K A I N J I POWER STATION: AN OVERVIEW

Power supply in Nigeria started in Lagos in 1896, when the men came to this part of the world to exploit raw materials for their industry.

As the move from the coastal area of Lagos to the interior to exploit cocoa in the West, Rubber and oil in the East and groundnut in the North, they stalled more generators in Kaduna, Ibadan, Enugu and Kano.

These generators were maintained and controlled by Public Works Department (PWD).

By 1950, Electricity Corporation of Nigeria (ECN) was established. Therefore, the control and maintenance of the Electricity undertakings were taken from PWD and handed over to ECN.

When the growth of industries and rapid urbanization; the demand for electricity rose faster than supply. This prompted the ECN, in 1951 to authorize the study of the HYDRO-ELECTRIC POTENTIALS of River Niger for large and cheap supply of Electricity.deral Government, in 1963 commissioned Netherland Engineering Consultant (NEDECO) to carry out hydrological survey of the Niger and Benue Rivers, followed by (ECN) in 1958, who commissioned Balfour Beatty Company Ltd. to specifically study hydrological potentials of the Niger, around Jebba.

The two Engineering Consulting Firms – NEDECO and Balfour Beatty – published their joints reports in 1961. The report recommended that the first dam be built at Kainji about 102 Kilometres up stream of Jebba.

By 1962, Niger Dams Authority (NDA) was instituted by an act of parliament the proposed Hydro – Electric Station in Kainji.

The construction work was contracted to IMPREGILO as major contractor. IMPREGILO is a consortium of three Italian companies: Impresit, Giriola and Lodigiani. Fund for the construction of the dam was provided by the following governments and international organizations:

  1. Federal Government of Nigeria
  2. Government of Netherlands
  3. International Bank for Reconstruction and development
  4. Institute Di credito per le imprese Di publica Utilita
  5. U.K. Export credit Guarantee Department

Construction work on Kainji Dam took off in 1964 with an inaugural ceremony performed by the then Prime Minister of the Federation, Alhaji Abubakar Tafawa Balewa. In his speech, he said. This is a practical Nigerian Project that will supply Electricity to every region in the federation and create room for greater unity.

The construction lasted for four years. By 1968, it was ready for commissioning with 4 sets of Kaplan turbines, Units 7, 8, 9 & 10 of 80MW each totaling 320MW. The station was officially commissioned in February 1969 by Major General Yakubu Gowon.

In 1976, two additional sets of Kaplan turbine, Units 11 & 12 of 100MW each were installed, bringing the installed capacity of the station to 520MW.

To further increase the installed capacity, two additional sets of fixed blade or base load machines were installed, Units 5 & 6 of 120MW each, making the total installed capacity of the station to be 760MW in 1978.

Units 1, 2, 3, & 4 are open pits fervently awaiting the installations of additional four machines to beef up power generation. The installation of these four machines will complete the design of Kainji Power Station to effectively stabilize Power Supply in Nigeria.

 KAINJI LAKE OR RESERVOIR

The formation of the Lake at the completion of the dam caused the resettlement of 44,000 people of Borgu Emirate and Yauri Emirate.

They were resettled at New Bussa and Yelwa. The Lake has two flooding seasons, the white flood and the black flood. The white flood is the accumulation of rainfall within the country that flows into the Lake. While the Black flood is the accumulation of rainfall from Gunea, Mali and Niger that flows into the Lake. The White flood arrives the lake in July since its journey to the Lake is not too far from the Lake. The Black flood arrives in December as it has to travel long distance from Guinea, Mali and Niger Republic to the Lake.

The length of the Lake is 136 Kilometres long. The Width is 24 Kilometres at its widest point with maximum head elevation at 141.73 meters. While the maximum tail elevations is 104 meters. The minimum head elevation at which the plant can operate is 132 meters. The total storage capacity is 15 billion cubic meters, 3 billion constitute the dead storage, that is, water below the pen stock. The remaining 12 billion constitute the life or usable storage.

The hydrology department of the station monitors the water from its source at Futa Jalion highland in Guinea for water management.

The department takes the data inflow of water into the Lake and the ourflows, such as Turbine discharge, spill way discharge, evaporation and spillage.

THE DAM

The dam is across River Niger on kainji Island. It was built to impound water to generate Electricity. It has the main dam and the Saddle dam. The main dam consists of the concrete dam. The Saddle dam is a safety device to ease the main dam in the event of flooding. The Saddle dam us rock filled.

The dam has intake gates, each intake has a steel opening of 8.55 meters in diameter. This is called the penstock. It is where water from the Lake passes through to rotate the turbine and convert mechanical energy to electrical energy.

The height of the dam from its toe to the crest is 65.5meters. The length is 8.04 Kilometers. In compliance with the international law on dams across international rivers, Kainji dam has two navigational locks the upper and lower locks.

These locks are opened for the navigation of barges of boats from the upstream to downstream of the dam.

DAM INSTRUMENTATION

The purpose of dam instrumentation is to monitor the safe data behavior of the fill dam embankment and the concrete structure operation and timely warming if the development of any unusual condition overall structure stability of the different part of the dam e.g.

  1. Main dam consist of the concrete gravity structure
  2. The rock fill dam right fill dam and left fill dam.
  3. Saddle dam

 The equipment use for monitoring the safety of the dam is as follows:

  1. Piezometer Hydro Piezometer electronic piezometer
  2. Plumb line
  3. Extenzometer (Rod & Tape)
  4. Relief well
  5. Stand well
  6. Seepage measurement
  7. Extension Gauge
  8. Totalizing Wear

RELIEF WELL

The purpose of relief well is to reduce the seepage pressure in the soil foundation at the toe of the dam

STAND PIPES

The purpose of the stand pipe is to check the seepage pressure which could lead to piping or jeopardize the stability of the saddle dam through the foundation

SEEPAGE MEASUREMENT

The seepage observation to the detection and interpretation of changes in the rate and characteristics of the flow, knowledge of the leakage past of the dam.

EXTENTION GAUGE

Monitor deflection of the dam embankment and settlement of the dam embankment.

TOTALIZING WEAR

To monitor the total seepage water at the toe of the saddle dam.

THE PIEZOMETER

Hydraulic piezometer are used to monitor the pore pressure the piezometer and embedded in the core material of the rock fill dam. They are also installed in the foundation and the embankments, and so also the electronic piezometer are used to monitor water pressure in the dam foundation and embankment.

PLUMB LINE

The plumb lines are installed in the concrete dam to measure the displacement of the part of the structure relating to a fixed other foundation level. They are installed in the spillway, intake block 1, intake block 6, intake block 10, service bays and one inverted in intake block 1. The only one indirect plumb lines monitor the movement of the dam foundation relating to the anchor is observed.

EXTENZOMETER

The purpose is to monitor the swelling of the concrete structure due to attach aggregate reaction in the concrete dam and across the spillway gate. The rod also monitor the deflection and structure change in the concrete dam.

HYDROLOGICAL INFORMATION

1.         Crest Maximum Elevation                      -           145.0m

2.         Maximum Lake Elevation                       -           141.0m

3.         Minimum Lake Elevation                        -           129.0m

4.         Normal Maximum tail race Elevation       -           129.0m

5.         Maximum Crest Height to Foundation      -           65.5m

6.         Length of Dam                                       -           5.50m

7.         Spillway (Four Radial Gates)                  -           15m x 15.3m x each

8.         Spillway Discharge Capacity                  -           7900m3/sec

9.         Intake gate 24 fixed wheel                      -           4.88m x 10.8

10.        Hydraulic head                                      -           24m 42.2m

11.        Navigation                                             -           13400m3

12.        Length of Improve River Channel            -           6500m

13.        Awuru lock maximum height                   -           7.7m

14.        Total Storage                                         -           15 x 103m3

15.        Maximum Useable Storage                     -           12 x 103m3

16.        Minimum Useable Storage                      -           3 x 103m3

17.        Length of Kainji Reservoir                       -           136km

18.        Maximum width of the widest portion       -           24km

 

For convenient hydrological operations, River Niger is divided into Upper Niger, Middle Niger and Lower Niger. Kainji Dam is located on the middle Niger. At this area, it is fed by many tributaries such as R. Malando, R. Danzaki and R. Sokoto/Rima etc.

Kainji reservoir experiences two dual flood regime, i.e. Black and white flood. Back water effect of the reservoir can be felt as far back as Kawara Village after Yauri in Kebbi State. Measurement of rise and fall of Lake Elevation on daily basis in an hydrological priority.

Monitoring of the tributary and main channel flows by current mater method (discharge measurement) which facilitates the study of the regime of each river flow into the basic and this enhances optimum power generation. Biannual maintenance of automatic and manual staff gauges of the entire basin is another important priority so as to acquire regular and accurate hydrological data.

TRANSFORMER DECK

The step-up and step-down transformers are sited on the transformer deck. The step-up is used to step-up voltages from 16kv to 330kv to the National grid. While the step-down is used to step-down voltages from 16kv to 11kv for station services or local use.

THE SWITCH YARD

The switch yard is situated on the remaining part of Kainji Island. Electricity is transmitted from the transformer deck through 6 x 330ka lines to the switch yard. Each line at the switch yard has Sf6 breaker to break circuit when there is fault. From the switch yard, it is switched on through 2 x 33kv lines to Jebba transmitting station and 1 x 330v lines to Birnin-Kebbi transmitting station.

COMMUNICATION

The station generates Electricity into a poll called the National grid, being controlled by National Control Centre (NCC) at Osogbo in order to communicate systems in its communication network. The communication systems are Nitel Plc., Telex Intercom, Fax and Radio.

CONTROL ROOM

The control room is the power room of the station. It is from this room all the plant operations are controlled.

STAFF SCHOOLS AND TRAINING

The power station has Primary and Secondary Schools for Staff Children and other Children of the Community. Students of various institutions come to Kainji for visual and practical learning either on industrial attachement (IT) or educational visit.

PHCN HOSPITAL

The station has since inception, been able to keep the population of the community healthy. This has been made possible by the well equipped hospital with qualified personnel being operated and managed by kainji Power Station.

SPORT AND SOCIAL CLUB

Sporting and recreational facilities are provided by management for sports development and social interaction. This, no doubt has eased tension, reduced boredom and created sound minds in the sound bodies.

IMPORTANCE OF THE STATION

Kainji is the main stay of power generation in Nigeria. Since its machines are suitable for frequency regulation to sustain power generation. Therefore, the station’s importance cuts across every stratum of human endeavors, Political, Social, Economic, Tourism, Navigation, Fishing, Agriculture.

POLITICAL

The station fosters unity, as it renders services to every part of the country and different tribes live together as staff of the station.

SOCIAL

Social institutions like School, Hopsital, Homes, Offices, Communities, Towns, Cities etc. Need Electricity to stay alive.

ECONOMIC

Electricity is the mainstay of any economy. It is needed for industrial and commercial growth. Also, the indices for measuring the growth of any economy is the quality if its electricity generation.

TOURISM

Visitor from every part of the country and foreigners, especially students of various institutions, visit the power station to acquaint themselves with the workings of an hydro-electric station like Kainji.

NAVIGATION

Navigation has been made easy with the construction of kainji dam. Apart from the rapids, which on record caused the death of Mongo park, that have been removed, the flood control by the dam management has been navigating less risk in the area of Kainji dam.

FISHING

The vastness of Kainji Lake, allows for the catching of 7000 metric tons of fish annually. This provides the needed protein for growth and body building.

AGRICULTURE

With Kainji Lake, farming through irrigation, has been made possible through out the year. In addition, the Lake has increased the soil fertility of villages by the ….

ACHIEVEMENT OF THE STATION

1.                   Major repair of broken down generators

2.                   Local production and fabrication of part for plant maintenance

3.                   Major repair of broken down transformers

4.                   Sustaining the dam from collapsing over the years

COST OF CONSTRUCTION

The cost of construction was in 1968, 89 Million Pounds. It took 20,000 men of nine different nationalities, almost five years to complete the project. Kainji, the oldest hydro-generating station in Nigeria, has over the years, sustained power supply system in Nigeria with dedicated staff. The station looks ahead for brighter future in power generation.

TECHNICAL DATA TO NOTE:

Crest Elevation of Dams                        -           475.0ft (145.0meters)

Normal Maximum Water

Surface Elevation                      -           465.0ft (141.9meters)

Unit 7, 8, 9, 10, 11, 12 speed      -           115RPM

Unit 5, 6 speed                          -           107.2RPM

Normal Maximum Tail                -           350.0ft (128.0meters)

Water Elevation                         -           500,000cu yards

Soft Excavation                         -           4,200.00cu meters

Rock Excavation                       -           4,500.00cu Yards