• Your morning coffee can deliver more than a caffeine hit. (Getty images)
You’ll never look at your coffee the same way again.
By
Yasmin Noone

27 Feb 2018 - 11:58 PM  UPDATED 28 Feb 2018 - 8:42 AM

We’ve got some sad news for all the well-intentioned, eco-friendly coffee drinkers out there who sip from a KeepCup and only buy sustainably sourced coffee beans. You may not be doing enough to prevent coffee-related products ending up in landfill.

Around six million tonnes of spent ground coffee (what’s leftover when a coffee bean is ground and discarded) makes it to landfills around the world every year. That volume is pretty much equal to the capacity of Great Pyramid of Giza in Egypt, and the figure doesn’t even include other coffee-waste items like the natural by-products of coffee: the coffee berry or unused seeds.

In the City of Sydney alone, 2016 estimates suggest that over 920 cafes and coffee shops in the area sold around 100 million cups of coffee in one year, which produced 3,000 tonnes of waste coffee grounds. Planet Ark says 93 per cent of this waste in the city currently goes to landfill, as few retailers know what to do with spent ground coffee.

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But there’s another serious consequence of spent ground-coffee ending up in landfill. A new study, co-authored by RMIT University food technology scientist Dr Tien Huynh shows that ground coffee waste is comprised of tannins, caffeine and chlorogenic acid, which can be “lethal to all organisms” in high doses.

Around six million tonnes of spent ground coffee (what’s leftover when a coffee bean is ground and discarded) makes it to landfills around the world every year. That volume is pretty much equal to the capacity of Great Pyramid of Giza in Egypt.

“Imagine if you drink one coffee, you feel okay,” says Dr Huynh. “If you have 10 coffees, you will feel hyperactive and be almost bouncing off the walls. What about if you had six million tonnes?

“So then, think about what would happen to plants and animals that fed off the waste. This amount of coffee waste in landfill has major effects – including death – on [land and sea] from mice to fish and fungi.​”

“If we are all drinking coffee and throwing the waste by-product away – which goes to landfill – when it starts to break down, it will become quite toxic. It could make us all very sick. We are contributing to that situation and we don’t see it. But if we implement steps to fix this situation, then we can drink coffee without the guilt.”

Upcycling possibilities

The good news is that we can either recycle or upcycle coffee waste to prevent it from going to landfill.

Planet Ark says studies have shown that spent coffee grounds can be used to help your mushrooms grow and work best on oyster mushrooms.

In London, wasted coffee grounds are currently being used to power the city’s buses. The initiative, announced last year, upcycles coffee waste to create a kind of biofuel, coffee oil, that can be placed in select London buses without modification.

“If you have 10 coffees, you will feel hyperactive and be almost bouncing off the walls. What about if you had six million tonnes? So then, think about what would happen to plants and animals that fed off the waste."

“In Australia, we haven’t done anything as mind-blowing with coffee waste, but we are starting to see some coffee shops give away coffee grounds to consumers for free. It’s a great initiative,” says Dr Huynh. 

“The best way that people can use spent coffee grounds at home is to compost the spent coffee beans – put it out in the sun for almost a month and allow microorganisms to break it down. Then use it in a worm farm, as worms can survive acidic environments. The worms break down the coffee and then you can use it on plants.”

Dr Huynh says she uses the spent coffee grounds from a RMIT University café (which she gets in exchange for fresh parsley) for research purposes, so her team can investigate alternative uses.

From next month, she’ll also be leading a research trip to Vietnam, which will see students investigate whether coffee waste can be used to create building materials or a brain-health supplement.

The coffee lover also recommends that Australian councils adopt coffee waste recycling plans and consider developing better infrastructure and incentives for collection. For example, she says, the introduction of a four-bin system of waste collection – one for landfill, another for recycling, one for garbage and a separate bin for coffee waste – would see households and industries recycling coffee waste.

“If I was Goddess of the universe, that is what I would do," she says. “I’d also want the people who drink the coffee to be more aware of coffee waste. They can still drink their coffee without guilt, but they should start thinking about the ways they can help reduce coffee waste – as we all have a part to play.”

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