Nuclear Energy and Other Source of Energy
Energy
Energy has
taken the place of basic need in our daily life. One way or another everything
depends on upon energy. The source of energy is the one which can provide an
adequate amount of energy in a convenient form over a long period of time.
Thus, we can say that energy required in every field. Usually, energy in
the form of fuel and electricity is used to carry out all the activities
whether in houses, offices or industries. All sources of energy can be divided
into two main categories: renewable sources of energy and non-renewable sources
of energy.
Renewable Sources of Energy
The sources
of energy which are inexhaustible and are being continuously supplied by nature
are known as renewables sources of energy.
For examplei) Wind ii) Flowing water
iii) Ocean tidal energy iv) Interior of the earth v) Biogas Renewable Sources
of Energy vi) The sun vii) Plants and vegetables
Non-renewable Sources of Energy
The sources
of energy which are exhaustible and have been formed in nature long ago are
known as non-renewable sources of energy.
Example: i) Coal ii) petroleum iii)
fissionable materials like uranium iv) Natural0gas
These
sources of energy are also known as conventional sources of energy.
Importance of Energy
Importance
of energy in our everyday life are as follows:
- we need the energy to develop a
personality,
- to sustain life energy is needed,
- to cook food and performing daily
activities like sitting, talking, walking, thinking etc,
- to do different mechanical work life
lifting a load, driving automobiles, carrying things from one place to
another place etc.
Energy Crisis
The
continuous use of a non-renewable source of energy causes the serious problem
of energy scarcity. Such an energy scarcity is known as an energy crisis. Due
to the overgrowth of modern civilisation1 and ever increasing population more
energy has been used up. For example, the petroleum products, coal etc are
being finished, forests are being reduced and the ground level has decreased. Overuse
of non-renewable source of energy has brought this scarcity.
Conservation of Energy
In order to
solve energy crises, we have to reduce the use of excess energy which is called
conservation of energy. The following steps are to be taken to conserve the
energy.
- The renewable is created in sources
of energy should be used in place of non-renewable one.
- The use of firewood should be reduced
as far as possible.
- Deforestation should be stopped and
forestation should be implemented.
- Solar and electrical vehicles should
be used in place of petroleum vehicles.
- The world’s population must be
controlled.
- Awareness about the importance of
energy conservation should people.
Transformation of energy
The process
of changing or converting one form of energy into another form is known as
transformation energy.
Some of the
examples of transformation of energy are:
- When we listen to music then
electrical energy is converted into sound energy. In the case of watching
TV, electrical energy is converted into sound energy and light energy.
- When an electric current passes
through an electric bulb, it glows and gives out light and heat.
Electrical energy is converted into heat and light energy.
- When we rub our hand, they become
warm. In this case, mechanical energy is converted into heat energy.
- When a pendulum swings, the potential
energy is converted into kinetic energy and vice-versa.
Nuclear Energy
The energy
released during a nuclear reaction is called nuclear energy. Nuclear energy can
be obtained from two types of reaction: nuclear fission and nuclear fusion.
Nuclear fission
The process
in which the heavy nucleus of a radioactive atom splits up into smaller nuclei
when bombarded low energy neutrons is called nuclear fission. A tremendous
amount of energy is released from nuclear fission which is converted into
electric energy.
When uranium
235 atoms are bombarded with slow neutrons, the heavy uranium nucleus breaks up
to produce two medium weight atoms, barium -139 and krypton-94, with emission
of 3 neutrons.
92U235+0n1→56Ba139+36Kr94+0n1+Tremendous
amount of energy
92U235+0n1→56Ba139+36Kr94+0n1+Tremendous
amount of energy
Nuclear Fusion
The process
in which two nuclei of light elements combine to form a heavy nucleus, is
called nuclear fusion.The nuclear reactions which occur at extremely high
temperature are called thermonuclear energy.
When
deuterium atoms are heated to an extremely high temperature under extremely
high pressure, then two deuterium nuclei combine together to form the heavy
nucleus of helium, and a neutron is emitted.
1H2+1H2→2He3+0n1+Tremendous
amount of energy
1H2+1H2→2He3+0n1+Tremendous
amount of energy
Thermal Power Plant
A thermal
power plant produces electricity by burning coal or oil.
Working of a Thermal Power Plant
Coal or oil
is burnt in a furnace to produce heat energy. This heat energy is used to boil
water in order to produce steam. The steam produced in the water reservoir is
allowed to fall in the turbine rotates it with high pressure. The steam falling
on the turbine rotates it with high speed. A generator or dynamo connected with
the turbine through an axis rotates with high speed and produce electricity.
The electricity so produce is transmitted to a distant place through
transmission wires.
Hydroelectric Power Plant
The
electricity produced by the flowing water is known as hydro-electric power.
For the
construction of hydro-electric power plant, a dam or water reservoir is made
over a river. The energy stored in a dam which has potential energy is allowed
to fall on the water wheel or turbine. Flowing water with potential energy
makes turbine rotate with an axle and the armature of the generator. The
armature of the generator between two poles of a strong magnet. The rotation of
the armature of the generator rotates within two poles of a strong magnet. The
rotation of the armature of the generator between two poles of a strong magnet
gives rise to electric current or electricity. This electricity is transmitted
to the sub-stations through a transformer for further distribution to the houses
factories.
Principle of Generation of Hydroelectricity
The potential energy of water stored in a dam is converted into
kinetic energy of the falling water. The water falls on the turbine, so kinetic
energy of the flowing water is converted into kinetic energy of the armature of the
generator connected to the turbine. Then kinetic energy is converted into
electrical energy known as hydroelectricity.
Advantage
- It does not cause any environmental
pollution.
- Hydroelectricity is a cheap and
renewable source of energy.
- The hydroelectric power plant can be
set up anywhere at a suitable place.
Disadvantage
- Hydroelectric power is generated only
near the rivers having water throughout the year. The electric power has
to be carried to the sub-stations for distribution to the house and
factories situated far off from the sites of hydroelectric power stations.
This is done through the transmission wires, so a lot of money has to
spend on this process.
- A large area of fertile land
submerged at the site of the dam constructed for tapping energy from the
flowing water.
- A large number of people residing
near the site of a dam are dislocated. So, a lot of problems are to be
faced in rehabilitating.
- Large ecosystems are destroyed when
land is submerged under the water reservoir of a dam.
Applications of Hydroelectricity
- Hydroelectricity can be used in
transportation.
- It can be used for various household
purposes such as cooling, heating, lighting etc.
- It can be used to irrigate
agriculture land.
- Hydroelectricity can be used in
industries to operate various machines.
Wind Energy
The wind
possesses kinetic energy. The kinetic energy of the wind is known as wind
energy.
Uses of Wind Energy
The kinetic
energy of the wind can be used to
- move the sail boats in lakes, rivers
and seas.
- operate water pumps to draw
underground water.
- run the flour mills to grind the
grains.
- produce electricity.
A device
used to convert wind energy into the mechanical energy of the machine is called
windmill.
Construction
It consists
of a wheel rotates about an axle mounted on a pole. The wind energy is used to
rotate the wheel about its axis.
Uses
- The windmill to operate a water pump
- The windmill for producing
electricity
Windmill to operate a water pump
The axle of
the windmill is connected to a crank rod. The free end of the water pump rod or
piston is connected to U-bend of the crank rod.
Working:
When the wind strikes the blades of the windmill, the kinetic energy of the
wind is used to rotate the wheel of the windmill. As a result, the axle or
shaft attached to the wheel rotates which turns the crank rod. The u-bend of
the crank rod produces up and down motion of the piston of the water pump.
Hence, the underground water is drawn to the surface of the earth.
Windmill for producing electricity (wind generator)
When the
armature of a generator rotates between two poles of the strong magnet, then
electricity is produced. Windmill rotates when the wind falls on the wheel of a
windmill. So the armature of the generators rotates between two poles of a
magnet along with the rotation of the wheel of the wind. Electric current is
produced. This is how, the kinetic energy of the wind is converted into
electric energy.
Advantages
- Wind energy produces no smoke and no
harmful gases.
- Wind energy is free and running it is
also very economical.
- The source of wind energy is
unlimited.
Bio-mass energy
During
photosynthesis process, solar energy is converted into chemical energy. So,
plants have stored chemical energy in the forms of biomass. The matter
contained in the body of different plants and animal have biomass. The gas
obtained from biomass is called biogas.
Advantages
- It is a renewable source of energy.
- It’s production is very economical.
Disadvantage
- Due to the release of smoke, it
causes air pollution.
- A large amount of energy cannot be
produced by biomass.
Application
- The biomass energy can be used in
the home for heating and cooling purposes.
- It can be used for heating food in
food industries.
- The biogas like gobar gas can be
used for lightening purposes.
Gobar gas or Bio Gas
Biogas is a
mixture of various gases formed when the animal dung is mixed with water and
ferment in the absence of air.
Biogas Plant
The
arrangement of producing biogas from animal dung, human excreta, industrial and
domestic wastes is known as biogas plant. The arrangement of producing biogas
from animal dung, human excreta, industrial and domestic wastes is known as
biogas plant. A biogas plant consists of a well shaped, underground tank T
called digester, which is made of bricks, and has a dome-shaped roof D. The
digester is a kind of sealed tank in which there is no oxygen which acts as a
gas-holder for the biogas. On the left side of the digester tank is sloping
inlet chamber I and on the right side is a rectangular outlet chamber O, both
made of bricks. The inlet chamber is for introducing fresh dung slurry into the
main digester tank whereas outlet chamber is for taking out the spent dung
slurry after the extraction of biogas. The inlet chamber is connected to a
mixing tank M while outlet chamber is connected to the overflow of tank F.
There is a gas out let S at the top of the dome having a value V.
Working
Cow-dung and water are mixed in equal proportions in the mixing tank
M to prepare the slurry. This slurry of dung and water is fed into the digester
tank T through the inlet chamber I. the digester tank is filled with dung
slurry up to cylindrical level, the dome being left free for the collection of
biogas. It might take 50 to 60 days for the new-gas plant to become operative.
Gradually when the biogas starts collecting in the dome, it exerts pressure on
the slurry in the digester tank and forces the spent slurry to go into overflow
tank F, through the outlet chamber O. the spent slurry is gradually removed by
the overflow of the tank. The spent dung slurry left after the extraction of
biogas is rich in iron and phosphorous compounds and forms good manure.
Advantages
- Biogas is used for cooking food and
heating water.
- Biogas does not produce smoke during
and hence there is no air pollution.
- It is the cheapest source of energy.
Solar Energy
The energy
emitted by the sun in the form of heat and light is known as solar energy. The
hot air rises up and the cold air from the surrounding rushes to occupy its
space. This is how the air moves. Moving air possesses kinetic energy which is
also termed as the wind.
Sunlight
makes photosynthesis possible through which plants prepare their food. The
solar energy evaporates the water oceans, lakes and ponds. The evaporated water
forms cloud. These clouds on cooling give rain. The rainwater is collected in
the reservoir having potential energy. Finally, potential energy is converted
into kinetic energy by letting water flow in higher speed. Kinetic energy
rotates the turbine which is connected with the huge magnet. Current is induced
by the magnet.
Even the
energy of fossil fuels like coal, petroleum and natural gas also comes from
solar energy. Due to high pressure, the biomass of dead animals and plants are
converted into the fossil fuels like coal petroleum and natural gases.
The sun
contains mainly light elements like hydrogen and helium. When the atoms of
these elements fuse together at an extremely high temperature in the interior
of the sun, a large amount of energy is radiated in the form of heat.
Solar Constant
The solar
constant is defined as the energy received from the sun in one second by the
unit square meter area of the outer edge of earth’s atmosphere exposed
perpendicularly to the radiation of the sun at average distance between the
earth and the sun. The upper part of the earth receives solar energy equal to
1.4-kilo joule per second per square meter (1.4 kJ/s m2). The amount
is known as solar constant.
Thus, solar
constant = 1.4 kJ/s m2 or 1.4 kW/m2
Application of Solar Energy
- It is used by green plants during
photosynthesis.
- The solar energy powers the flow of
wind.
- The solar energy causes rainfall by
evaporating water on the earth’s surface.
- It is used to produce electricity
from the solar cells.
- It is used for drying clothes and
food grains.
- It is used for transportation.
- The solar energy sustains all lives
on the earth.
- It is used for heating water using
the solar heater and various other purposes.
Solar Devices
The devices
which convert solar energy into other forms of energy are called solar devices.
Examples: solar cooker, solar furnace, solar water heater etc.
Solar Cookers
Construction:
It consists
of a wooden box in which a metallic box painted black is fitted. The space
between the wooden box and the metallic box is filled with an insulating
material which minimizes the heat loss by conduction and radiance. The metallic
box is covered by a thick glass sheet. A plane mirror is used to reflect the
sun rays into the box shown in the figure. The uncooked food placed in the
black container is put inside the box.
Working:
The plane
mirror reflector is adjusted in such a way that maximum sunlight falls on it.
The light reflected by the plane mirror falls on the thick glass sheet cover.
The heat radiation coming from the sun and have a short wavelength and high
energy pass through the glass sheet and is absorbed by the black container or
any other object placed in the box and black surface of the box. The
temperature inside the box is between 100 oC to 140 o C.
Advantages
- The cost of cooking food in the solar
cooker is very small as money is only spent upon solar cooker.
- It can cook two or three dishes at a
time.
- It saves the costly fuel like wood,
gas, kerosene oil etc.
- Nutrition value of the food is
preserved as there is no burning of fuel.
- It can cook multiple dishes at a
time.
Solar Heater
In a solar
heater, plane reflector the solar radiation is reflected into a blank pipe
containing water. If the solar radiation falls on the plane reflector, on the
black pipe it reflects the solar radiation. The black pipe absorbs the heat and
uses it for heating water in it.
Solar Furnance
It consists
of a large number of movable plane mirrors and a parabolic reflecting surface.
The parallel beam of light falling on the parabolic mirror is focused at a
small area, F
Application
A solar
furnace is used in melting metals of high melting point.
Solar cell
A device
which converts sunlight into electrical energy is known as a solar cell.
Construction
The solar
cell consists of an array of semiconductor device called diode. When solar
energy falls on such a diode, a small potential difference is created across
it. When the large numbers of diodes are connected in series, a large potential
difference can be obtained. As the large numbers of series of diodes are
connected in parallel, a large current can be obtained. Each diode is called
solar cell and an array of such cells is called a solar battery or solar panel.
For example, to run a water pump by the solar battery, the external battery is
connected to run an electric motor.
Advantages
The main
advantages of solar cells are
- Solar cells have no moving parts,
they require almost no maintenance, and work quite satisfactorily without
the use of any light focusing device.
- They can be set up in remote,
inaccessible and very sparsely inhabited area where power transmission is
difficult.
Uses of
Solar Cells
- They are used to operate electric
bulbs and tubes in the remote villages and area.
- They are used to supply electricity
in artificial satellites.
- They are used for operating traffic
lights.
- They are used in running light
vehicles like tempo, cars, microbuses etc.
- They are used in street lighting.
Fuel Energy
The material
which produces energy while burning is called fuels. Petrol, wood, kerosene,
diesel, etc are the examples of fuel.
Applications of Fuels
- Fuels are used for generating
electricity.
- Fuels are used in transportation.
- Fuels are used for cooking,
lightening and heating process.
- Fuels are used in industries for
various purposes.
- Fuels like petrol and diesel are used
in running various grinding mills.
Geothermal Energy
The earth
has three layers i.e., the core, the mantle and the crust. The core is the
central part of the earth surrounded by the mantle. The outermost part of the
earth which surrounds mantle is the crust. The mantle of the earth has molten
mass called magma. This magma consists of molten rocks, gases and steam at very
high temperature. Due to some geological changes, the hot magma rises up and is
collected in the crust of the earth. The regions in the crust where the hot
magma is collected are called hot spots. The heat energy stored in the hot
spots of the earth’s crust is called geothermal energy.
Advantages
- Geothermal energy causes no
pollution, so it is environmentally friendly.
- Geothermal energy can be converted
continuously into electricity throughout the air.
- The cost of converting geothermal
energy into electricity is very less.
Tidal Energy
The rise and
fall of the ocean due to the attraction of the moon is called tide. The rise in
water is called high tide and fall in water is called low tide. The kinetic
energy of water during tides is used to produce electricity.
Tides power
plants are constructed near Bays. Tides rising water is allowed to fall on the
turbine of the generator which produces electricity. Thus, the kinetic energy
of the water is converted into electrical energy.
During low
tides, gates of the dam are closed and hence the water level behind the dam
rises. The raised water has potential energy. Again gates are opened and the
water is allowed to fall back into the bay. This falling water is used to
rotate the turbine of the generator. Hence, the electricity is produced.
Global Energy Consumption Pattern and
Demands
The amount
of energy consumed by a country depends on the living standards of its citizens
and the degree of its industrialization. The average energy required for a man
to maintain his daily activities require about 20 k cal per day. At present,
the global energy consumption per capita per day is about 2000 times the 20 K
calorie he needs for maintaining life. The figure shows the global energy
consumption from 1900 to 1990.
At present,
about 40% of demand for energy in the world is obtained from oils. Similarly,
about 20% of the total energy consumption provided by coal, about 20% by
natural gas, wool 10%, nuclear resources 7% and hydroelectric power 3%.
Remaining required energy is fulfilled by the resources like solar energy,
tidal energy, wind energy etc.
Energy Use in Nepal
In Nepal,
existing energy sources are classified into two major groups:
- Conventional Energy Sources
- Alternative Energy Sources
Nepal is not
an industrially developed country. So that biomass energy as the burning of
wood, agricultural waste products, and animal waste are the important resources
of energy. About 94% of the total energy consumption of the country is met from
biomass, out of which 80% is met by burning wool and 8.5% from animal waste.
Pollution
Pollution is
the addition of something in the ecosystem, which has a detrimental effect on
the environment. Odum (1971) defined pollutants as an undesirable change in the
physical-chemical and biological activities. Air containing dust, smoke and CO2 makes
air polluted. Likewise, the high concentration of chemical fertilizer such as
nitrogen, phosphorous and potassium in the soil pollutes the land.
Types of pollution
Air pollution
An
undesirable change in the physical, chemical or biological characteristics of
air is called pollution. The substances which pollute the air called
pollutants.
Sources
of air Pollution
- The major industrial exhausts which
contain carbon monoxide, sulphur dioxide, an oxide of nitrogen, chlorine,
fluorine etc.
- Burning solid fuels such as firewood,
agricultural wastes, coal etc are the causes of air pollution.
- Chlorofluoro Carbon (CFC) and ammonia
released by the refrigerators etc.
- Different biocides such as
pesticides, insecticides, fungicides etc.
- Tobacco smoke.
- Electric power plants, burning
fossils fuels etc.
Control
of Air Pollution
- Control over the kinds of fuel used in
cars, aeroplanes, power stations, etc.
- The establishment of more smokeless
zones.
- Disposal of wastes by dilution
processes.
- The government should encourage
scientific societies and newspapers to create awareness among people about
pollution and environment.
- The garbage in big cities should be
treated with cobalt rays.
Effects
of Air pollution
- Air pollution causes respiratory
tract infection (RTI) and asthma.
- It deteriorates the cultural heritage
and trees.
- It brings various skin and eye
allergy.
- It is the main causes of global
warming
Water pollution
Degradation
in the quality of water is called water pollution. Water covers over the 3/4th
part of the earth’s surface. It is a very important resource for people and the
environment. Water pollution affects drinking water, rivers, lakes and oceans
all over the world. In many developing countries, it is usually a leading cause
of death, by people drinking from polluted water sources. Drainage and wastage
from industries, laboratory, hospitals, and homes are the main factors that
cause water pollution.
Causes of
water pollution
There are
various causes of water pollution. Main causes of water pollution are described
below:
- A mixture of the drain in water: In
urban areas drainage and drinking water pipe are brought through the same
route. If drainage pipe gets burst then drinking water pipe gets
contaminated with drain water which pollutes the water.
- Washing and cleaning near water
resources: In rural areas, many people shares common tap where they wash
their clothes and bath nearby water resources which pollute water.
- Mixing of fertilizers in water:
Farmers use different fertilizers on their farm which are carried to river
by rainfall. Fertilizers get mixed with the river.
- Wastage from different sectors:
Wastage produced by hospitals, industries, and houses are thrown in the
river. Due to lack of garbage disposal water gets polluted.
- Mismanagement of drain: Drains are
directly thrown into the water in urban areas. Sometimes people directly
throw wastage in water.
Control
of Water Pollution
- Renovating the existing sewer lines
and connecting them to the central sewer line by branch and trunk lines.
- All domestic sewage be centrally
collected.
- Industries may be forced to treat the
effluents to a requisite quality standard and to be connected to the main
sewer line.
- Wastes from other sources like cattle
fields and livestock farming should be managed properly.
- All municipal and industrial waste
water should be centrally collected and managed.
Effects
of water pollution
- Water pollution causes water-borne
disease like diarrhoea, dysentery, and cholera.
- It also brings various skin
allergies if taken the bath with polluted water.
- Acid rain deteriorates cultural
heritages.
- It has the negative impact on
plants.
- Aquatic animals cannot survive in
polluted water.
Global Warming
In the
atmosphere greenhouse effect is mainly due to the carbon dioxide layer. In the
upper atmosphere, there is a protective layer of ozone. This ozone layer does
not allow the ultraviolet radiation to enter into the earth’s atmosphere. Lower
atmosphere contains carbon dioxide which traps the infrared radiation from
different sources and maintains a suitable temperature. If there is an excess
of carbon dioxide in the atmosphere, the temperature of the earth increases
which is called global warming.
Acid rain
When the
various gases like CO2, SO2, NO2, combine with
rainwater then their respective acids will be produced. These acids will react
on the ground along with rain water in the cocktail form. This process is
called acid rain. In the atmosphere, these gases react with water vapour and
formed their corresponding acids like H2CO3, H2SO4, and
others. When rainfall occurs these acids get mixed with rain and forms acid
rain.
Effect of acid rain
- The acidity of the soil increases
which causes the reduction of productivity of the soil.
- The acidity of water bodies increases
which cause the decline in the population of aquatic organism.
Green House Effect
The
artificial house which is made by glass or plastic inside which the temperature
will be more than the outer environmental temperature is called greenhouse. The
artificial greenhouse provides controlled environment for plants.
Examples of Green House Effect
- The interior of a car parked in the
sunshine with its window becomes very hot due to the greenhouse effect.
- Rooms of a house in cold countries
whose windows are closed and sunlight fall on then become warm due to the
greenhouse.
- Solar cookers and solar furnace are
heated due to the greenhouse effect.
Advantages of artificial greenhouse
- It provides the controlled
environment for plants inside it. The plants which can be found in the
desert can be grown in the Himalayan region inside it.
- Those plants which are obtained in
summer can be planted in winter inside it.
The Atmosphere of the Earth is Natural
Green House
The water
vapours and carbon dioxide in the atmosphere are good observers of infra-red
radiation of longer wavelengths than that of the infra-red radiations of
shorter wavelengths. The solar radiation passes easily through the atmosphere.
The heat radiations passing through the atmosphere are observed by the earth’s
surface and various objects like plants, water and rocks. The temperature of
the earth increases. The earth’s atmosphere emits infrared radiation of longer
wavelengths. These infrared radiations of longer wavelengths are absorbed by
water vapours and carbon dioxide in the atmosphere. Due to this heat radiation,
the warming of the earth’s atmosphere takes place.
