How urban waste is being transformed into gourmet mushrooms

In the unlikely setting of a former Danish kebab factory, trash is being turned into treasure. Since 2016, Beyond Coffee has been using spent coffee grounds to foster a fungi-forward circular business model.

As it turns out, the discarded grounds provide a great growing medium for oyster mushrooms. So, Beyond collects containers full of the stuff from canteens around the city. The grounds are bagged, mixed with mushroom spores, and placed in the company’s treasury: four upcycled 40-feet freight containers with humidifiers saturating the air with the earthy smell of forest floor. The ambition is to turn as much urban waste as possible into value and to demonstrate how a circular food business can work in an urban environment, explains director Ebbe Korsgaard.

“Our aim is to keep waste streams in the city,” says Korsgaard, standing in one of the humid containers, surrounded by the spoils – or spores, rather – of his efforts. “Being in the city reduces transportation to a minimum.” Not only is the farm located close to the waste from which it produces, it’s also close to their end customers, namely local restaurants. “Being close to them also ensures that we can deliver the freshness and quality that they demand.”

Fungi exist all around us – without them there’d be no sourdough bread or kimchi – so when it comes to mushroom farming, avoiding contamination from other fungi is crucial. However, growing oyster mushrooms in coffee is relatively easy, even at home. According to Korsgaard, the coffee brewing process pasteurises the grounds to some extent, in other words killing the bacteria. After inoculation with the mushroom mycelium, usually colonised on grains, all our crop needs is a clean, humid space with a temperature between 20-24 degrees celsius for around two weeks before mushrooming magic sets in.

Across the world, fungi are having a moment with urban mushroom farms popping up from New York City to Rotterdam and, yes, Copenhagen. Since its inception, Beyond Coffee has been joined by other eager farmers intent on showing that urban mushroom production is a hyperlocal, sustainable venture that can put some of a city’s waste to good use.

In recent years, mushrooms have also gained impor stance when it comes to healing the mind. Researchers like David Erritzøe, at Imperial College in London, have demonstrated promising results in trials with psychedelic mushrooms for the treatment of depression. In November last year, pharmaceutical company Compass Pathways presented top-line results in a phase II clinical trial involving psilocybin for treatment-resistant depression. Almost a third of participants showed clinically relevant reductions in depression symptoms after three weeks.

Psychedelic mushrooms are also gaining traction in the mainstream, from micro-dosing tech bros in Silicon Valley to Gwyneth Paltrow, who in late 2019 sent her Goop employees on a psychedelic mushroom retreat in Jamaica. A Netf lix TV crew documented the experience.

At Beyond, there are no psychedelic mushrooms in the growing containers. Not yet. Instead, coffee grounds are getting a new, tasty lease of life. Korsgaard explains that when brewing coffee, only 0.2 percent of the beans’ nutritional value goes into the cup. The rest goes in the bin. The British Coffee Association estimates that two billion cups of coffee are consumed around the world every day. This creates an enormous amount of waste, but it inspired Beyond Coffee founders Tobias Lau and Thomas Harttung to change the cycle.

Every week, two tons of coffee grounds are collected. The 100 square metres of container grow space allows for around 800 kilos of fresh mushrooms a month. Just enough to make it worthwhile, says Korsgaard. His company has now managed to squeeze four extra containers into the space, which will soon double production and coffee waste collection. He believes in the value of this venture, despite knowing full well that the containers occupy space in one of the world’s most expensive capitals.

“We’re creating value from waste, and in our opinion, eight kilos of fresh mushrooms per square metre, every month of the year, is making good use of the space available,” he says. “Especially once production doubles.” It makes ecological and culinary sense. While meat is on retreat, mushrooms, with their rich umami flavour, are attracting the attention of chefs as an alternative to beef. Renowned Danish restaurant Noma just released a commercial mushroom garum from their fermentation lab, and while it sold out in an instant, the liquid seasoning was intended to show people how you can cook meatless meals with immense depth of flavour.

That’s exactly what Jason Renwick wants to do. The chef-restaurateur runs three vegan restaurants in Copenhagen, including fine dining spot Ark. Here, mushrooms are the ‘meat’ on the menu. Last year, the need for a steady supply of high-quality mushrooms made him go into business with Funga Farm, an urban farm spearheaded by self-taught mushroom entrepreneur Thomas Kyle Cometta, who grows rare varieties like blue oyster, coral teeth and the aptly named lion’s mane. It all takes place in a basement in Copenhagen’s bohemian Nordvest quarter.

A Brazilian jiu jitsu master and teacher, Cometta left his dojo in Berkeley in 2015 and relocated with his Danish girlfriend to Copenhagen to pursue a master’s degree in forest management. But when the in-laws took him on a mushroom foraging trip north of the city, fungi pulled him in another direction. “It blew me away. I started nerding out, researching online and reading books about mycology, and I found out how ignorant I’d been about mushrooms,” he says. “I thought wild mushrooms were dangerous. But the thought that you literally have this wild gourmet food growing everywhere really got me excited.”

It took a few years before Cometta finally quit school in 2019 to work with mushrooms full-time. Unlike Beyond Coffee, Funga Farm doesn’t grow in coffee grounds, but they still make use of waste from other industries. They create their own substrate for the mushrooms to grow in by mixing pelletised beech sawdust left over from lumbering and sawmills with alfalfa and wheat bran – a byproduct from the milling of flour.

Cometta prefers growing on wood because of the taste. “In the forest, the mushrooms break down wood,” he says. “We wanted to emulate their natural environment as much as possible, and wood is nutritionally dense, which really makes a difference in terms of taste in the final product. Small guys like us cannot compete in quantity, so we have to compete on quality.”

After Covid lockdowns, demand for Cometta’s product has surged, and he is now looking to expand to a larger location elsewhere in the city. He believes mushrooms are the perfect crop for an urban environment. “First of all, mushrooms don’t need sunlight or vast fields to grow in. Secondly, we want to reduce transport and be close to where our customers are,” he says.

Another entrepreneur arguing that urban farming is a great use of city space is Lasse Antoni Carlsen. After working with sustainable urban ecosystems for the past 10 years, Carlsen co-founded Bygaard (city-farm), situated at Copenhagen’s Refshaleøen, a former industrial area where workshops and warehouses are now home to startups and renowned restaurants such as Amass and Alchemist.

At Bygaard, Carlsen produces speciality mushrooms like nameko and pioppino in eight freight containers, situated right between the two restaurants. Noma, one of his customers, is just down the road. “Cities and food production are not necessarily opposites,” he argues. “Back in the day, the cities used to have lots of production. Limited space will always be an issue, but the mushrooms are stacked on shelves, which means we can grow one and a half tonnes of mushrooms a week in a very limited space.” He adds that since the containers are “modular and moveable,” they can be reconfigured at will, stacked way up high if needed.

As a small-scale farmer, Carlsen wants to be a part of a move towards a sustainable and regenerative production system. The farm is already a reality; the last part of the dream is a machine that will allow him to produce his own substrate from the city’s waste products. The substrate he uses now is organic and upcycled. However, it is imported from Germany, conflicting somewhat with his sustainable vision.

“Our goal has always been to upcycle some of the city’s organic waste. But as we set up during the pandemic, we needed to get a foothold and a financially sustainable business before taking the next step,” he says. Still, when it comes to Danish mushroom farming, one man’s trash is another man’s treasure or, perhaps more aptly, the world is their oyster mushroom.