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| Fig. 1: A beautiful coconut palm tree native to the South Pacific (Source: Wikimedia Commons) |
The use of biofuels as alternatives to diesel fuel is not a new practice. However, the optimization of coconut oil as biofuel is showing a relatively recent increase, primarily in the Pacific. This report will highlight the various techniques of using coconut oil as biofuel to run diesel engines while discussing pros and cons of said usage. Biofuels are indeed better for the environment than fossil fuel based diesel fuel, thanks to less harmful emissions, but economic advantages are also very important reasons for coconut biofuel use in the Pacific.
The coconut or copra (flesh from a coconut) market worldwide is suffering. This is due to high transport costs and also high inputs of labor in harvesting the copra, matched with low return. The utilization of copra as biofuel, specifically for vehicles and generators on Islands in the pacific would nearly eliminate transport cost, however would not drastically increase return. The most costly stage of copra oil production would be the cutting and drying of the copra, which accounts for 43% of the value of a liter of oil produced. [1] Economically, Copra oil yields a viable alternative to diesel fuels that would help stimulate local markets and decrease incoming transport costs, however, considering outgoing transport costs and the high labor costs, this biofuel would not provide a profitable resource to export worldwide.
Not only would coconut biofuel potentially help the Pacific economically, but it would also help the environment. Current petroleum based diesel fuel has been found to yield an increase in global warming and pollution. Biofuel such as copra oil has a much lower level of toxicity, yields far less harmful emissions to the environment, and is also biodegradable. [2]
Biofuel is produced through a chemical reaction called transesterifcation or alcoholysis. This reaction occurs between an alcohol such as methanol and a vegetable oil (in this case copra oil) in the presence of a catalyst such as sodium or potassium hydroxide. The reaction then yields a biofuel that contains many similar properties to conventional diesel fuel. [2]
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| Table 1: Traditional copra price composition. [1] |
| Triglyceride + 3ROH | catalyst → |
3R'CO2R + Glycerol |
Three techniques of using coconut oil in engines have been developed and studied:
Pure Coconut Oil in Unmodified Engines
The temporary use of coconut oil in unmodified engines has been shown to be effective. However, long-term use has yielded deposits on the engines that lead to loss of power output, engine deterioration, and even engine failure. [1]
Pure Coconut Oil in Modified Engines
Because copra oil has a much higher viscosity than regular diesel, the main modification needed is a fuel heater. This would heat the oil prior to injection allowing for the fuel and engine coolant to cross flow and would thus eliminate harmful deposits on the engine. [1]
Duel Fuel of Coconut Oil and Diesel in Modified Engines
These engines start on diesel fuel. Once the temperature of the engine is high enough, the fuel source switches over to coconut oil. Before shutting down, the fuel source is then switched back to diesel fuel. Because these engines only use coconut oil at high enough temperatures, harmful residue build up is eliminated. [1]
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| Table 2: Advantages and disadvantages of various coconut oil uses in compression engines. [1] |
It is confirmed that coconut oil blends yield a very comparable output of energy as conventional diesel. At the same time, coconut oil exhaust contains far less harmful emissions than that of conventional diesel exhaust. [3] With coconut biofuel being a viable alternative to conventional diesel fuel in terms of energy output and environmental effects, the question turns towards economics.
Although copra oil harvesting would provide local jobs, its high labor cost and transport cost would not make it a profitable export. However, for local use in the Pacific, it would do a good job of not only stimulating local copra markets, but also would decrease the dependency and transport costs that come with importing conventional diesel fuel. Overall, the use of coconut oil biofuel has the potential of being very beneficial to countries in the Pacific in environmental terms, and also could aid local economies.
© David Parry. 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.
[1] J. Cloin, "Cocogen Inception Report," South Pacific Applied Geosciences Commission, SOPAC Trip Report 372, March 2005.
[2] P. Nakpong and S. Wootthikanokkhan, "High Free Fatty Acid Coconut Oil as a Potential Feedstock for Biodiesel Production in Thailand," Renewable Energy 35, 1682 (2010).
[3] M. A. Kalam, M. Husnawan and H. H, Masjuki, "Exhaust Emission and Combustion Evaluation of Coconut Oil-Powered Indirect Injection Diesel Engine," Renew. Energy 28, 2405 (2003).
