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< prev - next > Energy Biogas biogas_experience_sri_lanka (Printable PDF)
Biogas technology and integrated development
Practical Action
Biogas plant owners were given training on operation and maintenance of
biogas units.
Some Impacts Of The Project
In Sri Lanka, women in rural villages are usually expected to provide hard
labour for domestic activities with little time for leisure. Involvement in the
collection of firewood for cooking, cleaning of animal sheds, fetching water for
drinking and washing take up all their time. While the introduction of biogas
does not solve all these issues, it has reduced the time women spend in the
collection of firewood and in the kitchen cooking and cleaning utensils. A recent
study done by Practical Action South Asia shows that 75% of the energy
requirement for cooking in these households are supplied by their household
biogas units. The women and girl children in average save 2 - 2 1/2 hours per
day when cooking with gas. Most of these females (79%) use this time for some
income earning activities in which they earn the equivalent of 24% of their
monthly income.
Women in beneficiary households who raise animals have expressed their
satisfaction with biogas units because it reduces their time in disposal of animal
waste. Previously, they collected animal waste and disposed of it far away from
the sheds, which was a time consuming and tiresome activity. Now the animal
waste is being diverted to the nearby biogas units with minimum effort. In
addition to the time saving, households using biogas have gained fairly high
social status in the villages.
A study has also shown that 30% of the households who own a biogas unit had
earlier used kerosene lamps. 82% of them were using bottle lamps which poses
severe health hazards. As highlighted earlier, the fertiliser value of the slurry is
an important determinant in adopting the biogas technology.
Therefore, the project initiated a study with the Department of Agriculture
Engineering, University of Ruhuna, to evaluate the bio fertilizer aspects of the
As revealed by this preliminary experiment conducted on fertilizer values of the
by-products of straw digesters, it has been documented that digested material is
enhanced with NPK after going through the digester due to the activities of the
microbial population. Therefore, the by-products have a very high bio fertilizer
value, which help to reduce the fertilizer budget of the farmer significantly. As
revealed by the experiments, 10 tons of digested straw can replace the entire
fertilizer demand of one hectare of paddy field. As such, if the average
landholding of a farmer is 0.25 ha, his entire fertilizer demand could be met with
two digesters of 1 ton capacity. Moreover, with current trends, rice grown with
bio (organic) fertiliser can fetch a high price in the market.
Another positive observation noted by some users were that when the slurry is
diluted with water and sprayed on green chilies, the plant is protected from leaf
disease. Leaves of plants grown on soil applied with slurry have shown greater
While energy and fertiliser remain the main uses of biogas at household level, it