Coffee could fuel cars, not just humans

While many of us see coffee as the fuel that gets us going for the day, scientists are working on literally using coffee as fuel to power cars, furnaces and other energy sources.

University of Cincinnati (UC) researchers Yang Liu, Qingshi Tu and Mingming Lu used a three-pronged approach to converting waste coffee grounds into energy sources including biodiesel and activated carbon by:

• extracting oil from the waste;
• drying the waste coffee grounds after oil removal to filter impurities in biodiesel production; and
• burning what was left as an alternative energy source for electricity - similar to using biomass.

The researchers collected waste coffee grounds from a Starbucks store on the UC campus then removed the oil and converted triglycerides (oil) into biodiesel and glycerin, a by-product. The coffee grounds were then dried and used to purify the biodiesel derived from the waste coffee grounds.

Preliminary results showed the coffee grounds’ oil content was 8.37 to 19.63%. The biodiesel made from coffee oil meets the ASTM International D6751 standard. Compared with petroleum diesel, the cleaner-burning biodiesel reduces the emission of carbon monoxide, hydrocarbons and particulate matters.

The efficiency of using the waste coffee grounds as a purification material to remove the impurities in crude biodiesel, such as methanol and residual glycerin, was slightly lower compared with commercial purification products.

However, the researchers report that results still indicate a promising alternative, considering the cost of purification products. Future research will continue to focus on improving the purification efficiency of waste coffee grounds-derived activated carbon.

In the US alone, more than 1 million tonnes of waste coffee grounds are produced. The majority of this is dumped in landfill.

The researchers say their method of producing biodiesel would not only open landfill space, but also creates biodiesel from a non-food source, unlike corn- and soybean-derived biofuels.

Liu presented a summary of the research at the American Chemical Society’s (ACS’s) 246th National Meeting & Exposition.