Mini and micro hydro developments and prospects for electrification of remote locations in Tanzania
3. EXAMPLES OF RECENT MICRO HYDRO DEVELOPMENT
Vast areas of densely populated mountains of Tanzania have little chance for grid connections in the near future.
Off-grid hydropower stations have been developed for coffee, tea and processing plants, mission- and church centres and hospitals; only few of them serve also for the electricity supply of nearby communities.
Starting from village level, hydro mills have been introduced since 1983 with the aim of electrification in a development process. The tendency is now for direct electrification with mills in the villages, where first examples have been implemented.
With the liberalisation of the power sector private investment in hydropower is now an attractive option for micro-, mini-and small hydropower development.
In Tanzania, a country rich in water resources, power generated in big hydro stations cover the main demand. The national grid linking the big centres of the country has been extended to rural development areas in recent years. At the same time vast areas of the water-rich mountains, often densely populated, lack the chance of connection to the grid and depend on their own isolated development.
Diesel engines drive, as power source at low initial investment costs proved uneconomic and not successful, now with prohibitive high prices for the poor rural population.
Great hope lies therefore in the development of waterpower.
In the following the simplified definition of "MHP for "mini and micro hydropower is used, covering the power range of approximately 5 to 900 kW unit size.
2. REVIEW OF DEVELOPMENT OF MHP
2.1 HYDRO ELECTRICITY SUPPLY FOR FARMS AND INSTITUTIONS
The first water power initiatives dates back now 100 years.
In 1986 a survey was done in the area of Tanga and neighbouring regions of small hydropower plants that were not owned by Tanesco, the national Power Corporation.
The development of small hydropower for farms started in the German colonial time and was later intensified during the time of the British mandate. Sisal plants, tea and coffee farms and other processing plants as well as medical and religious institutions built up their own small hydropower stations.
As the "Tanganyika Electricity Supply Company developed the Pangani falls for a bigger power station the supply was connected to the towns of Tanga in the east and Moshi and Arusha in the northwest. Most of the stations, developed for power consumption by their own hydropower were then linked to the grid and most of them gave up their operation in the course of time. (Map/Fig. 1)
The survey revealed the development potential of more than two Megawatt in more than fifteen turbine plants. (Table) At the time of study this development was however not encouraged as Tanesco still had the status of a monopoly company and the parallel operation to the grid was not settled at that time. Similar developments on smaller scale were observed in other areas.
1) There were a number of unidentified ruins
2) Status 1986, now probably far less in operation
2.2 INITIATIVE BY CHURCH COMMUNITIES
Substantial growth in small hydropower development in remote locations came from church communities where their centres as hospitals, schools and other institutions needed power; often the communities around benefited from the electric supply. About twenty stations were developed like this in the time dating now more than fifteen-years back; recent initiatives by church and partner support for local communities show promising results.
2.3 ATTEMPT FOR SHD (SMALL HYDRO DEVELOPMENT)
When the development of small hydropower was focussed on in the 1980s a bilateral supported attempt was made by Tanesco to set up small mini hydropower in remote locations. It turned out that such projects are not feasible as the rural area lack the economic base for the investment and the absorption of the power and the project initiative failed.
2.4 MHP PLANTS DELIVERED TO TANZANIA
There were few suppliers who dominated the provision of hydropower plants. Their reference lists reflect the clients, period of installation activities and the majority of existing plants.
3. EXAMPLES OF RECENT MICRO HYDRO DEVELOPMENT IN TANZANIA
3.1 WATER MILLS AS VILLAGE POWER SOURCE
Twenty years ago, at that time of severe shortage followed by price increase of fuel a first hydro mill (grain mill) was set up in the Usambara Mountains.
In the following years this model of hydro mill has been spread to the southern highlands of Tanzania mainly in the district of Mbinga where eight stations were set up by the communities. In the process of establishing these mills a technology based on local resources was established, Tanzanian technicians and craftsmen trained to erect those plants independently on their own and they have executed the last plants themselves.
Under the supervision of an experienced Tanzanian technician - we may call him a "millwright- the mills with all their steelwork, pipes, gates ... were manufactured locally - leaving only the dependence on the turbine.
Originally it was intended to manufacture cross flow turbines as established in other countries like Nepal, Indonesia and Peru, however this attempt failed due to the resources and declining industrial developments in the eighties. So the technology to use pumps in reverse operation was introduced as a simple reliable technology to be handled by the local people. These pumps were then copied even and manufactured in the country.
Fig. 2: Typical watermill plant
3.2 THE WATER MILL AND ELECTRIFICATION POTENTIAL
As a tradition in the developed countries where the water energy source serves initially for food processing, later as multi-purpose-power source for many activities, industrialisation, leading to electrification ultimately.
The model set up in these Tanzanian watermills leaves the option for electrification:
- All mills are now equipped with car dynamos that charge batteries for the mill lighting, as well as for clients who bring their batteries to the mills for recharging. Small "home systems with energy saving bulbs are now established in the villages around the mills.
- A free shaft of the mill leaves the option to add a generator to be operated in the evening for lighting. This type of electrification is now in preparation after the mills have been serving for a long time and generate an income to the community that justifies the extension for electrification.
Fig. 3: Hydro mill drive for multi-purpose-use:
food processing in daytime - lighting in evening
3.3 FROM WATERMILL TO DIRECT ELECTRIFICATION
As the mills are located near the waterfalls the women have to walk all the way from their home to the mill which is recognised as a great handicap. Therefore the tendency is now to generate electricity at the waterfall site and supply the village with electricity. This model has recently been established in Mavanga, a village in the southern highlands, with great success.
The community executed much of the work whereas the craftsmen, the "fundis, guided by the experienced technician, did the skilled work. Under his guidance the electro-mechanical plant was set up consisting of two pumps working as turbines operating on one generator at a high efficiency, with electronic load controller (ELC). The nine kilometres HT transmission line with transformers, the distributions and hundred-fifty house installations, five mills, connection to hospital, schools and institutions have meanwhile been completed, working reliably since their commissioning one year ago. - The whole project was established and supervised by Tanzanian personnel.
The high investment of the equipment would not have been possible without the support of German partner communities that contributed imported equipment. The local contribution by the development department of the Diocese with their infrastructure facilities gave also the organisational and financial support when establishing the independent community power supply. The community has organised itself and formed committees converted now in the executing body whose members are volunteers and a skilled electrician and a plant operator who are permanently employed and paid by the income of the power sales.
A lump sum is charged for the private houses connected, whereas all commercial consumers such as shops, mills, institutions have to pay a commercial rate, which brings the major income to the community. All tariffs are slightly below the national tariffs to honour the high self-contribution of the community.
As Tanzania is still enjoying a great sympathy from countries abroad and has many benefactors to communities and development initiatives, this model may be a good example of community self-help.
A community mobilisation and the personal initiative of Tanzanians to their own development and their input in money and their dedication shows the way reflecting also the high quality of the communitys spirit in Tanzania.
Fig. 4: Mavanga village hydro electric plant - 2 x 80 kW - pump as turbine
The extension of grid to remote locations is limited, isolated locations have little chance for the development of their hydropower sources for their own supply. Private and community development projects could therefore play an important role.
The legislation has now been prepared for a liberal power market and investment in the power sector is encouraged.
Rules, regulations and the whole frame work required for setting up private power generation should be elaborated to encourage investors and give them the safety for investment and operation.
It is world wide recognised that investment for MHP is initially high and requires support, subsidy, or favourable credits for a take-off.
If bi- or multi-lateral support of any type is given for the development of MHP, ways should be found to let private investors also benefit.
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