Coffee as a Biofuel for London Buses

Introduction

Fig. 1: Red double decker bus in London. (Source: Wikimedia Commons)

London is very well known for its iconic red double decker diesel buses (Figure 1), fostering more than 9,500 buses on the streets today. [1] London has a long history of poor air quality, and since 2010 has had illegal levels of air pollution due in part to diesel vehicles. This toxic air contributes to at least 9,000 premature deaths each year. [2] Due to these health risks, the government has taken to improving air quality by targeting major contributors to air pollution such as vehicles. On top of recent additions of zero-emission double decker buses, transport officials are also exploring other fuels to power the buses while reducing diesel fumes. [2] What new fuels have they decided to explore? Waste coffee grounds.

How Does it Work?

Arthur Kay, founder of the startup bio-bean, partnered with Shell to research alternative ways to use coffee grounds waste. [3,4] Londoners create 200,000 tonnes of coffee ground waste per year, from their average 2.3 cups of coffee per day. [1] Bio-bean collects coffee ground waste from large coffee distributors like bakeries and factories, then processes it to extract coffee oil. They then combine the coffee oil with other fuels like petroleum diesel to make a hybrid B20 fuel. This B20 fuel may then be directly added into the diesel bus. [4] Coffee grounds are estimated to be 10-15% oil and have a high caloric content so they are a good option for a clean energy fuel. [5,6] Bio-bean estimates from their research that coffee oil makes 150% more energy than wood. [5] Although it does not eliminate all emissions, adding coffee oil as part of the fuel for the diesel buses reduces the amount of CO₂ produced, which helps to improve the air pollution in London. [4]

Conclusion

So far bio-bean and Shell have been able to extract 6,000 litres of coffee oil from waste coffee grounds, which is enough to power a bus for one year when combined with mineral diesel to form the B20 fuel. Out of the 200,000 tonnes of coffee ground waste created in London each year, the bio-bean factory can only process up to 50,000 tonnes of grounds per year, which introduces a huge limitation of resources. [4] The goal is to continue to search for ways to reduce carbon emissions and improve air quality in London. Bio-bean has also considered looking into expanding this project into the US, considering the US also produces large amounts of coffee ground waste per day per person. It is important to note that companies often report information about how they are "going green" without a lot of evidence to back it up. I am reporting what has been published on this subject, but I recognize that the important background information that proves how this new initiative helps improve air quality is missing.

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

[2] L. Hook, "Air Pollution: Why London Struggles to Breathe," Financial Times, 21 Aug 18.

[3] T. Smedley, "Arthur Kay: Guardian Sustainable Business Leader of the Year 2015," The Guardian, 30 Apr 15.

[4] I. Slav, "Is This the Ultimate Fuel for the Millennial Generation?," USA Today, 26 Nov 17.

[5] T. Smedley, "Waste Coffee Grounds Set to Fuel London with Biodiesel and Biomass Pellets," The Guardian, 13 Feb 14.

[6] M. Haile, "Integrated Volarization of Spent Coffee Grounds to Biofuels," Biofuel Res. J. 2, 65 (2014).