Principals of Hydro Elctricity Plants

3GW Mambilla Hydroelectric Power Project - Nigeria

Energy supports almost all human activities and is the backbone of industrialisation for all nations. Mega industrial complexes, the base of American economic power depend on assured supply of energy, which is why, America, would attempt to secure energy source, at any cost, anywhere in the world. Indeed, many sources of energy are available, ranging from fossil fuels including coal, hydropower, nuclear, winds and tidal waves, solar and geo-thermal sources.

 

Fossil fuels constitute the largest source of energy in the world but they are expensive to generate and maintain and are not renewable. Where hydropower potential exists, it is always the most preferred energy source mainly because it is cheap to generate and easy to maintain. In addition, its generation takes place in clean and quiet environment. Above all, it is the most easily renewable source. Solar energy, though has the similarities of hydropower, it is very expensive to generate per kilowatt-hour, not readily available in large quantities and has low generation efficiencies.

 

Towards a planned hydroelectric power development in the country, Zungeru dam construction was to follow Kainji, Shiroro and Jebba dams. Next in line were barrages of low head power plants to be constructed at Yola and Makurdi on river Benue and at Lokoja on the confluence of River Niger. The combined capacity of these four schemes has been estimated at between 2,000- 2,500MW.

 

Need to construct the Mambilla hydropower project

In the case of Mambilla hydropower scheme, there were to be series of cascading dams of high head plants which will feed into each other to generate up to 6,000MW of electricity. To realise this important project, there is a need for proper planning due to its large capital outlay. The recent move by the Federal government to engage the services of a Chinese firm to handle the project though late, is proper, if pursued to its logical conclusion. China with over 2,000 dams has more than half the number of dams in the world.  Moreover, Chinese engineers approach to dam projects is, generally, very comprehensive, as they try to incorporate hydropower units in almost all water storage structures. These range from flask-size turbines of less than 5KW capacity to mega size turbines greater than 100MWcapacity, depending on the nature of river flows.

 

With or without the Chinese involvement however, government needs to step up considerably, the process of hydro ad meteorological data collection at the dam sites which had stopped since early 80s when feasibility studies were carried out for the preliminary designs. Indeed, the regimes of the rivers have now changed thus, necessitating a change in the design parameters.

 

Advantages of harnessing the water resourcesof Mambilla

The Mambilla hydropower project if developed has the great advantage of harnessing all its waters from the Mambilla plateau as the entire catchments fall within the boundary of the country. Hence, there is no fear that the water resources would be diverted by another country.

The length of rainy season at the dam sites is fairly extended throughout the year; giving near continuous flows and steady power generation.

Besides generating abundant power that would complement the current power shortage in the country, transmission to demand areas would be readily carried out.

Large to medium scale industries would spring up particularly downstream of the dam sites as cheap and steady power would be available all the year.

The development of the project would be of immense strategic importance to the country in the event of either disruptions or exhaustion in fossil fuels supplies in future.

There is scope for increased tourism, as the series of cascading dams would offer beautiful sceneries, recreations, moderate the micro -climate and attract visitors within and across the boarders of the country.

By taking advantage of large volume of water available, there would be increased fish production, irrigated agriculture and the development of agro-allied industries besides water supply.

Should the government decide to engage direct labour in the constructions; considerable job opportunities will be created to ease the current unemployment.

Conclusion The present shortage of power in the country would have been avoided if the five hydropower plants including Mambilla hydropower project planned since early 80s have been duly executed. Current emphasis must shift from fossil fuels as they are not renewable and more expensive to generate. One of the advantages associated with hydropower plants include the storage of large volume of water which would have run to the oceans, are now put to multi-purpose uses.

Hydro Electricity - 3GW Nigeria

Hydropower is generated from the water flowing in the river or oceans. There are two water cycles involved in the generation of electricity. One water cycle is the natural cycle and the other is inside the hydropower station.

Water Cycle

Before seeing various types of hydropower in details let us see the water cycle that occurs during the generation of hydropower. There are two water cycles, one in nature and the other in the hydraulic power plant. Let us see both of them:

1) Water cycle in nature: In our natural environment there are number of oceans and rivers and then there is sun above them all. Due to solar energy the surface of the rivers and oceans get heated due to which the water on the surface evaporates. The evaporated water vapors move towards the upper layers of the atmosphere where they form the clouds. Upon precipitation of clouds rain occurs. Due to heavy rains large quantities of water flows through various parts of the earth in the forms of streams, channels and rivers. All the water from rivers is collected back to the oceans, where evaporation of water occurs again.

All these are seasonal processes with evaporation occurring mainly during the hot seasons, and rain falling during rainy seasons. In many geographical areas evaporation of water and rain can occur even during short periods like within days.

2) Water cycle in the hydraulic power plant: The water in rivers posses two types of energies: kinetic energy and potential energy. The energy of water due to its motion is called as kinetic energy. The energy of water due to its high level is called as potential energy. Depending on the type of hydraulic power plants kinetic and/or potential energy of water is used to generate electricity.

The most commonly used method of production of electricity from hydropower is by dams, which are constructed across the large rivers. The large quantities of water from river are diverted by pipelines also called as penstock, towards the main plant where large turbines are located. The water from penstock is allowed to fall on the large turbine blades that start rotating. The shaft of the turbine rotates in the electric generators where electricity is generated. This electricity is then passed to the transformers from where it is connected to the main national grid.

The water leaving the turbine flows back to the river at the lower levels. In almost all the plants where water is used to generate electricity, the motion of water is used to rotate the turbine which generates the electricity in the generators and the water flows back to the river or ocean.
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