- In modern life, energy is essential for various needs and is used in forms like mechanical, heat, chemical, and electrical energy.
- Electrical energy is mainly generated using the principle of electromagnetic induction, discovered by Michael Faraday.
- A potential difference is generated when there is a change in the magnetic field around a conductor, either by moving the magnet or the conductor.
- Electric generators convert mechanical energy into electricity, and turbines are used to rotate the magnets inside the generator.
- The type of energy source used to drive the turbine (e.g., water, steam, wind) determines the type of power station and turbine design.
Definitions [8]
Define.
Electromagnetic induction
It is the principle invented by Michael Faraday. According to this principle, whenever magnetic field around a conductor changes, a potential difference is generated across the conductor.
Definition: Electromagnetic Induction
The phenomenon in which a potential difference is generated across a conductor when the magnetic field around it changes, is called electromagnetic induction.
Definition: Electric Generator
A machine that generates electricity by using the principle of electromagnetic induction is called an electric generator.
Definition: Turbine
A device with blades that rotates when a fluid (liquid or gas) flows over it due to its kinetic energy, and is used to drive a generator, is called a turbine.
Define.
Nuclear fission
In nuclear fission, the atom of a heavy element is bombarded by a neutron to form an unstable isotope which further splits into two or more smaller nuclei releasing extra neutrons and large amount of energy and heat.
Definition: Environmental Pollution
Unwanted or harmful changes in the physical, chemical, or biological properties of air, water, or soil due to natural or human activities is called environmental pollution.
Definition: Green Energy
Energy generated from renewable, non-polluting sources like water, wind, sunlight, and biofuels that do not harm the environment is called green energy.
Definition: Solar Photovoltaic Cell
Solar photovoltaic cell converts the solar radiation energy directly into electrical energy. This is called solar photovoltaic effect.
Key Points
Key Points: Generation of Electrical Energy
Key Points: Power Plants Based on Nuclear Energy
- Working Principle: Nuclear fission of Uranium-235 or Plutonium releases heat, which is used to convert water into steam.
- Electricity Generation: The high-pressure steam rotates the turbine, which drives the generator to produce electricity.
- Energy Transformation: Nuclear energy → Thermal energy → Kinetic energy in steam → Kinetic energy in turbine → Electrical energy.
- Advantages: No air pollution, efficient source of energy, and less fuel required compared to thermal power plants.
- Problems: Produces radioactive nuclear waste and any accident can release harmful radiation.
Key Points: Power Plant Based on Thermal Energy
- Working Principle: Thermal power stations use steam to rotate turbines. Steam is generated by heating water using thermal energy from burning coal.
- Energy Conversion: Chemical energy in coal → Thermal energy → Kinetic energy in steam → Kinetic energy in turbine → Electrical energy via generator.
- Steam Recirculation: After rotating the turbine, steam is cooled in a condenser and converted back to water, which is then re-circulated to the boiler.
- Environmental Impact: Burning coal releases harmful gases (CO₂, SOx, NOx) and soot, causing air pollution and respiratory issues.
- Limitations: Coal reserves are limited, and dependence on them for electricity poses long-term sustainability issues.
Key Points: Power Plants Based on Natural Gas
- Working: Pressurised air and natural gas are burned in the combustion chamber to produce hot gases.
- Turbine Movement: These high-temperature gases rotate the gas turbine.
- Electricity Generation: The rotating turbine drives the generator to produce electricity.
- Energy Transformation:
Chemical energy in natural gas → Kinetic energy from combustion → Kinetic energy in turbine → Electrical energy
Key Points: Electric Energy Generation and Environment
- Environmental Effects: Fossil and nuclear fuels pollute the environment and generate harmful waste.
- Health Hazards: Emissions like CO₂, NO₂, and soot cause global warming and respiratory problems.
- Limited Resources: Coal and natural gas reserves are depleting and may last only 200–300 years.
- Nuclear Risks: Nuclear power involves radioactive waste and the danger of accidents.
- Green Energy Shift: Renewable sources like solar, wind, and hydro are eco-friendly and sustainable.
Key Points: Electricity Generation using Hydroelectric Energy
- Working Principle: Hydroelectric power plants use the potential energy of water stored in a reservoir, which converts into kinetic energy as water flows down.
- Turbine and Generator: The flowing water (kinetic energy) drives a water turbine, which in turn rotates a generator to produce electrical energy.
- Energy Conversion:
Potential energy of water → Kinetic energy of flowing water → Kinetic energy in turbine → Electrical energy - No Fuel Pollution: Since no fuel is burned in hydroelectric plants, there is no air pollution from combustion.
- Advantages & Concerns: Hydroelectric power gives uninterrupted generation if water is available, but reservoir storage may submerge land and affect living things in the river ecosystem.
Key Points: Electricity Generation using Wind Energy
- Working Principle: Wind energy uses the kinetic energy of moving air to rotate the blades of a wind turbine.
- Electricity Generation: The rotating turbine drives a generator, converting kinetic energy into electrical energy.
- Energy Transformation:
Kinetic energy in wind → Kinetic energy in turbine → Electrical energy. - Clean Energy: Wind energy is a clean and renewable source with no fuel combustion or air pollution.
- Limitations: Wind turbines require sufficient wind velocity, which is not available everywhere, limiting widespread use.
Key Points: Solar Photovoltaic Cell
- Working Principle:
Solar photovoltaic cells convert solar radiation energy directly into electrical energy through the solar photovoltaic effect. - Electricity Output:
A single silicon solar cell produces DC electrical power, and multiple cells can be connected in series and/or parallel to increase voltage and current. - Energy Transformation:
Energy in sunlight → Photovoltaic effect → DC electrical power. - Utility Conversion:
Since most appliances use AC power, DC electricity from solar cells is converted to AC using an inverter before feeding into the grid or loads. - Environmental Benefit:
Solar PV generation produces no air pollution and generates electricity without burning any fuel, though it works only when sunlight is available.
Key Points: Solar Thermal Power Plant
- Working Principle:
Solar thermal power plants use solar radiation to generate heat. This thermal energy is used to produce steam by heating water. - Electricity Generation:
The steam rotates a turbine, which in turn drives a generator to produce electricity. - Energy Transformation:
Solar energy → Thermal energy → Kinetic energy in steam → Kinetic energy in turbine → Electrical energy. - System Components:
Reflectors concentrate sunlight onto absorbers. The system includes a boiler/absorber, steam turbine, generator, condenser, pump, and cooling tower. - Environmental Impact:
It is a clean and renewable energy source. Since no fuel is burnt, it does not cause air pollution.
Important Questions [16]
- Give scientific reasons: It is absolutely necessary to control the fission reaction in nuclear power plants.
- Identify the Process Shown in Figure and Name It.
- Write the problems associated with hydroelectric power projects.
- Atomic power plant in Maharashtra is ______.
- Give a scientific reason. Power generation plant based on natural gas is eco-friendly.
- Observe the Diagram and Answer the Questions : 1) Which energy is generated from the power plant? 2) State its source.
- Incomplete combustion of fuels leads to formation of _______.
- What Are the Advantages of Hydroelectric Power Generation ?
- Write the advantages of the Hydroelectric Power project.
- Complete the stages in electric generator using wind energy.
- The Hydroelectric capacity of Koyna dam is ______.
- Give scientific reason: Hydroelectric energy, solar energy and wind energy are called renewable energies.
- Answer the following questions from figure: With reference to point B, potential energy of how much water reservoir in the dam will be converted into kinetic energy?
- Observe the given picture and answer the questions. Questions: (a) Identify the given diagram. (b) What is the source of energy in this project? (c) Why this source is supposed to be ecofriendly?
- Write limitations in an electric generator using wind energy.
- Make a table based on forms of energy and corresponding devices: Forms of Energy- Electric, Mechanical, Thermal, _________ Devices- _________,
Concepts [11]
- Energy and Use of Energy
- Generation of Electrical Energy
- Power Plants Based on Nuclear Energy
- Power Plant Based on Thermal Energy
- Power Plants Based on Natural Gas
- Electric Energy Generation and Environment
- Electricity Generation using Hydroelectric Energy
- Electricity Generation using Wind Energy
- Electricity Generation using Solar Energy
- Solar Photovoltaic Cell
- Solar Thermal Power Plant
