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Tropentag, September 20 - 22, 2017 in Bonn

"Future Agriculture: Social-ecological transitions and bio-cultural shifts"

Participative Development of a Top-Lit-Up-Draft Reactor for Simultaneous Cooking and Biochar Making

Yusto Yustas1, Valerian Silayo2, Frieder Graef3, Lutengano Mwinuka4

1Sokoine University of Agriculture (SUA), Engineering Sci. and Techn., Tanzania
2Sokoine University of Agriculture (SUA), Agri. Engin. and Land Planning, Tanzania
3Leibniz Centre for Agricultural Landscape Research (ZALF), Inst. for Land Use Systems, Germany
4The University of Dodoma (UDOM), Dept. of Economics and Statistics, Tanzania


In many countries biochar is being used as a valuable soil amendment improving the soil structure and nutrient holding and exchange capacity on a long-term base. Up to date many different technical devices with different capacities and technical qualities have been developed to produce the required biochar. The material used to feed these devices ranges from forest products to agricultural residues like maize cobs.
The present study describes the participative and gradual adaptation of an existing 200 litre Top-Lit-Up-Draft (TLUD) reactor (Pyrolyser) in Tanzania that as a first version was solely used for biochar production. After reflective stakeholder-scientist consultations it was sought to find a solution sufficing local demands of adding a cooking component to the biochar making by synchronising both. This device should be economically and technically feasible at minimal costs in Tanzania. A new reactor was designed to meet the requirements. Iteratively, modifications and test trials of the existing TLUD reactor design were done, and then the new reactor and its operating protocol were obtained and tested. The results showed that the new reactor, on average boiled 4.5 litres of water at 93°C within 44 minutes. Also, it produced 0.30 kg of biochar per kg of cobs fed, totalling 6.0 kg per reactor minimal filling. The reactor average operating temperature was 159°C. The initial cost (€ 68) of acquiring the new reactor may not be affordable for singe households in rural area but for stakeholder groups using it together. Household's saving which may be gained from commercialising the new reactor is assumed to amount (€ 37)/month. Apart from these promising parameters of the new reactor, more research is needed to unleash the full potential of its applicability in rural areas.

Keywords: Biochar, cobs, cooking, energy, fertiliser, firewood, household, reactor, TLUD, top-lit-up-draft

Contact Address: Yusto Yustas, Sokoine University of Agriculture (SUA), Engineering Sci. and Techn., SUA-DEST, Morogoro, Tanzania, e-mail: omukama.mugisha@gmail.com

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