Swapping some of the sand in concrete for spent coffee grounds could increase the strength of concrete by nearly 30%, a new study suggests.
A whopping 2 billion cups of coffee are consumed globally every day, according to the British Coffee Association. But most of the coffee grounds end up in landfills, where the waste slowly decomposes to produce methane, a greenhouse gas 21 times more potent than carbon dioxide, according to the new study.
Researchers in Australia may have found an efficient recycling solution for all this coffee waste: using it to replace some of the sand in concrete. The construction industry usually mines sand from rivers, lakes and deltas, so swapping out this important sediment could also protect habitats across the world, the team said. The concrete partially made of coffee grounds is also stronger than traditional concrete, they found.
It’s actually a biochar from spent coffee grounds. Biochar is a process of slow burn in a low oxygen environment.
So 1: it doesn’t resemble coffee by the time it’s put in. Closer to charcoal. Cute jokes about how nice the concrete will smell are fun, but off base.
And 2: Coffee probably isn’t the only base you could use for the biochar. It makes for a cute fuzzy headline that people love to share but it could prove more effective and economical in the end to make a biochar out of lentil chaff or something else. We need to see this put into practice at scale before we have any idea if gathering up coffee grounds from cafes to make concrete makes sense at all.
You seem to know what to do. I’m sending you my coffee grounds. Godspeed.
I’ll happily compost them.
Especially when coffee grounds are a wonderful addition to compost, and help the breakdown of the rest of the material.
Large scale composting of all organic material (or even small scale, really) is much more efficient and impactful than trying to collect only coffee grounds for this purpose.