2.6
Livestock
Keepers Group in Karatu
“(Kikundi cha Wafugaji Karatu – KIWAKA)”
2.6.1
Introduction
One member of the group participated in the
exhibition. The tubular plastic biodigester was demonstrated (Plate 14). The
digester is a low cost family size biogas system which use plastic sleeves to
meet the real economic concerns of rural farmers. It substitutes the use of
fuelwood and reduces pressure on forests.
Plate 14.
Exhibitor demonstrating the tubular
plastic biodigester
Due to their suitable carbon to nitrogen ratio(C:N)
and total solid content, cattle, pig and poultry manure is highly recommended as
raw materials for biogas production. Two cattle or eight pigs are enough to
produce dung for a 5m3 bio-digester, which produce enough gas for a
family of six people. The digester
provides gas at a rate of 0.354 M3 per day sufficient to cook meals for about 3
hours (Fig. 3).
Fig. 3 Low cost plastic Biodigester
6.1.1.1.1.1.1.1.1
O-GAS
In
order to maintain continuous production of biogas, six stages
are
involved. (Fig. 4)
2.6.2
Biogas production and utilization
Biogas technology has several advantages under
agroforestry systems (agrosilvopastoral and silvopastoral systems) and in
protecting the environment. The
major advantages are;
(a)
It provides alternative to fuelwood and thus reducing the rate of
deforestation
(b)
Improves women welfare by reducing workload of collecting fuelwood
(c)
Improves crop-tree livestock farming system through nutrient recycling.
(d)
Improves the health of women and children (otherwise exposed to harmful
smoke and fumes from traditional fuels) and provides non-polluting and smokeless
kitchen.
(e)
It is a relatively cheap source of energy compared to other fuel.
(f)
It promotes health by the safe treatment of manure-particularly human
wastes to prevent the spread of diseases.
As a renewable energy it provides reliable power
supply and is an environmentally friendly technology.
2.6.3
Benefits
and cost comparison
Bio-gas offers ernomous economic, social and
ecological advantages and has an important role to play in providing sustainable
energy production Lekule(1996), reported that, after adoption of biogas
digesters in Tanzania, woodfuel consumption decreased by 60%.
Comparing with other energy sources i.e. charcoal and
kerosene, a survey conducted in Tanzania showed that 3 bags of charcoal and 121
litres of kerosene were consumed per month in a family of six. If converted to
money, it is approximately U$ 8 for charcoal and U $ 49 for kerosene which
presents a real saving when biogas is used.
Construction cost of tubular plastic sleeve
bio-digester is less than US $ 100 as compared to US $ 1000, when constructing
large-scale conventional bio-gas plants (Table 1).
Table 1:
Estimated costs of materials for a family size tubular plastic bio-digester
based on the installation cost of bio-digesters in Tanzania
ITEM |
QUANTITY |
COST (U$) |
Polythene sheet(0.2)mm thick) |
18
kg |
40 |
Gas pipe (21 mm)id) |
15m |
9 |
PVC"T" and "L" pieces |
6 |
3.2 |
Steel pipe |
0.75m |
3 |
A tap (to control gas flow) |
1 |
3 |
PVC for inlet and outlet |
1.2m |
2.4 |
PVC, (10mm id) |
1 |
1.2 |
Inner tube strips |
20 |
0.6 |
Plastic bottle |
1 |
0.5 |
TOTAL |
|
62.9 |
SOURCES: Lekule (1996) |
|
|
For more information please contact;-
Mr. Emmanuel Silloh,
Kikundi cha wafugaji Karatu (KIWAKA),
P. O. Box
92, KARATU - ARUSHA.
The Management East African Crossborder Biodiversity Project acknowledges the East African Co-operation secretariat for the invitation to support the Exhibition by Jua Kali/Nguvu Kazi during the signing of the East African Cooperation Treaty.
We are grateful to the commitment and contribution from;
(a)
The Tanzania Association of Foresters (TAF) especially Mr. Jacob Mushi,
Executive Secretary for the overall coordination and guidance to other
participants
(b)
Mr. J. Massao and family Tree Nursery
(c)
KAKUTE Limited
(d)
TEMDO, Arusha
(e)
Njiro Wildlife Research Centre
(f)
“KIWAKA”
(g)
CAMARTEC
(h)
UNDP-GEF East African Crossborder Biodiversity Staff, Arusha
Special thanks are due to Mr. & Mrs. J. Massao of
“Matumizi endelevu ya misitu ya asili Iringa”. (Sustainable utilization of
natural resources and biodiversity conservation) Iringa for their support into
compilation of these proceedings.