Upgrading Kainji dam and improving electricity
Kainji dam is one of Nigeria’s oldest dams generating roughly 500 megawatts of electricity in 2017 for a nation with a population around 170 million! A dam located in Kainji, Niger State, Nigeria. Opened in 1968 with a construction cost of about $209 million. A dam of 8 turbines that gets its water supply from Kainji Lake with total installed capacity of 960 megawatts. Kainji Lake itself has a surface water level of approximately 1,243 Km2 with a maximum depth of 12.1 meters.
Due to the dam’s near zero hydroelectricity generation for a population of close to 170 million, 40% of which is majorly off the national grid, it became imperative for Drillbytes to drive the matter further and in doing this, the column sought the opinion of an international expert in power generation, transmission and distribution to seek for ways in which the dam and such others like Jebba and Shiroro can be a source of joy to Nigerians, a very much welcome relief from the current status of nightmare.
Drillbytes spoke with Mr Tunde Fasheun and he graciously bared his mind on what needs to be done in moving the dam and indeed, the other two; Shiroro and Jebba forward. His thoughts are here served for the benefit of the government, oversight agencies and electricity consumers.
“The key data sets that are crucial for determining the dam’s capacity to generate hydroelectric power are; the hydraulic head of the dam, the flow rate and turbine efficiency. Kainji dam serves multiple purposes which compete for the available water including losses to evaporation. Kainji is a sprawling lake of about 1,200 square kilometres with a 66m hydraulic head at the concrete section housing the turbines. Most of the structures were built from earth and the dam itself is one of the longest in the world.
The power station has a design generating a capacity of 960 megawatts (12 X 80 megawatts) base load but only eight (consisting of 4 X 80 megawatts Kaplan type turbines and 2 X 120 megawatts propeller type turbines with a total generating capacity of 760 megawatts baseload) of the planned twelve turbines was installed. Possibly, unpredictable flow in the Niger due to periodic droughts informed the decision not to install the four turbines and balance of plant, BOP.
The civil structure for the four turbines is in place. What is mind boggling is the turbine selection and use of a combination of different types of turbine design with varying output and efficiency. The Kaplan and propeller turbines are reaction turbines that need low hydraulic speed to operate, need more maintenance power and have relatively low efficiency. The over forty years old plant has inadvertently outlived its usefulness. Due to the surge in population growth and the corresponding demand for power, the Kainji dam and the other hydroelectric dams urgently need to be rehabilitated and upgraded to improve their power generation capacity.
The large reservoir, shallow altitude and high flow rate may have informed the choices made but there are limitations to what could be done to improve the dam’s efficiency due to its lowland gravity, the finite civil structures, layout and dimensions. Therefore, Kaiji hydroelectric power station may be better off by replacing the lower output Kaplan reciprocating turbines with a set of 200 megawatts Francis turbines that would increase its power generation output from 760 megawatts 2,400 megawatts. This potential should be investigated further to see how the dam can be moved further in the area of optimal performance.
Work is underway to rehabilitate the dam but then, such work should be looking into upgrading the turbines and balance of plant, BOP at the power station. The additional output combined with a sound upstream water quota agreement together with a good reservoir management practices should guarantee an uninterrupted supply of base load into the national grid. Similarly, Shiroro and Jebba hydroelectric power dams that make up the river Niger hydro scheme should be investigated for an upgrade and not just maintain the status quo”.
In concluding, Mr Fasheun submitted, “In resolving these issues, the federal government needs to spend money on upgrades, purchase additional thermal plants to serve as Peakers that kick in during peak loads only and through investment in a national control centre that manages load allocations under a National Electricity Agreement that ensures the power plants are not run down due to over use. More importantly, each of the 36 states in Nigeria can be encouraged to take responsibility for the power generation in their domain with such generated power fed into the national grid.
The state governments can pursue the private-public partnership, PPP option in this regard if, as everyone knows, they do not have needed funds irrespective of the Paris Club windfall. Furthermore, the implementation of a national water/ catchment policy framework that is mutually beneficial to all stakeholders should be looked into. Finally, market forces, and not government forces, should be allowed to determine pricing such that people will be free to choose who supplies them what and where, when such services are needed.”
It is clear from the submission above that the dam was delivered when the country had just about half of what it currently parades in the area of population, electricity demands and corresponding industrialization and urbanization, It is also clear that the structure built over forty years ago is in dire need of an upgrade badly needed to take Nigerians out of this stubborn darkness into the league of improved electricity.