A power plant, is an industrial location that is utilized for the generation and distribution of electric power on a mass scale. Many power stations contain one or more generators, a rotating machine that converts mechanical power into three-phase electric power (these are also known as an alternator). The relative motion between a magnetic field and an electrical conductor creates an electric current.
These are generally located in the sub-urban regions or several kilometers away from the cities or the load centers, because of its requisites like huge land and water demand, along with several operating constraints like waste disposal, etc.
For this reason, a power generating station has to not only concern itself with the efficient generation of power, but also in the transmission of this power. This is why power plants are often closely accompanied by transformer switchyards. These switchyards increase the transmission voltage of the power, which allows it to be more efficiently transmitted over long distances.
The energy source harnessed to turn the generator shaft varies widely and is chiefly dependent on the type of fuel used. The fuel choice dictates what we call the power plant, and this is how the various types of power plants are classified.
Types of Power Plants
The different types of power plants are classified depending on the type of fuel used. For the purpose of bulk power generation, thermal and hydropower are the most efficient. A power generating station can be broadly classified into the three above-mentioned types. Let us have a look at these types of power stations in detail.
Thermal Power Station
A thermal power station or a coal fired thermal power plant is by far, the most conventional method of generating electric power with reasonably high efficiency. It uses coal as the primary fuel to boil the water available to superheated steam for driving the steam turbine.
The steam turbine is then mechanically coupled to an alternator rotor, the rotation of which results in the generation of electric power. To enhance the thermal efficiency of the plant, the coal is used in the boiler in its pulverized form.
In coal fired thermal power plant, steam is obtained in very high pressure inside the steam boiler by burning the pulverized coal. This steam is then super-heated in the super heater to extreme high temperature. This super-heated steam is then allowed to enter into the turbine, as the turbine blades are rotated by the pressure of the steam.
The turbine is mechanically coupled with alternator in a way that its rotor will rotate with the rotation of turbine blades. After entering into the turbine, the steam pressure suddenly falls leading to corresponding increase in the steam volume.
After having imparted energy into the turbine rotors, the steam is made to pass out of the turbine blades into the steam condenser of the turbine. In the condenser, cold water at ambient temperature is circulated with the help of a pump which leads to the condensation of the low-pressure wet steam.
Then this condensed water is further supplied to low pressure water heater where the low pressure steam increases the temperature of this feed water, it is again heated in high pressure. This outlines the basic working methodology of a thermal power plant.
Advantages and disadvantage of Thermal Power Plants
|Fuel used i.e coal is quite cheaper||It pollutes atmosphere due to production of smoke and fumes|
|Initial cost is less as compared to other generating stations||Running cost of the power plant is more than hydro-electric plant|
|It requires less space as compared to hydro-electric power stations||The overall efficiency of the power plant is low|
Hydro-Electric Power Station
In Hydroelectric plants, the energy of the falling water is utilized to drive the turbine which in turn runs the generator to produce electricity. Rain falling upon the earth’s surface has potential energy relative to the oceans towards which it flows. This energy is converted to shaft work where the waterfalls through an appreciable vertical distance. The hydraulic power is, therefore, a naturally available renewable energy given by the equation:
P = gρ H
Where, g = acceleration due to gravity = 9.81 m/sec 2
ρ = density of water = 1000 kg/m3
H = height of fall of water.
This power is utilized for rotating the alternator shaft, to convert it to equivalent electrical energy.
An important point to be noted is that the hydro-electric plants are of much lower capacity compared to their thermal or nuclear counterpart.
For this reason, hydro plants are generally used in scheduling with thermal stations, to serve the load during peak hours. They in a way assist the thermal or the nuclear plant to deliver power efficiently during periods of peak hours.
Advantages and disadvantage of Hydro-electric Power Plants
|It requires no fuel, water is used for generation of electrical energy||It involves high capital cost due to dam construction|
|It is neat and clean energy generation||Availability of water depends upon weather conditions|
|Construction is simple, less maintenance is required||It requires high transmission cost as the plant is located in hilly areas|
|It helps in irrigation and flood control also||Impact on Fish. To create a hydro plant, a running water source must be dammed|
Other types of energy production methods
As mentioned above, energy generation methods are classified according to the power plant power supply. The most important of these methods were thermal and hydroelectric power plants.
Apart from these categories, smaller power plants can also be established. Most of these methods are known as alternative methods of generating electricity and are classified as follows:
- Solar energy (using solar panels)
- Geothermal energy (using the energy of the Earth’s core)
- Wind energy (using wind turbines)
- Tidal energy
These resources have grown in recent decades due to the declining trend in fossil fuel consumption. The importance of replacing these energies as sources of future energy supply has been discussed in other articles on the Blue&P site.