Building a hydropower plant, even small hydro plants, in almost all cases is a project which requires a larger investment.
Again the omnipresent question of feasibility often rules out minor projects even if the realization would be a success for the area. Not the production of electricity only but as well operating pumping stations and water treatment plants is a major purpose for hydropower.
Small hydropower stations in the range of up to 300 kW do have two outstanding advantages: They work independently from any grid as long as the water flow is reasonably constant, and they do not require the erection of long power lines that sometimes are subject to break downs by heavy weather, bush fires etc.
The most important condition to erect a small hydropower plant is that the contractor, if possible, can provide all components and do research, surveying and planning of the whole project.
Amongst many others, the Fonjumetaw project proved that it is possible to erect a micro hydropower plant at reasonable costs:
The enquiry was received by Heidemann Wasserkraftanlagen in 1988. The project was in a village called Fonjumetaw, about 30 km from the district city Dschang in the north west cameroon mountains .
As new equipment was basically considered too expensive it was decided to use refurbished components (link>refurbished turbines). After investigation it was found, that during the wet season there was plenty of water, but towards the end of the dry season the water flow could drop to a flow of 50 l/s. The best compromise was to use the average flow of approx. 400 l/s. so a maximum output of 50 kW, available over a substantial time of the year could be achieved, which was sufficient to power the hospital and a few small companies.
Difficult landscape and geological conditions required a difficult tracking of the penstock which had to rest on tall pylons, crossing the creek several times. A little weir catching the water from the creek without damming up too much was built across the valley in approx. 300 m distance from the power house.
A Francis spiral turbine was chosen which was produced in 1941 by Voith Heidenheim in Germany. Considering the remote position of the power plant it was decided to use also a refurbished speed governor and tirrill tension regulator rather than electronic controlling equipment. These components are no black boxes that need replacement or specialists and do have long delivery times, besides high costs, in case of failure, but are easily repairable by trained local people. Preparatory work began in fall 1988, construction in January 1989. In April 1989 the whole power plant was completed:
The dam, a penstock of 360 m length and 600 mm diameter, following a difficult track on pylons to the power house, the spiral francis turbine, speed governor, synchronous generator, switchboard and a 1,2 km powerline to the village.
The output is 50 kW at a head of 20 m and a max. consumption of 360 l/s During the past six years the power plant has been working with just one remarkable problem in the tension control system which could be solved by a few telephone calls and an on site repair by local personnel.
Remote area hydropower plants not necessarily have to produce electric energy but can also drive pumps directly. This applies when no or little electric energy is required and transforming losses can be aoided. An auxiliary small 220 VAC generator can be fitted to produce a minimum of electricity for lighting and controlling.
Carrying out complete small hydro projects has been and will remain a priority of Heidemann Wasserkraftanlagen.