The incredible dam / L’incroyable barrage

One evening, as every evening, the inhabitants lit their torches. Suddenly there was light, all the inhabitants wondered if it was the operation of the dam that provided them with this electricity

A dam is designed to regulate the flow or to store the water. In particular for flood control, irrigation, industry, hydroelectricity, fish farming, a supply of drinking water, etc. In nature there are also beaver dams.

We are in the vicinity of the hydroelectric dam of Kaléta, in a small village. The role of a dam is very important because it serves has to produce some electricity. The role of a dam is also to regulate the outflow or to store the water. It can be used for irrigation, industry, hydropower, fish farming, or as a supply of drinking water. The function of Kaléta is to produce some electricity for Guinea.

Catchment basin of Kaleta / bassin de retenue d’eau de Kaleta
Valve for collecting water / vanne pour capter de l’eau

First of all the dam holds back the natural flow of water. Large amount of water accumulate and form a reservoir (the normal Lake is 110 M²). Once the water is stored, they open valves so that the water rushes into penstocks. These pipes lead the water to the hydraulic plant below. This central force of water turns a turbine (there are 3 turbines, which have a capacity of 80MW each with facilities of 180 m 3 per second). Alternators work with the energy provided by the turbine, the generator produces an alternating electric current (an alternating electric current is a current that reverses direction twice per period and carries some amount of electricity), which is sent to a transformer. (A transformer modifies the values of tensions and strength of current delivered by the alternator). The more there is water the more there is power. The transformer raises the tension of the electric current produced by the alternator so that it can be more easily transported in the very high-voltage lines.

Very high voltage lines leaving Kaleta / Lignes à très haute tension partant de Kaleta

Abstract / Résumé

Un barrage hydroélectrique est un ouvrage d’art construit en travers d’un cours d’eau. On dit que la guinée est le château d’eau d’Afrique mais paradoxalement, nous n’avons ni eau ni électricité. Ce scandale ne pouvait pas durer voila pourquoi les Chinois ont construit le barrage hydroélectrique de Kaléta. Avec une puissance de 240,5 mégawatts. Il a fallut à l’état guinéen investir 526 millions de dollars.

Written by / écrit par:

Mamoudou Condé, Chérif Diallo, Moustapha Ndiaye

Photos: Christine Soumah