If you’re anything like us, your morning doesn’t get underway properly until you’ve had a chance to sit down with a nice cup of coffee. And with more than 2.25 billion cups of java consumed every day, the global coffee industry is second only to the oil industry in terms of value, ahead of things like sugar, gold and even natural gas.
But while we’ve been drinking coffee for its stimulating effect since the fifteenth century, society still hasn’t quite come up with a use for those annoying grounds left behind after every cup — unless you count some of these rather bizarre uses.
Garden fertilisers and celebrity skin treatments aside, a team of researches from the University of Bath in South West England have come up with a more practical use for coffee grounds they thing everyone will like: turning it into automotive biofuel.
As the researchers note (via TheGreenCarWebsite), the global coffee industry produces around eight million tons of coffee per year. Of that eight million tons of coffee, around twenty percent of the resulting coffee grounds consist of oil. Oil which can be turned into biodiesel.
One of the biggest problems with traditional crop-derived biofuels like bioethanol is that crops are grown exclusively for fuel use, taking up valuable land and resources which could be used to grow food crops.
“This oil also has similar properties to current feedstocks used to make biofuels,” said Dr Chris Chuck, Whorrod Research Fellow from the University of Bath’s department of Chemical Engineering. “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.”
In other words producing biofuel from coffee grounds is far more energy efficient than growing specialist crops for the same purpose.
It sounds great, but there’s a major problem: fuel yield.
While coffee grounds can be used to produce liquid biofuel, the ratio of unit mass to liquid fuel isn’t all that great. From 10 kilograms of used coffee grounds, Dr Chuck and his team can produce two litres of biodiesel.
According to the researchers, 10 kilograms of coffee ground is about the average waste produced by a small coffee shop. Meanwhile, even the Volkswagen Golf Bluemotion — one of the most efficient diesel cars on the market today — would struggle to manage more than about 40 miles on two litres of biodiesel.
You’d need something like the ultra-efficient Volkswagen XL1 plug-in hybrid to go a decent distance on that much fuel a day however, and only then if you got some electrical assistance from its on-board battery pack.
As you might expect, different coffee beans produced from different varieties of plans grown in different parts of the world all have slightly different chemical properties when used as biofuel. Although the researchers say additional biofuel could be produced from the wastage produced in the coffee roasting stage, it’s unlikely we’ll see any coffee-fuelled cars on the roads just yet.
While we tend to focus on non-combustible fuel types here at Transport Evolved, we do applaud those who are trying to find ways of taking waste products and turning it into fuel, especially if it comes from that elixir of life which gives us a kick every morning.
But if you don’t mind for now, we’re going to recommend that coffee stays the way it’s been for a long time: in that lovely morning beverage rather than in your fuel tank.
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