages, and pharmaceuticals.
Irish whiskey production generates 350,000 tonnes of spent grain annually. When this material is landfilled, each tonne can emit roughly 513kg of CO2e (greenhouse gases measured as carbon dioxide equivalent). Converting that waste stream into packaging feedstock simultaneously diverts organic waste and displaces fossil-derived foam. Some substrates even enable net carbon sequestration during growth. The company also operates a closed-loop production model using waste heat and rainwater to produce a fully compostable product.
The EU Single-Use Plastics Directive has already banned expanded polystyrene food and beverage containers. The forthcoming Packaging and Packaging Waste Regulation will require all packaging placed on the EU market to be recyclable by 2030, alongside a 5 per cent overall waste reduction target.
At the same time, Corporate Sustainability Reporting Directive (CSRD) requirements are increasing pressure on manufacturers to evidence Scope 3 emissions reductions (emissions from raw materials bought in) and material circularity.
Of course, polystyrene has already survived one seemingly fatal challenge when the 1987 Montreal Protocol banned the chlorofluorocarbons (CFCs) used to create it. But economics favoured its reformulation, and expanded polystyrene persists because it is cheap, standardised, and deeply embedded in global logistics chains. The challenge for mycelium, and regulators, is for the alternatives to make financial sense.
Stuart Mathieson is research manager with InterTradeIreland