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Scientists have discovered a simple process in which a 'green' biofuel made from waste coffee beans can power vehicles on our roads.
The process enables grounded waste coffee beans to store methane, along with the additional environmental benefit of recycling a waste product. Currently, these coffee grounds have no commercial value and are currently disposed of as a solid waste or, in some cases, used as fertilisers or burned.
Methane capture and storage provides a double environmental return – removing a harmful greenhouse gas from the atmosphere that can then be used as a fuel that is cleaner than other fossil fuels.
The process, which has been developed by researchers based at the Ulsan National Institute of Science and Technology (UNIST) in South Korea, involves soaking the waste coffee grounds in sodium hydroxide and heating to 700-900 degrees celsius in a furnace. This produces a stable carbon capture material in less than a day – a fraction of the time it takes to produce carbon capture materials.
The results of the process are published in the University's Nanotechnology journal.
Christian Kemp, an author of the paper now based at Pohang University of Science and Technology, Korea, said, “The big thing is we are decreasing the fabrication time and we are using cheap materials. The waste material is free compared compared to all the metals and expensive organic chemicals needed in other processes – in my opinion this is a far easier way to go.”
Kemp says he found inspiration for the scheme in his cup of coffee whilst discussing an entirely different project with colleagues at UNIST. “We were sitting around drinking coffee and looked at the coffee grounds and thought ‘I wonder if we can use this for methane storage?’”
The absorbency of coffee grounds may be the key to successful activation of the material for carbon capture. “It seems when we add the sodium hydroxide to form the activated carbon it absorbs everything,” said Kemp. “We were able to take away one step in the normal activation process – the filtering and washing – because the coffee is such a brilliant absorbant.”
Researchers at the University of Bath have also found waste coffee grounds to be a sustainable fuel source for powering vehicles. Researchers at the University made biofuel from ground coffee produced in 20 different geographic regions, including caffeinated and decaffeinated forms.
The study, published in the journal Energy Fuels, found that coffee has a reasonably uniform composition and physical properties for use as a fuel. That means all coffee waste could be a viable way of producing biodiesel.