Cheung Prey district, Kompong Cham province- As Phal Paat walks down the muddy path to his neighbor’s house in Trapaing Tmat village, he spots something residents haven’t seen much of lately: a pile of dead branches and brush at the base of some trees.
“Before, none of that would have been there,” the 36-year-old Phal Paat said.
A few months ago, the scrub would have been scooped up to burn for cooking. But the villagers no longer need firewood. They’ve found a much better energy source: dung.
Just as the residents of wealthier neighborhoods in Phnom Penh might compete to buy the latest SUV model of vehicle or home entertainment systems, villagers here have embraced excrement-fed biodigesters that provide power for lighting and cooking.
Since Phal Paat constructed the first biodigester in Trapaing Tmat village in May 2006, 15 more families have followed suit.
“It saves me a lot of time,” Phal Paat says of his biodigester. “There’s no need to collect firewood and I get more fertilizer [for farming].”
It also saves money, he said, adding that he once had to buy most of his firewood at a cost of about $0.35 per day. And prices are climbing.
“The cost of firewood increased because every day the forest gets farther and farther away,” Phal Paat said.
Constructed with bricks and mortar, and buried underground, biodigesters turn animal or human dung into both methane gas and slurry that can be used as fertilizer.
The process is relatively simple: Dung is mixed with equal parts water and dumped into the biodigesters’ main underground chamber.
Bacteria decompose the dung, giving off methane gas, which rises to the top of the chamber. The gas is piped to the farmer’s home, where it fuels a stove and gas lamps, sometimes a generator.
The decomposed slurry is pushed out of the chamber and makes an effective fertilizer.
The National Biodigester Program, a joint project between the Netherlands Development Organization and the Ministry of Agriculture, Forest and Fisheries, was established early last year to promote the alternative fuel source.
NBP sells four different sizes of biodigester-from 4 to 10 cubic meters-which range in cost from $300 to $450, said Jan Lam, the NBP’s senior adviser.
The Netherlands also gives a $100 subsidy to families who build them, and so far 700 biodigesters have been sold, Lam said.
The smallest biodigester needs about 20 kg of dung per day, which is about equal to the amount produced from two cows or six pigs, Lam said. Users can also connect a digester to a latrine, he added.
With money saved on not having to buy wood fuel for cooking, oil for lamps and electric batteries, families who buy a biodigester can pay off their initial investment in less than two years, according to the NBP.
Using dung for fuel also has the benefit of being cleaner than wood or charcoal.
The NBP is keen to emphasize the benefits of the biodigester’s bi-product, fertilizing slurry, which is no small thing since most of the people who have bought biodigesters are farmers.
The slurry is high in nitrogen and nutrients, does not emit the foul odor of unprocessed manure or chemical fertilizers, and does not attract bugs, which makes farms more sanitary, NBP adviser Kong Kee said.
Kang Chandararot, director of the Cambodian Institute of Development Study, said the biodigesters are one of the more promising sources of energy for people in Cambodia’s rural areas. “You can break even without much commitment,” he said. “You get cheaper energy, which means you save a lot and have a source for investment.”
Lam admits that biodigesters are really only practical for farming communities.
“You need farmers who are used to working with livestock. If you don’t have livestock, buy yourself a bottle of gas,” Jan Lam said.
Some of the residents using biodigesters in Trapaing Tmat village had some complaints of their own: The gaslight mantel in their homes was prone to breaking, and the stove flame was too strong.
Nevertheless, they said they were very excited to have a consistent supply of cooking fuel and light.
Phal Paat’s 66-year-old neighbor, Sek Nay, said he now views manure in a whole new light and, just as fire wood was once scarce in Trapaing Tmat, animal dung is now hard to find.
“Sometimes I sit and watch the cow and wait for dung to fall,” said Sek Nay, who hunts for manure in his rice fields and collects it in baskets.
“Everywhere, I look for dung,” he said.