Resource Use

Breakthrough sees new technique for turning coffee waste into biofuel

Researchers at Lancaster University say they have developed a method to significantly improve the efficiency of producing biodiesel from coffee waste.

The research team, led by Dr Vesna Najdanovic-Visak, published their findings in Environmental Chemical Engineering, with the new technique having the potential to produce 720,000 tonnes of biodiesel from high calorific value coffee grounds.

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Tradtionally, coffee grounds are converted into biodiesel through mixing with the chemical hexane. The mixture is left to cook at 60 degrees Celcius for between one and two hours to evaporate the hexane, leaving behind the oils needed to produce the biodiesel. Methanol and a catalyst are then added to the oils to produce biodiesel and a glycerol by-product.

Najdanovic-Visak’s team discovered, however, that simply by using methanol and a catalyst, and removing the addition of hexane from the process, the same biodiesel could be produced in just 10 minutes with less energy.

While hexane is used to extract oils from used coffee grounds, before being evaporated to leave just the oils, using methanol alongside a catalyst means that the oils can be extracted and converted into biodiesel simultaneously. The team calls this process in situ transesterification.

“Our method vastly reduces the time and cost needed to extract the oils for biofuel making spent coffee grounds a much more commercially competitive source of fuel,” said Dr Najdanovic-Visak. “A huge amount of spent coffee grounds, which are currently just being dumped in landfill, could now be used to bring significant environmental benefits over diesel from fossil fuel sources.”

Coffee waste represents a boon for biofuel production and the environment, with use of this readily available feedstock (more than nine million tonnes of coffee grounds were sent to landfill in 2014) freeing up land and water sources that would have been dedicated to expensive purpose-grown crops.

Breakthrough sees new technique for turning coffee waste into biofuel
Companies are waking up and smelling the potential for oils left in used coffee grounds and beans
War on coffee waste

Several businesses have begun to take up the idea of taking coffee waste and turning it into biofuels. In 2013, Arthur Kay founded the company bio-bean, which recycles waste coffee grounds into biofuels. The company has a team of 25 and a factory in Cambridgeshire capable of processing some 50,000 tonnes of coffee waste, with designs on increasing that capacity to 250,000.

High street coffee shop Caffè Nero has also been pushing ahead with a coffee-to-fuel project, with the company expecting to have converted 218 tonnes of used coffee grounds into 98 tonnes of biomass pellets – enough fuel to power 453 homes – in Greater London by July, after entering into partnership in February of this year with bio-bean and recycling firm First Mile.

The high street chain hopes to extend its initiative beyond Greater London this year, while Costa Coffee also entered into partnership with bio-bean at the end of 2016 and hopes to convert 3,000 tonnes of Costa’s waste coffee grounds into biofuel.

More information about the Lancaster University project can be found in the Journal of Environmental Chemical Engineering, while you can also read our interview with bio-bean founder Arthur Kay for more on making the most of used coffee beans.

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