Electricity, a Guinean monster / L’electricité, la bête noire des Guinéens

Did you know that there were only two turbines that kept Conakry lighted?

Indeed, Kaleta is currently the biggest hydroelectric dam of guinea. Its construction was completed in 2015. Since then, it supplies a good part of Basse Guinea and Conakry with electricity.

Dam (water retention) / barrage (retenue d’eau)

The Kaleta hydroelectric plant consists of a dam which serves as a reservoir of 22 million cubic meters of water. Along this dam are placed 3 penstocks each allowing the passage of 180 m3 of water to reach the power house. In the building, there are three generators and the control room with all the controls. Every generators produces 80MW .During the rainy season, three generators work .During the dry season only two generators can work because there is less water.

Penstocks / conduites forcées

The three penstocks   allow the reservoir water to go down to the turbines with a relatively high pressure.

Hydroelectric plants use machines called generators, it takes a lot of energy to spin these machine. For this purpose, the abundant water resources of the province and of the Konkoure river can be used. The electricity produced from the force of water is called hydroelectricity. At the heart of the power plant is the turbine wheel similar to a giant propeller; it can reach 8 meters of diameter. It is fixed to the rotor by a 5 meter propeller shaft; the turbine wheel operates the generators.

The water enters the building of machines through the penstock.

Then it enters in the spiral tarpaulin.

The spiral tarpaulin is a spiral shaped zone around the turbine. The spiral shape gives the water that enters a spiral movement that drives the turbine into motion.

Diagram of a generator on a control screen / schéma d’un générateur sur un écran de contrôle

When the water pressure makes the turbine rotate the rotor that is fixed rotates at the same time, and it produces electricity.

The quantity of water which passes  through  the penstock  directly  into the spiral tarpaulin and percusses the branches of the turbine causes it to rotate. When the turbines rotate, it produces mechanical energy, this mechanical energy is then transmitted by an iron shaft that connects the turbines and the alternators. The alternators turn the mechanical energy produced by turbines into electricity. Every turbine produces 10.5kv. This tension is then transferred to a transformer which converts it into 240 kW to make it easier to transport.

The transport of electricity is very complicated. Because its passes through several stages. Its takes a lot of work.

Abstract / Résumé

A kaleta le barrage hydroélectrique  est composé d’un réservoir de 22 millions  de mètres cubes d’eau. Par la réalisation de ce barrage la ville de  Conakry et une partie de la basse guinée sont alimentées en électricité et donc cela fait de ce barrage une importante source d’électricité pour les guinéens. Pour l’instant, en saison sèche, seuls deux générateurs peuvent fonctionner. Il faudra attendre le barrage de Souapiti pour que Kaleta puisse donner toute sa puissance.

Written by / écrit par

Cellou, Ahmad, Yaya, Eric

Photos: Christine Soumah

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