Can biogas digesters help to reduce deforestation in Africa?

Abstract

Biogas digesters could help to reduce deforestation in Sub-Saharan Africa by providing a source of energy that would otherwise be provided by woodfuel. However, the link between deforestation and use of woodfuel at global level is weak because fuel is often obtained from fallen wood or from sources felled for construction or land clearance. This paper examines the link between deforestation and use of woodfuel, and evaluates whether biogas digesters are likely to help reduce deforestation in Africa. Woodfuel production and consumption in Africa are increasing over time. Of the deforestation observed in 2010, we estimated that 70(±42)% can be attributed to woodfuel demand. Uncertainties in this figure arise from uncertainty in efficiency of energy use in different designs of wood-burning stoves, and the percentage of energy obtained from woodfuel in rural and urban populations. The contribution of woodfuel demand to deforestation is predicted to increase by 2030 to up to 83(±50)%. This is due to an increasing population requiring more woodfuel and so contributing to a higher proportion of total deforestation. Biogas production has the potential to reduce deforestation due to woodfuel demand by between 6 and 36% in 2010 and between 4 and 26% in 2030. This is equivalent to 10–40% of total deforestation in 2010, and 9–35% of total deforestation in 2030. The highest contribution to biogas production is likely to be from cattle manure, and the uncertainty in the potential of biogas to reduce deforestation is mainly associated with uncertainties in the amount of biogas produced per animal.