ELECTRICITY

Of the power sources, electricity is the cheapest. It is not exhaustible like coal or petroleum but is renewable.

The French have aptly described it as ‘white coal’.

There are two different sources of electricity. That which is derived from water sources (streams, glaciers, natural waterfalls or man-made dams) by hydro-turbines is referred to as hydroelectricity. When it is derived from generators driven by steam-turbines by burning coal, oil or natural gas, it is called thermal electricity. The former is best developed in the mountainous regions of temperate latitudes where precipitation is adequate and there are ideal sites for the location of hydroelectric power stations. The latter is widely scattered all over the world wherever mineral fuels are available for burning in the thermal-power stations. It is thus best developed in industrial districts and near coalfields. Large quantities of water are also necessary for cooling purposes in thermal plants.

 

Uses and advantages

In regions where coal and other mineral fuels are absent, electricity compensates for their deficiencies. In Switzerland, hydroelectric power is the chief source of motive power. Watches, machinery, precision instruments and electrical appliances are produced for export. All Swiss trains were electrified by 1961. There are a number of industries that can only be successfully undertaken with a very cheap supply of H.E.P e.g. the electro-chemical industries, especially the smelting of aluminium (from bauxite) and the production of nitrates and calcium carbides. This explains why countries like Norway, Sweden, Canada and Japan which are deficient in mineral fuels, are yet able to attain such a high level of technical development.

There are a number of advantages of electricity over other forms of energy.

1. Its cleanliness: Unlike coal, electricity does not give out smoke and it is never dirty. It can be conveniently used in kitchens, furnaces and radiators for heating and is without ashes or residue. In factories, offices and homes, a flick of the finger brings light to darkness almost instantly. It preserves food in refrigerators or deep-freezers. It is difficult to imagine what would happen if there were a power failure in the world for just a few hours.
2. Its unlimited degree of divisibility: By the use of simple mechanical devices such as transformers, electrical energy can be adjusted from a fraction of a watt to thousands of watts per hour. It is thus indispensable in modern complex manufacturers where the control of speed in machines or in furnaces is precise to a fraction of a second.
3. Convenient transport: Unlike coal or petroleum, electricity needs neither trucks nor pipes. By means of only wires and plugs, electric energy can be transported to consuming points over great distances and with the greatest of ease. With the use of large undersea cables, Sweden is able to “export” electricity across the Sound to Denmark. Very high voltage cables are now used to transmit electricity for distances over 1600 km (1000 miles) with negligible loss in energy.

 

Basic requirements for hydroelectricity development

For successful H.E.P. development, the following factors are essential:

1. A steep gradient or slope: This enables rivers or streams to plunge down swiftly to turn the hydro-turbines that generate hydroelectricity. Natural rapids and waterfalls are especially advantageous. The regions with the greatest H.E.P. development are those with the strongest relief: Scandinavia, Alpine Europe, Scotland, Canada, U.S.A. (Appalachians and Rockies),Japan and New Zealand.
2. A sufficient and constant volume of water: Regions with a heavy precipitation from either rain or snow throughout the year are ideal for generatingH.E.P. Large dams, made possible by the invention of special types of cement, and the development of hydro-turbines and electrical dynamos, enable large-scale hydroelectric schemes to be established. The artificial lakes, created by the erection of dams, hold water for use during periods of low precipitation. In the colder north, the freezing of rivers limits power generation.
3. Heavy capital outlay: Modern multipurpose schemes need a very large capital outlay. The initial cost of erecting a dam is so great that this is normally undertaken by the government, but the expenditure is worthwhile because the scheme may have a multiplicity of uses including H.E.P. generation, irrigation, flood-control and navigation. For instance, the Kainji Dam (Nigeria) cost about N180 000 000, while that of the Akosombo Dam(Ghana) cost even more. Once a dam is completed, its maintenance costs, in comparison with those of a thermal station, are much lower.
4. A large domestic and industrial market: For a dam to be worth constructing, there must be a fairly large market to make use of the H.E.P. generated. The cost of installing power plants, transforming stations, storage reserves and transmission lines is so great that a reasonable market must first be assured. The growth and decline of the market for both domestic and industrial uses will directly affect the profits made by the hydro-power stations. The high demand for cheap and abundant electricity by industrial Japan led to the expansion of H.E.P. development all over the country.

 

World production and distribution of electricity

Over two-thirds of the world’s electricity supply comes from thermal plants, mainly from the industrial areas.

The United States alone accounts for almost half the annual thermal electricity output, followed by Russia, United Kingdom, Germany, France and Japan.

As for hydroelectric power, it makes up only about a third of the world’s electricity supply.

The temperate lands of Europe and North America have, in fact, the greatest output of developed water power. In terms of individual countries, the United States is the greatest, producing 23 percent of the world’s H.E.P. Next is Canada, 15 percent, and third Japan, 10 percent. The other producers in order of importance are France, Sweden, Norway, Russia and Switzerland.

As the world’s output of developed hydropower differs so significantly from the tropics to the temperate lands, it is best to consider world distribution on a continental basis.

 

1) North America: The United States and Canada together make up about 40 percent of the world’s total developed H.E.P. They have some of the world’s best-known dams. The Grand Coulee Dam in Washington State is the world’s largest concrete dam, 183 m (600 feet) above river-level, and is multi-purpose. The Hoover or Boulder Dam of Arizona is 222 m (727 feet) high, the highest in the world. It controls the River Colorado, supplying water and electricity to the western U.S.A ., including Los Angeles and San Francisco, where prodigious quantities are needed everyday. The dam holds back the huge Lake Mead, which is like an inland sea. The St. Lawrence Seaway Scheme is for both electricity and navigation. The Kitimat Scheme in British Columbia was constructed to supply H.E.P. for aluminum smelting industries at Kitimat, with much of the imported bauxite coming from Jamaica. Under the Tennessee Valley Authority (T.V.A.), more than 30 multi-purpose dams have been constructed across many rivers to rehabilitate a vast devastated area as big as the whole of West Malaysia.

 

2) Europe: The European countries contribute another 40 percent of the world’s total H.E.P. It is best developed in countries lacking in coal and where the relief is rugged. Norway, with neither coal nor oil, fully developed its water resources for industrial and domestic use. She has in fact, the highest per capita output of water power in the world. Sweden’s chemical and metallurgical industries are based on ‘white coal’ and her rich deposits of iron ore. The swift glacially-fed streams of the Alps, the Apennines and the Pyrenees are all vital to the development of the industries of their respective countries: Switzerland, Italy and France. In Russia, the Dnieprostroi Dam on the river Dnieper is one of the largest dams in the world, and the country is rapidly expanding its electricity production with new dams such as those at Bratsk and Krasnoyarsk in Siberia.

 

3) Australia and New Zealand: Together, they account for not more than 2 percent of the world’s developed water power resources. The multi-purpose Snowy River Scheme of southeast Australia is the largest in Australasia and there are a number of smaller ones.

 

4) Asia: Almost a third of the world’s potential water power capacity is found in Asia, but in terms of developed H.E.P ., it is not so important, producing about 15 percent. Japan alone has developed more water power than all the other Asian countries combined. China has made remarkable progress in the last few decades, while Indo-Pakistan has many comprehensive schemes to meet the urgent needs for domestic lighting, irrigated farming and flood control.

In West Malaysia, the Chenderoh Dam on Sungai Perak supplies most of the power requirements for the local tin and rubber industries. The recently completed Abu Bakar Dam in the Cameroon Highlands will supply the H.E.P. requirements of central West Malaysia, particularly in conjunction with ambitious rural development programmes.

 

5) Africa: Despite its vast potential water power resources, Africa’s developed H.E.P. is not more than 1 percent of the world total. A number of dams have, however, been built, holding back some of the largest man-made lakes in the world. These include the Aswan Dam of Egypt, Akosombo Dam of Ghana, Sennar Dam of Sudan, the Kariba Dam on the Zambesi and those at the foot of the Owen Falls (Uganda) and Victoria falls, Zimbabwe.

Others include the Volta Dam of Ghana, the Kainji Dam (Nigeria) on the Niger, the Shiroro Dam on Kaduna river, the Kafue river Dam in Zambia, the Cabora Bassa Dam on the Zambezi river in Mozambique, and the Dam in the Ivory Coast.

 

5) South America: It has little-developed power resources, though the potential is good. There are good natural conditions for the siting of power stations in Brazil, Chile, Venezuela and the countries within the Andean Cordillera. The presence of oil has prevented the intensification of efforts in developing the water power resources of some of these countries.