Class 10 Sources of Energy Notes

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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:-

Uses:-

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.

Class 10