TDBP is a large scale project in the energy for cooking challenge. By installing biogas tanks in households the project aims at introducing a modern form of energy, methane gas, to substitute traditional biomass. The gas is produced by the bio-degradation of cattle dejections. Project target is 12.000 biogas tanks installed in rural areas by 2014.
In Tanzania wood is the main domestic fuel meeting 94% of national demand. 80% of its consumption is in rural area for domestic uses. Poor households spend a considerable share of their income, up to 35%, on domestic energy. Wood collection is a time-consuming activity and fuel wood is responsible for respiratory diseases and premature death especially in woman and children. The project consists in the installation of biogas tanks in rural households. Households need to have regular access to water and a minimum of 2 cows. The cow dejections are collected in the biogas tank where the methane emissions are captured and delivered to the kitchen to be used as fuel for cooking. The inert waste is used as fertilizer in agriculture. The project implied a preliminary assessment of alternative biogas technologies. A technology consisting in a gas tank built with bricks and cement was selected. The tank size may differ according to energy demand and the number of cows to feed the system. The brick and cement option is more expensive than alternatives but more durable and reliable. The project contributes to the energy for cooking challenge by exploiting a different source of fuel than wood. This is done by a decentralized model of gas production. Biogas tanks are locally built by a well-trained network of technicians. The technology is appropriate in rural areas where water and cows are available.
Tanzanian rural communities (some 70.000 individuals in 12.000 households) and the technicians involved in the project.
The project estimates 8,796 biogas plants installed by December 2013. Considering 6 people per household, direct beneficiaries are estimated around 55,000 corresponding to 0,2% of the rural population. Access to biogas means to benefit from a modern form of energy with lower pollution in the house, shorter time for cooking, collecting wood and setting the fire. The impact of the project in terms of avoided use of biomass is estimated in nearly 100,000 tons of biomass per year corresponding to some 8,000 ha of forested area saved from energy use. Avoided CO2 emission is calculated in 60,000 tons. Workload reduction on woman and children in some 2000 person-years. Direct employment creation at 840 person-years. The introduction of biogas plants also improves hygiene standards in households especially when human toilets are connected to the system. An indirect impact may also be seen in the increase of natural fertilizer available for agricultural uses.
The business model is designed on a decentralized strategy where technicians are the promoters of biogas in communities. Technicians from different areas of the country are trained. Each technician is asked to build two tanks, if successful he is supported to start up an own business. The project does not introduce cash incentives. Dissemination is done by word of mouth by observing the benefits of built plants. Micro credit schemes are introduced. The cost of a biogas plant ranges from 600 to 900€.
The management of a biogas plant needs a daily effort to feed and clean the tank. The household level has emerged as the most reliable context for installation. Biogas plants in institutional places, such as schools, have shown weak sustainability. The beneficiary needs a simple and reliable system to be managed. The project focuses on biogas from animal dejection only. No other organic matter is used for biogas production. In particular agricultural or vegetable residues are not used. The preliminary market and technology assessment proved to be useful in the project implementation. Potential biogas customers emerged to be more interested in a durable and reliable option than in a cheaper one.
TDBP is part of the Africa Biogas Partnership Programme, a partnership between the Netherlands’ Directorate General for International Cooperation (DGIS) that provides financial support, Hivos, responsible for fund management, and SNV for technical assistance. Camartec, a Tanzanian para-statal institution, is TDBP’s National Implementing Agency. The coordination and the management of the project is done by Camartec in Tanzania, assuring a strong ownership of project results. Locally TDBP tries to involve NGOs to enhance project dissemination in the communities and scale-up the project’s results. The Africa Biogas Partnership Programmme aims at replicating the strategy in Senegal, Burkina, Kenya, Uganda, Ethiopia for an overall target of 70.000 tanks . The work of the technicians is periodically assessed and monitored by Camartec. The project publishes and makes available project documentation, technical reports and system designs.
The drawing posted refers to a bio gas plant, specifically: • A concrete basin is built to mix cow dung, 1A. The basin is connected to the digester with a PVC pipe. Human toilette can also be connected, 1B. • The gas produced by the bio-degradation in anaerobic conditions of excrements accumulates in the top part of the digester, 2. The gas pressure pushes the exhausted sludges into the top chamber, 3. The top chamber gives pressure for the gas to reach the kitchen when the gas is fired; • through a valve, 4A, a pipe leads the gas to the kitchen, 5. An additional valve, 4B is for security purposes; • on the lowest point of the pipe a water trap, 6 is positioned in order to collect the condensing water that may obstruct the pipe. A valve let discharge the water on occurrence; • the residue of the anaerobic digestion process can be used as an organic fertilizer in agriculture, 7 A minimum of 20 kg of manure is daily required to feed the plant. A minimum of two cows is required. The ratio between cattle dung and water to feed the plant is 1 to 1.
Netherlands’ Directorate General for International Cooperation
Hivos, SNV, Camartec (NGOs)