Study finds waste coffee grounds can be used to make biodiesel

Jun 18, 2014 20:13 GMT  ·  By

According to a recent investigation whose findings are detailed in a paper in the ACS Journal Energy & Fuels, using coffee to power cars is not only doable, but, given the urgency to limit climate change and global warming, recommended.

At this point, coffee worshipers might feel the urge to jump off their seats and start going on and on about how there is sheer malice in suggesting that folks start pouring this divine brew in car tanks rather than down their throats.

However, it need be said that what researchers have in mind is something quite different, i.e. using waste coffee grounds to make biodiesel. Thus, their approach is a no harm, no foul type of idea.

As detailed in the ACS Journal Energy & Fuels, experiments and investigations carried out thus far have shown that, in order to make biodiesel from coffee, one must first soak the coffee grounds into an organic solvent.

This causes the oil contained in them to be released. Once collected, the oil needs to be subjected to a process known as transesterification. According to Phys Org, it is by means of this process that the oil is transformed into biodiesel.

“Around 8 million tonnes of coffee are produced globally each year and ground waste coffee contains up to 20% oil per unit weight. This oil also has similar properties to current feedstocks used to make biofuels,” says Dr. Chris Chuck.

“But, while those are cultivated specifically to produce fuel, spent coffee grounds are waste. Using these, there's a real potential to produce a truly sustainable second-generation biofuel,” the specialist goes on to explain.

Dr. Chris Chuck and his colleagues say that, according to evidence at hand, all waste coffee grounds can be used to make biodiesel, regardless of their origin. Different coffee varieties grown in different parts of the world birth very similar oils and can therefore support a growing biodiesel industry.

“The yields and properties of biodiesel can differ depending on the growth conditions of current biodiesel feedstocks, sometimes causing them to fall out of specification. The uniformity across the board for the coffee biodiesel fuel is good news for biofuel producers and users,” Dr. Chuck stresses.

“There is also a large amount of waste produced by the coffee bean roasting industry, with defective beans being thrown away. If scaled up, we think coffee biodiesel has great potential as a sustainable fuel source,” adds student Rhodri Jenkins.

It is estimated that just 10 kilograms (22 pounds) of coffee waste can be used to obtain about 2 liters of biofuel. To put things into perspective, it need be said that 10 kilograms of coffee waste is what a single small coffee shop produces on a daily basis.