Conventional Source of Electric Power Generation
There are mainly three conventional source of electric power generation, and they are thermal hydel, and nuclear energy.
Thermal Power Generation
In thermal power plant coal or diesel is burnt to produce sufficient heat. This heat energy is utilized to produce high temperature and high pressure steam in the boiler.This steam is then passed through the turbine blades and the turbine shaft rotates due to this steam pressure. The rotor of an alternator is mechanically coupled with the turbine shaft and hence it also rotates. This rotation produces electric power.
Hydel Power Generation
Here the water head is used to rotate the rotor shaft of an alternator. Water head can be naturally available or it can be created. In hilly region water head can be naturally available in the hill top natural lakes. In plain land, it can be created by constructing dams across suitable rivers. In comparing to a thermal power plant, hydel plants are more echo-friendly as they are free from fuel combustion. Also the running cost of hydel plant is much cheaper than that of thermal plants as there is no need of fuel to be burnt.Although running cost of a hydel power plant is quite low, but initial constructional cost of this plant is quite high as compared to thermal power plant. There is huge involvement of money in construction of dams and other necessary civil buildings. Water turbine generally runs at a low speed, hence number of poles in the generator is higher to achieve fixed 50 Hz power frequency. The number of pole in a hydel alternator may be up to 20 or more.
Nuclear Power Generation
It is estimated that, the coal reserve of our country will be exhausted within next 40 years if the coal is continued to be consumed in present rate. The solution of this situation is a nuclear power plant as thought. In a nuclear power station, Uranium235 is subjected to nuclear fission. In fission process, U235 is bombarded by a beam of neutrons. The collision of neutrons with the nucleus of U235 creates huge heat energy along with other neutrons. These newly created neutrons are called fission neutrons which again hit by other U235nuclear and create mare heat energy and other fission neutrons. During fission process the nucleus of U235 is divided into two parts. The fission process is commutative in nature. That is why, a nuclear reaction is a chain reaction and hence it should be allowed to be occurred in a controlled manner. The moderates and control rods are used to control this chain reaction.Moderators are used to reduce the velocity of neutrons and control rods are used to absorb neutrons for maintaining, required number of neutrons for the process. Moderators are made of heavy water or pure carbon and control rods are made of cadmium or boron steel. The speed of the nuclear reaction can be controlled by inserting control rods up to a desire deep into the reaction chamber. By pushing down and pulling up the control rods, the output of the nuclear generating plant is controlled. Although this process is not manual, it is controlled by the automatic feedback control system. The heat generated during fission is taken out from the reactor by means of coolant consisting of liquid sodium or some gaseous fluids. The coolant is circulated between heat exchanger and the reactor. It takes heat from the reactor and gives the heat to the water in the heat exchanger. Thus the water in the heat exchanger is converted to high pressure and high temperature steam. This steam then drives a turbine and exhausts into a condenser where it is condensed into water and cooled down for re- feeding to the heater changes again via a feed water pump. The main advantage of nuclear power plant is its minimum fuel consumption. It has been observed that for running a 1000 MW thermal power plant, nearly 6 × 106 kg of coal to be burnt every day, whereas in a nuclear power plant only 2.5 kg of Uranium to be consumed daily for getting same output. But the initial investment of nuclear power plant is quite high. It produces electricity without causing any air pollution, but, it has always a chance of radiation hazard because of leakage in reactor chamber. Another major disadvantage of this plant is its disposals, as because its disposals are not free from radioactivity.
Non Conventional Source of Electrical Power Generation
Although the main sources of electric power generation are thermal, hydel, and nuclear power plants, but still there are many other non conventional sources of power available. These non conventional sources, like wind power, solar power, MHD generation, biomass, fuel cell, etc. are becoming the promising alternative sources for electric power generation.