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SOURCES OF ENERGY
Energy comes in different forms and one form can be converted to another. For example, if we drop a plate from a height, the potential energy of the plate is converted mostly to sound energy when it hits the ground.
If we light a candle, the process is highly exothermic so that the chemical energy of the wax is converted into heat energy and light energy on burning.
A Good Source of Energy would be one
which has high calorific value
he easily accessible
be easy to store and transport
he economical
Sources of Energy
Conventional Source of Energy. Non-Conventional source of energy
Fossil Fuels
F-g., Cual & Petroleum Thermal Power Plant
Hydro Power Plants Bio-Mass hin gas plant Wind Energy
Solar Energy
Fg Solar Cooker, Solar Cell Panel
Energy From the Sea
E... Tidal & wave energy, O.F.
Energy
Geothermal Energy
Nuclear Energy.
Among the sources of energy, some of them get exhausted (Non Renewable) While some of them do not get exhausted, therefore called as Renewable source of energy. Examples
1. Non-Renewable source of energy - Coal, Petroleum, Natural Gas
2 Renewable Source of energy - Air, Water, Solar radiation, Geothermal
Energy, ncean waves etc.
CONVENTIONAL SOURCE OF ENERGY
Fossil Fuels: Fuels developed from the fossils. E.g., Coal & Petroleum.
Formed over millions of years ago have only limited reserves These are non-renewable source of energy
India has about 6% share in the world reserved coal, that may last 250 years more at the present rate of consumption.
2. They pose dangers of earthquakes, landslides etc.
Biomass is Agricultural & animal wastes that can be used as a fuel. E-g.. of Biomass Firewood, cattle dung, sewage, dry leaves, stems & bagasse
Normally biomass has low calorific value & produce lot of smoke when they are burnt. Their efficiency as a good fuel has been increased tremendously with the application of technology. For Eg.. Cow dung becomes efficient & cheap good fuel in a Bio-gas plant.
Charcoal is better fuel than wood because it does not contain water &
other volatile material which are present in wood.
Wood limited supply
Charcoal
Charcoal burns without smoke, flames & has high calorific value. Bio-gas is an excellent fuel & contain 75% of Methane (CH). It burns
without smoke, leaves no reciters like ash, with high heat capacity. Biogas is produced by anerobic decomposition of the slurry (cow dung+
water mixture) by microbes. This process is applied in a Bio gas plant.
The Biogas is stored in the gas tank from which they are drawn through pipes for use in a Bio-gas plant
Bio gas is used for lighting, cooking in the rural areas. While the slurry left behind is used as excellent manure, rich in nitrogen and phosphorous The large-scale use of Bio-wastes & sewage material provides a safe and
efficient method of waste-disposal besides supplying energy and manure.
WIND ENERGY
Unequal heating of the landmass and water bodies by solar radiation generates air movement & causes winds to blow. This kinetic energy of the wind can be used in do work.
This energy is utilized to lift water from the well & to generate electricity
in the wind mill. Actually, the rotatory motion of the windmill is used to turn the rotor of the turbine which then generate electricity through Dynamo.
The output of a single windmill is quite small so a number of windmills are
erected over a large area-called wind energy farm. India Ranked Fifth in the world in harnessing wind energy for the production of electricity. It is estimated that nearly 45,000 MW of electric power can be generated if India's wind potential is fully exploited.
The minimum wind speed for wind mill to serve as a source of energy is 20KMPH.
Advantages of Wind Energy
1. Eco friendly
2. Efficient source of renewable energy.
3. No recurring expenses for production of electricity
Limitations of Wind Energy
1. Wind energy farms need large area of land
Difficulty in getting regular wind speed of 15-20 KmPH. 3. Initial cost of establishing wind energy farm is very high.
4. High level of maintenance of blades of wind mill. Non-Conventional Sources of Energy
Solar Energy:
The energy emitted by the sun in form of heat and light is called solar energy. Solar Constant = 1.4k.d/s m²
Outer edge of the earth receives solar energy equal to 1.4 kJ/sm³ which is
known as solar constant.
Solar energy devices:
A large number of devices that utilize solar energy directly like:
in Solar Cooker
Solar furnaces
Solar cells
v) Solar water heaters.
Solar heating devices:
Use black painted surface because black surface absorbs more heat as compared to white or other surface.
Use of glass plate because it allows shorter infrarest radiations to pass through it but doesn't allow the longer wavelength infrared radiations to through it, that results in increase in temperature.
Solar Cooker:
Box type solar Cooker
It consists of a rectangular bos which is made up of material such as
plastic or wood.
Box is covered with black sheet and its inner walls are painted black to
increase heat absorption. Solar cookers are covered with glass plate and have mirrors to focus the rays of the sun and achieve a higher temperature,
Advantages:
Use energy which is available in plenty (Solar Energy)
2 Is pollution free.
2. More than one food can be cooked simultaneously
Disadvantages
Cannot be used for frying or baking purpose.
Food cannot be cooked at night or ou a cloudy day.
Direction of reflector of solar heating has to be changed from time to time
to keep it facing the son
Solar Cells:
Solar cells are device that convert Solar energy into electricity.
Develops a voltage of 0.5-IV and can produce about 0.7W of electricity.
Advantages of Solar Cell
1 Require a little maintenance
2 Have no moving part.
No focusing device is required
Can be set up in remote areas.
3 Environment friendly Le., do not cause pollution.
Disadvantage of Sular Cells
It requires high cost 2 Efficiency is low
3. Initial cost of installation is quite high.
Uses of Solar Cell
1. Used in calculators, watches etc.
2 Used in artificial satellites and space probes. 3. It is used in radio or wireless transmission system.
Solar Panel
A large number of Solar Cells connected to each other in an arrangement is
called solar panel. Material used for making solar cells
Silicon
Silver is used for inter connection of cells.
Energy from the Sea or Ocean
The energy from the sea is available in the following forms.
(i) Energy of Sea Waves
The waves are generated by the strong winds that blows across the sea. The kinetic energy of this moving water rotates the turbine of a generator
Limitation
When strong winds stop blowing, the generator stops producing electricity
(ii) Tidal Energy
The tidal energy possessed by water during tides.
The tides are caused due to gravitational force of attraction exerted by the moon on the water of the ocean. This form of energy is harnessed by constructing a dam across a narrow
opening to the sea.
A turbine fixed at the opening of the dam converts tidal energy to electricity.
(iii) Ocean Thermal Energy
The power plants used to harness the ocean thermal energy is known as
"Ocean Thermal Energy Conversion plant) (OTEC)
Temperature difference between surface water and water at the depth of 2km should be 20°C or more.
The warm surface water is used to boil ammonia (liquid)
The vapors of the liquid are used to run the turbine of generator.
The cold water (from deeper layers) is pumped up to condense the vapors into liquid.
Geothermal Energy
1. Energy stored as heat inside the earth
2 The steam of underground water is taken out by sinking pipes through holes drilled in the earth's crust. The steam under high pressure is used to rotate the turbines of the generator to produce electricity.
Nuclear Energy
Nuclear energy is the energy which is stored in the nucleus of an atom.
Nuclear energy is of two types
(1) Nuclear fission- nucleus of a heavy atom (Uranium) when bombarded with low energy ncutron split (break down) into lighter nuclei and huge amount of energy is released
(ii) Nuclear Fusion - When two lighter nucleic joins up to form heavy nucleus
and tremendous amount of energy is released.
Nuclear fission process is utilized in nuclear reactors to produce
electricity.
Major Nuclear power plants: Tarapur, Rana Pratap Sagar. Kalpakkam.
Advantages of Nuclear Energy: 1 Large amount of energy is released.
In nuclear power plant, the nuclear fuel is inserted once to get energy over
a long period of time.
Disadvantages of Nuclear Energy:
1. High cost of installation.
2 Environmental contamination may occur due to improper nuclear waste disposal.
Environmental Consequences
1 Energy sources should be used judiciously otherwise it would disturb the environment.
Use of clean fuels like CNG (compressed natural gas) because burning of
fossil fuel causes greenhouse effect.
Assembly of devices like solar cell (otherwise renewable source of energy)
would have caused environmental damage. How long will energy source last
the sources of energy can be divided into two categories:
(i) Renewable sources of energy e.g., wind, sun, biogas
(ii) Non-renewable sources of energy e.g., Coal. Petroleum, Natural Gas.
Continuous use of non-renewable source of energy is a matter of concern because ultimately the deposit of these sources will be completely finished on the other hand renewable sources of energy will last forever eg.. sun as a source of energy will be available for a very long period of time
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