Answer
“Sources of Energy”
Since electrical energy is produced
from energy available in various forms in nature, it is desirable to look into
the various sources of energy.
These sources of energy are: (A) The Sun (B) The Wind
(C) Water (D) Fuels
(E)
Nuclear energy.
Out of these sources, the energy
due to Sun and wind has not been utilised on large scale due to a number of
limitations. At present, the other three
sources viz., water, fuels and nuclear energy are primarily used for the
generation of electrical energy.
(A) The
Sun. The Sun is the primary source of
energy. The heat energy radiated by the
Sun can be focussed over a small area by means of reflectors. This heat can be used to raise steam and electrical
energy can be produced with the help of turbine-alternator combination. However, this method has limited application
because : (1) it requires a large area for the generation of even a small
amount of electric power (2) it cannot be used in cloudy days or at night (3)
it is an uneconomical method. Nevertheless, there are some locations in the
world where strong solar radiation is received very regularly and the sources
of mineral fuel are scanty or lacking.
Such locations offer more interest to the solar plant builders.
(B) The
Wind. This method can be used where
wind flows for a considerable length of time. The wind energy is used to run
the wind mill which drives a small generator.
In order to obtain the electrical energy from a wind mill continuously,
the generator is arranged to charge the batteries. These batteries supply the
energy when the wind stops. This method
has the advantages that maintenance and generation costs are negligible.
However, the drawbacks of this
method are (a) variable output, (b) unreliable because of uncertainty about
wind pressure and (c) power generated is quite small.
(C) Water. When water is stored at a suitable
place, it possesses potential energy because of the head created. This water energy can be converted into
mechanical energy with the help of water turbines. The water turbine drives the alternator which
converts mechanical energy into electrical energy. This method of generation of electrical
energy has become very popular because it has low production and maintenance
costs.
(D) Fuels. The main sources of energy are
fuels viz., solid fuel as coal, liquid fuel as oil and gas fuel as natural
gas. The heat energy of these fuels is
converted into mechanical energy by suitable prime movers such as steam
engines, steam turbines, internal combustion engines etc. The prime mover drives the alternator which
converts mechanical energy into electrical energy. Although fuels continue to enjoy the place of
chief source for the generation of electrical energy, yet their reserves are diminishing
day by day. Therefore, the present trend
is to harness water power which is more or less a permanent source of power.
(E) Nuclear energy. Towards the end of Second World
War, it was discovered that large amount of heat energy is liberated by the
fission of uranium and other fissionable materials. It is estimated that heat produced by 1 kg of
nuclear fuel is equal to that produced by 4500 tones of coal. The heat produced due to nuclear fission can
be utilised to raise steam with suitable arrangements. The steam can run the steam turbine which in
turn can drive the alternator to produce electrical energy. However, there are some difficulties in the
use of nuclear energy. The principal
ones are (a) high cost of nuclear plant (b) problem of disposal of radioactive
waste and dearth of trained personnel to handle the plant.
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