Researchers produce biodiesel from leftover coffee grounds

Dr Vesna Najdanovic senior lecturer in senior lecturer in chemical engineering and Dr Jiawei Wang were part of an international team that grew algae which was processed into fuel. 

According to the British Coffee Association, approximately 98 million cups of coffee are drunk each day in the UK alone, leading to a considerable amount of spent coffee grounds that are processed as general waste, often ending up in landfill or incineration.

The researchers found that spent coffee grounds provide nutrients to feed, and a structure on which the microalgae (Chlorella vulgaris sp.) can grow. Consequently, they were able to extract enhanced biodiesel that produces minimal emissions, good engine performance, and meets US and European specifications. 

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The study, Enhancing growth environment for attached microalgae to populate onto spent coffee grounds in producing biodiesel, appears in Renewable and Sustainable Energy Reviews.

Up till now, algae has been grown on materials including polyurethane foam and nylon that don’t provide any nutrients. However, the researchers found that microalgal cells can grow on the leftover coffee without the need for external nutrients.