POWER SOURCES IN AFRICA
Energy/ Power Sources
Africa has various sources of energy or power distributed unevenly over Africa. The main sources of power are Hydro-Electricity Power (HEP), coal, mineral oil, thermal power and nuclear power. Africa accounts for 8% of the world’s known oil reserves (10.5billion tones) and natural gas reserves (10,000 billion m³); 28% of the uranium reserves (432,000 tons); 6% of the world’s coal reserves (61.7 billion tons) and one-third of the world’s hydro-electricity potential (1,590 giga watts). South Africa with 91% of Africa’s coal reserve (280 million tons), has the largest coal reserve in the continent and produces more than 280 million tons of coal per annum, making the country the world’s seventh producer. These are all non-renewable sources of energy. Minor sources are mainly renewable sources of energy, such as wind, solar, geothermal and tidal power, which have remained essentially unexploited.
HEP is the most important source of power in Africa, hence it requires a detailed examination.
Hydro-Electric Power (HEP)
As earlier highlighted, HEP is the most important source of power in Africa and accounts for 80% of the power produced in the continent, which stood at 350, 000 giga watts in 1996. Many rivers and watercourses in Africa have the potential for the construction of HEP stations.
In Central Africa, notable dams in the region include Inga dam in Democratic Republic of Congo (DRC), Cahora Bassa dam in Mozambique, Kariba dam in Zimbabwe, Edea dam in Cameroon, the Congo basin alone holds half of the continents potential. Others are Akosombo dam in Ghana, Kainji dam in Nigeria, Kossou dam in Cote d’Ivoire, Garafiri dam in Guinea and Aswan dam on the Nile in Egypt. About 40% of the world’s HEP potential is found in Africa. The continent has a number of advantages over other continents and regions. These include:
- Many rivers on the continent have very large volumes of water due to the heavy tropical rainfall. This is essential for powering the HEP turbines.
- The rivers have steep gradients. They drop sharply from the source, on the African Plateau, to the ocean plains. Cataracts and falls are therefore a common feature along the courses of many of the rivers. This provides ideal sites for the construction of HEP stations.
- There are no structural weaknesses on the bedrock of the continent. It is generally stable and free from earth tremors and earthquakes that can be a threat to dams.
- African rivers do not freeze in winter unlike their temperate rivers. This facilitates the sustained flow of water throughout the year.
In summary, the main geographical conditions necessary for the development of HEP are regular and sufficient quantities of rainfall, steep slopes to the fall of water, narrow and deeply incised valleys, impermeable rocks to facilitate impounding of water and available market for HEP.
Though Africa has a large potential and comparative advantage over other continents in the development of HEP, its level of development has remained very low. This is essentially due to a number of problems:
- It is capital intensive and requires high technology, which a majority of countries in the continent lack.
- Due to the low level of industrialization in the continent, the demand for power is very low; hence, it will be wasteful and economically not viable to develop HEP for the domestic market.
- Most of the rivers flow through relatively dry regions, such as, the savanna. They are exposed to a high rate of evaporation; as a result, rivers experience seasonal fluctuation in their flow.
- The majority of the rivers in Africa, cross many countries before discharging their waters into the ocean; for this reason dam construction along most of the rivers in the continent requires the support and guarantee of other countries.
- Most of the best sites for the development of HEP are found in remote locations, far removed from areas of high demand for power, such as, urban and industrial areas. Power, therefore, has to be transmitted over long distances and at great cost.
The Akosombo Volta Dam
Akosombo Dam on River Volta was built to provide hydroelectric power for the Accra-Tema region of Ghana. Proposals to dam the Volta date from 1915. A 1959 study by Kaiser Engineers and Contractors initiated construction and the dam was inaugurated in 1966. The cost was underwritten by the World Bank and the governments of Ghana, the United States and the United Kingdom.
Akosombo is an earth-filled dam, 640 m (2,100 ft) in length and 74 m (243 ft) above the lower water level. The reservoir, Lake Volta, has an area of 8,480 sq km (3,273 sq mi) and a length of 400 km (249 mi). It displaced some 80,000 people. The dam’s installed generating capacity is 912 MW. Because of fluctuations in reservoir level, energy production has been unreliable. Major consumers, such as the Volta Aluminium Company at Tema, have had to adjust production accordingly and agreements to export electricity to Togo and Benin have been affected.
Plans to irrigate the Accra Plain have been curtailed and transport on Lake Volta remains poorly developed. While the Volta River Project has resulted in reductions in malnutrition and river blindness, some diseases, such as schistosomiasis, sleeping sickness and malaria, have increased in the settled areas around the lake. The situation of the dam in a zone of seismic activity has also caused concern.
In summary, the importance of Akosombo Dam to the Ghanian economy includes:
- Power Generation: It generates about 550MW out of its installed capacity of 912MW, through its six turbines. Power is distributed via a transmission network that is about 1,000km long. The power is essentially used for the smelting of bauxite, for the development of industries and for domestic consumption.
- Urban Development: The construction of the Volta dam has hastened urban growth in the Volta region of Ghana. A city such as Tema, which was essentially a fishing settlement and involved in primary production has been changed into an industrial centre with the capacity to produce service goods for both the domestic market and for export.
- Irrigation: The Volta Lake is an important source of water for irrigation in the region. This is particularly necessary due to the fact that the south-east of Ghana where the dam is located has a semi-arid (savanna) climate; and hence requires irrigation waters for effective production of such crops as rice, sugar cane, groundnut, maize and tobacco among others.
- Transportation: The Volta Lake is an important inland water-way in the region, transporting people, industrial and agricultural products to the market. The major transport operator on the lake is the Volta Lake Transport Company, which moves more than 20,000 tons of cargo and 30,000 passengers annually.
- Fishing: The Volta Lake has provided a good fishing ground for the fishing industry in the region. It is estimated that 25, 000 tons of fish is caught annually from the Lake.
- Foreign Exchange: The export of power from Volta Dam to such neighbouring countries as the Republic of Benin and Togo yield scarce foreign exchange for the country.
- Tourism: The construction of the Volta Dam has boosted the tourism industry in the region. New international hotels are developed and tourists come from Africa and other parts of the world.
- Climatic Modification: The large body of water in the form of dams and lakes created in the process of developing HEP stations tend to modify the climate of such region or area. This is a common occurrence in a semiarid region, where the dammed water or lake helps to regulate unnecessary flooding during the rainy season and also prevents a very low level of water during the dry season. However, the large body of water is usually lost to evaporation in a process called evapo-transpiration.