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Grounds for Concern: Weird and Wonderful Uses for Coffee Grounds

Coffee is the second most traded commodity in the world (after oil) and the second most popular drink in the world (after water). In the UK, sales have grown steadily by 10% per year and it’s a popular way for countless busy workers to start their day.

However, one downside of coffee’s incredible popularity is the huge volumes of waste coffee grounds that are left behind. Half a million tonnes per year in the UK alone – which are often sent to landfill. As the coffee grounds decompose in the airless conditions of landfill, they give off harmful greenhouse gasses.

Just like your morning cup can help you rise to the challenges of the day, some innovative companies have risen to the challenge of reusing or recycling waste coffee grounds. Here are five companies giving them a new lease of life:

1. Food for Mushrooms

Coffee grounds are rich in nutrients and therefore make an excellent food source for mushrooms. You can grow your own mushrooms in your own spent coffee grounds but it’s quite tricky. Many amateur growers accidentally end up with nothing more than mouldy coffee grounds instead.

For an easier and more reliable introduction to mushroom growing, the not-for-profit enterprise GroCycle makes “grow-your-own” oyster mushroom kits. All you have to do is cut an opening in the bag of coffee grounds, soak it in water and keep the mushrooms moist as they grow.

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I’ve used a GroCycle kit and it’s great fun to watch the mushrooms grow from tiny dots to large clusters. It’s a great one to introduce kids (and adults) to growing at home, and the mushrooms are delicious – and not at all coffee-flavoured! Despite being much more reliable than the DIY approach, the kits aren’t entirely foolproof as they can sometimes become infested with flies. If this happens, all is not lost as you can just compost the coffee grounds – flies and all.

2. Coffee as a Biofuel

Coffee grounds give off a lot of energy when burned, so they are a promising fuel source.

London start-up bio-bean collects waste grounds from instant coffee factories, offices and cafés across the country and converts them into more convenient pellets and “logs”, which are burned to heat buildings.

The factory can process up to 10% of the UK’s coffee ground waste. Not only does this reduce fossil fuel use (as the coffee logs are burnt instead), but it means a smaller amount of coffee grounds are sent to landfill, and methane emissions are also reduced.

Coffee grounds contain a lot of oil prior to being turned into solid fuel. It’s bio-bean’s aim to capitalise on this through the development of a bio-diesel in the future.

3. Turning Coffee into Ink

Domestic Stencilworks, a small screen printing studio in California, claims to be the only printer in the world to print designs on clothes using ink made from coffee grounds.

The grounds are mixed with vinegar and heated to form a thick, gloopy liquid. Having invested four years in discovering how to make the perfect durable ink, Domestic Stencilworks isn’t giving away all of the secrets of the process. You can let them do all the hard work though, and order online!

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4. 3D Printing Coffee

Printing is no longer limited to two dimensions. The range of materials that can be used to for 3D printing is quite astonishing – glass, precious metals, even ice cream!

Now we can add coffee to the list of printable materials. 3Dom USA and c2renew worked together to devise a mixture of plastic and coffee grounds that can be used by many standard 3D printers. Alas, the material is not safe to use with hot liquids. The world is not quite ready for its first 3D printed coffee cup just yet (contrary to some suggestions in the media), but maybe one day…

5. Turning Coffee Grounds into Coffee Cups

Those hoping for a coffee-based coffee cup may take heart from Kaffeeform’s initiative (you can set their homepage to English language in the bottom right hand corner). The company gathers coffee grounds from cafés in Berlin, mixes them with wood particles and natural resins and moulds them into lightweight, washable, mildly coffee-scented cups and saucers. It takes the grounds from six cups of espresso to make one cup and saucer. The circular economy at its finest!

With so many ways of recycling coffee grounds there are fewer and fewer reasons to send them off to landfill. Perhaps as awareness of these alternative uses grows, cafés and entrepreneurs will create more value from this resource instead of letting it go to waste.

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