Cleaner Integral Utilisation of Sisal Waste for Biogas and Biofertilizers
In Kenya, Tanzania and neighbouring countries biogas is traditionally established in small and very small installations and is used for providing household energy and for supplying social institutions with energy for cooking, heating and lighting.Supported by GTZ, more than 1,000 small and medium-size plants and one bigger digester with more than 100m³ have been installed by CARMATEC in Tanzania from 1983 on.
A pilot project managed by the United Nations Industrial Development Organization (UNIDO) titled 'Cleaner Integral Utilisation of Sisal Waste for Biogas and Biofertilizers' involved a biogas pilot plant at the Hale Sisal Estate in the Korogwe District of Tanga region.
According to press releases the project showed that sisal residues are an efficient substrate for anaerobic digestion generating gas, electricity, and bio-fertilizer. The plant was able to yield 150 kilowatts of electricity from the plantation's harvesting and processing residues, enough to power a nearby hammer mill for pulp making. In 2007, UNIDO announced that the results will be transferred to other interested sisal growing nations for replication.
The Project cost was estimated at US$1.5 million. Financiers included the Common Fund for Commodities (CFC), UNIDO, the Tanzanian Government and privately owned company Katani Limited (http://news.mongabay.com/bioenergy/2007/10/unido-trials-sisal-waste-for-biogas-and.html<span />).
In the report “Small-Scale Bio-energy Initiatives” of Practical Action (2009) this biogas power plant is described as “Case 4 - Tanzania Sisal Biogas”. High potential livelihoods outcomes are stated amongst others: an 80% increase in the number of children attending school and improved health care due to the provision of electricity to the social institutions. However, this positive report also documents that the originally planned second and third phase of the plant development were never realized. This can be seen as an indicator for the potential lack of profitability of the plant.
More recent communications from GTZ staff referring to this sisal farm in Tanzania state that the design didn’t seem to be well adapted to the required sisal operations, and it had substantial operating problems due to technical components of low quality (Franz, v. Mitzlaff, 2009).
