For many of us, coffee runs our lives. Without the bitter, caffeinated brew, most of us wouldn't be able to get up in the morning or avoid fading in the afternoon. Now, new research from the University of Bath suggests we might want to get our cars as hooked on java as we are. Regardless of the variety of coffee used, the UK institution has found that coffee grounds are a great source to create biodiesel.

The idea of creating biodiesel from coffee grounds goes back several years, but it's still being researched and refined. The process works by soaking the grounds in an organic solvent and then putting them through a process called transesterification. The BBC show Bang Goes the Theory even converted a Volkswagen Scirocco to run on the gasified coffee years ago.

The Bath study tested 20 different coffee variations across region, brewing technique and even caffeinated versus decaffeinated to determine if the changes affected oil content. It turned out that it didn't. Fresh grounds contained between 11 and 15 percent oil by weight for the varieties it tested, and used ground contained between 7 and 13 percent.

Coffee ground-based biofuel could be revolutionary. Researchers who authored the study think that the conversion process is simple enough that it could be done by neighborhood coffee shops to create a personal supply of biodiesel. They predict a shop producing about 22 pounds (10kg) of grounds a day could make about half a gallon of biofuel (2 liters). While that's a relatively small amount, it's from a source that would otherwise usually just be thrown away. Scroll down to read the University's press release about the study, and click here to read its abstract.
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Could you run your car on coffee?

Researchers used 20 different types of coffee to assess the quality of biofuel produced from each one

New research from our Centre for Sustainable Chemical Technologies shows that waste coffee grinds could be used to make biodiesel.

Oil can be extracted from coffee grounds by soaking them in an organic solvent, before being chemically transformed into biodiesel via a process called "transesterification". The study, recently published in the ACS Journal Energy & Fuels, looked at how the fuel properties varied depending on the type of coffee used.

As part of the study, the researchers made biofuel from ground coffee produced in 20 different geographic regions, including caffeinated and decaffeinated forms, as well as Robusta and Arabica varieties.

Dr Chris Chuck, Whorrod Research Fellow from our Department of Chemical Engineering, explained: "Around 8 million tonnes of coffee are produced globally each year and ground waste coffee contains up to 20 per cent oil per unit weight.

"This oil also has similar properties to current feedstocks used to make biofuels. 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 research found that there was a reasonably standard composition and little variation in the relevant physical properties of the fuels, irrespective of the source. This means that all waste coffee grounds are a viable feedstock for producing biodiesel.

Dr Chuck explained: "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."

The researchers suggest that while coffee biodiesel would be a relatively minor part of the energy mix, it could be produced on a small scale by coffee shop chains to fuel vehicles used for deliveries. These same delivery vehicles could be used to collect spent coffee grinds and take them to a central biodiesel production facility to be processed. Companies such as London-based bio-bean already produce biodiesel and biomass pellets from waste coffee grounds.

Rhodri Jenkins, a PhD student in Sustainable Chemical Technologies and first author of the study, said: "We estimate that a small coffee shop would produce around 10kg of coffee waste per day, which could be used to produce around 2 litres of biofuel.

"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."

The researchers are also looking at using other types of food waste as a feedstock to make biofuels and expect to publish their findings later in this year.


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  • 17 Comments
      2 wheeled menace
      • 6 Months Ago
      Wow, half a gallon of fuel from 22 pounds of waste.. that could replace 0.0000001% of our nation's oil supply.. i see how that's revolutionary :)
      Mike
      • 6 Months Ago
      Used coffee grounds are great for the garden too. Changes the pH level in the soil.
      swaggreg
      • 6 Months Ago
      This is a two-year-old story. Google it if you don't believe me. What gives?
      Tesla Fan
      • 6 Months Ago
      coffee sucks
        Mike
        • 6 Months Ago
        @Tesla Fan
        I love coffee and it doesn't require graphite....
      Cruising
      • 6 Months Ago
      This is impressive figures but I can't stand coffee drinkers always complaing about how they "need" it or some slight differences in flavors get their panties in a bunch. I don't want a car as irritable as they are. LOL
      justgoawaymad
      • 6 Months Ago
      bla bla bla this is the newest and greatest yada yada. You know it just does not matter until you talk money. I like the idea of something like this but cut to the chase. Is it economically practical or not? Is that soooo hard to address in the article?
      SquareFour
      • 6 Months Ago
      This would be another good way to recycle a heavily used item, but it depends on production costs, as it always does. A bigger prob for this could be the predicted extinction of the Arabica bean in 60-80 years.
        foamypirate
        • 6 Months Ago
        @SquareFour
        Right, just like corn has gone extinct due to ethanol production, eh?
      goodoldgorr
      • 6 Months Ago
      I recommend sewage instead, there is a bigger quantity per capita and it depollute.
      vt8919
      • 6 Months Ago
      The world is on the verge of a coffee shortage and they think using more of it will help?
      nolimit092
      • 6 Months Ago
      And how much energy, time and cost in chemicals will it take to make $2/day worth of bio diesel?
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