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

Hell without electricity / L’enfer sans electricité

You are watching Secret Story,  one of your favorite shows, you are on the edge of your seat to see what is going to happen between Anaïs and Darko and all of a sudden… POP ! The electricity cuts off ! Why, oh Why ???

To begin with, you must know that in Guinea, electricity is mostly produced by big generators and by the Kaleta hydroelectric plant. Kaleta pumps out 300,000 volts. During the rainy season Kaleta can produce up to 240 megawatts but during the dry season Kaleta can only produce 160 megawatts at its maximum capacity. So Kaleta produces less energy during the dry season.

The 3 generators of Kaleta / Hall des générateurs à Kaleta

Moreover, since 2015, (when Kaleta was completed), the energy consumption in Guinea has doubled. To provide extra energy to the capital, especially during the dry season, the Guinean Government has to use huge fuel generators. They emit a lot of pollution into the environment. Man-produced C02 is causing global warming, it is now known with high certainty and it has been confirmed by observations. More shockingly, those who contribute the least to greenhouse gases emissions, developing countries like Guinea, will be most impacted by climate change. So it is important to adopt clean sources of energy in Guinea. In addition, to fuel these big generators you need gas, the price of a liter of gas is 8921,76 GNF, approximately  90 cents. It is very costly for the government.

There are also serious problems of energy distribution in Guinea. The energy produced in Kaleta needs to be carried and distributed to Conakry…

Powerlines at Kaleta /Lignes à haute tension à Kaleta

In Guinea the electricity distribution causes a serious problem to the population because the materials are old and most of all the powerlines are much older compared to the ones you can see at Kaleta.

Yet progress is being made, because Guinea will soon have too much energy when the dam of Souapiti is operational in 2020.

A view of Souapiti, near Kaleta / vue de Souapiti, près de Kaleta

Guinea will then have the opportunity to export electricity to neighboring countries with wires. Electricity allows a strong economic development because it allows the industries to be able to settle inside the country thanks to the energy to develop their activities at prices much cheaper than if we use generators.

Guinea has 23 watersheds and 14 are shared with neighboring  countries. Most of the great rivers take their source on Guinean soil. The construction of the dams allows  countries to control the flow of water. An electric power station is an industrial site intended for the production of electricity. The electric power station by means of the electricity network, is ensured there by the conversation in electrical energy of primary energy, a primary energy which can be mechanical(force of wind, force of the water of the tidal rivers).

Soon Guinea will be an electric heaven!

Abstract / Résumé

En Guinée l’électricité est principalement produite par de grands générateurs et par la centrale hydraulique Kaleta.

Le barrage de Kaleta  distribue de l’électricité en Guinée. On peut dire que le barrage est un élément important pour le pays. Il est utile pour le pays mais malheureusement c’est  insuffisant pour alimenter tout le pays tant que le barrage de Souapiti ne sera pas achevé.

Written by / écrit par:

Sofia Rose, Kadiatou, Nagham, Matour

Photos: Christine Soumah

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

And then there was light… a dream come true! / Et la lumière fut! Un rêve devenu réalité…

We lived in darkness without an exit door, we were desperate. When as if by magic came a hero which drove away the darkness in our city. It is called Kaleta.

Kaleta was a dream for the government for thirty years. After a lot of statistics and studies and calculations, the government decided to invest money in the project. Guineans decided to collaborate with French and Chinese companies for the construction. The companies who participated in the construction of the Kaleta dam are CIW (China International Water and Electricity Corporation).

the dam of kaleta / le barrage de Kaleta

Kaleta was built between 2013 an 2015, in 3 years and a half instead of 4 years and a half. It is the first big dam in Guinea and there will be a second one soon. Kaleta is located more than 70 km away from Conakry. In the plant there are 8 levels underground and the dam is 53 meters high.

In the control room, there are computers and screens which are necessary to control all the machines, such as the alternators, the turbines and the alternators.

shaft of the turbine / arbre de la turbine

The alternator is
used to convert mechanical energy into electrical energy. The transformer can be used to change the voltage of the current. A hydraulic turbine is a rotating machine that produces mechanical energy from moving water (stream or tide) or potentially moving (dam). It is the essential component of hydroelectric power plants to produce electricity from a water flow.

Today, the electricity that is produced is not enough for the whole country. The Guineans need roughly 270 megawatts on the network. During the rainy season (from June to September), there is a lot of water, but during the dry season there is less water. So the dam cannot work at full capacity. Today in Kaleta only 2 turbines are working, they produce between 100 and 150 megawatts. The power of the dam depends on the quantity of water.

location of the Souapiti dam / site du barrage de Souapiti

A second dam will soon be built to supply Kaleta with a constant flow of water and to produce more electricity for the whole country. Guinea will then sell energy to neighboring countries. That second dam will be called Souapiti.


Abstract / Résumé

Kaleta un rêve devenu réel

Un projet conçu en 2013 et terminé en 2015. Aujourd’hui la centrale de Kaleta nourrit une partie de la Guinée en électricité, cette source est située au village de Kaleta dont le barrage tient son nom. Le fonctionnement des machines comme les générateurs, les turbines, est contrôlé par de nombreux ordinateurs depuis la salle de contrôle. Kaleta ne peut pas fournir assez d’énergie pour alimenter toute la Guinée. Elle a besoin d’une forte pression pour faire fonctionner les 3 turbines, ce qui est uniquement possible pendant la saison de pluie. Un nouveau barrage est en cours de construction, qui alimentera aussi Kaleta en eau, donc il permettra a Kaléta de produire plus d’électricité. Ce nouveau barrage se trouve à Souapiti.

Written by / écrit par

Mariam, Alice, Salematou et Tess