Organic waste such as dead plant material, animal manure and kitchen waste can be converted into a gaseous fuel called biogas, which can be used for cooking.
To produce biogas biodegradable waste is placed in a digester where the absence of oxygen promotes anaerobic digestion. The gas created by this process is primarily methane and carbon dioxide. There are two basic types of digester - floating dome and fixed dome. The latter have proved to be the most trouble free in terms of performance and maintenance, provided the construction carried out to specification.
Is biogas the answer for poor families in developing countries ?
Small-scale biogas plants can provide cooking fuel for individual households in settled rural communities where families own at least 5 cattle. The cost of the digester is usually out of the reach of most families living on small incomes. Biogas has limited application for the very poorest in such communities as they do not generally own cattle.
The photos on this page illustrate the construction of a small fixed dome biogas digester in the kitchen garden of a family home and the simple cooking stove connected to the resulting gas supply. This digester was grant-aided as an awareness-raising demonstration at the home of a skilled mason who received training in both construction and maintenance. The mason was also involved as a community 'mover and shaker' in promoting other appropriate technologies such as simple mud and brick smokeless fuel-efficient cookstoves and twin-pit pour-flush toilets.
This simple fixed dome digester was developed by the Deutsche Gesellschaft fuer Technische Zusammenarbeit (GTZ) - now the Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ). GTZ have published a wealth of information on biogas, including a paper on biogas programme implementation and cost and benefits.
There are many other ways of using biogas on a much larger scale, which require significant investments, but they are generally not suited to small communities with limited technical and financial capacities.