Small Hydro Systems
Tanzania has considerable potential of small hydropower (capacity of less than 10MW). Utilisation of small hydro power has not been optimally realized due to inadequate hydrological data; competing interests between developing the sites and usage of land and water resources by the affected communities and institutions; inadequate technical capacity to design, construct, operate and maintain the projects; lack of transmission infrastructure; and lack of facilities to match load demand with the electrical output.
Other challenges are vandalism of electric power infrastructure; tariffs charged do not generate sufficient revenues to cover capital as well as operation and maintenance costs of the projects; inappropriate standards, legal and regulatory regime, destruction of catchment areas threatens long term viability of small hydro power projects and inadequate financial resources and technical personnel for carrying out feasibility studies and development of sites.
The objective of a small hydropower scheme is to convert the potential energy of a mass of water, flowing in a stream with a certain fall to the turbine (termed the "head"), into electric energy at the lower end of the scheme, where the powerhouse is located. The power output from the scheme is proportional to the flow and to the head.
Although it is not easy to provide a detailed guide on how to evaluate a scheme, it is possible to describe the fundamental steps to be followed, before deciding if one should proceed to a detailed feasibility study or not. A list of the studies that should be undertaken:
1) Topography and geomorphology of the site.
2) Evaluation of the water resource and its generating potential,
3) Site selection and basic layout
4) Hydraulic turbines and generators and their control
5) Environmental impact assessment and mitigation measures.
6) Economic evaluation of the project and financing potential,
7) Institutional framework and administrative procedures to attain the necessary consents.
The water flowing along natural and man-made canals, conducted by low and high-pressure pipes, spilling over weir crests and moving the turbines involves the application of fundamental engineering principles in fluid mechanics.