Small-scale farmers at the Kenyan Coast mainly use fuel wood for cooking.
With the increase in population over the last years this results in
increasing and rapid deforestation, causing direct severe environmental
problems such as increased soil erosion, loss of soil fertility, loss of
water in catchments areas and even loss of biodiversity. Furthermore this
energy source (e.g. wood) is almost exhausted. It is therefore essential
that other means of fuel sources for communities and small-scale farmers
have to be found (e.g. for cooking and lighting).
Alternative system to the drum digesters for renewable energy-resource on small and medium scale
farms and other sources of bio-waste.
Promote and develop a low cost biogas system for small scale farmers
with up to 10 livestock units
System easy to handle while in use
System imbedded in the
environment of organic sustainable
Farmer training in Biogas-production
On 24. December 2004 the PDB was filled and went into
production of biogas.
Bamburi North Quarry, Mombasa, Kenya
The PBD is a cost effective system for the digestion of manure from 1 - 2 livestock
It is built within a short time. However the
design of the grave and the handling of the plastic tube needs extra care.
This digester type has many advantages compared to the oil drum
The PBD can be directly connected to the animal shed in order to capture the
maximum of manure, urine and water and to reduce the handling.
The capacity can be built according to the available manure. 5 m of PBD
with a diameter of 67 cm can be operated with 1 cow.
The gas yield is higher as the retention period is longer.
In a 24-hour period the average gas volume produced was 275 litres
With this amount of gas a low pressure cooker could be operated for
about 1 hour.
Lifespan of the digester is much longer: 2 - 4 years (experience from other
sites) compared to 1 year of the oil drum type (our own
Cheaper to build: For the same amount of produced gas at least 3 oil
drum digesters would be needed
The biofertilizer can directly be brought to the fields as the
concentration is much thinner (more water) compared to the one from the oil
The oil-drum digester however is a good supplement for demonstration purposes as it is possible to look inside the digester and to see what is going on and that there are no hidden gadgets / miracles.