SOURCES OF ENERGY
KEY CONCEPTS AND GIST OF THE LESSON
INTRODUCTION
- Energy comes in different forms
and energy can only be converted from one form 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.
CHARACTERISTIC OF A GOOD SOURCE
- which has high calorific value.
- be easily accessible.
- be easy to store and transport
- be economical.
- Intermediate Ignition
temperature.
- Eco-friendly.
- Less combustible.
- Fossil fuels * Solar Energy
Eg. Coal &
Petroleum. Solar Cooker, Solar Cell Panel
- Thermal Power Plant * Energy From the sea
- Hydro Power Plants Eg. Tidal
& wave energy, O.T. Emergy
- Bio-Mass bio gas plant* Geothermal Energy
- Wind 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
- Air, Water, Solar
radiation, Geothermal Energy, ocean waves etc.
Conventional Source of Energy
1. Fossil Fuels: Fuels developed from the fossils. e.g.
Coal & Petroleum.
- Formed over million 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.
Disadvantages of Burning Fossil Fuels
- Released oxides of Carbon,
Nitrogen, Sulphur (acidic in nature)cause Air pollution & Acid rain
& green-house effect.
A Model of
Thermoelectric Production.
- The Tennis ball having three
slits filled with semicircular (plaster or Metallic) tins is our Turbine
for generating electricity. Actually the steam produced impart energy to
rotor of turbine which can move shaft of the generator to produce
electricity. A very large amount of fossil fuels are burnt in Thermal
Power Plant to heat up water to produce steam.
- Hydro-power Plants convert the potential energy of falling water
into Electricity since there are few water-falls which could becaused as a
source of potential energy, hence this is the reason, a large number of
dams are built all over the world.
- Around 25% of our country’s
energy requirement is met by Hydro Power Plants
Dams are constructed to :
- Prevent flooding of river,
provide water for irrigation & to generate hydroelectricity.
Disadvantages of construction of Big Dams
1. Submerging/Loss of
large variety of Flora fauna and human settlements& rotting of submerged
vegetation release green house gas (CH4).
2. They pose dangers
of earthquakes, landslides etc.
Improvements in the Technology
for using Conventional sources of energy :
Biomass is
Agricultural & animal wastes that can be used as a fuel. E.g. of Biomass –
Firewood, cattle dung, sewage, dry leaves, stems.
- 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 e.g. 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.
Charcoal burns without
smoke, flames & has high calorific value.
- Bio-gas is an excellent fuel & contains 75% of
Methane (CH4).It burns without
smoke, leaves no residues like ash, with high heat capacity.
- Bio-gas is produced by
anaerobic decomposition of the slurry(cow dung + water mixture) by
microbes. This process is applied in a Bio gas plant.
- The Bio-gas 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 provide 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 to do work.
- This energy is utilised 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 20 KMPH.
Advantages of Wind Energy
1. Eco friendly
2. Efficient source of renewable energy.
3. No recurring expenses for production of electricity
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
2. Difficulty in getting regular wind speed of 15-20 Km PH.
3. Initial cost of establishing wind energy farm is very high.
4. High level of maintenance of blades of wind mill.
2. Difficulty in getting regular wind speed of 15-20 Km PH.
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 = 1.4
(kJ/s.m2)
Outer edge of the
earth receives solar energy equal to 1.4 kJ/s.m2 which is known as solar constant.
Solar Energy Devices: A large number of devices that utilize solar
energy directly like :
(i) Solar Cooker
(ii) Solar furnaces
(iii) Solar cells
(iv) Solar water heaters
(ii) Solar furnaces
(iii) Solar cells
(iv) 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 wave lengths infrared radiations to enter through it but
doesn’t allow the infrared radiations to exit through it, causing more
green House effect that results in increase in temperature.
SOLAR COOKER
Box Type Solar Cooker
- It consists of a rectangular
box 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.
1. Use energy which is
available in plenty (Solar Energy)
2. Is pollution free.
(i). Cannot be used for frying or baking purpose.
(ii). Food cannot be cooked at night or on a cloudy day.
(iii). Direction of reflector of solar heating has to be changed from time to time to keep it facing the sun.
2. Is pollution free.
(i). Cannot be used for frying or baking purpose.
(ii). Food cannot be cooked at night or on a cloudy day.
(iii). Direction of reflector of solar heating has to be changed from time to time to keep it facing the sun.
SOLAR CELLS
- Solar cells are device that
convert Solar energy into electricity.
- Develops a voltage of 0.5 – IV
and can produce about 0.7 W of electricity.
Advantages of Solar Cell
- Require a little maintenance
- Have no moving part.
- No focusing device is required
- Can be set up in remote areas.
- Environment – friendly i.e. do
not cause pollution.
Disadvantage of Solar Cells
1. It require high
cost
2. Efficiency is low
3. Initial cost of installation is quite high.
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.
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
(ii) Tidal energy
iii) Ocean Thermal Energy.
(ii) Tidal energy
iii) Ocean Thermal Energy.
(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
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 vapours of the liquid are
used to run the turbine of generator.
- The cold water (from deeper
layers) is pumped up to condense the vapour 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.
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
- Nuclear fission nucleus of
a heavy atom (Uranium) when bombarded with low
energy neutron split (break down) into lighter nuclei and huge amount of energy is released - Nuclear Fusion When
two lighter nuclei join 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.
2. In nuclear power plant, the nuclear fuel is inserted once to get energy over a long period of time.
2. 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.
2. Environmental contamination may occur due to improper nuclear waste disposal.
How long will energy source
last: 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 e.g sun as a source of energy
will be available for a very long period of time.
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