Spotlight: Some background (technical) facts pertaining to a festering problem!: Power generation for dummies!
No offence meant! I just could not resist the temptation to use a familiar expression. That is all. Actually, no one is really dumb for not knowing how electric power is generated, which is a specialised area of knowledge. Any way, here is how, in a somewhat simplistic explanation.
(The government's efforts towards overcoming the power shortage in the country or mitigating its ill effects and the results will be the subject of a later SPOTLIGHT piece). A generator (of electric power) has a drum-like rotating part (rotor) much like your pump motor has. All around its periphery are conductors (usually insulated copper wire) wound round the rotor to form a "winding".
Electric current and the power it brings with it, flows through a conductor (copper or aluminium wire, for example) when the conductor cuts (moves across) a magnetic field. A magnetic field is an area in which the effect (pull or push of a magnet is felt). Surrounding the rotor of the generator is a magnetic field in which the rotor rotates.
As it rotates, an electric current is generated in the conductors in the winding on its periphery. This current is continuously collected and passed along short and long distances to be connected to your electric bulbs, fans, TVs, machines of all kinds and so on, collectively called the electric load or just load.
GETTING THE GENERATOR TO ROTATE So the main step in obtaining electric power from a generator is getting the rotor of the generator to rotate continuously. There are various ways of achieving this in different power production systems. More commonly used systems are: (a) Hydroelectric systems (b) Thermal Systems (c) Nuclear system and (d) Solar Systems. Each is different from the other but the first three produce electric power through rotating the rotor of a generator, whereas solar power systems directly convert heat in solar radiation into electric current.
HYDRO ELECTRIC SYSTEM This system produces the cheapest electricity. Snow melting on high mountains as well as rain water flowing down to lower levels in the form of a river or nallah, is collected in small or big reservoirs by building a high wall (dam) across the flow of water. When the water in the reservoir has risen to a certain height, the gates built into the dam at its base, are opened and the water is allowed to fall along concrete channels on to a wheel with cup like vessels attached to its periphery.
This is the water turbine located at the base of the dam. As the gushing water fills the first cup, its force turns the turbine and the next cup comes in line of the flow to take in water and move around down and so on. Under constant force of flowing water, the turbine turns rapidly at its designed speed. Attached to the turbine is the rotor of the generator, which therefore turns with the turbine and produces electric power, as described.
THERMAL POWER SYSTEM In thermal power production fossil fuel (furnace oil) or gas is burnt to heat water to form steam. Steam at high pressure is produced and stored in boilers. A steam jet, at high pressure from the boilers, is directed against blades fixed to a wheel (steam turbine) which rotates at a predetermine speed.
Attached to the turbine wheel again is the rotor of a generator, which therefore rotates with it and produces electric power in the same manner as in the hydroelectric system. This is called the external combustion system because the combustion or burning of the fuel takes place inside the boiler ie outside the power-producing engine.
In internal combustion engines on the other hand, a predetermined amount of fuel (diesel, petrol, or gas) is periodically (several times a second) ignited inside a cylinder (for example in the common "generating sets") and the resulting "explosion" is used to drive a piston back and forth inside the cylinder. This reciprocating (back and forth) movement of the piston is converted through mechanical linkage into a rotary motion required to rotate a generator rotor to produce electric power.
NUCLEAR POWER SYSTEM In nuclear power stations the element Uranium is enriched through a complicated process to such an extent that, through other processing steps, too technical to be described here, it can be made to release a tremendous amount of energy in the form of heat. If the energy is not released in a controlled manner, an atomic explosion is the result.
For production of electric power, the energy is released in a safe, graduated and controlled manner. The heat thus obtained is used to produce high pressure steam as in the case of thermal generation and is again used in the same manner to rotate a turbine-generator set to produce electric power.
WIND POWER Wind power uses the energy of wind to rotate a huge fan. The rotation of the fan causes the generator rotor to rotate through a linking mechanism and electric power is produced. This method is suited to coastal areas with high winds most of the year. Part of the power can be stored in batteries to be used during relatively short periods of low or no wind.
SOLAR CELLS Energy is produced in Solar cells in an entirely different manner from the above. Solar cells are a device for converting heat from solar radiation (sunlight falling on the cells) directly into electricity. There are no moving parts in this form of energy production. Surplus energy is stored in batteries to be used at night or in very cloudy weather when there is no or very little sunlight.
Roofs covered with solar cells covering a large area meet the needs of people in a building, in remote areas, inaccessible to power distribution systems. Car tops covered with solar cells are providing power to drive experimental cars. Calculators use a small solar cell to supplement battery power.
Under various stages of development are many other ways of producing electric power. Power from tides or from gases, produced by human or animal waste, or from converting certain plants to chemicals with heating value are either being already used or are under development.
ENERGY ONLY CHANGES FORM A word about energy (defined as capacity for doing work) - of whatever kind! It is a well known principle of physics that energy cannot be created from nothing. It can change its form and can take many forms. Let us consider the very interesting case of Hydro-electric power. The energy conversion begins with the sun.
The heat of the sun evaporates the water in the oceans and seas. The evaporated water rises above the earth's surface and gains potential energy which is the energy a body has by virtue of its height (position) above ground level. The energy of the heat provided by the sun is thus converted to potential energy. As the clouds move to colder regions, they either convert to rain or become snow on mountain tops. Water both from rains and melted snow begins its journey back towards the sea.
On its way, some of it is collected into reservoirs by constructing a fairly high dam across it path. When the dam has filled to the desired extent, it is still at a considerable height above the sea level, despite having come down from the clouds or the mountains. Thus, it still has considerable potential energy left. When the gates of the reservoir are opened, the water rushes down, thus converting part of its potential energy into kinetic energy, which is the energy possessed by a moving body because of its being in motion.
As the rushing water moves over the water turbine, some of its kinetic energy is used up in driving the water turbine, which in turn rotates the generator, which produces electric power. The water then moves on further down, along canals to be used for irrigation, before eventually ending its journey back into the sea (with near zero energy) from which it started as water vapor, courtesy Allah's bounty in the form of the life-sustaining sun!
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