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UPDATED 1 Sept: The EI library in London is temporarily closed to the public, as a precautionary measure in light of the ongoing COVID-19 situation. The Knowledge Service will still be answering email queries via email , or via live chats during working hours (09:15-17:00 GMT). Our e-library is always open for members here: eLibrary , for full-text access to over 200 e-books and millions of articles. Thank you for your patience.
Waste coffee grounds could fuel vehicles
The European Union has set ambitious targets for biofuels – those derived from renewable biological material rather than fossil resources – to make up 10% of all transport fuels by 2020. Innovative London start-up Bio-Bean is aiming to help hit this target by producing biodiesel from waste coffee grounds, writes Oliver Robinson.
Bio-Bean was started in 2012 by UCL alumnus Arthur Kay. Since then, the company has won several competitions including The Mayor’s Low Carbon Prize in 2012 and £400,000 from the Postcode Lottery Green Challenge in 2014. These helped fund the commercialisation of the process to make useful fuel products from the 500,000 tonnes of waste coffee grounds that currently go to landfill each year in the UK.
Bio-Bean’s goal is to save not only the 1.8mn t/y of carbon dioxide generated by the UK’s waste coffee, but also the roughly £50mn it costs companies to dispose of it. The company is currently commissioning a facility to turn up to 50,000 t/y of coffee grounds into biodiesel for vehicles and biomass pellets to burn for heating.
According to Dr Rhodri Jenkins of Bath University, who has carried out extensive research into making biofuels from waste, improbable as it may seem at first, coffee grounds are an excellent feedstock for producing biofuels. Between 10–20% of the weight of a coffee bean is oil, and nearly all of this remains in the coffee grounds after use. Despite the fact that traditional biofuel feedstocks such as rapeseed have slightly higher oil content, they are expensive to cultivate. Dr Jenkins explains that in normal biodiesel production ‘at least 75% of [the cost] is accounted for by the feedstock. That’s the growth and cultivation of it. If you use coffee waste you have essentially got a zero cost feedstock.’
The process of biochemical extraction by which biodiesel is taken from coffee grounds is well known and not energy intensive.First the oil is separated from the fibre of the grounds using an organic solvent like hexane. Once separated, the oil (triglyceride) molecules, made up of three long carbon chains in a Y-shape joined at the centre by a glyceride backbone, must be broken down. This is done using sodium hydroxide as a catalyst along with methanol. This removes the glycerine backbone, replacing it with methanol and forming fatty acid methyl esters – otherwise known as biodiesel. The separated glycerine is then a waste product which can itself be useful in other applications.
Research carried out by Dr Jenkins indicates that using this process on the 500,000 tonnes of waste coffee grounds the UK currently produces each year could yield up to 80mn litres of biodiesel. This would be a significant contribution to the 1,356mn litres of biofuel consumed in the UK last year, which was 3.54% of all transport fuel.
In addition, the remaining 80–90% of the coffee grounds that are not composed of oil will be made into biomass pellets for burning, which Bio-Bean claims could ‘power up to 16,000 homes’.
