Topic 1: Introduction to Energy
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Introduction
Energy is one of the most fundamental parts of our universe.
We use energy to do work. Energy lights our cities. Energy powers
our vehicles, trains, planes and rockets. Energy warms our homes,
cooks our food, plays our music, gives us pictures on television.
Energy powers machinery in factories and tractors on a farm.
Energy from the sun gives us light during the day. It dries our
clothes when they're hanging outside on a clothes line. It helps plants grow. Energy stored in plants is
eaten by animals, giving them energy. And predator animals eat their prey, which gives the predator
animal energy.
Everything we do is connected to energy in one form or another.
Energy is defined as: "the ability to do work."
When we eat, our bodies transform the energy stored in the food into energy to do work. When we
run or walk, we "burn" food energy in our bodies. When we think or read or write, we are also doing
work. Many times it's really hard work!
Energy causes things to happen around us. Look out the window.
During the day, the sun gives out light and heat energy. At night, street lamps use electrical energy to
light our way.
When a car drives by, it is being powered by gasoline, a type of stored energy.
The food we eat contains energy. We use that energy to work and play.
We learned the definition of energy in the introduction:
"Energy Is the Ability to Do Work."
Energy can be found in a number of different forms. It can be chemical energy, electrical energy, heat
(thermal energy), light (radiant energy), mechanical energy, and nuclear energy.
Energy is measured in many ways.
One of the basic measuring blocks is called a Btu. This stands for British thermal unit and was invented
by, of course, the English.
Btu is the amount of heat energy it takes to raise the temperature of one pound of water by one
degree Fahrenheit, at sea level.
One Btu equals about one blue-tip kitchen match.
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One thousand BTU roughly equals: One average candy bar or 4/5 of a
peanut butter and jelly sandwich.
It takes about 2,000 BTU to make a pot of coffee.
Energy also can be measured in joules. Joules sounds exactly like the
word jewels, as in diamonds and emeralds. A thousand joules is equal to a
British thermal unit.
1,000 joules = 1 Btu
So, it would take 2 million joules to make a pot of coffee.
The term "joule" is named after an English scientist James Prescott Joule
who lived from 1818 to 1889. He discovered that heat is a type of energy.
One joule is the amount of energy needed to lift something weighing one pound to a height of nine
inches. So, if you lifted a five-pound sack of sugar from the floor to the top of a counter (27 inches),
you would use about 15 joules of energy.
Around the world, scientists measure energy in joules rather than Btus. It's much like people around
the world using the metric system of meters and kilograms, instead of the English system of feet and
pounds.
Like in the metric system, you can have kilojoules — "kilo" means 1,000.
1,000 joules = 1 kilojoule = 1 Btu
Do you know that…?
A piece of buttered toast contains about 315 kilojoules (315,000 joules) of energy. With that energy
you could:
Jog for 6 minutes
Bicycle for 10 minutes
Walk briskly for 15 minutes
Sleep for 1-1/2 hours
Run a car for 7 seconds at 80 kilometers per hour (about 50 miles per hour)
Light a 60-watt light bulb for 1-1/2 hours
Or lift that sack of sugar from the floor to the counter 21,000 times!
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Electric Energy
Electricity figures everywhere in our lives.
Electricity lights up our homes, cooks our food,
powers our computers, television sets, and
other electronic devices. Electricity from
batteries keeps our cars running and makes our
flashlights shine in the dark.
Here's something you can do to see the
importance of electricity. Take a walk through
your school, house or apartment and write
down all the different appliances, devices and
machines that use electricity. You'll be amazed
at how many things we use each and every day
that depend on electricity.
But what is electricity? Where does it come
from? How does it work? Before we
understand all that, we need to know a little bit
about atoms and their structure.
All matter is made up of atoms, and atoms are made up of smaller particles. The three main particles
making up an atom are the proton, the neutron and the electron.
Electrons spin around the center, or nucleus, of atoms, in the same way the moon spins around the
earth. The nucleus is made up of neutrons and protons.
Electrons contain a negative charge, protons a positive charge. Neutrons are neutral – they have
neither a positive nor a negative charge.
There are many different kinds of atoms, one for each type of element.
An atom is a single part that makes up an element. There are 118
different known elements that make up every thing! Some elements like
oxygen we breathe are essential to life.
Each atom has a specific number of electrons, protons and neutrons. But
no matter how many particles an atom has, the number of electrons
usually needs to be the same as the number of protons. If the numbers
are the same, the atom is called balanced, and it is very stable.
DID YOU KNOW?
Energy makes everything happen and can be
divided into two types:
Stored energy is called potential energy.
Moving energy is called kinetic energy.
With a pencil, try this example to know the
two types of energy.
Put the pencil at the edge of the desk and
push it off to the floor. The moving pencil
uses kinetic energy.
Now, pick up the pencil and put it back on
the desk. You used your own energy to lift
and move the pencil. Moving it higher than
the floor adds energy to it. As it rests on
the desk, the pencil has potential energy.
The higher it is, the further it could fall.
That means the pencil has more potential
energy.
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So, if an atom had six protons, it should also have six electrons. The
element with six protons and six electrons is called carbon. Carbon is
found in abundance in the sun, stars, comets, atmospheres of most
planets, and the food we eat. Coal is made of carbon; so are diamonds.
Some kinds of atoms have loosely attached electrons. An atom that loses
electrons has more protons than electrons and is positively charged. An
atom that gains electrons has more negative particles and is negatively
charge. A "charged" atom is called an "ion."
Electrons can be made to move from one atom to another. When those
electrons move between the atoms, a current of electricity is created. The electrons move from one
atom to another in a "flow." One electron is attached and another electron is lost.
This chain is similar to the fire fighter's bucket brigades in olden times. But instead of passing one
bucket from the start of the line of people to the other end, each person would have a bucket of
water to pour from one bucket to another. The result was a lot of spilled water and not enough
water to douse the fire. It is a situation that's very similar to electricity passing along a wire and a
circuit. The charge is passed from atom to atom when electricity is "passed."
Scientists and engineers have learned many ways to move electrons off of atoms. That means that
when you add up the electrons and protons, you would wind up with one more proton instead of
being balanced.
Since all atoms want to be balanced, the atom that has been "unbalanced" will look for a free
electron to fill the place of the missing one. We say that this unbalanced atom has a "positive
charge" (+) because it has too many protons.
Since it got kicked off, the free electron moves around waiting for an unbalanced atom to give it a
home. The free electron charge is negative, and has no proton to balance it out, so we say that it has
a "negative charge" (-).
So what do positive and negative charges have to do with electricity?
Scientists and engineers have found several ways to create large numbers of positive atoms and free
negative electrons. Since positive atoms want negative electrons so they can be balanced, they have
a strong attraction for the electrons. The electrons also want to be part of a balanced atom, so they
have a strong attraction to the positive atoms. So, the positive attracts the negative to balance out.
The more positive atoms or negative electrons you have, the stronger the attraction for the other.
Since we have both positive and negative charged groups attracted to each other, we call the total
attraction "charge."
Energy also can be measured in joules. Joules sounds exactly like the word jewels, as in diamonds
and emeralds. A thousand joules is equal to a British thermal unit.
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When electrons move among the atoms of matter, a current of electricity is created. This is what
happens in a piece of wire. The electrons are passed from atom to atom, creating an electrical
current from one end to other, just like in the picture.
Electricity is conducted through some things better than others do. Its resistance measures how well
something conducts electricity. Some things hold their electrons very tightly. Electrons do not move
through them very well. These things are called insulators. Rubber, plastic, cloth, glass and dry air
are good insulators and have very high resistance.
Other materials have some loosely held electrons, which move through them very easily. These are
called conductors. Most metals – like copper, aluminum or steel – are good conductors.
Thermal Energy
Geothermal Energy has been around for as long as the Earth has existed. "Geo" means earth, and
"thermal" means heat.
So, geothermal means earth-heat.
Have you ever cut a boiled egg in half? The egg is similar to
how the earth looks like inside. The yellow yolk of the egg is
like the core of the earth. The white part is the mantle of the
earth. And the thin shell of the egg, that would have
surrounded the boiled egg if you didn't peel it off, is like the
earth's crust.
Below the crust of the earth, the top layer of the mantle is a hot liquid rock called magma. The crust
of the earth floats on this liquid magma mantle. When magma breaks through the surface of the
earth in a volcano, it is called lava.
For every 100 meters you go below ground, the temperature of the rock increases about 3 degrees
Celsius. Or for every 328 feet below ground, the temperature increases 5.4 degrees Fahrenheit. So, if
you went about 10,000 feet below ground, the temperature of the rock would be hot enough to boil
water.
Deep under the surface, water sometimes makes its way close to the hot rock and turns into boiling
hot water or into steam. The hot water can reach temperatures of more than 300 degrees
Fahrenheit (148 degrees Celsius). This is hotter than boiling water (212 degrees F / 100 degrees C). It
doesn't turn into steam because it is not in contact with the air.
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When this hot water comes up through a crack in the earth, we call it a hot
spring, like Emerald Pool at Yellowstone National Park pictured on the left. Or,
it sometimes explodes into the air as a geyser, like Old Faithful Geyser pictured
on the right.
About 10,000 years ago, Paleo-Indians used hot springs in North American for
cooking. Areas around hot springs were neutral zones. Warriors of fighting
tribes would bathe together in peace. Every major hot spring in the United
States can be associated with Native American tribes. California hot springs, like
at the Geysers in the Napa area, were important and sacred areas to tribes
from that area.
In other places around the world, people used hot springs for rest and relaxation. The ancient
Romans built elaborate buildings to enjoy hot baths, and the Japanese have enjoyed natural hot
springs for centuries.
Radiant Energy
Radiant energy is the energy of electromagnetic waves. The quantity of radiant energy may be
calculated by integrating radiant flux (or power) with respect to time and, like all forms of energy, its
SI unit is the joule. The term is used particularly
when radiation is emitted by a source into the
surrounding environment. Radiant energy may
be visible or invisible to the human eye.
The term "radiant energy" is most commonly
used in the fields of radiometry, solar energy,
heating and lighting, but is also sometimes used
in other fields (such as telecommunications). In
modern applications involving transmission of
power from one location to another, "radiant
energy" is sometimes used to refer to the
electromagnetic waves themselves, rather than
their energy (a property of the waves). In the past, the term "electro-radiant energy" has also been
used.
Radiant energy is used for radiant heating. It can be generated electrically by infrared lamps, or can
be absorbed from sunlight and used to heat water. The heat energy is emitted from a warm element
(floor, wall, overhead panel) and warms people and other objects in rooms rather than directly
heating the air. Because of this, the air temperature may be lower than in a conventionally heated
building, even though the room appears just as comfortable.
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Chemical Energy
Chemical energy is one form of potential energy, along with mechanical
energy, gravitational energy, nuclear energy and electrical energy. All
of these forms of energy are stored within an object and are converted
to forms of kinetic energy when a force or change is applied. The
different forms of kinetic energy are radiant energy, which includes
light, x-rays and radio waves, heat, motion and sound.
As stated by the first law of thermodynamics, energy can neither be
created nor destroyed; it can only be converted from one form to
another. During chemical reactions, molecules can be created or
destroyed. If a product is created, the chemical energy is stored in the
bonds that make up the molecules. If something is broken down, the chemical energy is released,
usually as heat. If a reaction releases energy, it is called exothermic, and if it absorbs energy, it is called
endothermic.
One example of chemical energy is that found in the food that we eat. Energy is stored in the bonds of
the molecules that make up food. When we eat the food, the large molecules are broken down into
smaller molecules that can be used by the cells of the body. The process of breaking down and using the
food by our cells is called respiration. During respiration, the chemical energy is converted to heat,
kinetic energy, and other forms of chemical energy, like that stored in the fat cells in our body.
Food is just one example of a fuel — it is how animals, including humans, fuel their bodies. Other forms
of fuel include wood and chemicals, such as petroleum. When wood is burned, the chemical energy
within the cells of the wood break and heat is released. In the engine of a car or truck, the energy in the
gasoline is converted to heat and motion, to make
the car move.
Kinetic energy can also be converted to potential
energy. During the process of photosynthesis carried
out by plants, radiant energy, or the light from the
sun, is converted into chemical energy, which is
stored within the plant. When animals eat the plants,
the reverse reaction takes place. The bonds are
broken, which releases stored chemical energy for
the animal to use.
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Stored Mechanical Energy
There are two main types of mechanical energy. They are
motion energy and stored mechanical energy.
Motion energy: This is the energy something has because it is
moving (eg a speeding cricket ball). You can feel the effect of this energy if the cricket ball hits you.
Motion energy is also called kinetic energy.
Stored mechanical energy: This is energy something has stored in it because of its height above the
ground or because it is stretched or bent or squeezed (eg in a stretched rubber band). You can feel it
when the band is released.
Stored mechanical energy is also called potential energy.
Potential Energy
An object can store energy as the result of its position. For example, the heavy ball of a demolition
machine is storing energy when it is held at an elevated position. This stored energy of position is
referred to as potential energy. Similarly, a drawn bow is able to store energy as the result of its
position. When assuming its usual position (i.e., when not drawn), there is no energy stored in the
bow. Yet when its position is altered from its usual equilibrium position, the bow is able to store
energy by virtue of its position. This stored energy of position is referred to as potential energy.
Potential energy is the stored energy of position possessed by an object.
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Nuclear Energy
Another major form of energy is nuclear energy, the energy that is trapped inside each atom. One of
the laws of the universe is that matter and energy can't be created nor destroyed. But they can be
changed in form.
Matter can be changed into energy. The world's most famous scientist, Albert Einstein, created the
mathematical formula that explains this. It is:
This equation says:
E [energy] equals m [mass] times c2 [c stands for the velocity or the speed of light. c2 means c times
c, or the speed of light raised to the second power — or c-squared.]
Please note that some web browser software may not show an exponent
(raising something to a power, a mathematical expression) on the Internet.
Normally c-squared is shown with a smaller "2" placed above and to the right
of the c.
Scientists used Einstein's famous equation as the key to unlock atomic
energy and also create atomic bombs.
The ancient Greeks said the smallest part of nature is an atom. But they did
not know 2,000 years ago about nature's even smaller parts.
Atoms are made up of smaller particles -- a nucleus of protons and neutrons, surrounded by
electrons which swirl around the nucleus much like the earth revolves around the sun.
An atom's nucleus can be split apart. When this is done, a tremendous amount of energy is released.
The energy is both heat and light energy. Einstein said that a very small amount of matter contains a
very LARGE amount of energy. This energy, when let out slowly, can be harnessed to generate
electricity. When it is let out all at once, it can make a
tremendous explosion in an atomic bomb.
A nuclear power plant (like Diablo Canyon Nuclear Plant
shown below) uses uranium as a "fuel." Uranium is an
element that is dug out of the ground many places around
the world. It is processed into tiny pellets that are loaded
into very long rods that are put into the power plant's
reactor.
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The word fission means to split apart. Inside the reactor of an atomic power plant, uranium atoms
are split apart in a controlled chain reaction.
In a chain reaction, particles released by the splitting of the atom go off and strike other uranium
atoms splitting those. Those particles given off split still other atoms in a chain reaction. In nuclear
power plants, control rods are used to keep the splitting regulated so it doesn't go too fast.
If the reaction is not controlled, you could have an atomic bomb. But in atomic bombs, almost pure
pieces of the element Uranium-235 or Plutonium, of a precise mass and shape, must be brought
together and held together, with great force. These conditions are not present in a nuclear reactor.
The reaction also creates radioactive material. This material could hurt people if released, so it is
kept in a solid form. The very strong concrete dome in the picture is designed to keep this material
inside if an accident happens.
This chain reaction gives off heat energy. This heat energy is used to boil water in the core of the
reactor. So, instead of burning a fuel, nuclear power plants use the chain reaction of atoms splitting
to change the energy of atoms into heat energy.
Power plant drawing courtesy Nuclear Institute
This water from around the nuclear core is sent to another section of the power plant. Here, in the heat
exchanger, it heats another set of pipes filled with water to make steam. The steam in this second set of
pipes turns a turbine to generate electricity. Below is a cross section of the inside of a typical nuclear
power plant.
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Another form of nuclear energy is called
fusion. Fusion means joining smaller nuclei
(the plural of nucleus) to make a larger
nucleus. The sun uses nuclear fusion of
hydrogen atoms into helium atoms. This gives
off heat and light and other radiation.
In the picture to the right, two types of
hydrogen atoms, deuterium and tritium,
combine to make a helium atom and an extra particle called a neutron.
Also given off in this fusion reaction is energy! Thanks to the University of California, Berkeley for the
picture.
Scientists have been working on controlling nuclear fusion for a long time, trying to make a fusion
reactor to produce electricity. But they have been having trouble learning how to control the
reaction in a contained space.
What's better about nuclear fusion is that it creates less radioactive material than fission, and its
supply of fuel can last longer than the sun.
Energy conservation is…
Reduction in the amount of energy consumed in a process or system, or by an organization or
society, through economy, elimination of waste, and rational use.
Energy should be conserved since we are consuming disproportionate amount of energy and that day
is not far when all our Non-Renewable resources will expire forcing us to rely just on Renewable
Sources. The electricity that we use comes from nuclear power, coal power plants, Oil that we use to
run our vehicles are fossil fuels that were created million of years ago from decaying plants. When
burned they emit carbon-dioxide which is harmful to humans and the environment.
Apart from these it also helps us to save money, mitigates the numerous
adverse environmental and social impacts associated with energy production
and consumption. These include air pollution, acid rain and global warming, oil
spills and water pollution, loss of wilderness areas, construction of new power
plants, foreign energy dependence and the risk of international conflict over
energy supplies. Energy conservation extends the lifetime of equipment and
reduces the maintenance cost by operating less hours and at less than
maximum capacity.
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Reduce Consumption on Non-Renewable Sources
Consumption on Non-Renewable sources must be reduced as much as possible.
1. Resource Depletion: By using these resources in excess, they are going to deplete one day and
will take another millions of years to form again.
2. Save Money: Usage of fluorescent bulbs , solar electricity may cost expensive initially but prove
to be cost-effective in the long run. Many energy efficiency and conservation measures are
better investments than the stock market or bank interest.
3. Reduce Carbon-dioxide: If Non-Renewable resources are used up to the limit they may also help
in reducing the carbon-dioxide. Pollution from nuclear and coal power plants cause diseases like
asthma, emphysema etc.
4. Climate Change : Due to increase int the rate of these resources it also affect the climate
greatly, Drought, Severe storms, floods, land loss, erosion of soil and heat deaths are few
examples of climate change.
5. Ozone Layer Depletion: Ozone layer in the atmosphere protect us from ultraviolet rays from
reaching the earth thus, making life on the earth possible.
6. Adverse affect on humans and the environment: Extraction of Uranium and Coal from beneath
the earth cause huge affect to the lives of cola miners. These people have high cancer death
rates. They also harm the environment and agricultural lands.
7. Acid Rain: Coal power plants and vehicles emit sulfur dioxide (SO2) and nitrous oxides (NOx).
These travel beyond the local area and are harmful to the health throughout whole regions.
When SO2/NOx and water vapor mix under certain conditions, sulfuric acid and nitric acid, know
as acid rain, are formed. This is very harmful to the lungs. It kills fish in lakes, corrodes property
(buildings, monuments, cars), harms the soil (releasing toxins), and harms trees and crops.
8. Global Warming: With so much dependence on Non renewable sources, global warming is
taking place all over the world and the result which is glaciers are melting which is causing the
rise in the sea level.
Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the
amount of energy required to provide products and services. For example, insulating a home allows a
building to use less heating and cooling energy to achieve and
maintain a comfortable temperature. Installing fluorescent
lights or natural skylights reduces the amount of energy
required to attain the same level of illumination compared to
using traditional incandescent light bulbs. Compact fluorescent
lights use two-thirds less energy and may last 6 to 10 times
longer than incandescent lights. Improvements in energy
efficiency are most often achieved by adopting a more
efficient technology or production process.
There are various different motivations to improve energy
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efficiency. Reducing energy use reduces energy costs and may result in a financial cost saving to
consumers if the energy savings offset any additional costs of implementing an energy efficient
technology. Reducing energy use is also seen as a key solution to the problem of reducing emissions.
According to the International Energy Agency, improved energy efficiency in buildings, industrial
processes and transportation could reduce the world's energy needs in 2050 by one third, and help
control global emissions of greenhouse gases.[3]
Energy efficiency and renewable energy are said to be the twin pillars of sustainable energy policy.[4]
In many countries energy efficiency is also seen to have a national security benefit because it can be
used to reduce the level of energy imports from foreign countries and may slow down the rate at
which domestic energy resources are depleted.
Renewable Energy & Non Renewable Energy
The energy sources from which we gain energy are classified broadly into 2
groups namely:
Renewable and Non-Renewable (Fossil Fuels)
Renewable Sources
Renewable Sources include solar, wind, geothermal, biomass and hydro power. Solar energy is the
energy that we get from the sun. It is the major source of energy among all the nations. However,
there are major drawbacks related to limited production as well as high costs that don't allow people
to use it in a wider scale. Solar energy is responsible for growth of plants and indirectly, the existence
of all animal life. Wind energy is used in large farm fields where they can use windmills to provide
power for the accomplishment of agricultural tasks has contributed to the growth of civilization.
This apart from solar is another clean and renewable source of energy. The major drawback is that it
can be used only in the coastal regions and can be noisy too. Geothermal energy is the energy stored
inside the earth. The center of the earth has temperature about 6000 degrees F. The heat that is
stored inside the earth is used to produce steam, which is then used to drive electrical generators. The
main advantage of it is that it does not cause any pollution and no fuel is needed. However, hazardous
steams and gases may come out from bottom that may cause harm to mankind.
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Biomass energy is the energy that we get from the organic materials. Biomass is simply the conversion
of stored energy in plants into energy that we can use. Thus, burning wood is a method of producing
biomass energy. "Bioconversion" uses plant and animal wastes to produce "biofuel" such as methanol,
natural gas, and oil.
It in turns causes pollution when you burn them but is
relatively cheap and freely available. Hydroelectric energy is
the use of running of water to generate electricity. To trap
this energy a dam is built usually in a river or lake and water
is allowed to flow through tunnels in the dam to turn the
turbines and thus drive generators. No waste or pollution is
caused and power can be generated through out the year
but if the dam is built it may cause the flood in the large area and therefore getting the suitable site
may be difficult.
Non-Renewable Sources
Non-Renewable Sources include fossil fuels (Coal, Oil and gas) and Nuclear energy. They're called fossil
fuels because they were formed over millions and millions of years by the action of heat from the
Earth's core and pressure from rock and soil on the remains (or "fossils") of dead plants and animals.
Fossil fuels are relatively easy to use to generate energy because they only require a simple direct
combustion. However, a problem with fossil fuels is their environmental impact. When used on a
larger scale they may deplete from the earth after some years and also cause the great deal of air
pollution.
Coal is crushed to a fine dust and burnt. Oil and gas can be burnt directly. Although very large amount
of electricity can be produced at one place, it has a lot of disadvantages. The major drawback is the
pollution which in turn causes greenhouse effect which may lead to global warming. Also, coal fired
power stations need huge amount of fuel. With the large drawbacks of fossil fuels, scientists across
the world are moving there focus from fossil fuels to Nuclear energy.
Non renewable energy source is the element uranium, whose atoms we split (through a process called
nuclear fission) to create heat and ultimately electricity. Most of the nations have started building
nuclear reactors in order to avoid using fossil fuels which contribute to global warming. Some military
ships and submarines even have nuclear power plants for engines. Nuclear power produces around
11% of the world's energy needs, and produces huge amounts of energy from small amounts of fuel,
without the pollution that you'd get from burning fossil fuels. Nuclear power is reliable and does not
produce smoke or waste but if any thing goes wrong, a nuclear accident can be a major disaster.
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People all across the globe use these energy sources to generate electricity for homes, business,
factories and schools. We use this energy to light bulb, run computer, refrigerators, washing machines
and air conditioners etc. We use energy to run our cars and trucks. Both the gasoline used in our cars,
and the diesel fuel used in our trucks are made from oil. Since, renewable sources are not used on much
wider scale and use of Non-renewable sources cause pollution to the environment and may extinct if
used in a hazardous manner, so the need of the hour is to conserve these resources and use them in an
efficient manner to minimize the wastage and making this planet a better place to live in.
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