Using Coffee as Fuel

Introduction

Fig. 1: Fuel from coffee is being used to power London buses like this one. (Source: Wikimedia Commons)

Caffeine is one of the most popular drugs used worldwide. It is consumed in a variety of forms to help people start and finish their day. Coffee, one of the most ubiquitous drinks, is known for its high caffeine content. However, coffee may now be able to provide energy to more than just people. Researchers have found that coffee grounds are as much as 10-15% oil by weight, and that it can be extracted and converted into biodiesel for as little as one dollar a gallon. [1] The new biofuel is even being used, in part, to power London buses like the one shown in Fig. 1. [2]

How its Done

The old process involved cooking a mixture of hexane and coffee grounds and cooking it for two hours. Once the hexane had evaporated, methanol and a catalyst are added which would create a biodiesel. [3] However, researchers at the University of Lancaster have made the process significantly quicker and easier. They remove the hexane from the process and can have it completed in just ten minutes. [3] Gains like this are crucial in the fuels industry which requires such high levels of efficiency.

Benefits and Drawbacks

Biofuels, while innocuous on the surface, have received some negative press for not being all they make themselves out to be. Some of the side effects of the creation and processing of biofuels can release significant amounts of carbon dioxide. For example, turning left over stalks and corn leaves can release much more carbon dioxide than one would expect. [4] Coffee grounds do not have these same consequences. [1] This process would allow for over 720,000 tonnes of coffee grounds to be given a purpose instead of going to the landfill. [4] Yet, this is far from the cure all for the current energy crisis. Even if all the worlds coffee grounds were used to create fuel it would only offset energy consumption by one percent. [1] Furthermore, there is not a centralized system to collect and process coffee grounds so it will be challenging to collect even a small fraction of the worlds spent coffee. [1]

Conclusion

The ongoing quest to make make the world function on sustainable energy is a noble one. It seems unlikely that any one great invention will be able to cure all the flaws in the current system. That is why technology like this should be praised for what it offers, rather than looked down upon for its small scale. Not to mention, exhaust from this biofuel smells like coffee. [1]

© Bennett Williams. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

References

[1] H. Fountain, "Diesel Made Simply From Coffee Grounds (Ah, the Exhaust Aroma)," New York Times, 15 Dec 08.

[2] A. Cowell, "Wake Up and Smell the Traffic? London Tries Coffee to Power Buses," New York Times, 20 Nov 17.

[3] V. Najdanovic-Visak et al., "Kinetics of Extraction and In Situ Transesterification of Oils from Spent Coffee Grounds," J. Environ. Chem. Eng. 5, 2611 (2017).

[4] S. Li, "Biofuels May Be Worse for Environment Than Gasoline in Short Run, Study Says," Los Angeles Times, 21 Apr 14.