Africa Needs Alternative Sources of Energy
lass=story-body>ENERGY is the key to man's greatest goal and to his dreams of a better world. We need energy to enjoy life on earth. The power of doing work possessed by body or system of bodies available to human society was in the past limited to solar energy trapped by green plants, which produce organic matter. It was the biological oxidation of this organic matter which fuelled the muscles' power while combustion of organic matter provided energy for other purposes such as lighting, cooking, heating etc. The formation of fossil fuels (coal, oil and natural gas) is also due to photosynthesis carried on by plants which occurred millions of years ago.
Chupp, 2004, in one of his class lectures pointed out that "... Spatial variation exists in global energy consumption and the amount consumed at a place is not necessarily commensurate to the available resources in that place". Minimum per capita energy requirement of man is about 2000 kcals, which is the quantity required to keep him alive and is obtained from the food he eats. Per capita consumption of energy is not the same all over Nigeria.
It is highest in what I may describe as Government Reserved Areas (GRA). Less than 20 per cent of the Nigerian population consumes about two-third of the total energy supply. To millions of people living in Nigeria electricity is still a dream, fossil fuels are difficult and costly to obtain and biomass (fuel wood) constitutes the only source of energy.
In Nigeria, the pressure of heavy demand has slowly been reducing the fuel wood resource base. Over millions of people now experience acute fuel wood shortage. As fuel wood largely comes from forest, consequences of fuel wood scarcity are severely damaging the forest and wildlife. Coal, oil and natural gas represent the photosynthesis output of green plant, which occurred millions of years ago. Though the renewal of fossil fuel resources is taking place somewhere under the sediments, there is, however, rapid consumption of these materials, hundreds of times faster than their formation, which shall in the near future deplete these deposits (Asthana, 2003). Fossil fuel is therefore non-renewable source of energy as it is impossible to cut consumption down to the level at which it is being formed.
But the question is, what are the alternative sources of energy after the depletion of fossil fuels? Asthana 2003 pointed out that the fuel for future should be convenient, clean, and less wasteful of energy, and should be renewable so that there is no threat of its depletion. Important energy resources, which may be tapped as an alternative to fossil fuels, are: Wind power, tidal power, energy of waves, thermal energy of oceans, geo-themal energy, direct use of solar energy and hydrogen.
In Nigeria where persistent strong winds blow, wind power can be put into use as done in some parts of the world since ancient times. Across the passing air current large fans are placed whose revolving motion is carried down, through a shaft to drive water pumps, windmills, turbines etc. though the main draw back of wind power is its erratic and irregular supply. However, there are places where strong winds blow for most of the day or night. At these places this inexpensive, inexhaustible energy resource can be used to save power obtained from other sources by concentrating work during the periods when wind power is available.
During rising tides too, water may be diverted through suitable channels to inshore reservoirs, driving the turbines during its entry. The stored water may gradually be released driving the turbines again during the periods of low tide. In this way an inexhaustible, clean and cheap power shall be available to mankind. Total tidal energy has been estimated to be about two times 10 joules per day. In a similar vein, air currents rubbing the surface produce waves, which are pushed to the shore. Its energy is dissipated as waves floating propeller placed in shallow water along the shore may be kept in a state of continuous motion by these waves. Their kinetic energy can be used to drive turbines maintained on floats or on platforms erected for the purpose in shallow waters.
Alternatively there is often a large temperative difference between the upper and the lower layers of seawaters. In the tropics where Nigeria belongs, surface waters (at 28-3C) are warmer by 5-120oC than the layers about 1000 metres below. This temperature difference as put forward by a French scientist in the early 1881 A.D, can be utilised to generate electricity with the help of some low boiling point working fluid (like liquid ammonia or propane).
Geo-thermal Energy is another important source worth explaining. Temperature of earth increases at a rate of 20-75oC per kilometre as we move down from the earth surface. Circulating water through pipes to raise steam and generate electricity could use the heat. For satisfactory result it would be useful to drill and locate the turbines near already known hot springs or thermal springs. Similarly, the Earth receives about 75,000 times 10 KW of energy from the sun every day. Just 0.1 per cent of this energy is sufficient to meet the energy requirement of the entire world. At noon, the solar energy striking an area of 12,550 square kilometres if converted to electricity shall be equal to the peak generation capacity of all power plants in the world. Only a part of the roof of an average house in Nigeria if covered with solar panels can provide sufficient energy to meet the entire energy requirement of the house.
Finally, the natural gas and oil hydrogen can also provide the concentrated energy needed in domestic establishments, factories and motor vehicles. Hydrogen when burned produces 284 kilo-joules per mole of energy (or 142 kilo- joules per gm) and the product of combustion is watervapours only. H2 plus O = H20 plus 284 kilo joules per mole. Whether we like it or not, Nigeria is an agricultural country. Majority of our population lives in the villages. A large part of total energy used in Nigeria comes from fuel wood and fossil fuels. These conventional source of energy are non renewable and their use is invariably associated with problems of environmental pollution. Hydroelectric power generation has its own draw backs. Large-scale use of wood, which is an important source of energy in Nigeria, leads to deforestation. Moreover, the centralised system of generation, which we have developed, with conventional sources of energy involves large distribution networks. These are wasteful and expensive to maintain. Non-conventional sources provide energy in a decentralise manner to small areas where it is difficult to carry fossil fuel or power lines. Large-scale use of non-conventional energy resources tends to reduce the burden from conventional energy systems and therefore it is helpful in enlarging their life span.
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