A Social Ekonomic Study of a Small-Scale Biogas Facility. : Designing and construction for a single household for the production of biogas from easily accessible substrates such as human faeces, household waste, garden waste and manure.

Sammanfattning: Increased access to energy is a key factor to reduce poverty and to gain increased development and prosperity. Access to energy is not equally distributed globally. On average a Swedish person consumes more energy than 12 individuals in Tanzania. The Msambara village arose in the 1930s. 80% of the inhabitants are children and the families are large. Life expectancy is 52 years for women and 54 for men. The entire region is very poor and the standard of living in Msambara is low, even compared to other parts of the country. In rural Msambara in Tanzania the cooking method is very primitive and is usually carried out indoors on three stones. Indoor pollution is contributing to eye infections. Incomplete combustion not only emits greenhouse gases increasing global warming, but also more directly emits particles effecting human health. Women and girls are particularly vulnerable to burning caused by air pollution, especially since they are responsible for cooking. The women pull a heavy load in the household work. They are responsible for raising and caring for children, managing farms, collecting firewood, fetching water, visiting the market and cooking for the family. The adoption of biogas technology reduces the need for traditional energy and thereby reduces environmental degradation. In addition, the residue is an improved agricultural fertiliser. Biogas technology has social considerations; burning of biomass for cooking reduces indoor air pollution and reduces workload to collect firewood, often performed by women. Moreover, biogas is desirable from an economic point of view. The method in this work can conveniently be divided into three different parts. These are the designing and construction process as well as the socio-economic study. The socio-economic component is split into two different sections, which are field study and data modelling. The study shows that the social negative impact may or may not be reduced by the introduction of the biogas facility, but the biogas facility in the way it is made will potentially contribute to sustainable economic growth for the household. It also shows that the household’s organic waste produced from human, animal, kitchen and garden waste is enough to provide the necessary gas needed for cooking and no additional firewood will be needed. Two diary cows, in addition to the household’s waste, will provide enough gas needed to introduce cooling capacity for food storage. By adding cooling capacity in the household, time will be saved from the food preparation process but the introduction of biogas itself will not reduce the individual work burden when no cooling capacity is installed. The study also shows that placing the digester in the ground makes a stable environment for the mesophilic and methanogenic microbes. The Socio-economic study indicates that by introducing an alternative method to cooking, positive health effects will arise and the household benefits economically. It is not possible from this thesis to conclude that by adding and treating human toilets as a substrate that possible health benefits will take place.