Tubular polyethylene biogas digesters : development and testing of a biogas technology in Malawi to reduce deforestation and support climate change mitigation and adaptation

Abstract: The aim of the study was to install a biogas system consisting of three tubular polyethylene biogas digesters at a rural household in Malawi and to evaluate the constructed biogas system with regards to relevant system parameters. The purpose was to evaluate if the technology is a possible solution to reduce deforestation and support Malawi in climate change mitigation and adaptation. The study was carried out in the southern part of Malawi in cooperation with the University of Malawi. Locally available materials were used to construct and install the system. Three different feed materials, cow, goat and a mix of cow and goat manure, were used in order to determine which one was best suited to utilise as a digester substrate. After the installation, measurements of temperature, pH, biogas production, biogas composition and system functionality were made. The results of the study show that a biogas system with tubular polyethylene biogas digesters can be successfully installed at a rural household and that the most suitable feed material is a mix of cow and goat manure. The study and the conducted testing also makes up basic research to further establishing that tubular polyethylene biogas digesters can be used as a part of the solution to reduce deforestation and support climate change mitigation and adaptation in Malawi.