Sources of Energy SSLC Karnataka 10 Science Notes

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  • Energy is obtained by converting one source of energy to another source of energy. E.g. chemical energy from wax in candle produces light energy in form of  light.
  • Good sources of energy :
    1. It should produce large energy per unit volume.
    2. Should be easily available.
    3. Should be easy to store and transport.
    4. Should be more economical.
    • Conventional / Non renewable source of energy : Sources of energy that will vanish over a period of time. E.g. Fossil fuels, coal, firewood, etc.


  • Conventional source of energy : Fossil Fuel


      • Fossil fuels constitutes coal and petroleum.
      • Coal is obtained from earth’s crust, and mainly used in production of electricity.
      • Petroleum is obtained from sea, and is mainly used as fuel in vehicles.
      • Burning or combustion of fossil fuels causes air pollution which ultimately leads to acid rain, global warming, etc.
      • Air pollution must be prevented by improving combustion techniques.  
    • Conventional source of energy : Electricity Production [Refer the video to understand in detail]
      • Take a tennis ball and attach metal strip to it such that it appears like fan.
      • Tie a tennis ball at centre of axle so as to rotate it freely.
      • Apply steam produced from pressure cooker on the tennis ball.
      • It rotates ball as well as shaft simultaneously which produces electricity.
      • Hence, mechanical energy is converted to electrical energy.
    • Conventional source of energy : Thermal power plant [Refer the video to understand in detail]
      • Heat is generated by burning fossil fuels which is used to heat water and form steam.
      • Steam under pressure is applied to rotate blades of turbines. (Heat energy ⟶ Mechanical energy)
      • This rotation produced electricity. (Mechanical energy ⟶ Electrical energy)


  • Conventional source of energy : Hydroelectric power plant [Refer the video to understand in detail]


      • Stored water from dam is allowed pass through penstock. (Potential energy ⟶ Kinetic energy).
      • Water is let to fall on blades of turbines so that it start rotating. (Kinetic energy ⟶ Mechanical energy).
      • Rotation of turbines produces electricity. (Mechanical energy ⟶ Electrical energy)


  • Improvements in conventional Source of energy : Biomass


    • Biomass : Fuels obtained from plants and animals. E.g. wood, cow dung, etc.
    • Technological innovations :
      1. Wood : Wood is burnt in less oxygen to form charcoal. Charcoal has higher efficiency and produces less smoke.
      2. Cow dung : Used in production of biogas / gobar gas. It is has high efficiency and produces less smoke.
    • Biogas plant : [Refer the video to understand in detail]
      1. Slurry (cowdung + water) with other wastes like vegetable is fed to digester through inlet tank.
      2. In digester, anaerobic microorganisms decomposes  these material in absence of oxygen to form methane, carbon dioxide, hydrogen and hydrogen sulphide.
      3. Gas is collected in gas tank above the digester and is supplied as a fuel.
      4. Remaining waste product i.e. manure is collected in outlet tank .
    1. Advantages of biogas:
      1. More efficient, contain 75% methane, produces large energy.
      2. Manure obtained is used as fertilizers.
      3. Best way to decompose waste.
      4. Also used for lighting.
  1. Improvements in conventional Source of energy : Wind Energy [Refer the video to understand in detail]
    • Wind energy is used to lift up water from wells using wind mills. Wind mills are huge fan like structure supported with strong support. Blades of wind mill undergo rotation when come across wind. Rotation of blades rotates shaft and water is lifted up from well (Kinetic Energy ⟶ Mechanical Energy).
    • Technological innovations : Wind energy is used to produce electricity with help of windmills. The rotatory motion of the blades of the windmills is used to rotate the turbines, and hence electricity is produced. (Mechanical energy ⟶ Electrical energy).
    • Advantages :
      1. Environment-friendly source of energy.
      2. Efficient source of energy.
      3. Renewable.
      4. Economically helpful.
    • Limitations :
      1. Can be established only in places where wind blows at faster rate in maximum portion of year.
      2. Minimum speed of air must be 15 km / hr.
      3. Require large area.
      4. High establishment cost.
      5. Require high maintenance cost.
  2. Nonconventional / Renewable source of energy : These sources of energy can be regained , hence, are also known as never ending source of energy. E.g. sunlight, wind, tidal energy, etc.
  3. Nonconventional of energy : Solar energy
    • Solar energy is energy obtained from sun which is used in technological inventions like Solar Cooker, Solar Water Heater, Solar Cells.    
    • Solar Cooker :
      1. It is made of black box, glass sheet and reflecting mirror.
      2. Mirror in cooker directs sunlight into box.
      3. Heat from sunlight is trapped in black box with help of glass sheet.
      4. Gathered heat is used to cook food.
      5. Similarly, solar energy is used to heat water using solar water heater.
    • Solar cell :
      1. Converts solar energy to electrical energy. A typical solar produce 0.7 W of electrical power. Collectively it produces large amount of electrical power.
      2. Advantages : Produces satisfactory energy output, requires less maintenance, can be established in remote locations( like mountains).
      3. Disadvantages : Less availability of high quality silicon, expensive manufacturing process, less energy production.
      4. Applications : Used in artificial satellites, radio, TV relay stations, traffic signals, street lights.
  4. Non-Conventional Sources of energy: Energy from Sea [For more details refer video]
    • Tidal Energy :  Energy obtained from difference in high tides and low tides.
      1. Dam are constructed at the narrow opening of the sea.
      2. Tidal energy from sea is converted into electrical energy by rotating turbines.
    • Wave energy : Waves from sea forces water into the pipes which helps in rotation of turbines thereby producing electrical energy.
    • Ocean Thermal Energy : Water on sea surface is hot while at bottom of sea is cold. This temperature difference is used to obtain electricity.
      1. Ammonia is boiled at sea surface where temperature of water is more. Hence, vapors of ammonia is formed which rotates the turbines to produce electricity.
      2. Cold water from bottom of sea is used to convert vapors of ammonia into liquid.
      3. Temperature difference of water in sea must be greater than 20℃.
  5. Geothermal Energy : [Refer the video to understand in detail]
    • Due to geological changes magma gets pushed upward in rock and get trapped in region called hotspot.
    • Stream of cold water is passed to hotspots which converts water into steam, which helps the turbine to rotate and produce electricity.
    • Advantages : Have very less production cost.
    • Disadvantage : places with hotspots are very few on earth hence, ue of this energy is less.
  6. Nuclear Energy : [Refer the video to understand in detail]
    • Fission Reaction : Nucleus of heavy atoms (e.g. Uranium) is unstable,  such that if neutron is bombarded it breaks the nucleus into daughter nuclei and 3 neutrons, thereby producing large energy.
    • Advantages : A nuclear reactor is designed, and by controlled fission water is converted to steam and which rotates turbines to produce electricity.
    • Disadvantage :  
      1. Problem of storage and disposal of nuclear waste.
      2. Nuclear waste is harmful for environment.
      3. Accidental leakage of radiation can cause destruction.
      4. Plant need very high establishment and maintenance cost.
  7. Environmental Consequences :
    • Parameters to choose source :
      1. Ease of extracting energy
      2. Economics of extraction process
      3. Efficiency of process
      4. Environmental considerations
    • Impact on environment and threat to exhaust : Every fuel has an effect on environment. E.g Burning of fossil fuel causes air pollution . also many  of fuel are exhaustible, if continuously used they will come to an end over a period of time. E.g. coal, petroleum, etc.
  • Difference between conventional and non conventional source of energy
Conventional source of energy Nonconventional source of energy
  • Also known as non renewable / exhaustible sources of energy
  • Also known as renewable / inexhaustible sources of energy
  • Cause pollution in environment
  • Are mostly pollution free
  • Expensive in maintenance and storage
  • Less expensive and easy to maintain
  • E.g. coal, petroleum, natural gas, etc.
  • E.g. solar energy, tidal energy, etc.

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