Farmers and everyone else out there can reduce their fuel costs, improve their health and help preserve local forests by harvesting natural gas from rotting manure.
The use of bio-gas plants, which store the decomposing manure and capture the natural gas it releases, can improve farmers’ lives, while protecting the environment. Bio-gas digesters are used in many parts of the world, including Africa.
These plants, also called digesters, typically take the form of a sealed brick-lined pit, in which the manure ferments. The bio-gas that escapes from the manure is half carbon dioxide, but about half methane, the main component of natural gas, and is piped off to be burnt in stoves or gas lamps.
Many farmers in Uganda own animals like cows and pigs which supply them with of manure every day – which is enough to keep the digester well supplied.
After investing in bio-gas plants, a typical farming family can reduce their consumption of both firewood and kerosene by as much as about 60%.
The savings on fuel mean the plants, which cost between sh800,000 and sh2m to install, depending on capacity, pay for themselves in about two years.
Before acquiring a digester, many families have to scavenge for firewood sometimes illegally. But after acquiring one, they save more money and also have less negative impact on the forests.
Replacing paraffin, charcoal and firewood with cleaner-burning bio-gas also greatly reduces indoor air pollution, a leading cause of death for rural villagers, especially women and children. People who use bio-gas make fewer visits to the doctor for smoke-related problems such as respiratory infections.
Farmers can also spread the leftover slurry from the bio-gas plant on their fields, reducing the need for chemical fertilisers, and saving them even more money.
