CBSE – 10th Standard Science

Class 10 Chapter 14 – Sources of Energy

Sources of Energy

  • The total energy during a physical or chemical process is
  • Energy can neither be created nor destroyed.
  • Energy comes in different forms and one form can be converted to another.
  • The total energy during a physical or chemical process remains the same.
  • Any source of energy we use, to do work, is consumed and cannot be used



  • The exploitation of coal as a source of energy made the industrial revolution possible.
  • Increasing industrialization has led to a better quality of life all over the world.
  • The growing demand for energy is largely met by the fossil fuels – coal and
  • The fossil fuels are non-renewable sources of energy.
  • Air pollution caused by burning of coal or petroleum products
  • The oxides of carbon, nitrogen and sulphur that are released on burning fossil fuels are acidic oxides.
  • By burning of carbon, nitrogen and sulphur, leads to acid rain which affects our water and soil resources.
  • Air pollution; recall the green-house effect of gases like carbon dioxide.
  • The availability of electrical energy to each individual in a country is one of the parameters to measure the growth of the country.
  • The pollution caused by burning fossil fuels can be somewhat reduced by increasing the efficiency of the combustion process and using various techniques to reduce the escape of harmful gases and ashes into the surroundings.
  • In gas stoves and vehicles fossil fuels are the major fuels used for generating electricity.
  • Various sources of energy can be harnessed to run the turbine and generate
  • Large amount of fossil fuels are burnt every day in power stations to heat up water to produce steam which further runs the turbine to generate electricity.
  • The transmission of electricity is more efficient than transporting coal or petroleum over the same distance.

Thermal Power Plant

  • Many thermal power plants are set up near coal or oil fields.
  • The term thermal power plant is used since fuel is burnt to produce heat energy which is converted into electrical energy.
  • Another traditional source of energy was the kinetic energy of flowing water or the potential energy of water at a height.

Hydro Power Plants

  • Hydro power plants convert the potential energy of falling water into electricity.
  • Since there are very few water-falls which could be used as a source of potential energy, hydro power plants are associated with
  • In the last century, a large number of dams were built all over the world.
  • A quarter of our energy requirement in India is met by hydro power plants.
  • In order to produce hydel electricity, high-rise dams are constructed on the river to obstruct the flow of water and thereby collect water in larger reservoirs.
  • The dams can be constructed only in a limited number of places, preferably in hilly terrains.



  • Cow-dung, various plant materials like the residue after harvesting the crops, vegetable waste and sewage are decomposed in the absence of oxygen to give bio-gas.



  • Since the starting material is mainly cow-dung, it is popularly known as ‘gobar-gas’.
  • A windmill essentially consists of a structure similar to a large electric fan that is erected at some height on a rigid support.
  • To generate electricity, the rotatory motion of the windmill is used to turn the turbine of the electric generator. The output of a single windmill is quite small and cannot be used for commercial purposes.
  • Wind energy is an environment-friendly and efficient source of renewable energy. It requires no recurring expenses for the production of electricity.
  • A black surface absorbs more heat as compared to a white or a reflecting surface under identical conditions.

Energy from the Sea

  • Tidal energy is harnessed by constructing a dam across a narrow opening to the sea.
  • Wave energy would be a viable proposition only where waves are very strong. A wide variety of devices have been developed to trap wave energy for rotation of turbine and production of electricity.

         Geothermal Energy

  • When underground water comes in contact with the hot spot, steam is generated. Sometimes hot water from that region finds outlets at the surface. Such outlets are known as hot springs.

              Nuclear Energy

  • The major hazard of nuclear power generation is the storage and disposal of spent or used fuels – the uranium still decaying into harmful subatomic particles radiations
  • Nuclear energy was first used for destructive purposes before nuclear power stations were designed.
  • The energy source we select would depend on factors like the ease and cost of extracting energy from the source, the efficiency of the technology available for using that source of energy and the environmental impact of using that source.


Differences between nuclear fission and fusion