With the world lurching towards an energy crisis, it is little known that there is a virtually untapped source of energy in every farm and every household in the world: manure. With basic technology, it is possible to produce from manure a clean gas that can be used for cooking or lighting, or even to produce small amounts of electricity.
While this is an energy source that is unexploited in the West, in impoverished Sri Lanka, Practical Action, one of the charities in The Independent's Christmas Appeal, is using it to transform the lives of farmers.
R N Nandawathie lives in the undulating lowlands of Uva province, in the Sri Lankan interior. This is a long way from the tropical beaches, and few tourists make it up here. Ms Nandawathie lives with her husband and two children in a simple wooden hut. In the rain, the road to the house is impossible to drive on and you have to walk.
Less than 50 per cent of Uva is connected to the Sri Lankan power grid. Up here there is no electricity, and at night it is so dark you can see the fireflies dancing in the distance. But while the houses all around are in pitch darkness, Ms Nandawathie's is bathed in light: the family uses a solar power cell donated by Practical Action.
That is not all. While the neighbours still have to go out each morning to collect firewood to cook on, Ms Nandawathie has a gas stove connected to a rubber tube that snakes around to the back of the house, where the family cows are kept. The cooker runs on biogas. There is no bad smell, the gas produces a clean, smokeless blue flame, and it is less explosive than the liquid petroleum gas that is commercially available in Sri Lanka.
"The best thing about it is the time I save," says Ms Nandawathie. "Cooking rice over firewood took 15 minutes. With the gas it takes just five minutes. And I don't have to spend the time each morning gathering firewood." It has freed up precious time to spend with her eight-year-old son, Sathsara, and her four-year-old daughter, Himanchi.
Cooking over firewood leaves thick black soot on pots and pans, and Ms Nandawathie used to spend hours scouring them. With the smokeless gas the soot is a problem of the past. The family also has a biogas lantern for when the solar cells run out. It can be easily filled up with gas and produces a steady light.
Ms Nandawathie and her husband, V G Padmasiri, lead a precarious financial existence. Mr Padmasiri used to work in a concrete factory, but when the workforce was cut he and his wife set up their own family business. In the monsoon, they farm their small patch of land. That brings in about $50 (£28) a month. In the dry season, they make bricks, which they sell locally, making about $90 a month.
They bought their four cows a year ago, planning to sell the milk. At the time, they had no idea the cows could also provide cooking gas and lighting. When they heard of Practical Action's simple biogas scheme, they asked to join up.
The process is simple. The cow manure is collected and fed into a large pit called a "biogas digester". There, it is mixed with water to an exact ratio, and simply left to ferment. The biogas, which is 55 to 70 per cent pure methane, is collected via a rubber tube as it is produced. Once the gas is removed, the residue that is left behind is high-grade fertiliser, meaning there are no waste products.
Ms Nandawathie already uses the fertiliser for her chillis, and plans to use it on more of her farmland.
The technology is simple and easily maintained: just a pit and a length of hose. There are several safety features, including a pool of water over the pit so that bubbles will warn of any gas leak. Collecting the manure may seem a little unappealing, but it is nothing out of the ordinary for a small-scale Sri Lankan farmer.
Any manure will do. Practical Action has set up other families with biogas digesters for pigs and buffalo. Even human manure will produce biogas, though that is a source that so far remains unexploited.
Practical Action supplies the technology on the principle that the family must also invest some of its own money in the biogas digester: that way it has a stake in it and is more likely to work to make it a success. The Sri Lankan government is also backing the scheme, and putting up some of the money. The basic pattern is one-third from Practical Action, one-third from government, and one-third from the family.
In Ms Nandawathie's case, the family was able to meet its share of the contribution by supplying its home-made bricks for the digester. As well as supplying the technology free, Practical Action has a technical adviser who visits regularly and is always available to help with any biogas problems.
For Ms Nandawathie, it has improved her family's quality of life. The next plan is to run a line across the hillside to her ageing mother's house, to supply that with biogas as well.Reuse content