| abstract | - Bulk electric power is produced by special plants known as generating stations or power plants. A generating station essential employs a prime mover coupled to an alternator for the production of electric power. The prime mover(e.g., steam turbine, water turbine etc.) convert energy from some form into mechanical energy. The alternator converts mechanical energy of the prime mover into electrical energy. The electrical energy produce by the generating station is transmitted and distributed with the help of conductors to various consumers. It may be emphasized here that apart that apart from prime mover-alternator combination, a modern generating station employs several auxiliary equipment and instrument to ensure cheap, reliable and continuous service. Depending upon the form of energy converted into electrical energy, the generating stations are classified as under: (i) Steam power stations (ii) Hydroelectric power stations (iii) Diesel power stations (iv) Nuclear power stations **Steam-electric Power Plant (Thermal Station)** A generating station which converts heat energy of coal combustion into electrical energy is known as a steam power station. A steam power station basically works on the Rankine cycle. A steam-electric power plant is a power plant in which the prime mover is steam. Water is heated, turns into steam and spins a turbine. After it passes through the turbine, the steam is cooled and condenses. Steam-electric plants are very similar to one another, only the heat source is different. Almost all coal, nuclear, geothermal, solar thermal electric and many natural gas power plants are steam-electric. Natural gas is frequently combusted in gas turbines as well boilers, and it is possible to make coal and nuclear plants that are not steam electric, though all major plants are. Large solar power tower and solar parabolic trough type solar thermal electric plants are steam-electric, but solar dishes and solar ponds usually use a Stirling engine. The vast majority of electricity is produced by steam-electric power plants. The only other types of plants that currently have a significant contribution are hydroelectric and gas turbine plants, which can burn natural gas or diesel. Photovoltaic panels, wind turbines and binary cycle geothermal plants are also non-steam electric, but currently do not produce much electricity. A generating station which utilized the potential energy of water at a high level for the generation of electrical energy is known as a hydro-electrical power station. Hydroelectricity is electricity obtained from hydropower. Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator, although less common variations use water's kinetic energy or dammed sources, such as tidal power. Hydroelectricity is a renewable energy source. Hydro-electric power station are generally located in hilly areas where dams can be built conveniently and large water reservoirs can be obtained. In hydro-electric power station, water head is created by constructing a dam across a river or lake. From the dam, water is led to a turbine. The water turbine captures the energy in the falling water and changes the hydraulic energy (i.e., product of head and flow of water) into mechanical energy at the turbine shaft. The turbine drives the alternator which converts mechanical energy into electrical energy. The energy extracted from water depends not only on the volume but on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock. A generating station which diesel engine is used as the prime mover for the generation of electrical energy is known as a diesel power station. In a diesel power station, diesel engine is used as the prime mover. The diesel burns inside the engine and the products of this combustion act as the “working fluid” to produce mechanical energy. The diesel engine drives the alternator which converts mechanical energy into electrical energy. As the generation cost is considerable due to high price of diesel, therefore, such power station are only used to produce small power. These plants are also used as standby sets for continuity of supply to important points such as hospitals radio station, cinema houses and telephone exchanges. **Nuclear Power Station** A generating station in which nuclear energy is converted into electrical energy is known as a nuclear power station. In nuclear power station, heavy elements such as Uranium(U235) or Thorium(Th 232) are subjected to nuclear fission in a special apparatus known as a reactor. The heat energy thus released is utilized in raising steam at high temperature and pressure. The steam runs the steam turbine which converts steam energy into mechanical energy. The turbine drives the alternator which coverts mechanical energy into electrical energy. The most important feature of a nuclear power station is that huge amount of electrical energy can be produced from a relatively small amount of nuclear fuel as compared to other conventional types of power stations. It has been found that complete fission of 1 kg of Uranium (U235) can produce as much energy as can be produced by the burning of 4,500 tons of high grade coal. Although the recovery of principal nuclear fuels (i.e., Uranium and Thorium) is difficult and expensive, yet the total energy content of the estimated world reserves of these fuels are considerably higher than those of conventional fuels, viz., coal, oil, and gas. At present, energy crisis is gripping us and therefore, nuclear energy can be successfully employed for producing low cost electrical energy on a large scale to meet the growing commercial and industrial demands. S.No. Item
* Steam power station
* Hydro-electrical power plant
* Diesel power plant
* Nuclear power plant 1. Site Such plants are located at a place where ample supply of water and coal is available, transportation facilities are adequate Such plants are located where large reservoirs can be obtained by constructing a dam. e.g., in hilly areas Such plants can be located at any place because they require less space and small quantity of water. These plants are located away from thickly populated areas to avoid radio active pollution. 2. Initial cost Initial cost is lower than those of hydroelectric and nuclear power plants. Initial cost is very high because of dam construction and excavation work. Initial cost is less as compared to other plants. Initial cost is highest because of huge investment on building a nuclear reactor. 3. Running cost Higher than hydroelectric and nuclear plant because of the requirement of huge amount of coal. Practically nil because no fuel is required. Highest amount all plants because of high price of diesel. It has the minimum running cost because small amount of fuel can produce relatively large amount of power. 4. Limit of source of power Coal is the source of power which has limited reserves all over the world. Water is the source of power which is not dependable because of wide variations in the rainfall every year. Diesel is the source of power which is not available in huge quantities due to limited reserves. The source of power is the nuclear fuel which is available in sufficient quantity. It is because small amount of fuel can produce huge power. 5. Cost of fuel transportation Maximum because huge amount of coal is transported to the plant site. Practically nil. Higher than hydro and nuclear power plants. Minimum because small quantity of fuel is required. 6. Cleanliness and simplicity Least clean as atmosphere is polluted due to smoke. Most simple and clean. More clean than steam power and nuclear power plants. Less cleaner than hydro-electric and diesel power plants. 7. Overall efficiency Least efficiency Most efficient. Overall efficiency is about 85%. More efficient than steam power station. Efficiency is about 35%. More efficient than steam power station. 8. Starting Requires a lot of time for starting. Can be started instantly. Can be started quickly. Can be started easily. 9. Space required These plants need sufficient space because of boiler and other auxiliaries. Require very large area because of the reservoir. Require less space. These require minimum space as compared to any other plant of equivalent capacity. 10. Maintenance cost Quite high as skilled operating staff is required. Quite low. Less. Very high as highly trained personnel are required to handle the plant. 11. Transmission and distribution cost Quite low as these are generally located near the load centers. Quite high as these are located quite away from the load centers. Least as they are generally located at the center of gravity of the load. Quite low as these are located near load centers. 12. Standby losses Maximum as the boiler remains in operation even when the turbine is not working. No standby losses. Less standby losses. Less.
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