Waste valorisation opportunities for bush encroacher biomass in savannah ecosystems: a comparative case analysis of Botswana and Namibia

Bush encroachment of savannah ecosystems in countries like Botswana and Namibia has been identified as a major problem threatening biodiversity, grazing land productivity and the generation of groundwater. Incidentally, the same problem presents a huge biomass energy resource opportunity which can be exploited through various technologies. This paper defines the scope of the problem in Botswana, comparing with the well documented and partly proven case of encroacher bush waste valorisation in Namibia. This biomass is therefore a large homogeneous sustainable waste resource base that is perennially available, due to the drought-hardiness of the encroachers. It is however, necessary to conduct preliminary studies to explore prospects and possibilities, benchmarking with globally renowned biomass experts like Germany and the United Kingdom. The study shows that the issue of bush encroachment in Botswana has been documented from as far back as 1971, though earlier studies were mostly evaluations from a natural resources perspective which did not proffer solutions. Besides a project by United Nations Development Programme to try and benchmark from Namibia’s biomass to charcoal initiatives from their encroacher bushes, there is no documented effort by Botswana to derive value out of the vast resource which has invaded thousands of hectares of rangelands. Meanwhile, Namibia has recorded significant success in converting the encroacher bushes into wood chips for use in boilers (heat production) for a cement plant, charcoal for domestic and commercial heating/cooking and briquettes for power generation. Feasibility studies have been made for the possibility of scaling up these projects, while exploring other existing and emerging sustainable technologies like pelletizing, gasification, pyrolysis and engineered wood products. Essentially, a review of the existing problem in Botswana, experiences for various cases and recommendations by experts make this compilation valuable for the nation and other regions experiencing the same problem.