Rural Energy in Kenya: Is There a Future for Biogas? A Survey

Most rural people in Kenya rely principally on human and animal muscle power in their work as subsistence farmers, herdsmen, fisherman, or small-scale crop farmers. All the agricultural processes (ranging from ploughing to harvesting) are done largely by hand, with some help from draft animals and simple tools. Firewood is their principal cooking and heating fuel while kerosene in used for lighting. Their economic growth is hence blocked by the energy crisis. Due to their heavy dependence on biomass – mainly firewood, crop residues, and animal dung – they deprive the soil of essential nutrients and pose a threat to the agricultural lands due to deforestation and the resulting soil erosion. The problem of rural energy, therefore places the provision of food and other basic needs at risk. A technology which extracts a more useful and convenient form of fuel from biomass without destroying its fertilizer value than the traditional conversion method of direct combustion is highly desirable. Anaerobic digestion of agricultural residues generates biogas which can be used directly for lighting, cooking, electricity generation, or to power an IC engine for water pumping or milling. The remaining sludge forms a good fertilizer. This paper reviews the role of biomass in meeting Kenya's energy needs and how biogas can contribute in alleviating the rural energy crisis. Biogas production and utilization technology was introduced in Kenya in 1954 but by 1986 there were less than 200 installed biogas plants and less than 25% of these were operational. A survey of installed biogas plants (across the country) was carried out (using questionnaires and interviews) to identify the factors that have inhibited the adoption of biogas technology in Kenya; and the problems which have caused the failure of many of the installed plants. The paper gives a detailed discussion of the findings. The survey showed that amoung the reasons for nonadoption are: lack of capital and sufficient input materials (animal dung and water); limited dissemination of technical knowledge and experience to operate biogas plants; and the lack of credit and extension facilities. It was also found that problems such as scum build-up and corrosion, and the lack of sufficient knowledge on the operation and maintenance of the digesters especially on feeding and feedstock dilution (leading to low gas production) has resulted to many failures. The paper attempts to answer some of the problems which have resulted to the many failures and hindered widespread acceptance of biogas technology in Kenya. Finally the issue of dissemination is discussed.