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Electricity, Heat and Fertilizer from Sisal- Biogas and Waste

Under the main project for "roduct and Market Development for Sisal and Henequen", UNIDO has been working with various stakeholders including at the international level, CFC and FAO and at the local level - M/s. Katani Ltd., Tanzania Sisal Board, Ministry of Agriculture and Food Security, Ministry of Industry, Trade and Marketing, ARI – Mlingano in attempting to move Sisal processing from merely producing the traditional fibre and twine products towards a wider array of industrial products with significant market potentials. It is a well known fact that the traditional methods utilize around 2 to 4 percent of the total Sisal plant and either use the rest as re-fertilizer material or discard it as waste with some detriment to the environment.

Through intensive research and analysis it has been shown that Sisal can be potentially used for the following products:

  • Cordage – Rope, Twine and yarn
  • Composite materials – Automobile components, Construction roofing and paneling materials
  • Woven materials – Carpets, Bags and Buffing cloth
  • Organic fertilizer
  • Animal Feedstock
  • Industrial Alcohol (Ethanol)
  • Pharmaceutical products (Inulin)
  • Pulp and Paper (specialty paper, reinforcement)
  • Energy (Biogas, Electricity)

The last item (Energy) on the above list, has been the focus of the pilot demonstration project, which UNIDO has been contributing to through its initiative on "Rural Energy for productive use" with the support from CFC. In collaboration with personnel from Katani Ltd. And German sub-contractor Bioenergy Berlin Gmbh an electricity generating unit has been setup, utilizing biogas, produced through anaerobic digestion of the sisal processing waste. The project is situated at the Katani Sisal estate in Hale, Tanga. Bioenergy Berlin Gmbh  supplied equipment from China, constructed the civilworks in addition to commissioning the plant and training Katani ltd. Staff in operation and maintenance of the systems.

Appropriate training programs and studytours to biogas production facilities in China, were organized to enable staff at Katani ltd. to gain valuable experience in the operation and maintenance of medium-scale biogas energy systems. The equipment suppliers have remained in close contact with staff at Katani Ltd in order to offer further support. The biogas is produced with the waste derived from the Sisal decortication plant. The stored biogas is then used to run two 150Kw electricity generators for a rated total electricity output of 300 Kw. The electricity is used mainly within the decortication plant and some of the excess can also be supplied to the domestic quarters within the estate. The excess biogas can also be distributed to surrounding communities to cover cooking and lighting requirements.

The project is a good example of how cleaner and renewable energy technologies can significantly reduce environmental pollution and degradation of the ecosystems while providing surplus energy for productive use. Soil fertility will also be improved by the bio-fertilizer by-products from the process. The project demonstrates the potential for significantly improving economic viability for the sisal processing industry through the provision of cheaper and cleaner energy generated from process waste and thus enhancing overall competitiveness in local and international markets. Excess energy produced in this manner can be potentially fed to the grid or  distributed to surrounding rural populations.

The concept on production of bio-energy from sisal waste was developed in 2005 within the context of the larger CFC - financed “Product and Market Development of Sisal and Henequen Products” project. Katani Ltd, are the main counterpart together with the Ministry of Agriculture and Food Security and Tanzania Sisal Board.

Future Outlook

The concept of using agro and agro-processing wastes for the generation of energy is one that has been successfully  applied in various projects utilizing a wide variety of agro-waste stock. The technology lends itself to easy replication within Tanzania and Africa, in the wider context. Although the particular application of Sisal processing waste for production of biogas on this scale is first, the production of biogas from organic wastes is common around the world and the technology has been developed to cater for all types of requirements – micro, small, medium and large scale production units are available which utilize a wide variety of organic feedstock for production of heat and electricity.

Africa has large amounts of biomass resources, which if appropriately harnessed could go a long way towards meeting the energy requirements of local communities.

 


Sisal bio-gas plant