Many households in Africa are increasingly facing problems with energy supply. The availability of traditional cooking fuels such as wood, agricultural waste, dried dung and charcoal is declining, while commercial fuels are too expensive and their availability unreliable. Women and children spend hours collecting wood, animal dung or crop residues. This takes precious time, and precious lives; the indoor pollution caused by cooking with traditional biomass leads to acute respiratory infection, the world's greatest child killer. Often, the same households are also facing the consequences of lacking sanitation, resulting in water borne diseases affecting mainly women and children.
There is - in short - a large demand in Africa for more sustainable energy sources and improved sanitation. Domestic biogas can meet that demand. It uses domestic resources like manure produced by cattle, pigs and poultry as well as human excreta. It is roughly estimated that around 100 million households are living in the rural areas in Africa. Half of those possess livestock that provide the input material for biogas digesters. Water is essential for a biogas installation to function. Only a part of the African population has access to sufficient water. The potential market could roughly account between 30 and 50 million installations.
Bio digester operation mainly includes feeding the plant with a mixture of dung and water. This is not very time consuming, usually taking up to 20 to 30 minutes per day, for farmers with livestock on-site and access to water. The digester converts animal dung and other organic materials into combustible biogas. Biogas can be used in simple gas stoves for cooking and in lamps for lighting. The bio-slurry left over from this process is easily collected and can be used as a potent organic fertilizer to improve crop yields. Removing the fermented material takes place automatically as the bio slurry is discharged into a compost pit through a channel or pipe. Maintenance is restricted to occasional checking and, when necessary, repairs of piping and fittings. The plant itself, when operated properly, needs minimal care.
On average, farmers with at least 2-3 cows or 7 pigs, or a flock of 170 poultry, can generate sufficient gas to meet their daily basic cooking and lighting needs. Within the same design, different plant sizes can be constructed to allow for the actual livestock holding and biogas requirement of the family. Clearly, the obvious advantage of domestic biogas is providing energy for cooking and lighting. Substituting conventional cooking material such as, fuel wood, charcoal, and dung cakes, not only saves fuel costs, but also reduces the workload of women and children involved in the collection or preparation of these traditional energy sources.
Equally importantly, the indoor air pollution associated with cooking on inefficient wood stoves is virtually eliminated with biogas. The fertilizer closes the nutrient cycle, and also reduces soil degradation and erosion. In addition, the biogas process is carbon neutral, contributing to the global reduction of greenhouse gas emissions.
Bio digesters improve health by providing a cleaner cooking fuel (biogas) thus avoiding respiratory and eye diseases caused by the smoke inherent to traditional ways of cooking, particularly open fires. Women have the greatest risk of a range of diseases including, chronic obstructive pulmonary diseases (COPD), respiratory illnesses, eye diseases, and tuberculosis. Children, particularly those under 5 years of age, are at high risk of contracting acute respiratory illnesses such as, pneumonia. Operating a biogas plant implies that manure is directly fed to the plant, keeping the farmyard cleaner and producing valuable organic fertilizer from the bio-slurry, which is a by-product. A further improvement is possible by connecting latrines to the digester. Sometimes this is not feasible due to local practices and beliefs.
To date, a small number of biogas plants have been installed in Africa; although, most of these plants have fallen into disuse. However, there is reason for optimism, based on the experience in Asia. In Nepal, a dedicated marketing approach has resulted in the sale of more than 150.000 bio digesters and over 95 % of these plants are operational. It may be argued that circumstances in Africa differ from those in Asia. Yet, local conditions can vary significantly within the African continent itself. No fundamental reason seems to exist why dedicated marketing programmes would not work in Africa. A first technical market survey has indicated a market of around 20 million households in Africa.
At present there is a need to develop a commercial market for the biogas plants. On the demand side, households need access to micro-credit and special credit schemes. On the supply side, commercial companies, including small entrepreneurs and large companies, need to be developed. Training (both technical and business development), capacity building, loan disbursement, as well as, awareness raising, product marketing, and quality control will be required to attract potential clients.
Biogas for a better life.
Jesper Kirknæs, November 2009.