Energy recovery from sludges: selection of case studies in Subsaharan Africa

Energy and waste management and water supply are possible means of increasing the quality of life in development countries. One of the Millennium Development Goals (MDG, defined by the UN in September 2000) is to halve, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation (under MDG 7 Ensure environmental sustainability). Although access to energy is not explicitly included in the MDG list, it surely may enable to reach some of these goals, such as: • MDG 1 Eradicate extreme poverty and hunger, trough the development of small economic activities to supply energy services to the population; • MDG 2 Achieve universal primary education: supplying energy to primary and secondary schools the access to education and communication will be extended; • MDG 3 Promote gender equality and empower women: the reduction of wood consumption will increase women quality of life, leaving them enough time to develop their economic activities; • MDG 4 Reduce Child Mortality Rate and MDG 5 Improve maternal health, reducing the exposure to indoor pollutants produced during the wood combustion in poorly efficient stoves; • MDG 7: Ensure environmental sustainability, reducing the deforestation. In this paper we present two different case studies were organic waste management, access to clean water and energy were faced: water supply and sanitation in Ghana; sanitation and energy supply in northern Tanzania. The water supply and sanitation sector in Ghana faces severe problems even if the sector has been gradually modernized through the creation of an autonomous regulatory agency, introduction of private sector participation, and decentralization of the rural supply. The water supply and sanitation infrastructure is insufficient, especially in rural areas and concerning sanitation, with a very poor control oh hygienic aspects. The proposal regards toilet facilities building and wastewater depuration system. The proposed solution can contribute to face the problem of water supply and sanitation and can be easily adopted and results interesting also under the economic point of view. Best Ray - Bringing Energy Service to Tanzania Rural Area is an European Commission funded project (2008-2011) that aims at providing energy services to poor un-served rural communities living in Arumeru District, Northern Tanzania, through appropriate and renewable technologies. A particular attention was focused on biogas technologies, trough the participation to the Tanzanian Domestic Biogas Programme. Domestic biogas plants convert animal manure and human excrement at household level into small, but valuable, amounts of combustible methane gas that can be used in simple gas stoves for cooking or in lamps for lighting. Farmers may use biogas especially in remote rural areas where the electric grid is still not present or would be too costly to be developed. Given the success history of TDBP, the Best Ray project team explored the possibility to install three bigger biogas plants to supply energy for the kitchens of three secondary schools. Biogas plants can be connected directly to the toilets. In this case Biogas production from toilet can fulfill between 9 a 19% of the secondary schools energy requirement. In order to completely substitute wood consumption, between 25 and 108 cows would be needed in the three schools. The introduction of cattle in the school is not feasible in the short term and goes beyond the project goals. Furthermore, the most critical issues are those regarding the management of the plants: it is not clear who would be responsible for the proper management of the plant. Turn over of personnel in the secondary school is unpredictable and often occurs. Training of local personnel is therefore not enough to assure the management of the plan in the coming years. Sludge disposal is also a critical issue: sludge obtained from human manure may have residual pathogen load and must be treated properly. One possibility would be to use it in jatropha plantations, since jatropha is not edible, but plantations are too close to the classrooms and/or to the dormitories, causing odour and health risks. Considering the limited impact of biogas production on wood consumption and the relevant risks associated with the construction and the management of the plan the suggestion was to give up the project of biogas in school. On the contrary the experiences gained on the domestic biogas program and the success of the pilot projects are showing a much larger potential for a small scale biogas plans dissemination. To make a biogas plan sustainable in the medium long run it is necessary that the management, the ownership and the benefit of the installation to be in the same individual. This can only be obtained at domestic level. Finally, since all the schools consume more wood than expected, a better investment would be the investigation of the causes of this over consumption and eventually the substitution of the fireplace with more efficient ones. Biogas plants for cooking and lighting in this particular area can be seen as an appropriate technology when they are installed in households, while show too many management problems when installed in schools, resulting there totally unappropriate.