Class 10 Sources of Energy Notes

Notes Previous Years Questions Important Questions

Sources of Energy Notes

Characteristics of a good source of energy:-

  • Should have high calorific value.
  • Easily available.
  • Easy to transport & store.
  • Should be economical.
  • Should be ecofriendly.
  • Safe & convenient to use.

Renewable source of energy:-

The source of energy which can be continuously generated by natural processes & whose supply is unlimited is called renewable sources of energy. Ex:- Tidal energy, Wind energy, Solar energy, Hydral energy, etc.

Non-renewable source of energy:-

The sources of energy which were produced by natural processes & whose supply is limited are called non-renewable sources of energy. Ex:- Coal, Natural gas, Petroleum, etc.

Conventional sources of energy:-

The sources of energy which have been used since over a long time are called conventional sources of energy. Ex:- Fossil fuel, Thermal power plants, Hydro power plants etc.

Fossil Fuels:-

The fuels formed by the remainings of prehistoric plants & animals which get buried deep inside the earth under high pressure & high temperature are called fossil fuels.

  • Coal:- It is a mixture of carbon & compounds of carbon containing hydrogen, nitrogen, oxygen, & sulphur.
  • Petroleum:- It is a mixture of several solid, liquid & gaseous hydrocarbons mixed with water, salt & earth particles.
  • Natural gas:- It consists of methane, ethane, propane.

Disadvantages of fossil fuels:-

  • Burning of fossil fuels causes air pollution.
  • Burning of fossil fuels releases acidic oxides which lead to acid rain.
  • Green house gases like carbon dioxide are also released on burning of fossil fuels.
  • They leave residue after burning.

Thermal power plant:-

It converts heat energy produced by the combustion of fossil fuels to electrical energy.

Advantages of thermal power plant:-

  • High amount of electricity is produced.
  • A big source of employment.

Disadvantages of thermal power plant:-

  • It causes air pollution.
  • Large area is required to set the plant.
  • It produces a large amount of residue.

Hydro power plant:-

It converts potential energy of falling water into electricity.

Advantages of hydro power plant:-

  • It is renewable source of energy.
  • The moving water is available free of cost.
  • Dams constructed for hydro power plants are used for many purposes like fishing, irrigation, tourism, etc.
  • It does not cause any environmental pollution like smoke.
  • It controls flood.

Disadvantages of hydro power plant:-

  • A large agricultural area gets submerged in dam.
  • The dam can be constructed only in hilly terrains.
  • It decreases the fertility level of soil in downstream areas.
  • A large variety of plants, animals & their habitats get submerged in water.
  • It disturbs the natural flow of water.
  • Many people have to displace from their places.
  • The vegetation that gets submerged under water decomposes anaerobically & produce methane gas which is a green house gas.

Bio mass:-

The waste materials of living things such as cow dung & dead parts of plants & animals which are used as a source of energy is called bio mass.

Bio gas:-

  • It is a mixture of methane (75%), carbon dioxide, hydrogen and hydrogen sulphide.
  • It is produced by the anaerobic decomposition of animal waste like dung & plant waste.

Advantages of bio gas:-

  • It burns without smoke.
  • It leaves no residue.
  • Its calorific value is high.
  • It is convenient to use.
  • The slurry left behind is rich in nitrogen & phosphorous & so it is used as excellent manure.

Wind energy:-

Advantages of wind energy:-

  • Wind energy is renewable source of energy.
  • It is ecofriendly.
  • Wind energy farm requires no recurring expenses.

Disadvantages of wind energy:-

  • It can be established only at those places where wind blows for most of the time in a year.
  • It works only when the speed of wind is more than 15 km/h.
  • Wind energy farm requires a large area of land i.e., about 2 hectares of land is needed to generate 1 MW electricity.
  • The setting up of wind energy farm is very expensive.
  • The tower and blades need high level of maintenance.

Non-conventional Sources Of Energy:-

Solar Energy:-


  • It is used in solar cookers and solar water heaters.
  • It is used in solar cell panels to generate electricity.

Advantages of solar energy and solar cell panel:-

  • It is ecofriendly.
  • It is a renewable source of energy.
  • It is available free of cost.
  • It can be established in remote areas.
  • Solar cell is used in artificial satellites, radio or TV relay stations, traffic signals, calculators etc.

Disadvantages of solar energy and solar cell panel:-

  • Special grade silicon used for making solar cell is limited.
  • The entire process of manufacture of solar cell is very expensive.
  • Its efficiency is very low (A typical solar cell develops a voltage of 0.5–1 V and can produce about 0.7 W of electricity).
  • It cannot generate electricity at night and on cloudy day.

Solar Cell:- It is a device that converts solar energy into electrical energy.

Solar Cell Panel:- The combination of solar cells to produce large amount of electrical energy is called solar cell panel.

Energy from the sea:-

Tidal energy:-

Tide:- The change in the level of ocean water due to the gravitational pull of the moon and the sun is called tide.

Advantages of tidal energy:-

  • Ecofriendly.
  • No recurring expenses is required.
  • Renewable source of energy.

Disadvantage of tidal energy:-

  • There are very few narrow openings to the sea where the dams can be constructed to harness tidal energy.

Wave energy:-

The kinetic energy of strong waves produced near sea-shore is used to run turbine & generate electricity.

Advantages of wave energy:-

  • Ecofriendly.
  • No recurring expenses is required.
  • Renewable source of energy.

Disadvantage of wave energy:-

  • Wave energy can be harnessed to generate electricity only when the waves are very strong.

Ocean thermal energy:-

The difference in temperature of water at the surface & at the depth is exploited to generate electricity. The warm surface water is used to boil ammonia & turbine is run by the vapours of ammonia. The cold water from the depth is pumped up to condense vapour again to liquid.

Advantages of ocean thermal energy:-

  • Ecofriendly.
  • No recurring expenses is required.
  • Renewable source of energy.

Disadvantage of ocean thermal energy:-

  • Ocean thermal energy can be used only when the difference in temperature between surface water & water at depth of about 2 km is 293 K (20°C) or more.

Geothermal energy:-

The steam trapped in the rocks in the earth’s crust is used to run turbine and generate electricity.

  • Hot spots:- The regions in the earth’s crust where molten rocks are trapped are called hot spots.
  • Hot springs:- The outlets of hot water at the surface of the earth are called hot springs.

Advantages of geothermal energy:-

  • Ecofriendly
  • Economically cheaper

Disadvantage of geothermal energy:-

  • Only few sites are available where geothermal energy can be exploited.

Nuclear Energy:-

Nuclear Fission:- When low energy neutron is bombarded on the nucleus of heavy atom (such as thorium, plutonium, uranium), it splits into lighter nuclei. This phenomenon is called nuclear fission.

Nuclear fusion:- The joining of lighter nuclei to make a heavier nucleus in the presence of very high temperature & pressure is called nuclear fusion.

  • In nuclear power plants, nuclear fission is used.

Advantage of nuclear energy:-

  • In nuclear reactors, the amount of energy produced is very high.

Disadvantages of nuclear energy:-

  • The used fuels like uranium decays into harmful radiations. So the storage & disposal of used fuels is very challenging.
  • There is a risk of accidental leakage of nuclear radiation.
  • The cost of installation of nuclear power plant is very high.
  • There is a limited availability of uranium.


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