Jakarta Globe, Ismira Lutfia | January 07, 2011
In an effort to wean rural communities off inefficient and costly kerosene, Indonesian researchers have developed an alternative fuel from a common plant.
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| Researchers say the fruit of the bintaro can be used to make an oil that may be able to replace kerosene. |
The new fuel is derived from the seed of the sea mango tree (Cerbera manghas), known locally as bintaro.
Aris Purwanto, head of the research team at the Bogor Institute of Agriculture (IPB), said the idea came after rising kerosene prices in the Teluk Meranti area of the Riau Islands forced villagers to switch to burning wood for cooking.
“The bintaro tree grows all year round and a tree of at least three years of age can produce an average of 300 to 400 fruit a year,” Aris said during a presentation on Wednesday.
To extract the bintaro oil, researchers removed the seeds from the ripened fruit, then dried and crushed them. Aris said 2.9 kilograms of seed yielded one liter of oil.
In an interesting aside, he said the seed kernels contain the toxic substance cerberin, which is often used by local farmers to poison wild animal pests that damage their crops.
“Even in its raw phase, the oil can be used to fuel an electricity generator,” Aris said.
But the researchers experimented further, refining the oil by mixing it with water and storing it until an oil-water dispersion was achieved.
This refined oil, they said, can be used to fuel a fire, such as in a kerosene stove.
However, Aris said that because it had a much higher viscosity than kerosene or diesel, and hence different combustion properties, stoves and generators would have to be modified slightly to ensure the oil worked.
The viscosity difference means that the bintaro oil is too thick to vaporize into a flammable spray, as required in the combustion chamber of a kerosene stove or diesel-powered generator.
To use it to power a generator, for instance, a converter must first be used to heat the oil to 70 degrees Celsius to lower its viscosity to the level of diesel.
Even then, the generator needs to have been running for four to five minutes on diesel before the bintaro oil can be added to the external tank and the diesel supply shut off.
Aris acknowledged bintaro oil could not yet be classified as a biofuel, and was not yet a viable replacement for conventional fossil fuels.
He said that with only four months of development behind it, more research and processing was needed before bintaro oil could viably generate sufficient power to fuel heavier machinery such as motor vehicles.
In the meantime, he said, it is sufficient for basic cooking needs such as boiling water or cooking rice, allowing it to take over some of the role of kerosene.
“We aim to develop this as an alternative energy source for people in remote areas, so that they’re not overly dependent on kerosene,” he said .
He added that bintaro trees were common in many rural areas and relatively easy to grow, making it easy for villagers to collect the necessary seeds.
The tree is also frequently used in greening projects in residential areas across the country .
Marzuki Effendi, one of the Teluk Meranti villagers who attended Wednesday’s presentation, said that bintaro-fueled stoves produced an intense blue flame that brought water to the boil in just four minutes.
With kerosene, he said, boiling water took eight minutes.
Marzuki said another downside to kerosene was its high cost.
The fuel typically costs Rp 6,000 to Rp 8,000 (66 to 88 cents) per liter in the area, he said.
Kerosene distributed to the public is supposed to be subsidized by the government, although distributors almost invariably charge a commission on sales.
In addition to being expensive, it is increasingly difficult to source, a result of the government’s plan to replace it with liquefied petroleum gas.
However, the kerosene-to-gas campaign has concentrated largely on urban areas, with many rural communities yet to receive the free liquefied petroleum gas stoves and canisters that are part of the program.
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