From Tables 1 and 2, note the high level of use of biogas plants especially in Nandi area. The level of
adoption is mainly attributed to the dissemination strategy adopted by CITC. A biogas extension service
has been established to provide advice and post-installation support services to the users. The
approach has helped users to properly operate and maintain their biogas plants. On the other hand,
areas like Kisumu where customer support is inadequate, levels of use are generally low.
Factors affecting the performance of biogas plants.
The survey identified certain crucial factors which contribute to successful performance of biogas
plants. They include:
Technical problems
The most important cause of abandonment of plants after installation is technical in nature and mostly
relates to leaking gas holders, digesters and gas delivery pipes.
Water
A significant number of the plants visited in Meru were found to have been abandoned after the water
supply the system originally depended on, broke down. The amounts of water the farmers were able to
collect from distant rivers or boreholes was only sufficient for domestic use. There is need for adequate
supply of water if operation of biogas plants is to be successful. Water is needed for mixing the cow
dung to form slurry and for cleaning the zero-grazing unit.
Number of cows
A family of eight in Eldoret with only one cow was struggling to find enough dung to feed the plant. The
plant was producing very little gas and the family had to switch to woodfuel to meet their energy needs.
Mode of stock keeping
In another case in Meru, a user was having problems operating his plant despite owning five cows. The
problem was related to his mode of keeping his stock. He had not stabled his cows and collection of
dung was difficult and tiring. The cows were living on a three-acre farm and collection of dung required
that the farm worker move to all corners of the farm collecting dung; a task that he never did
satisfactorily. As a result, very small amounts of dung were collected. The dung was then mixed with
excessive quantities of water forming a slurry with low organic content which could only produce
meagre amounts of gas.
Size of the biogas plant/energy requirements
Twenty five per cent of the plants visited in Meru were not producing enough gas to meet the users'
energy needs. By systematically eliminating other factors that could cause low gas production, the
problem was traced back to the capacity of the installed plants. Daily gas output was low in relation to
the amounts required for cooking and lighting. The situation was observed in all areas except Nandi
and Eldoret.
Arrangement of biogas system components
The biogas system comprises the zero-grazing unit, the biogas plant, farm house (where biogas
appliances are located) and the farm on which the slurry is applied. To keep the labour input minimal,
the system needs to be well-planned. First, the distance between components should be as short as
possible. Secondly, the zero-grazing unit should be located on a higher ground than the other
components of the system. In situations where the terrain is sloppy, the biogas plant should be located
on the higher part of the slope.
In cases where the arrangement of components is not properly done, operational difficulties related to
increased labour input were evident. For example, there was irregular feeding of the plant and
consequently, suboptimal performance.