Sources of Energy Class 10 Notes Science Chapter 14

1. Source of energy:

Any system from where energy can be trapped is called a source of energy. There are two types of sources of energy:
(i) Renewable sources of energy: The energy which can be generated by us or which are constantly being generated by natural processes or whose supply is unlimited are known as renewable sources of energy. e.g., Sun, wind, flowing water.
(ii) Non-renewable sources of energy: The energy which were produced in the past by natural processes, whose supply is limited and which we cannot generate again are known as non-renewable sources of energy. e.g., coal, petroleum, natural gas.

2. Conventional energy:

It means the energy source which is obtained from fixed reserves in nature like oil, gas and coal.
Conventional sources of energy:

(i) Fossil fuels: Fossil fuels comprise of coal and petroleum, these are non-renewable sources of energy, so we need to conserve them. There are many disadvantages of burning fossil fuels. Burning of coal and petroleum causes air pollution.
(ii) Thermal power plant: In thermal power plants, fuel is burnt to produce heat energy which is further converted into electrical energy.
(iii) Hydropower plants: In hydropower plants, the potential energy of water is converted into electricity.

3. Improvements in the technology for using conventional sources of energy
(i) Biomass: In the context of energy production, biomass means any organic matter from which we can get energy on a renewable basis. Biogas is a combustible mixture of gases produced by the decomposition of biomass, especially animal waste and sewage.
(ii) Advantages of biogas: Biogas is an excellent clean fuel that bums without smoke. It leaves no ash on burning. Biogas plants represent a safe and useful way of waste disposal. Use of biogas in rural areas leads to saving of fire wood and reduces deforestation.
(iii) Preparation of biogas: Biogas is prepared by anaerobic fermentation of biomass. Biomass contains complex molecules like carbohydrates, fats, cellulose, etc.

4.Wind energy: When wind blows with a sufficient speed, it gets ability to do some work, it means wind possesses energy called wind energy.
Uses of wind energy:

  1. It is used to sail boats.
  2. It is used to generate electricity.
  3. It can be used to run wind mill which is further utilised :
  4. to grind wheat and grains.
  5. to pump out water from the earth’s crust.

Wind mill: It is a device which is used to convert wind energy into useful mechanical work.
Wind farms: When large number of wind mills are installed over a large area to harness wind energy commercially, like to generate electricity commercially (large scale), they are called wind farms.

5. Solar energy:

The energy coming with the rays of the sun is called solar energy. The fusion reaction taking place inside the sun provide very large amount of heat and light.
Solar cookers: Box type solar cookers can achieve temperatures of the order of 100-l 40°C. Frying and making chapattis are generally not possible in a box type solar cooker.

Advantages of solar cooker:

  1. Solar cookers use no fuel. This saves cost as well as reducing environmental damage caused by fuel use.
  2. Solar cookers uses solar energy to heat and cook food, which is available in unlimited amount for free. Therefore operating a solar cooker is not expensive.

Disadvantages of solar cooker:

  1. It can not be used at nights or during cloudy days.
  2. It takes a long time for cooking.

6. Solar cells: It is a device which is used to convert solar energy into electrical energy. Solar cells are made up of semi-conductors like silicon, germanium, gallium, etc.
Uses of solar cells:

  1. Solar cells are used to provide energy to artificial satellites and space probes.
  2. Solar cells are used as a source of electricity on oil drilling platforms and light house.
  3. Solar cells are used to run small electrical devices like watches, calculators, etc.

7. Solar panel: When a large number of solar cells are put together to draw high voltage for commercial purposes then it is called solar panel.

8. Energy from the sea: The energy from the sea can be obtained mainly in three forms:
(i) Tidal energy: It is a form of energy which is obtained from the ocean in the form of tidal waves.
(ii) Wave energy: It is another form of ocean energy which can be harnessed, wind blowing across the surface of ocean are converted into waves. These waves carry energy called wave energy.
(iii) Ocean Thermal Energy (0. T.E): Temperature difference between layers of water at different depth in the sea can also be used to produce electricity. The energy present in this form is called ocean thermal energy.
These plants can operate if the temperature difference between the water at the surface and water at depth up to 2 km is 20°C or more.

9. Geothermal energy: Geothermal energy is the energy stored as heat in the earth. It heats rocks and water below the ground.

10. Nuclear energy: The energy released during nuclear reactions is called nuclear energy because it comes from the nuclei of atoms. Nuclear energy is generated by two types of nuclear reactions:

(i) Nuclear fission: In a process called nuclear fission, the nucleus of a heavy atom (such as uranium, plutonium or thorium), when bombarded with low-energy neutrons, can be split apart into lighter nuclei.
(ii) Nuclear fusion: Fusion means joining lighter nuclei to make a heavier nucleus, most commonly hydrogen or hydrogen isotopes to create helium, such as

Hazards of nuclear power generation: The major hazard of nuclear power generation is the storage and disposal of spent or used fuels. Improper nuclear- waste storage and disposal result in environmental contamination. Further, there is a risk of accidental leakage of nuclear radiation.