GAS produced from human and animal feces could well be the salvation to some of Cambodia's
social and ecological problems.
That's right, excrement from animals and humans could supply poor inhabitants of
this country - whose forests are being rapidly depleted - with, if it's used correctly,
an endless, almost cost-free supply of "bio-gas" to be used in place of
It's success in Cambodia has been proven. Since 1994, the Ministry of Agriculture
(MOA), together with the Food and Agriculture Organization (FAO) and Lutheran World
Service, has been promoting the "bio-digester" concept nationwide.
A feat in no-frills engineering, this $40 wonder relies entirely on the natural synchronicity
between man's biological clock and his outside environment.
Watered-down feces - cow, pig, or human - is fed through an eight-meter long plastic
duct. The experts say the digester is supposed to function like a normal digestive
The 50 percent feces-50 percent water cocktail is either poured from a bucket into
the canal or passed into it via an optional latrine, which can be piped into the
As the waste ferments, it emits methane - "bio-gas" - which is channeled
through a steel tube into the kitchen, where it comes out through the stove, or is
caught in a one cubic meter plastic bag which acts as a reservoir.
The blue flame will burn eternally, the experts say, provided the bio-digester is
kept going properly and there is a constant supply of excrement.
The effluence can also be used as a fertilizer in vegetable patches and rice paddies,
and can even be used for growing aquatic plants to feed fish.
Khieu Borin, a researcher with MOA, says this method of fermentation is greener than
simply exposing fresh manure to the sun.
"Fresh manure contains fibers which need twice the amount of oxygen to be broken-down,"
he says. "Fresh manure emits methane fumes which are harmful to the ozone layer,
whereas the methane which burns in a bio-gas equipped kitchen burns more cleanly
The digester was pioneered by Indian scientists, who introduced a concrete prototype
here in 1990. But, according to Borin, its $500 price-tag was seen as exorbitant
for a country which has an annual per capita income of $200.
FAO then modified the digester, he says. It designed a plastic version which was
lighter, more compact, and cheaper than the original.
At present, about 500 units are being used in Cambodia, mostly in Kandal, Thakmao,
Svay Rieng, and Prey Vieng provinces where there are scant supplies of free firewood.
So far, as a result of its bio-digestion programme, MOA has achieved an 80 percent
switch from consumption of firewood to bio-gas in those areas.
Provided there are adequate credit schemes in place and farmers are properly trained
in the maintenance of bio-gas units, they will be able to do away completely with
their dependency on firewood, Borin says.
Peak Try's family of eight, residents of Svay Rieng have had their lives transformed.
Their dependency on firewood had gone. It has freed up time which the family can
now devote to more productive activities, such as schooling and learning new skills.
"Life used to be very difficult," says Wan Savy, Try's 18 year-old son.
"I would spend a few hours every day, collecting firewood and drawing water
from the nearest well."
"Now that I don't have to collect firewood any longer, I can devote more time
to my studies," he adds. "My aim is to be a doctor, so I can come back
to my village to cure my parents and neighbors, when I need to."
MOA officials say that now experiments with bio-digesters have been successful in
arid parts of Cambodia where firewood is scarce and costly, they are hoping to launch
Bio-Gas pilot projects in more remote provinces where there is the threat of deforestation.
The real challenge, say the experts, lies in breaking through the mindsets of a peasants
who have traditionally relied on abundant stocks of firewood from nearby forests
to take them through to the next day.