• Shalini Guleria

Fuel from Coffee: New Research Shows it's Possible

Your Starbucks coffee is not just your daily fuel, it could power your car as well

The world is running out of oil. Some may think that “oil depletion” is just a hoax but the harsh truth is that oil reserves are depleting, maybe not as dramatically as the news presents it but there has been a noticeable reduction. It is, however, obvious, we now use more cars than ever and the world’s population has increased, incomes have increased, and so has fuel consumption. It is estimated that globally we consume the equivalent of over 11 billion tonnes of oil in fossil fuel every year. Crude oil, which is used for making petrol, paraffin, diesel oil etc., is the major fossil fuel in use. Studies have shown that crude oil reserves are vanishing at the rate of 4 billion tonnes every year, at this rate, we will run out of oil by 2052. While scientists are attempting to find alternates, an interesting one has popped up recently, and you probably already consume it at your local Starbucks. Yes, coffee may be a new fuel source, not just for you, but for your car as well.

Biofuel, in simple terms is a fuel that is produced through biological processes, such as agriculture and anaerobic digestion, unlike the extreme pressurisation which created fossil fuel. Biofuels can be obtained from plants or agricultural, commercial and domestic waste with relative ease- the jargon for this being “First Generation Fuel”. The utilization of these resources leads to the formation of biofuels such as bioethanol, biodiesel, biogas, bioethers etc. Ironically, one of the biggest disadvantages of biofuels is the availability of raw material. This is largely because of issues of segregation of waste. A solution is to have captive crop production for the exclusive purpose of using the harvest to manufacture of biofuel. But given that we already face a shortage of arable land and the existence of chronic food shortages, this is not feasible.

Scientists are currently working to find ways to utilize biomass (which refers to living organisms or in most cases, plant-derived materials) to produce second generation biofuels. And here it is that coffee comes into the picture.

Figure: Biofuel production cycle (Ref: https://allofeco.com/pros-cons-biofuel/)

Coffee being one of the largest agricultural products has a growing demand in today’s world. In recent years there has been a significant increase in coffee production and consumption, and consequently, in coffee waste generation. An average cafe uses 32kg of coffee beans in a week, producing 60kg of spent coffee grounds every week. The contribution from cafes and industry has led to a worldwide generation of approximately 6 million tons of waste coffee grounds (WCG) per year. Most of this is sent to landfills or used as compost which acidifies the soil, leading to toxic effects. This has led to consideration of a new approach to utilize waste coffee grounds by using them to manufacture biofuel, namely, biodiesel and bioethanol. Waste coffee grounds mainly comprise of cellulose, hemicellulose and fatty acids (oil) that are involved in the production of bioethanol and biodiesel.

Figure: Waste coffee grounds to biofuel (Ref: https://www.fastcompany.com/1114012/waste-coffee-grounds-make-great-biofuel)

Researchers have successfully converted WCG to biofuel in laboratories, but to fulfill even a part of the fuel demand, the process will have to prove feasible at an industrial scale. As a biochemical engineers team decided to upscale this lab scale process to an industrial scale and the results seem promising. The flowchart below shows a basic schematic of an industrial plant required for the process. The flow rates used in the schematic are not representative of real world production but only represent data from North New Zealand. It has been estimated by scientists that WCG can potentially add 340 million gallons to the world’s fuel supply, which is quite a significant contribution.

Figure: Industrial process of WCG conversion to Biofuel

Biofuel attained from the WCG is known to be more stable and also results in a higher yield compared to the other raw materials. A lot of research will be required before production becomes commercial, however, it is feasible and that in itself is promising. So now whenever you drink that cup of coffee you can remember that one day this coffee will be fuelling your cars.

About The Author

Shalini Guleria is currently pursuing her Masters in Tissue Engineering where her research is focused on developing better treatment and detection techniques for Cancer. She is presently associated with Scion Research, New Zealand and holds a Bachelor's Degree in Chemical and Biological Engineering from the University of Waikato, New Zealand. Shalini has won two consecutive national awards at the prestigious Sir Paul Callaghan Eureka Awards for engineers and scientists. Apart from sciences, she is also a highly talented artist.

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