Coffee Grounds: Future Energy Resource

Coffee grounds might serve as a cheaper and cleaner energy source, say researchers.

Yang Liu, a graduate student in environmental engineering in UC's College of Engineering and Applied Science (CEAS), 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.

Taste of Coffee - Types of Coffee Drinks and Varieties
Coffee is a great beverage prepared from the seeds of Coffea plant. Different types of coffee include espresso, cappuccino, Café latte, frappe, iced coffee.

The researchers launched the project in 2010, gathering waste coffee grounds in a five-gallon bucket from a Starbucks store on UC's campus. After collection, they removed the oil from the waste coffee grounds and converted triglycerides (oil) into biodiesel and the byproduct, glycerin. The coffee grounds were then dried and used to purify the biodiesel they derived from the waste coffee grounds.

The preliminary results showed that the oil content in the waste coffee grounds was between 8.37-19.63 percent, and biodiesel made from coffee oil meets the ASTM International D6751 standard.

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.

Quiz on Coffee
‘Coffee sets the blood in motion and stimulates the muscles; it accelerates the digestive processes, chases away sleep, and gives us the capacity to engage a little longer in the exercise of our intellects.’ – Honoré de Balzac (paraphrasing Brillat-Savarin) Traité des Excitants Modernes (1838). Coffee – summary. This quiz will give you the details.

Compared with petroleum diesel, the cleaner-burning biodiesel reduces the emission of carbon monoxide, hydrocarbons and particular matters (PM).

The researchers say the method they're exploring to produce biodiesel would not only open landfill space, but it also holds promise in creating biodiesel from a natural product.