*3.4.5 Local production and use of biogas*

This technology refers to the production of combustible gas within small-scale digesters at the household level. It is based on the utilization of plant and animal residues as organic wastes that are decomposed in anaerobic tanks, forming methane and a digested slurry byproduct useful as an organic fertilizer and soil amendment [36]. Gasses rise and collect through an outlet for burning as cooking fuel and the sediments sink into sludge for later collection. Gasses may be produced in a variety of vessels located above- or belowground. These reactors may be fashioned from metal tanks, built from concrete, or purchased as complete units. Attraction to this technology is growing across the Sahel because of its socioeconomic and environmental benefits, and it has a proven ability to improve the lives of rural households that would otherwise burn wood and charcoal, or cook using purchased kerosene [5]. The diversification of energy supply creates economic opportunity to those who build and equip these digesters, and it reduces local air pollution and deforestation due to firewood collection and charcoal making, and increases sequestration of carbon into soils amended with the digested organic sludge. Carbon sequestration is also achieved by the substitution of renewable energy production from methane as compared to reliance upon fossil fuels. Biogas generation is best considered among a suite of rural development options that are designed to educate stakeholders and supply the hardware and infrastructure it requires [37].
