It’s no longer new that coffee wastes are being turned to biofuels. Several coffee shops right now advocate this green conversion. But researchers have found a new way to do this, far more efficient than previous methods.
To turn spent coffee grounds into biodiesel, the usual process involves mixing of the grounds with hexane and cooking the mixture at 60°C for between 1-2 hours. The hexane is then evaporated to leave behind the oils. Finally, to make the biodiesel, methanol and a catalyst are added. There is a by-product of glycerol which also needs to be separated from the fuel.
This process is shortened into just one step by chemical engineers at Lancaster University. They were able to make the existing process of many stages into one known as in-situ transesterification, which combines extraction of the oils from the spent coffee grounds and the conversion of it into coffee biodiesel.
Producing biodiesel in the new method still involves methanol and a catalyst, but without the hexane.
The researchers also discovered that the optimal time for the process was 10 minutes to gain the same yield of oils from the spent coffee grounds, offering significant savings in time and energy from the previous method.
Dr Najdanovic-Visak, a lecturer in Lancaster University’s Engineering Department, said, “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.
Source: Kona Earth
“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,” he added.
It was discovered that in 2014, more than 9 million tonnes of spent coffee grounds were sent to landfill.
Meanwhile, the researchers estimate that the process could potentially produce 720,000 tonnes of biodiesel annually from spent coffee grounds.
Source: Science Daily