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From coffee grounds to gourmet

June 1, 2017

Volunteers turn coffee grounds into delicious mushrooms
Coffee grounds and oyster mushrooms are not within Solar’s normal area of activity. So when a group of young Danish entrepreneurs needed help with their fun and sustainable idea, we said yes to contribute to this somewhat different project.

Picture a colourful freight container with graffiti decorations at a deserted port. Then imagine the piercing sound of an angle grinder, leading you to Esben Vestergård Pedersen, who is working on turning three old freight containers into sustainable shops that will be open to visitors all through the summer.

- We collect the coffee grounds from cafés and restaurants in the city of Aarhus. We graft it with fungal spores, and three weeks later, we can reap fresh oyster mushrooms from the coffee grounds, which would otherwise have just ended up in the trash, he explains.

Using heat pumps to create different climates
Each of the three freight containers must provide a different climate to help the mushrooms grow. I this connection, Solar provided heat pumps, installation equipment as well as the tubes the mushrooms will grow on. – I got an email from Esben describing his idea. It wasn’t exactly related to any of Solar’s usual activities, but the idea behind the project just appealed to me – and, of course, we’re all for sustainability, says Climate and Energy Product Manager Rasmus H. Vemmelund, Solar.

Photo: Julie Kristensen /

In the first container, the coffee grounds are mixed with glumes and lime and bagged. Afterwards, the bags are hung in the next container, which is completely dark and 20-25 degrees Celsius. – the third container is where the magic happens, this is where the mushrooms pop out of the bags, Esben Vestergård Pedersen explains.

The third container has light but is a bit colder than the others, as it should lead the mushrooms to think that winter is coming and it’s the last chance for them to come out. – Within 10 days, they’ll be big enough to harvest. Then, we wait another 10 days for them to come out again. When harvested, we’ll sell the mushrooms to the restaurants and cafés from which we got the coffee grounds. This way, everything is recycled, Esben Vestergård Pedersen says.

Grow your own mushrooms at home

If you ever come by the shop on the port of Aarhus, you will be able to buy your own mushroom kit, so that you can grow mushrooms in your kitchen at home using your own used coffee grounds.

”We don’t make a living solely on standard tasks, we also make a living on being creative and innovative, and this project is indeed creative and innovative! So we definitely wanted to give them our support,” says Rasmus H. Vemmelund of Solar.

Get more information about the sustainable project on the group's facebook page

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