On the left, a Hermès bag made using fine mycelium as a leather alternative, made in partnership with the biotech company MycoWorks; on right, a sheet of mycelium "leather."
A natural material that looks and feels like real leather is taking the fashion world by storm. Scientists view mycelium—the vegetative part of a mushroom-producing fungus—as a planet-friendly alternative to animal hides and plastics.
Products crafted from this vegan leather are emerging, with others poised to hit the market soon. Among them are the Hermès Victoria bag, Lululemon's yoga accessories, Adidas' Stan Smith Mylo sneaker, and a Stella McCartney apparel collection.
The Adidas' Stan Smith Mylo concept sneaker, made in partnership with Bolt Threads, uses an alternative leather grown from mycelium; a commercial version is expected in the near future.
Adidas
Hermès has held presales on the new bag, says Philip Ross, co-founder and chief technology officer of MycoWorks, a San Francisco Bay area firm whose materials constituted the design. By year-end, Ross expects several more clients to debut mycelium-based merchandise. With "comparable qualities to luxury leather," mycelium can be molded to engineer "all the different verticals within fashion," he says, particularly footwear and accessories.
More than a half-dozen trailblazers are fine-tuning mycelium to create next-generation leather materials, according to the Material Innovation Initiative, a nonprofit advocating for animal-free materials in the fashion, automotive, and home-goods industries. These high-performance products can supersede items derived from leather, silk, down, fur, wool, and exotic skins, says A. Sydney Gladman, the institute's chief scientific officer.
That's only the beginning of mycelium's untapped prowess. "We expect to see an uptick in commercial leather alternative applications for mycelium-based materials as companies refine their R&D [research and development] and scale up," Gladman says, adding that "technological innovation and untapped natural materials have the potential to transform the materials industry and solve the enormous environmental challenges it faces."
In fewer than 10 days in indoor agricultural farms, "we grow large slabs of mycelium that are many feet wide and long. We are not confined to the shape or geometry of an animal."
Reducing our carbon footprint becomes possible because mycelium can flourish in indoor farms, using agricultural waste as feedstock and emitting inherently low greenhouse gas emissions. Carbon dioxide is the primary greenhouse gas. "We often think that when plant tissues like wood rot, that they go from something to nothing," says Jonathan Schilling, professor of plant and microbial biology at the University of Minnesota and a member of MycoWorks' Scientific Advisory Board.
But that assumption doesn't hold true for all carbon in plant tissues. When the fungi dominating the decomposition of plants fulfill their function, they transform a large portion of carbon into fungal biomass, Schilling says. That, in turn, ends up in the soil, with mycelium forming a network underneath that traps the carbon.
Unlike the large amounts of fossil fuels needed to produce styrofoam, leather and plastic, less fuel-intensive processing is involved in creating similar materials with a fungal organism. While some fungi consist of a single cell, others are multicellular and develop as very fine threadlike structures. A mass of them collectively forms a "mycelium" that can be either loose and low density or tightly packed and high density. "When these fungi grow at extremely high density," Schilling explains, "they can take on the feel of a solid material such as styrofoam, leather or even plastic."
Tunable and supple in the cultivation process, mycelium is also reliably sturdy in composition. "We believe that mycelium has some unique attributes that differentiate it from plastic-based and animal-derived products," says Gavin McIntyre, who co-founded Ecovative Design, an upstate New York-based biomaterials company, in 2007 with the goal of displacing some environmentally burdensome materials and making "a meaningful impact on our planet."
After inventing a type of mushroom-based packaging for all sorts of goods, in 2013 the firm ventured into manufacturing mycelium that can be adapted for textiles, he says, because mushrooms are "nature's recycling system."
The company aims for its material—which is "so tough and tenacious" that it doesn't require any plastic add-on as reinforcement—to be generally accessible from a pricing standpoint and not confined to a luxury space. The cost, McIntyre says, would approach that of bovine leather, not the more upscale varieties of lamb and goat skins.
Already, production has taken off by leaps and bounds. In fewer than 10 days in indoor agricultural farms, "we grow large slabs of mycelium that are many feet wide and long," he says. "We are not confined to the shape or geometry of an animal," so there's a much lower scrap rate.
Decreasing the scrap rate is a major selling point. "Our customers can order the pieces to the way that they want them, and there is almost no waste in the processing," explains Ross of MycoWorks. "We can make ours thinner or thicker," depending on a client's specific needs. Growing materials locally also results in a reduction in transportation, shipping, and other supply chain costs, he says.
Yet another advantage to making things out of mycelium is its biodegradability at the end of an item's lifecycle. When a pair of old sneakers lands in a compost pile or landfill, it decomposes thanks to microbial processes that, once again, involve fungi. "It is cool to think that the same organism used to create a product can also be what recycles it, perhaps building something else useful in the same act," says biologist Schilling. That amounts to "more than a nice business model—it is a window into how sustainability works in nature."
A product can be called "sustainable" if it's biodegradable, leaves a minimal carbon footprint during production, and is also profitable, says Preeti Arya, an assistant professor at the Fashion Institute of Technology in New York City and faculty adviser to a student club of the American Association of Textile Chemists and Colorists.
On the opposite end of the spectrum, products composed of petroleum-based polymers don't biodegrade—they break down into smaller pieces or even particles. These remnants pollute landfills, oceans, and rivers, contaminating edible fish and eventually contributing to the growth of benign and cancerous tumors in humans, Arya says.
Commending the steps a few designers have taken toward bringing more environmentally conscious merchandise to consumers, she says, "I'm glad that they took the initiative because others also will try to be part of this competition toward sustainability." And consumers will take notice. "The more people become aware, the more these brands will start acting on it."
A further shift toward mycelium-based products has the capability to reap tremendous environmental dividends, says Drew Endy, associate chair of bioengineering at Stanford University and president of the BioBricks Foundation, which focuses on biotechnology in the public interest.
The continued development of "leather surrogates on a scaled and sustainable basis will provide the greatest benefit to the greatest number of people, in perpetuity," Endy says. "Transitioning the production of leather goods from a process that involves the industrial-scale slaughter of vertebrate mammals to a process that instead uses renewable fungal-based manufacturing will be more just."
With conventional fuel cells as their model, researchers learned to use similar chemical reactions to make a fuel from microbes in pee.
Plus, urine contains water, phosphorus, potassium and nitrogen, the key ingredients plants need to grow and survive. Human urine could replace about 25 percent of current nitrogen and phosphorous fertilizers worldwide and could save water for gardens and crops. The average U.S. resident flushes a toilet bowl containing only pee and paper about six to seven times a day, which adds up to about 3,500 gallons of water down per year. Plus cows in the U.S. produce 231 gallons of the stuff each year.
Pee power
A conventional fuel cell uses chemical reactions to produce energy, as electrons move from one electrode to another to power a lightbulb or phone. Ioannis Ieropoulos, a professor and chair of Environmental Engineering at the University of Southampton in England, realized the same type of reaction could be used to make a fuel from microbes in pee.
Bacterial species like Shewanella oneidensis and Pseudomonas aeruginosa can consume carbon and other nutrients in urine and pop out electrons as a result of their digestion. In a microbial fuel cell, one electrode is covered in microbes, immersed in urine and kept away from oxygen. Another electrode is in contact with oxygen. When the microbes feed on nutrients, they produce the electrons that flow through the circuit from one electrod to another to combine with oxygen on the other side. As long as the microbes have fresh pee to chomp on, electrons keep flowing. And after the microbes are done with the pee, it can be used as fertilizer.
These microbes are easily found in wastewater treatment plants, ponds, lakes, rivers or soil. Keeping them alive is the easy part, says Ieropoulos. Once the cells start producing stable power, his group sequences the microbes and keeps using them.
Like many promising technologies, scaling these devices for mass consumption won’t be easy, says Kevin Orner, a civil engineering professor at West Virginia University. But it’s moving in the right direction. Ieropoulos’s device has shrunk from the size of about three packs of cards to a large glue stick. It looks and works much like a AAA battery and produce about the same power. By itself, the device can barely power a light bulb, but when stacked together, they can do much more—just like photovoltaic cells in solar panels. His lab has produced 1760 fuel cells stacked together, and with manufacturing support, there’s no theoretical ceiling, he says.
Although pure urine produces the most power, Ieropoulos’s devices also work with the mixed liquids of the wastewater treatment plants, so they can be retrofit into urban wastewater utilities.
This image shows how the pee-powered system works. Pee feeds bacteria in the stack of fuel cells (1), which give off electrons (2) stored in parallel cylindrical cells (3). These cells are connected to a voltage regulator (4), which smooths out the electrical signal to ensure consistent power to the LED strips lighting the toilet.
Courtesy Ioannis Ieropoulos
Key to the long-term success of any urine reclamation effort, says Orner, is avoiding what he calls “parachute engineering”—when well-meaning scientists solve a problem with novel tech and then abandon it. “The way around that is to have either the need come from the community or to have an organization in a community that is committed to seeing a project operate and maintained,” he says.
Success with urine reclamation also depends on the economy. “If energy prices are low, it may not make sense to recover energy,” says Orner. “But right now, fertilizer prices worldwide are generally pretty high, so it may make sense to recover fertilizer and nutrients.” There are obstacles, too, such as few incentives for builders to incorporate urine recycling into new construction. And any hiccups like leaks or waste seepage will cost builders money and reputation. Right now, Orner says, the risks are just too high.
Despite the challenges, Ieropoulos envisions a future in which urine is passed through microbial fuel cells at wastewater treatment plants, retrofitted septic tanks, and building basements, and is then delivered to businesses to use as agricultural fertilizers. Although pure urine produces the most power, Ieropoulos’s devices also work with the mixed liquids of the wastewater treatment plants, so they can be retrofitted into urban wastewater utilities where they can make electricity from the effluent. And unlike solar cells, which are a common target of theft in some areas, nobody wants to steal a bunch of pee.
When Ieropoulos’s team returned to wrap up their pilot project 18 months later, the school’s director begged them to leave the fuel cells in place—because they made a major difference in students’ lives. “We replaced it with a substantial photovoltaic panel,” says Ieropoulos, They couldn’t leave the units forever, he explained, because of intellectual property reasons—their funders worried about theft of both the technology and the idea. But the photovoltaic replacement could be stolen, too, leaving the girls in the dark.
The story repeated itself at another school, in Nairobi, Kenya, as well as in an informal settlement in Durban, South Africa. Each time, Ieropoulos vowed to return. Though the pandemic has delayed his promise, he is resolute about continuing his work—it is a moral and legal obligation. “We've made a commitment to ourselves and to the pupils,” he says. “That's why we need to go back.”
Urine as fertilizer
Modern day industrial systems perpetuate the broken cycle of nutrients. When plants grow, they use up nutrients the soil. We eat the plans and excrete some of the nutrients we pass them into rivers and oceans. As a result, farmers must keep fertilizing the fields while our waste keeps fertilizing the waterways, where the algae, overfertilized with nitrogen, phosphorous and other nutrients grows out of control, sucking up oxygen that other marine species need to live. Few global communities remain untouched by the related challenges this broken chain create: insufficient clean water, food, and energy, and too much human and animal waste.
The Rich Earth Institute in Vermont runs a community-wide urine nutrient recovery program, which collects urine from homes and businesses, transports it for processing, and then supplies it as fertilizer to local farms.
One solution to this broken cycle is reclaiming urine and returning it back to the land. The Rich Earth Institute in Vermont is one of several organizations around the world working to divert and save urine for agricultural use. “The urine produced by an adult in one day contains enough fertilizer to grow all the wheat in one loaf of bread,” states their website.
Notably, while urine is not entirely sterile, it tends to harbor fewer pathogens than feces. That’s largely because urine has less organic matter and therefore less food for pathogens to feed on, but also because the urinary tract and the bladder have built-in antimicrobial defenses that kill many germs. In fact, the Rich Earth Institute says it’s safe to put your own urine onto crops grown for home consumption. Nonetheless, you’ll want to dilute it first because pee usually has too much nitrogen and can cause “fertilizer burn” if applied straight without dilution. Other projects to turn urine into fertilizer are in progress in Niger, South Africa, Kenya, Ethiopia, Sweden, Switzerland, The Netherlands, Australia, and France.
Eleven years ago, the Institute started a program that collects urine from homes and businesses, transports it for processing, and then supplies it as fertilizer to local farms. By 2021, the program included 180 donors producing over 12,000 gallons of urine each year. This urine is helping to fertilize hay fields at four partnering farms. Orner, the West Virginia professor, sees it as a success story. “They've shown how you can do this right--implementing it at a community level scale."
