How coffee grounds are being repurposed

A few years ago, Australian roasters Single O determined that spent coffee grounds accounted for more than 20 per cent of its carbon emissions. The number shocked CEO Mike Brabant.

“This is impactful because coffee grounds produce off-gas methane which is about 30 times more harmful than carbon dioxide,” he says. “With nearly 75,000 tonnes of coffee grounds ending up in landfills across Australia each year, we knew we had to make a change.”

It’s estimated Australian landfill is made up of 3 per cent spent coffee grounds. But innovations are helping to reduce the amount, from circular economy waste management to a construction industry development that may also improve the sustainability of concrete production.

To rectify the carbon emissions from its coffee waste, Single O partnered with local composting services Org and Mallow Sustainability. The business also collects coffee chaff from its production and transports it to Soil Co, a Wollongong-based composter. “This is currently about 25 bins per week, which equates to over 7,000 kilograms of coffee chaff per year,” says Brabant.

Expanding on the mission, Single O partnered with Reground in 2022 to allow its Victorian clients to have their spent grounds collected. Reground is a social enterprise helping companies and individuals to create a circular economy through waste collection and minimisation.

“To date, this has resulted in almost 30,000 kilos of grounds diverted, avoiding over 55,000 kilos in greenhouse gas emissions or [over] 815,000 lattes’ worth. This means that instead of contributing to methane emissions, our spent grounds are turned into compost, enriching local gardens and ecosystems.”

Single O aims to halve carbon emissions by 2026 and achieve Net Zero by 2030. “We’ll keep innovating and exploring new ways to reduce our environmental impact,” says Brabant.

While small, eco-focussed businesses like Single O are making progress, coffee waste in Australia is a large-scale problem that requires matching solutions. For researchers at RMIT University, turning spent coffee grounds into biochar for concrete production may provide a solution to the landfill issue, while also reducing the demand on natural resources needed to make concrete.

“This is an opportunity to reduce the amount of material that goes into landfill and commit to the circular economy,” says BildGroup Chief Executive Officer Stephen Hill. “So as part of that initiative, five tonnes of used coffee granules have been diverted into a product called biochar.”

To create the biochar, spent coffee grounds are roasted in a pyrolysis unit without oxygen at 350 degrees Celsius. The biochar coffee replaces a portion of the sand in concrete, which is an essential component of concrete. While many modern processes require sand – including glass-making, solar panels, computer chips, and sand-casting – concrete is its principal user.

In 2019, the BBC reported that “the demand for that material is so intense that around the world, riverbeds and beaches are being stripped bare, and farmlands and forests torn up to get at the precious grains”.

“[Coffee concrete is] a solution that can reduce the amount of waste going into landfill, it can reduce emissions, and it reduces our reliance on natural resources,” says MRPV Senior Project Engineer Kristian Horana.

Major Road Projects Victoria (MRPV) and project contractor BildGroup used concrete mixed with biochar made from spent coffee grounds in the Pakenham Roads Upgrade. It follows the world-first successful trial of coffee concrete in a Gisborne, Victoria footpath earlier this year.  

While the industry is still on the road to a fully circular coffee economy, it certainly is one that is paved with good intentions. And soon, it might also be paved with coffee.

Images: Single O and Pete Glenane, HiVis Pictures

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