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| | + | = Introduction = |
| | | | |
| − | = Scope of this document =
| + | This is a resource document for teachers on the |
| | + | various topics of energy covered in high school. This contains |
| | + | resource and reference material for the teachers as well as |
| | + | classroom-based activities and discussions that the teacher can use |
| | + | to build conceptual clarity and understanding. |
| | + | |
| | | | |
| − | The following note is a background document for | + | This resource contains sections on what does |
| − | teachers. It summarises the things we will need to know. This note is
| + | energy mean, the relation between work done and energy, various forms |
| − | meant to be a ready reference for the teacher to develop the concepts
| + | of mechanical energy and the units of measuring power. Further |
| − | in energy from Class 6 onwards to Class 10.
| + | conversion between various forms of energy is explored. The resource |
| | + | also discusses renewable and non-renewable energy sources with a |
| | + | detailed discussion on atominc energy as well. Energy flow in the |
| | + | universe and eecosystem is also discussed to connect the living |
| | + | ecosystem to the sources of energy, particularluy solar energy. |
| | + | Energy storage and management are also discussed in this resource. |
| | + | Where necessary, activities have been described in detail for the |
| | + | teacher to use in the classroom. The resource also points to |
| | + | additional web resources. |
| | | | |
| | | | |
| − | This document attempts to cover all the topics
| + | '''E'''nergy is the basis of human |
| − | identified in the concept map. To plan the actual lessons, the
| + | life. Every single aspect of human experience whether it be in the |
| − | teacher must use this in connection with the theme plan.
| + | external world or what we do or what is done to us can be adequately |
| | + | described either as a transfer of energy in one form from one place |
| | + | to another or the transformation of energy from one form to another. |
| | + | What is the meaning of energy? How does one measure it? What are the |
| | + | various forms in which energy manifests itself? How is energy |
| | + | obtained and transformed from one form to the other? How can energy |
| | + | be conserved? How do the production and utilization of energy in its |
| | + | various forms affect our environment? What is the source of all |
| | + | energy? What kind of energy flows and conversions take place in the |
| | + | environment? These are some questions we will explore here. |
| | | | |
| | | | |
| | + | = Concept Map = |
| | + | |
| | + | <br> |
| | + | <br> |
| | | | |
| | + | |
| | + | [[Image:Energy%20for%20KOER_html_m5d4a74f5.jpg]]<br> |
| | + | <br> |
| | | | |
| | + | |
| | + | <br> |
| | + | <br> |
| | | | |
| | | | |
| − | = Theme Plan = | + | = Work, Energy and Power = |
| − |
| + | |
| − | {| border="1"
| + | We often use the terms work in ordinary |
| − | |-
| + | conversation. Further, we also say that energy is needed to do work. |
| − | |
| + | We will explore the idea of work done, energy, power and energy |
| − | '''CLASS'''
| + | conversions in this section. |
| | | | |
| | | | |
| − | |
| + | Some of the key ideas to be covered in this |
| − | '''SUB-TOPIC'''
| + | section are: |
| | | | |
| | | | |
| − | |
| + | # Work has a physical meaning in relation to the force operating and this is linked to the concept of energy. Such work done can be measured in physical terms. |
| − | '''CONCEPT
| + | # What do we mean when we say an object has energy? We are introduced to the idea of kinetic and potential energy. |
| − | DEVELOPMENT'''
| + | # Effectivesness of doing work is called power; work, energy and power have units of measure. |
| − | | + | |
| | + | == Concept flow == |
| | + | |
| | + | === What does work done mean? === |
| | | | |
| − | |
| + | We often use the terms work in ordinary |
| − | '''KNOWLEDGE
| + | conversation. We say for example “This job requires a lot of work”. |
| − | OUTCOMES'''
| + | What does ‘work’ really mean here? Further, we also say that |
| | + | energy is needed to do work. We will explore the idea of work done, |
| | + | energy, power and energy conversions in this section. |
| | | | |
| | | | |
| − | |
| + | Work always involves some opposing forces. What |
| − | '''SKILL
| + | do we mean by this? If we lift a box from the ground level and place |
| − | OUTCOMES'''
| + | it on a high shelf, we feel tired after the job is completed; we feel |
| | + | that we have done some work. How is this done? Gravity pulls the |
| | + | box and hence we are doing work against this gravitational force. |
| | + | This is true for any type of work. |
| | | | |
| | | | |
| − | |
| + | Suppose that instead of lifting the box, we push |
| − | '''ACTIVITIES'''
| + | it across a rough floor. In this case, we are not working against |
| | + | the gravitational force-the box is at the same height throughout the |
| | + | movement. Instead, we are now working against the frictional force |
| | + | that exists between the moving the box and the floor. |
| | | | |
| | | | |
| − | |-
| + | In physical terms, work done is |
| − | |
| + | directly proportional to both the applied force and the distance |
| − | 6
| + | through which the force acts. |
| | | | |
| | | | |
| − | |
| + | '''How do we measure work here?''' |
| − | Work
| |
| − | ,measurement of work
| |
| | | | |
| | | | |
| − | |
| + | We know that there is some cause, a force that |
| − | Work
| + | results in a change in state of an object. When such a change in |
| − | is something done. Work always involves overcoming some opposing
| + | state occurs, it often results in a change in energy of the object. |
| − | force; force does workand produces a change in energy. Work done
| + | Is this waiter carrying a tray doing work? |
| − | is directly proportional to both the applied force and the
| |
| − | distance through which the force acts
| |
| | | | |
| | | | |
| − | |
| + | When force acts over a period of time, there is an |
| − | They
| + | impulse I = F x t = m(v – mu) is the change in momentum of the |
| − | will know that work is done on a body only when it is displaced
| + | body. Let us now look at what happens when force acts on an object |
| | + | over a distance along the direction of the force. In we say work is |
| | + | done by a force if the force acts on an object over a distance and we |
| | + | say that the work done W = Force F x distance travelled along the |
| | + | direction of the force. |
| | | | |
| | | | |
| − | |
| + | [[Image:Energy%20for%20KOER_html_m7d349003.png]]Notice |
| − | They
| + | that the work done is the same in all the three cases above though |
| − | will learn to calculate the work done when a known force is
| + | the force applied is different. Greater the angle of inclination, |
| − | applied on a body and the distance travelled is measured.
| + | greater is the force needed. |
| | | | |
| | | | |
| − | |
| + | Thus W = F x d if the distance travelled d is in |
| − | Activity
| + | the same direction as the force. If the direction in which the object |
| − | 1
| + | is moving is at angle θ then the distance travelled in the direction |
| | + | of the force would be d Cos θ and the work done would be W = f x d |
| | + | Cosθ. |
| | | | |
| | | | |
| − | |-
| + | [[Image:Energy%20for%20KOER_html_6f7bb14c.gif]]If |
| − | |
| + | the force is acting perpendicular to the direction of the work done, |
| − | 7
| + | there is no work done. If you are carrying a heavy bag in your hand |
| | + | and walking, though you may feel tired, no work is done in the |
| | + | physical sense, because there is no energy change that has occurred |
| | + | for the bag. |
| | | | |
| | | | |
| − | |
| + | Work done, is defined as a particular form of |
| − | Types
| + | product of two vectors – force and displacement. Such a product is |
| − | of energy-Kinetic and potential
| + | called the scalar product and the resulting quantity is a scalar. In |
| | + | the context of work done, this is easy to understand. You don’t do |
| | + | work in a particular direction – you just do work. |
| | | | |
| | | | |
| − | |
| + | The unit of work done is joules. 1 J of work is |
| − | The | + | said to be done when a force of 1 N causes a displacement of 1 m. |
| − | energy that an object possesses by virtue of its motion is
| |
| − | Kinetic energy.The energy that an object possesses when it is
| |
| − | lifted to a height or it is put under strain is potential energy.
| |
| | | | |
| | | | |
| − | Potential
| + | When work is done, it is done over a certain time. |
| − | energy is potential for energy.
| + | The rate of doing work is defined as the power. Power is defined as |
| | + | (work done)/ time taken. |
| | | | |
| | | | |
| − | |
| + | Power = work done/ time = force x displacement/ |
| − | A
| + | time = force x velocity |
| − | moving body possess Kinetic energy and the energy stored in a
| |
| − | body is potential energy
| |
| | | | |
| | | | |
| − | |
| + | Its unit is Watt. |
| − | Observes
| |
| − | different situations in daily life when and where a body possess
| |
| − | kinetic energy and potential energy
| |
| | | | |
| | | | |
| − | |
| + | === Energy, types of energy-Kinetic and potential === |
| − | Activity
| |
| − | 2
| |
| − | | |
| | | | |
| − | |-
| + | When an object is moved against a force, work is |
| − | |
| + | done and energy is spent in the process. Thus we say “A person |
| − | 8
| + | must have a lot of energy to do a hard day’s work”. In fact one |
| | + | way to define energy is: Energy is the capacity to do work. |
| | | | |
| | | | |
| − | |
| + | The word ‘energy’ is derived from the Greek |
| − | Different
| + | '''''energia''''''''-en means ''''''''‘in’'''''''' |
| − | forms of kinetic energy and potential energy
| + | and''' '''''ergon'''''''', means |
| | + | ''''''''work'''''. |
| | | | |
| | | | |
| − | |
| + | [[Image:Energy%20for%20KOER_html_77958556.jpg]][[Image:Energy%20for%20KOER_html_4c924b2.jpg]]<br> |
| − | Kinetic
| + | <br> |
| − | energy is there when there is motion. Object possesses potential
| |
| − | energy in different forms.
| |
| | | | |
| | | | |
| − | |
| + | <br> |
| − | Identifies
| + | <br> |
| − | Kinetic energy and potential energy in various forms
| |
| | | | |
| | | | |
| − | |
| + | <br> |
| − | Observes
| + | <br> |
| − | the different forms of energy in terms of kinetic energy and
| |
| − | potential energy
| |
| | | | |
| | | | |
| − | |
| + | <br> |
| | + | <br> |
| | | | |
| | + | |
| | + | <br> |
| | + | <br> |
| | | | |
| | | | |
| − | |-
| + | <br> |
| − | |
| + | <br> |
| − | 9
| |
| | | | |
| | | | |
| − | |
| + | Energy is defined for an object in a particular |
| − | | + | state. When work has been done on an object, its energy changes. At |
| | + | a very basic level, there are two forms of energy – kinetic energy |
| | + | and potential energy. |
| | | | |
| | | | |
| − | |
| + | For example, a block is lying at rest on a table. |
| − | Power
| + | It is pushed and it acquires a uniform velocity. Now the block has |
| − | is the rate at which work is done or energy is used or supplied
| + | acquired some energy (kinetic energy, as we will define shortly). |
| − | and therefore is calculated by dividing the work done or energy
| + | While the cause of the change in the state was a force (the push), it |
| − | used or supplied in the process by the time taken by the process.
| + | has resulted in the body acquiring a change in energy. |
| | | | |
| | | | |
| − | |
| + | We can see that there are two ways of describing |
| − | Learns
| + | this (and for that matter, any) process. One is to study the cause |
| − | that energy used to do a work varies from person to person and
| + | (the force) and the other is to examine the change in energy. |
| − | varies for different activities. Understands the way machines
| |
| − | work.
| |
| | | | |
| | | | |
| − | |
| + | '''Understanding Kinetic Energy''' |
| − | Uses
| |
| − | the unit of power in their daily life. Example in the electricity
| |
| − | bills.
| |
| | | | |
| | | | |
| − | |
| + | If an object is moved from rest to a uniform |
| − | Chart
| + | velocity, horizontally, it has acquired kinetic energy. Conversely, |
| − | of energy requirements for various activities
| + | if an object is moving with a velocity ‘v’ and has to be stopped, |
| | + | work needs to be done. Let us understand this mathematically. |
| | | | |
| | | | |
| − | |}
| + | Let us say an object of mass ‘m’ is moving |
| | + | with a velocity ‘v’ and is brought to rest by a retarding force |
| | + | over a distance ‘s’ |
| | | | |
| − | | + | |
| − | | + | The |
| − |
| + | acceleration = v<sup>2</sup>/ 2s |
| − | {| border="1"
| |
| − | |-
| |
| − | |
| |
| − | '''CLASS'''
| |
| | | | |
| | | | |
| − | |
| + | The force required = m x a |
| − | '''SUB-TOPIC
| |
| − | '''
| |
| | | | |
| | | | |
| − | |
| + | = m x v<sup>2</sup>/ |
| − | '''CONCEPT
| + | 2s |
| − | DEVELOPMENT'''
| |
| | | | |
| | | | |
| − | |
| + | Work done = |
| − | '''KNOWLEDGE
| + | force x displacement |
| − | OUTCOMES'''
| |
| | | | |
| | | | |
| − | |
| + | = (m x v<sup>2</sup>/ |
| − | '''SKILL
| + | 2s) x s |
| − | OUTCOMES'''
| |
| | | | |
| | | | |
| − | |
| + | = ½ m v<sup>2</sup> |
| − | '''ACTIVITIES'''
| |
| | | | |
| | | | |
| − | |-
| + | This is the expression of the kinetic energy that |
| − | |
| + | the object had. |
| − | 10
| |
| | | | |
| | | | |
| − | |
| + | If this object is a car and it was brought to rest |
| − | Fossil
| + | by braking, the kinetic energy was lost as heat energy due to |
| − | fuels-formation and processing of coal and petroleum.
| + | friction (braking) between the road and the car tires. The total |
| | + | energy remains conserved; it merely moves from one form to another. |
| | | | |
| | | | |
| − | |
| + | All energy is due to |
| − | Fossil
| + | motion and is kinetic energy. The energy that an object possesses |
| − | fuels are a result of processes that occur over a long time;
| + | by virtue of its motion is Kinetic energy. |
| − | non-renewable. All fossil fuels are exhaustible.
| |
| | | | |
| | | | |
| − | |
| + | [[Image:Energy%20for%20KOER_html_m23570b7e.gif]]'''Understanding |
| − | Fossil
| + | Potential Energy''' |
| − | fuels are the result of decomposition of living matter. coal is a
| |
| − | fossil fuel which is obtained from dead plant matter which
| |
| − | consists primarily of carbon, hydrogen and oxygen and it can be
| |
| − | used with or without processing. Whereas petroleum is a fossil
| |
| − | fuel which is a mixture of hundreds of hydrocarbon compounds
| |
| − | together with small amounts of compounds of other elements and it
| |
| − | should be used only after processing.
| |
| | | | |
| | | | |
| − | |
| + | If an object is lifted from the ground to a |
| − | Uses
| + | certain height, work has been done in moving it and this is stored in |
| − | the fossil fuels judiciously.
| + | the object as potential energy. If the object is dropped, it will |
| | + | fall to the ground with a velocity and will acquire kinetic energy. |
| | | | |
| | | | |
| − | |
| + | * Potential energy can be more usefully understood and described as potential for energy. When a body has potential energy, it has the capacity to do work. When a spring is compressed, work has been done on it. If it is released, the spring can do work. The potential (for) energy that it has allows the spring to do work. |
| − | locating
| + | * [[Image:Energy%20for%20KOER_html_7e8255f0.gif]]It is also useful to think of potential energy in terms of change in energy level with respect to a zero. The surface of the earth has been arbitrarily assumed to be at zero potential energy. |
| − | coal reserves on a map
| + | * The potential for energy is with respect to a zero defined for a system. The potential energy is, therefore, always to be referred to in terms of a system. The potential energy of the object-earth system was changed when it was lifted to a height ‘h’. |
| − | | |
| | | | |
| − | |-
| + | If an object of mass ‘m’ is raised to a height |
| − | |
| + | ‘h’, work has been done. |
| − | | |
| | | | |
| | | | |
| − | |
| + | Work done = m x g xh |
| − | Biomass
| |
| − | energy
| |
| | | | |
| | | | |
| − | |
| + | = mgh |
| − | Energy
| |
| − | can be converted from one form to another – can be produced
| |
| − | from household waste.
| |
| | | | |
| | | | |
| − | |
| + | This is stored in the object as potential energy |
| − | Biomass
| + | and when the object falls, gets converted into kinetic energy. In |
| − | energy is the energy produced by the waste material and dead
| + | this particular case, the potential energy is referred to as |
| − | parts of living objects.
| + | gravitational potential energy. An object can also possess potential |
| | + | energy if it is put under strain. Then it has energy stored in it |
| | + | because of the work done to bring it in that condition. In a time |
| | + | piece, the main spring, for example, once wound keeps unwinding and |
| | + | driving the clockwork mechanism for many hours. Here the coiled |
| | + | spring has energy stored in it because of the work done on it while |
| | + | winding. |
| | | | |
| | | | |
| − | |
| + | Potential energy is the potential for energy that is built in an |
| − | Separates
| + | object. The energy that an object possesses when it is lifted to a |
| − | the solid wastes , like vegetable wastes,dead leaves from wastes
| + | height or it is put under strain is potential energy. |
| − | like plastics,glass, etc., before disposing.
| |
| | | | |
| | | | |
| − | |
| + | ==== Activity 1 (Self-evaluation for student) ==== |
| − | Visit
| |
| − | to a biogas plant
| |
| − | | |
| | | | |
| − | |-
| + | [[Image:Energy%20for%20KOER_html_m13b54311.gif]]Knowing |
| − | |
| + | that the PE at the top of the stairs is 50 J, what is the potential |
| − | | + | energy at the various positions? |
| | | | |
| | | | |
| − | |
| + | <br> |
| − | Solar
| |
| − | energy
| |
| | | | |
| | + | |
| | + | === Potential Energy – Kinetic energy changes during free fall === |
| | | | |
| − | |
| + | <br> |
| − | Sunlight
| |
| − | is a mixture of light of various wavelengths, each of different
| |
| − | energy. Among the radiations emitted by the sun the Ultraviolet
| |
| − | and infrared radiations has more energy. This energy can be
| |
| − | harnessed in different ways so that we can use this energy as an
| |
| − | alternative source for fossil fuels. This is free pollution and
| |
| − | renewable form of energy.
| |
| | | | |
| | + | |
| | + | === Conservation of energy === |
| | | | |
| − | |
| + | The key idea here is that the total energy of the |
| − | Learns
| + | system is conserved. Potential energy can be converted into kinetic |
| − | that Sun's energy can also be trapped and used as a form of
| + | energy and vice versa. But the total energy remains unchanged. |
| − | energy in their daily life.
| |
| | | | |
| | | | |
| − | |
| + | In more general terms, the law of conservation of |
| − | Uses
| + | energy states that energy can neither be created nor destroyed; but |
| − | Solar equipments like solar heater, solar lights,Solar cookers
| + | can be transformed from one form to another. |
| − | etc., in their daily life as they use solar energy-renewable and
| |
| − | pollution free energy.
| |
| | | | |
| | | | |
| − | |
| + | ==== Activity : Conservation of mechanical energy in a pendulum ==== |
| − | Exhibiting
| + | |
| − | the solar equipments
| + | ==== Objectives: ==== |
| | + | |
| | + | # To study the motion of a simple pendulum |
| | + | # To observe the different factors on which the motion of a simple pendulum depends |
| | + | # Develop an understanding that gravity is a conservative force |
| | + | |
| | + | ==== Method: ==== |
| | + | |
| | + | [[Image:Energy%20for%20KOER_html_m72c98b84.png]]Use |
| | + | the PhET simulation Pendulum Lab. |
| | | | |
| | | | |
| − | |-
| + | For this we will need to open an application |
| − | |
| + | called PhET on the computer. You can find PhET under Applications> |
| | + | Education> Science. PhET is an educational resource that contains |
| | + | computer demonstrations of experiments and activities. When we click |
| | + | on Play with sims – it will open simulations in various subjects. |
| | + | We will click on Physics and scroll down to the simulation on |
| | + | Pendulum Lab. |
| | | | |
| | + | |
| | + | When we want to open a simulation, we click on |
| | + | the green rectangle which says “Run Now”. |
| | | | |
| | | | |
| − | |
| + | ==== Running the simulation ==== |
| − | Wind,
| + | |
| − | Running water, Ocean-Waves and tides and Ocean thermal gradients,
| + | '''Screenshot #1''' |
| − | Geothermal energy as a source of energy
| |
| | | | |
| | | | |
| − | |
| + | [[Image:Energy%20for%20KOER_html_m6465bb7e.png]]'''Questions:''' |
| − | Learns
| |
| − | that other than sun there are many other sources of energy which
| |
| − | are easily available, pollution free and inexhaustible.
| |
| | | | |
| | | | |
| | + | # Notice where the pendulum is – is it higher, lower or at the same level as the central position? |
| | + | # Notice the graph – what are the two variables on the bar chart? |
| | + | # What do you think will happen to the pendulum next? |
| | + | |
| | + | Screenshot #2 |
| | | | |
| | + | |
| | + | [[Image:Energy%20for%20KOER_html_m4498abd8.png]]'''Questions:''' |
| | | | |
| | | | |
| − | |
| + | # Notice where the pendulum is – has it moved? What can you say about its movement? |
| − | Wind
| + | # Notice the graph – what are the variables on the bar chart? |
| − | energy is the energy of motion of air is the energy which is
| + | # What are the values of PE and KE as compared to total energy? |
| − | inexhaustible and permanent source of energy where there will
| + | |
| − | always be winds. (See note below table)
| + | Screenshot #3 |
| | | | |
| | | | |
| − | |
| + | [[Image:Energy%20for%20KOER_html_706b8b67.png]] '''Questions:''' |
| − | Uses
| |
| − | the alternative energy source which is easily available to them.
| |
| | | | |
| | | | |
| − | |
| + | # Notice where the pendulum is – has it moved? Is it higher or lower than the central position? |
| − | Making
| + | # Did you notice anything about the speed of the bob as it moves from one extreme position to another? |
| − | a Phirki, a common toy of a child which works by a wind force.
| + | # Notice the graph – what are the variables on the bar chart? |
| − | Visit to a Hydroelectric power station.
| + | # What has happened to the values of the KE and PE as compared to total energy? |
| − | | + | # What do you think is happening? Is this what you will think will happen when you try this experiment? Why? Why not? What is different? |
| | | | |
| − | |-
| + | '''Screenshot #4''' |
| − | |
| |
| − | | |
| | | | |
| | | | |
| − | |
| + | [[Image:Energy%20for%20KOER_html_1fe1122b.png]]<br> |
| − | Small
| |
| − | scale storage, large scale storage
| |
| | | | |
| | | | |
| − | |
| + | '''Questions:''' |
| − | Various
| |
| − | sources of generation of power is associated with a problem of
| |
| − | power fluctuates During day time power can be supplied fully from
| |
| − | different sources whereas to work during night time storing up of
| |
| − | energy is necessary. Depending upon the purpose energy can be
| |
| − | stored in small scale and also large scale. For small scale
| |
| − | storage primary cells and secondary cells can be used. But to
| |
| − | meet the large energy requirements of homes and industry storage
| |
| − | batteries are impractical.
| |
| | | | |
| | | | |
| − | |
| + | # Notice where the pendulum is. This extreme position to the right is at a different height than before. Why? What role does friction play and where does it come from |
| − | Learns
| + | # Look at the graph – what are the variables in the bar chart? Where has the thermal energy come from? |
| − | that harnessed energy can also be stored to use when in need.
| + | # What do you expect will happen to the simple pendulum? |
| | + | |
| | + | ==== Mechanics of the simple pendulum ==== |
| | + | |
| | + | The motion of a pendulum is a classic example of |
| | + | mechanical energy conservation. A pendulum moves it sweeps out a |
| | + | circular arc, moving back and forth in a periodic fashion. Neglecting |
| | + | air resistance (which would indeed be small for an aerodynamically |
| | + | shaped bob), there are only two forces acting upon the pendulum bob. |
| | + | One force is gravity. The force of gravity acts in a downward |
| | + | direction and does work upon the pendulum bob. However, gravity is an |
| | + | internal force (or conservative force) and thus does not serve to |
| | + | change the total amount of mechanical energy of the bob. The other |
| | + | force acting upon the bob is the force of tension. Tension is an |
| | + | external force and if it did do work upon the pendulum bob it would |
| | + | indeed serve to change the total mechanical energy of the bob. |
| | + | However, the force of tension does not do work since it always acts |
| | + | in a direction perpendicular to the motion of the bob. At all points |
| | + | in the trajectory of the pendulum bob, the angle between the force of |
| | + | tension and its direction of motion is 90 degrees. Thus, the force of |
| | + | tension does not do work upon the bob. |
| | | | |
| | | | |
| − | |
| + | Since there are no external forces doing work, the |
| − | Uses
| + | total mechanical energy of the pendulum bob is conserved. |
| − | the storage batteries such as dry cells and uninterrupted power
| |
| − | supplies for continuous operation of their costly equipment,
| |
| − | computers and other strategic gadgets.
| |
| | | | |
| | | | |
| − | |
| + | === Power, energy units and conversions === |
| − | Exhibiting
| + | |
| − | the dry cells and secondary cells used in the UPS
| + | One important aspect of the processes producing or |
| | + | using or/and converting energy from one form to another is the rate |
| | + | at which this is done. For example, two persons perform equal |
| | + | amounts of work by lifting identical boxes from the ground level and |
| | + | keeping them on a shelf .One of them does this rapidly while the |
| | + | other does it slowly. Although the total work done by each person is |
| | + | the same, the two persons work at different power levels. The faster |
| | + | working person converts his body’s chemical energy into work at a |
| | + | more rapid rate than the slowly working person |
| | | | |
| | | | |
| − | |-
| + | Power is the rate at which work is done or energy |
| − | |
| + | is used or supplied and may therefore be calculated by dividing the |
| − | | + | work done (or energy used or supplied) in the process by the time |
| | + | taken by the process. Work |
| | + | is done over a certain time. Rate of doing work is power. Power is |
| | + | different even if energy is the same. |
| | | | |
| | | | |
| − | |
| + | Energy or work is measured in Joules (J) and time |
| − | Atoms,
| + | is measured is seconds (s) and so the unit of power is the '''joule |
| − | Isotopes
| + | per second (J/s),''' This unit is given the special name '''WATT (W)''' |
| | + | where |
| | | | |
| | | | |
| − | |
| + | 1watt =1 J/s |
| − | The
| |
| − | smallest entities into which the elements can be divided are
| |
| − | called atoms. The protons and neutrons which are the particles
| |
| − | of atoms bound together immensely by strong forces called nuclear
| |
| − | force. Atoms of the same element which exist in different forms
| |
| − | as a result of having different numbers of neutrons in their
| |
| − | nuclei are called isotopes.
| |
| | | | |
| | | | |
| − | |
| + | 1000watt =1 |
| − | Understands
| + | kilowatt=1kw |
| − | the basic structure of the atom, atomic weight, and isotopes.
| |
| | | | |
| | | | |
| − | |
| + | 1000,000 watt =1megawatt=1MW |
| | | | |
| | + | |
| | + | 1,000,000,000watt =1gigawatt=1GW |
| | | | |
| | | | |
| − | |
| + | 1,000,000,000,000watt =1terawatt=TW |
| − | Exhibiting
| |
| − | the periodic table of elements, exhibiting the chart of different
| |
| − | isotopes
| |
| | | | |
| | | | |
| − | |-
| + | A commercial unit energy that we often hear about |
| − | |
| + | on out electricity bills is the '''kilowatt hours (kwh).''' |
| | + | 1kilowatt hour is the energy used or supplied when 1kw power is used |
| | + | or supplied for one hour. '''1kwh is equal to 3.6 million joules.''' |
| | | | |
| | + | |
| | + | === Energy Units and conversions === |
| | + | |
| | + | The basic unit for the measurement of energy in |
| | + | the metric system is the joule, but there are also other units in |
| | + | common usage. The kilowatt hour is usually used to describe |
| | + | electrical energy. The '''calorie''' which is defined as the amount |
| | + | of heat energy required to raise the temperature of 1g of water |
| | + | through 1degree Celsius, is the unit primarily used to measure heat |
| | + | and also to describe the energy content of food stuff. |
| | | | |
| | | | |
| − | |
| + | = Energy in the world = |
| − | Nuclear
| |
| − | fission
| |
| − | | |
| | | | |
| − | |
| + | The transformations of energy from one form to |
| − | Nuclear
| + | another and the efficiency of the transformation processes are |
| − | fission is a process of releasing a large amount of energy by
| + | studied in Physics, Chemistry and Biology. While so far we have |
| − | hitting a neutron on unstable elements and making them split.
| + | discussed potential energy and kinetic energy (expressed as thermal |
| − | This is carried out in a nuclear reactor.
| + | energy in molecules), we see around us energy in various forms such |
| | + | as electrical energy, solar energy tidal energy hydro energy, |
| | + | geothermal energy and so on. All these forms of energy fall under the |
| | + | two categories of energy kinetic and potential. Potential energy is |
| | + | the stored energy and the energy of position and can be understood as |
| | + | potential for energy. Chemical energy, nuclear energy, stored |
| | + | mechanical energy and gravitational energy are all forms of potential |
| | + | energy. |
| | | | |
| | | | |
| − | |
| + | In this section, we will explore the following: |
| − | Understands
| |
| − | the process of generating nuclear energy by the process of
| |
| − | nuclear fission.
| |
| | | | |
| | | | |
| − | |
| + | # Matter contains internal energy caused due to molecular motion |
| − | Pupil
| + | # Energy can be conveted from one form into another |
| − | draw the diagrams of the nuclear reactors
| + | |
| − | | + | === Energy in matter === |
| | | | |
| − | |
| + | The molecules in every bit of matter solid, liquid |
| − | | + | or gas are in a continual state of motion. This random motion of |
| | + | molecules(or atoms) constitute an internal kinetic energy or thermal |
| | + | energy that an object possesses even though the object as a whole |
| | + | may not be in motion. Thermal energy is thus manifestation of the |
| | + | motion of the molecules of a substance. A change in the thermal |
| | + | energy of an object can be brought about by supplying heat to the |
| | + | object. For example, by repeatedly hitting a block of metal with a |
| | + | hammer, its atoms are caused to move rapidly, thereby raising the |
| | + | thermal energy of the metal block which as a result becomes hot. |
| | | | |
| | | | |
| − | |-
| + | The primary source of all energy on the Earth is |
| − | |
| + | the Sun, though there are some small amounts of energy that come from |
| − | | + | the Earth's interior as well as cosmic radiation. Tidal energy is |
| | + | also caused by the gravitational pull of the Earth. Powered by the |
| | + | Sun, energy constantly flows through the Earth's surface and |
| | + | environment. |
| | | | |
| | | | |
| − | |
| + | === Laws governing the energy of the universe === |
| − | Nuclear
| |
| − | fusion
| |
| − | | |
| | | | |
| − | |
| + | Studying the flow of energy and understanding the |
| − | Joining
| + | processes in the world is called thermodynamics. This branch of |
| − | together of lighter atoms to form heavier atoms and releasing
| + | science involved asking questions about how processes happen in the |
| − | enormous amount of energy is nuclear fusion. Nuclear fusion
| + | world around us. For example, why are certain processes irrevesible? |
| − | reaction is happening in the sun.
| + | What makes a chemical reaction takes place? When does heat flow |
| | + | from one object to another? |
| | | | |
| | | | |
| − | |
| + | Exploration of these concepts resulted in the |
| − | Understands
| + | formulation of two laws: |
| − | that we are getting tremendous amount of energy by the process of
| |
| − | fusion reaction in the sun.
| |
| | | | |
| | | | |
| − | |
| + | # The first law of thermodynamics states that the total energy of a system and its surroundings remains constant. In other words, the energy of the universe is constant. This law implies that energy is conserved and the energy content of the system takes two forms - work and heat. |
| − | Differentiate
| + | # The second law of thermodynamics states that the entropy of the universe is always increasing. This can be summarized by stating that the universe always moves in a direction of increasing randomness. |
| − | between nuclear fission and nuclear fusion
| |
| − | | |
| | | | |
| − | |
| + | === Some processes of energy conversion === |
| − | | |
| − | | |
| | | | |
| − | |-
| + | We have seen that energy occurs in various forms. |
| − | |
| + | These different forms of energy can be converted from one form to |
| | + | another. |
| | + | |
| | + | |
| | + | * For example, when we switch on an electric light firstly, we can see the transfer of electrical energy from the power plant to our home, and then the conversion of electric energy into heat energy, part of it into visible light. This light energy is not destroyed but it is absorbed by the walls, ceiling and floor and other objects, finally to be converted into heat. Electric energy → heat energy+ light energy |
| | + | * In a power plant, chemical energy stored in fossil fuels such as coal, oil or gas is converted into heat energy in the boiler by combustion. This heat energy changes water from liquid state to steam. This heat energy of steam is converted in part, into mechanical energy in the steam turbine. This mechanical energy is then converted into electrical energy in the generator. From the generator it is transferred by the electric cables to various points where it can be used for further transfer to homes and industries etc., Chemical energy → heat energy → steam energy → mechanical energy electrical energy → light energy+ heat energy+ mechanical energy |
| | + | * In the running of a car the chemical energy hidden in the explosive mixture of petrol vapour and air is converts by the spark into heat energy. The heat energy, in turn is converted in part, into mechanical energy of motion of the pistons in the cylinders. The mechanical energy of the pistons is transferred to the drive shaft and from there to the wheels to move the car. Chemical energy → heat energy → mechanical energy |
| | + | * All biological processes throughout the domain of living things can also be shown to be energy conversion processes. The digestion of food is a combination of rather complicated processes but what it amounts to is the transformation of chemical energy locked in the food into heat energy to keep the body warm, and into mechanical energy to enable the body to do work by moving its various parts or itself as a whole besides synthesizing some compounds. There is also some conversion into electrical energy to establish communication between various parts of the body through the nervous system. |
| | + | * Chemical energy → heat energy + mechanical energy + electrical energy In all the above examples energy is converted from one to another, but the total energy in any energy conservation process always remains constant; that is energy can neither be created nor destroyed. This is the law of conservation of energy. |
| | + | |
| | + | = Biological energy flow = |
| | + | |
| | + | We saw earlier that energy flows constantly |
| | + | through the Earth and its environment. Plants fix the solar |
| | + | radiation into carbohydrates and form the basis of much of the energy |
| | + | flow in the world. Either through the food chain or through the |
| | + | accumulation as fossil fuels, this accounts for the bulk of the |
| | + | energy in the world. |
| | | | |
| | + | |
| | + | == Concept Flow == |
| | + | |
| | + | # Energy flows are essential to life processes and we need to study biological energy flows also to understand flow of energy. |
| | + | # We cannot discuss energy without discussing the connection with food and how energy flows through living organisms through food. This flow of energy through living organisms is called a food chain. |
| | + | |
| | + | === Energy flow in an ecosystem === |
| | + | |
| | + | An ecosystem is a community where living and |
| | + | non-living things interact. There are two main processes in an |
| | + | ecosystem – energy flow and nutrient flow. The energy flow in an |
| | + | ecosystem happens through the food chain. |
| | | | |
| | | | |
| − | |
| + | === Activity: Energy flow through a food chain === |
| − | Threats
| + | |
| − | from fossil fuels, combustion of fuels, effects of carbon
| + | ==== Objectives ==== |
| − | monoxide and carbon dioxide, Thermal pollution and effects of
| + | |
| − | nuclear radiations
| + | # To understand the way energy flows in an ecosystem |
| | + | # To explore the connections between different cycles and processes in an ecosystem |
| | + | |
| | + | ==== Method ==== |
| | + | |
| | + | Watch the following videos on food chain |
| | | | |
| | | | |
| − | |
| + | * Food chain in Africa [[http://www.youtube.com/watch?v=3Bn7wdCP2v4&feature=related]] |
| − | There
| + | * Interactions in an ecosystem [[http://www.youtube.com/watch?v=XJ6VtduDSyY&feature=related]] |
| − | are a numerous environmental problems associated with the
| + | * Description of a food chain and web [[http://www.youtube.com/watch?v=9eZBzfnAogU&feature=related]] |
| − | extraction, transportation and utilisation of fossil fuels.
| + | * Interactions and energy flow in an ecosystem [[http://www.youtube.com/watch?v=o_RBHfjZsUQ]] |
| − | Understands that there are harmful effects on the environment by
| + | |
| − | the over use of fossil fuels, electricity generating plants, and
| + | <u>'''Questions:'''</u> |
| − | also nuclear reactors.
| |
| | | | |
| | | | |
| − | |
| + | * When we say food web, what comes to your mind? Why do you think it is called food web? |
| | + | * What are the implications of laws of thermodynamics on how much energy is transferred in a food chain? |
| | + | * Can you think why there are few consumers and large number of producers? What happens when a consumer eats a producer? |
| | + | * In the local ecosystem, provide examples of each of these categories in your area – producer, consumer and decomposer? |
| | + | * For this web to work properly, what is needed? |
| | + | * What is energy flow? How does it flow – from small organisms to large or large organisms to small? Why do you think so? What elements do you observe in the ecosystem that give you this idea? |
| | + | * Is the tiger 'bad' because it ate the goats? Why is the tiger eating the goat? |
| | + | |
| | + | ==== Methods of energy flow ==== |
| | + | |
| | The | | The |
| − | burning of fossil fuels releases a variety of noxious gases and
| + | laws of thermodynamics we saw earlier govern the processes in a food |
| − | particulate matter into the atmosphere. Carbon monoxide and
| + | chain also. For example, the first law tells us that an organism can |
| − | carbon dioxide which are the pollutants produced by the burning
| + | only use the energy it receieves whereas the second law tells us that |
| − | of fossil fuels constitute a serious environmental problem. All
| + | not all of the energy received by an organism can be used – some of |
| − | electricity generating plants produce unwanted heat which is
| + | it will be lost as heat. At each level of the food chain, the amount |
| − | released to the atmosphere. Nuclear reactors harmful substances
| + | of energy that gets transferred to the next trophic level is only a |
| − | which can are very harmful to living organisms.
| + | portion of the energy present in the lower level. This fraction |
| | + | varies widely across ecosystems. When finally organisms die and |
| | + | decay they pass the materials of life in simple forms to other |
| | + | organisms (nutrient flow). This energy flow is not cyclic – |
| | + | continuously less and less energy is available. So then, how do |
| | + | ecosystems continue? They depend on an external source of energy |
| | + | called the Sun. If the Sun's energy is not available in usable form, |
| | + | life on Earth may not be possible any longer. |
| | | | |
| | | | |
| − | |
| + | = Conventional sources of energy = |
| − | | |
| − | | |
| | | | |
| − | |
| + | We saw how the solar energy is responsible for |
| − | | + | producing organic compounds that sustain energy flow in the living |
| | + | world. Availability of energy resources and harnessing them for |
| | + | multiple applications have concerned the human society for centuties. |
| | + | Advances in technology and society have always been linked to the |
| | + | access of and use of natural energy resources. In this section, we |
| | + | will look at some of the major sources of energy that are used by |
| | + | human beings in our endeavours. |
| | | | |
| | | | |
| − | |-
| + | == Concept flow == |
| − | |
| + | |
| − | | + | Some key ideas we will explore in this section |
| | + | are: |
| | | | |
| | | | |
| − | |
| + | # Solar enerrgy is the source of almost all energy on the Earth |
| − | Need
| + | # Fossil fuels are exhaustible and needs thousands of years to form. |
| − | for Judicious Use of energy, minimising energy
| + | # Biomass energy which comprises parts of living things is also a source of energy. |
| − | | |
| | | | |
| − | |
| + | === Forest === |
| − | Depletion
| |
| − | of energy sources is too fast. Therefore mankind has to adopt a
| |
| − | judicious approach towards consumption of energy sources. Mankind
| |
| − | has to adopt different steps to minimize the wastage of energy.
| |
| − | | |
| | | | |
| − | |
| + | Firewood has been the major source of energy |
| − | Understands
| + | during most of man’s history and it continued to remain the most |
| − | that there is a need to use the available energy judiciously
| + | important fuel until the middle of nineteenth century. Firewood is |
| | + | obtained from the forests and is primarily used for heating and |
| | + | cooking. The other fuel which has been traditionally used here is |
| | + | animal dung cakes. The animal dung mainly consists of undigested |
| | + | plant material which on drying, gives a product that readily burns. |
| | + | One of the disadvantages of both firewood and animal dung cakes as |
| | + | fuels is that they give a lot of smoke on burning. |
| | | | |
| | | | |
| − | |
| + | With the industrial revolution in Europe, people |
| − | Adopts
| + | learned to transform the energy from coal to mechanical energy in |
| − | steps to minimize wastage
| + | machines. This led to increased demand for energy. The discovery of |
| | + | coal, followed by oil and natural gas fulfilled these demands to a |
| | + | large extent and these fuels since then have been the primary sources |
| | + | of world’s energy. |
| | | | |
| | | | |
| − | |
| + | === Fossil fuels === |
| − | | |
| − | | |
| | | | |
| − | |}
| + | All these fuels - coals, oil and natural gas- are |
| − | Running water is an easily
| + | derived from the slow decay of living organisms such as trees, algae |
| − | available source of energy. It is available free and does not pollute
| + | and small marine animals for millions of years and are therefore |
| − | the environment. Ocean energy-Tides, rising and falling of the ocean
| + | known as fossil fuels. The fossil fuels are being consumed at an |
| − | level due to the moon's gravitational pull can be harnessed to
| + | appreciable rate. Although their new deposits continue to be |
| − | extract energy. Waves,which keep the ocean water in continual motion
| + | discovered, the world reserves of these fuels are limited. Further, |
| − | can be used to produce energy. The heat contained in the ocean waters
| + | these energy sources take millions of years to form and therefore |
| − | heated by the sun can be converted into electricity by utilising the
| + | fossil fuels are also known as non-renewable sources of energy. |
| − | difference in temperature between the surface and lower depths.
| + | These fuels once exhausted cannot be replaced quickly when exhausted. |
| − | Geothermal energy -Underground water which oftens gets heated and
| + | Hence these are also called as exhaustible resources. |
| − | produces steam and hot water and comes out as hot springs and geysers
| |
| − | can be utilised.
| |
| | | | |
| | | | |
| − | = Syllabus = | + | === Formation of fossil fuels === |
| | | | |
| − | # Kinetic and Potential Energy – the definitions and formula
| + | ==== Coal ==== |
| − | # Heat and Sound
| |
| − | # Forms of energy – main sources of energy, changes from one form to another
| |
| − | # Law of conservation of energy
| |
| − | # Force causes change in a body; measurement of work
| |
| − | # Structure of atom
| |
| | | | |
| − | = Curricular Objectives =
| + | [[Image:Energy%20for%20KOER_html_m7a3827ce.jpg]]Fossil |
| | + | fuels-coal, oil and natural gas-are the result of decomposition of |
| | + | living matter. Coal is obtained from dead plant matter which consists |
| | + | primarily of carbon, hydrogen and oxygen. |
| | + | |
| | | | |
| − | # The first objective is to introduce children to basic concepts of work. We introduce that work always involves overcoming some opposing force. We then look at work done is directly proportional to both the applied force and the distance through which the force acts.
| + | [[Image:Energy%20for%20KOER_html_m6d44a4fd.jpg]]On |
| − | # In this section, the children are introduced the meaning of energy. We introduce that the body moves and does work only when the energy is supplied to it. This is followed by the concepts of kinetic and potential energy.
| + | dry land, this matter rots away by bacterial action in presence of |
| − | # In this section, we introduce the different forms of Kinetic and potential energy and conversion of one form to another to meet our needs for home and industry.
| + | atmospheric oxygen to form carbon dioxide and water. But in swampy |
| − | # In this section we introduce the meaning of power, units of power and the energy requirements for various activities
| + | locations, the dead plant matter is covered with water and is, |
| − | # .In this section,we introduce the conventional sources of energy -fossil fuels-formation of fossil fuels, supply of fossil fuels, processing of fossil fuels- coal and petroleum and also the Biomass energy-raw materials used in this and brief introduction of the biogas plant.
| + | therefore, protected from the oxidising action of air. Instead, it |
| − | # In this section we introduce the non conventional sources of energy-solar energy which is readily available to us ,inexhaustible, free from pollution. We have also disussed harnessing solar energy in different ways for different purposes. We have also discussed other non conventional sources of energy like wind energy, ocean energy-energy from tides, and energy from waves-Geothermal energy and also the methods of storing energy.
| + | is attacked by bacteria which do not require free oxygen in order to |
| − | # In this section , children are introduced the basic structure of the atom-no of protons, no of electrons and the no of neutrons in each atom . Once the children are introduced the structure of atom and then we introduce the concept of isotopes and then the uranium isotopes which involves in fission process. We further introduce the nuclear reactors-thermal and fast breed reactors. After this we discuss briefly what is happening inside the sun, how energy is generated in the sun , fusion processes and fusion reactors.
| + | live. In the process oxygen and hydrogen of the dead plant matter |
| − | # In this section, we briefly discuss the numerous environment problems associated with the extraction, transportation and utilization of fossil fuels, the effects of burning fossil fuels-effects of carbon Dioxode and
| + | gradually escape and the residue, therefore, becomes richer and |
| − | # Carbon Monoxide on the environment,‘thermal pollution' which basically refers to the detrimental effects of discharges of unwanted heat into the environment.
| + | richer in carbon. The end product of the bacterial action is a |
| − | # In this section, we create awareness about the need for judicious Use of energy and how to minimise wastage so that we can then be put to some useful 'use' in future and also to remember, energy saved is energy produced.
| + | soggy, carbon-rich substance called peat. |
| − |
| |
| − | = Energy =
| |
| − |
| |
| − | '''E'''nergy is the basis of human life. Every
| |
| − | single aspect of human experience whether it be in the external world
| |
| − | or what we do or what is done to us can be adequately described
| |
| − | either as a transfer of energy in one form from one place to another
| |
| − | or the transformation of energy from one form to another.
| |
| | | | |
| | | | |
| − | What is the meaning of energy? How does one
| + | [[Image:Energy%20for%20KOER_html_m29549bc5.jpg]]Over |
| − | measure it? What are the various forms in which energy manifests
| + | long periods of time the peat is covered with sand, silt and clay. |
| − | itself? How is energy obtained and transformed from one form to the
| + | As peat gets compressed and heated further due to geological changes, |
| − | other? How can energy be conserved? How do the production and
| + | more gases are forced out and therefore the proportion of carbon |
| − | utilization of energy in its various forms affect our environment?
| + | continues to increase. In this way, peat is gradually converted into |
| | + | various forms of coal such as lignite, bituminous coal and |
| | + | anthracite. |
| | | | |
| | | | |
| − | == Work, measurement of work == | + | ==== Petroleum and natural gas ==== |
| | | | |
| − | We often use the terms work in ordinary
| + | In contrast to coal, the raw material in the |
| − | conversation. We say for example “This job requires a lot of work”.
| + | formation of oil and natural gas consists mainly of marine organisms, |
| − | What does ‘work’ really mean here? If we lift a box from the
| + | mostly plants that grow near the surface of the sea. When these |
| − | ground level and place it on a high shelf, we feel tired after the
| + | organisms die and accumulate in basins, where the water is stagnant, |
| − | job is completed; we feel that we have done some work. How is this
| + | they are also protected from atmospheric oxidation. The dead marine |
| − | done? Gravity pulls the box and hence we are doing work against this
| + | matter is decomposed by anaerobic bacteria. Oxygen, nitrogen and |
| − | gravitational force. This is true for any type of work.
| + | other elements escape leaving mainly compounds of carbon and hydrogen |
| | + | called hydrocarbons. The accumulating covering layer of sediments |
| | + | provides heat and pressure that convert the hydrocarbon material into |
| | + | droplets of liquid oil and bubbles of natural gas. As more |
| | + | sedimentary deposits are laid down over periods of time, the pressure |
| | + | increases and the oil and gas are forced into nearby porous sand or |
| | + | sandstone. Gradually the oil and gas migrate upward through the sand |
| | + | and they then either escape to the surface or are trapped beneath |
| | + | layers of clay stone. This migration process separates the oil from |
| | + | underground water because water molecule readily adhere to sand |
| | + | whereas oil molecules do not. Thus the oil tends to collect in the |
| | + | pore spaces of sandy rocks beneath roof rocks with natural gases on |
| | + | the top. |
| | | | |
| | | | |
| − | Work always involves overcoming some opposing
| + | === Biomass Energy === |
| − | forces. Suppose that instead of lifting the box, we push it across a
| |
| − | rough floor. Suppose that instead of lifting the box, we push it
| |
| − | across a rough floor. In this case, we are not working against the
| |
| − | gravitational force-the box is at the same height throughout the
| |
| − | movement. Instead, we are now working against the frictional force
| |
| − | that exists between the moving the box and the floor.
| |
| − | | |
| | | | |
| − | === How do we measure work here? ===
| + | Fossil fuels are derived from plants, trees and |
| | + | animals that lives millions of years ago. It took the remains of |
| | + | these organisms millions of years of burial under tremendous pressure |
| | + | and the internal heat to turn into coal, oil, or gas that we use as |
| | + | fuel today. We cannot get fossil fuels from the plant and animal |
| | + | waste that we produce today. But they, too form a substantial source |
| | + | of energy in the form of biomass. Biomass means the waste material |
| | + | and dead parts of animals that are living today. It includes |
| | + | garbage, industrial waste, crop residue, sewage and plant waste such |
| | + | as dead leaves and wood. These wastes can be both wet and dry. Wet |
| | + | wastes are in the form of animal excreta or domestic and industrial |
| | + | residues. Dry wastes refers to leaves, wood, paper, straw, fruit |
| | + | skin and others. There are two ways of using biomass as a source of |
| | + | energy. One is to burn the dry biomass directly to produce heat and |
| | + | generate steam. Another method is to convert this biomass into |
| | + | gaseous fuels called biogas by fermentation. |
| | + | |
| | | | |
| − | We know that there is some cause (we have defined
| + | The raw material used for the production of biogas |
| − | it as force) that results in a change in state of an object. When
| + | is cow dung mixed with water which is taken in an insulated, |
| − | such a change in state occurs, it often results in a change in energy
| + | air-tight container called digester. In the digester, bacteria break |
| − | of the object.
| + | the raw material into simpler chemicals by a process known as |
| | + | anaerobic decomposition. Other bacteria then convert the chemicals |
| | + | into a biogas for fuel. The gas consists of mainly methane and is |
| | + | drawn out through a gas outlet pipe. |
| | | | |
| | | | |
| − | We had also looked at what happens when a force
| + | Wet wastes from household and industries too can |
| − | acts over a period of time and we saw that the Impulse I = F x t =
| + | be used to produce methane gas. Wastes may be dumped in deep pits. |
| − | m(v – mu) is the change in momentum of the body.
| + | Wells are then drilled down into the waste. A pipeline is then |
| | + | drilled down into the waste. A pipeline is then to recover the gas |
| | + | produced by the natural decomposition of the material. |
| | | | |
| | | | |
| − | Let us now look at what happens when Force acts on
| + | === From fossil fuel to electricity === |
| − | an object over a distance along the direction of the force. In we say
| |
| − | work is done by a force if the force acts on an object over a
| |
| − | distance and we say that the work done W = Force F x distance
| |
| − | travelled along the direction of the force.
| |
| − | | |
| | | | |
| − | Thus W = F x d if the distance travelled d is in
| + | The most convenient usable form of energy is |
| − | the same direction as the force. If the direction in which the object | + | electricity. In all the sources of energy above, the heat generated |
| − | is moving is at angle θ then the distance travelled in the direction | + | from the combustion of fuel is used to boil water to produce steam |
| − | of the force would be d Cos θ and the work done would be W[[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_6d9bf88e.gif]] | + | which powers a turbine. This mechanical energy of turbine is |
| − | = f x d Cosθ
| + | converted into electricity in generators. These stages involve |
| | + | various losses and therefore the overall efficiency of these plants |
| | + | is never more than 40 percent. It is, however, possible to cut short |
| | + | the above energy conversion stages and convert heat from the |
| | + | combustion of fuels directly into electricity using a magneto-hydro |
| | + | dynamic generator, popularly known as MHD generator, which works on |
| | + | the basic phenomenon of electromagnetic induction. Another method of |
| | + | increasing the efficiency of power generation is also through the use |
| | + | of combined cycle power plants. |
| | | | |
| | | | |
| − | If the force is acting perpendicular to the
| + | === Processing of coal and petroleum === |
| − | direction of the work done, there is no work done. If you are
| |
| − | carrying a heavy bag in your hand and walking, though you may feel
| |
| − | tired, no work is done in the physical sense, because there is no
| |
| − | energy change that has occurred for the bag.
| |
| − | | |
| | | | |
| − | Work done, is defined as a particular form of
| + | Coal, which is essentially pure carbon, is chiefly |
| − | product of two vectors – force and displacement. Such a product is
| + | used as a combustion fuel. The reaction of carbon with atmospheric |
| − | called the scalar product and the resulting quantity is a scalar. In
| + | oxygen to produce carbon dioxide is an exothermic reaction that |
| − | the context of work done, this is easy to understand. You don’t do | + | releases about 7,840 kilocalories/kg of carbon and this reaction is |
| − | work in a particular direction – you just do work.
| + | responsible for the heat energy derived from burning coal. Burning |
| | + | of coal produces large quantities of fly ash and noxious gases such |
| | + | as a sulphur dioxide and related compounds which cause atmospheric |
| | + | pollution. Coal is therefore converted into a cleaner fuel, coke, by |
| | + | heating crushed coal to high temperatures in the absence of air. |
| | + | Coal can also be converted into liquid and gaseous fuels which can |
| | + | partially replace the fuels derived from petroleum. |
| | | | |
| | | | |
| − | The unit of work done is joules. 1 J of work is
| + | Unlike coal and natural gas which can be used |
| − | said to be done when a force of 1 N causes a displacement of 1 m.
| + | directly as fuels without processing, petroleum or crude oil is not |
| − | | + | directly usable. The name ‘petroleum’ is derived from the Latin |
| − |
| + | words ''petra'' meaning ‘rock’ and ''oleum'' |
| − | When work is done, it is done over a certain time.
| + | meaning ‘oil’. Therefore, it means rock oil, to distinguish it |
| − | The rate of doing work is defined as the power. Power is defined as
| + | from animal or vegetable oils. Petroleum, also often called crude |
| − | (work done)/ time taken.
| + | oil, is a mixture of hundreds of hydrocarbon compounds together with |
| − | | + | small amounts of compounds of other elements. The exact composition |
| − |
| + | of crude depends upon many factors such as its age and the types of |
| − | Power = work done/ time
| + | organisms from which it is formed. So, every deposit of crude oil |
| | + | is a unique mixture whose exact composition differs even from |
| | + | deposits separated from it vertically or horizontally by a few metres |
| | + | of rock. Natural gas is normally associated with crude oil. It is a |
| | + | mixture of gaseous hydrocarbons, mainly methane and ethane. The |
| | + | non-hydrocarbon compounds present in crude oil are mainly compounds |
| | + | of sulphur, nitrogen and oxygen. Other elements present in very |
| | + | small amounts include vanadium, nickel, chlorine, arsenic and lead. |
| | | | |
| | | | |
| − | = force x displacement/ time | + | ==== Detection of Oil ==== |
| − | | |
| | | | |
| − | = force x velocity
| + | The method generally used for locating oil |
| | + | deposits is the seismic survey. Shock waves generated by surface |
| | + | explosive charges travel through rock layers and are reflected back |
| | + | by various geological structures and possible locations where oil |
| | + | might be trapped can be found. To find whether oil is really present |
| | + | and whether it can be economically extracted, it is necessary to |
| | + | drill a well. |
| | | | |
| | | | |
| − | Its unit is Watt.
| + | ==== Extraction and refining of Oil ==== |
| − | | |
| | | | |
| − | Does work always involve change? It may seem from
| + | Once the oil has been found by drilling the well, |
| − | the previous discussion that any change involves work. Sometimes the | + | the next step is to operate the well; that is, to raise the oil to |
| − | change may not be easily visible. For example, is the boy in the fig
| + | the surface. After extraction, the oil is usually transported to a |
| − | doing some work? One may say he is not as nothing seems to be
| + | refinery through pipelines. From offshore platforms, the oil is |
| − | changing. The position of the boy remains the same, the position of
| + | sometimes transported to the shore in large tankers. The natural gas |
| − | the weight remains the same and no object in the picture is moving.
| + | produced in the process is also transported by large pipelines. |
| − | But if one were to hold the weight in one’s outstretched hand
| |
| − | standing in the same position, one would quickly feel tired as one
| |
| − | loses energy.
| |
| | | | |
| | | | |
| − | == Key vocabulary ==
| + | Crude oil is processed in a refinery by fractional |
| − |
| + | distillation. This process involves heating the crude oil in a tall |
| − | # Friction -A force opposing the relative motion of two surfaces in contact.
| + | tower so that various components are distilled out of it and can be |
| − | # Gravity- the force with which earth attracts every object towards its centre.
| + | trapped at various levels in the tower. In this process the use is |
| | + | made of the fact that the different hydrocarbon compounds in the |
| | + | crude have different boiling points and hence can be separated at its |
| | + | boiling point. The lightest compounds such as gases which have low |
| | + | boiling points rise to the top and the heavier oils with higher |
| | + | boiling points are collected lower down. |
| | + | |
| | | | |
| − | == Additional web resources ==
| + | The various fractions may then be further |
| − |
| + | processed by cracking or refining, both of which involve the use of |
| − | '''1)''' [[http://www.youtube.com/watch?v=8J_z3_3pue0]]
| + | catalysts-substances which facilitate the chemical reactions without |
| | + | themselves undergoing any change. Catalytic cracking, often called |
| | + | cat-cracking, is a means of breaking down the heavier distillates to |
| | + | form lighter compounds. |
| | | | |
| | | | |
| − | '''2)
| + | The various fractions obtained after refining are |
| − | [[http://www.youtube.com/watch?v=sOa7EpJf89I&feature=related]]'''
| + | used for different purposes The gas fraction, like natural gas, is |
| | + | used chiefly as a fuel for heating. Petrol is used in spark ignition |
| | + | internal combustion engines that require a fairly volatile fuel. |
| | + | Kerosene is used as a lighting and cooking fuel in villages, and also |
| | + | in tractors and jet engines. Diesel is used in diesel engines. |
| | | | |
| | | | |
| − | = Energy, types of energy-Kinetic and potential = | + | = Non conventional Sources of energy = |
| | | | |
| − | When an object is moved against a force, work is
| + | The conventional sources of energy discussed in |
| − | done and energy is spent in the process. Thus we say “A person
| + | the previous section are exhaustible and cannot be quickly replaced |
| − | must have a lot of energy to do a hard day’s work”. In fact one
| + | when exhausted. It takes millions of years for these sources to be |
| − | way to define energy is: Energy is the capacity to do work.
| + | formed from the decay of living organisms. These sources are, |
| | + | therefore, also known as non-renewable sources of energy. In |
| | + | contrast, we have another class of the sources such as the sun, wind, |
| | + | waves, tides, and geothermal heat which are inexhaustible. These |
| | + | sources of energy are, therefore, known as renewable sources of |
| | + | energy. |
| | | | |
| | | | |
| − | The word ‘energy’ is derived from the Greek
| + | == Concept flow == |
| − | '''''energia''''''''-en means ''''''''‘in’''''''''
| + | |
| − | and''' '''''ergon'''''''', means | + | # Unlike fossil fuels and to some extent, forest and biomass, non-conventional sources of energy are renewable and can potentially be used for longer periods of time |
| − | ''''''''work'''''.
| + | # A major problem in harnessing these sources of energy is that the energy released by them is highly diffused as compared with the energy obtained from fossil fuels or nuclear fuels. |
| | + | # Considerable research is on to make these sources of energy viable. |
| | + | |
| | + | === Solar energy === |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_77958556.jpg]][[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_4c924b2.jpg]]
| + | The source of energy most readily available to us |
| | + | is the sun. Solar energy has several advantages over the other |
| | + | energy sources. It is inexhaustible; it is free from any pollution |
| | + | and unlike fossil fuels, transformation of solar energy does not |
| | + | produce any toxic by-products. |
| | | | |
| − | Energy is defined for an object in a particular
| + | |
| − | state. When work has been done on an object, its energy changes. At
| + | Nature provides some concentration of the sun’s |
| − | a very basic level, there are two forms of energy – kinetic energy | + | energy in the form of wind and waves. The gradients set up in the |
| − | and potential energy.
| + | atmosphere by solar heating turn some of its energy into the movement |
| | + | of large masses of air, thereby providing wind energy. This wind, in |
| | + | turn, whips up the waves in the sea which at places can provide |
| | + | highly concentrated energy. But none of these sources of energy in |
| | + | their natural form can as yet provide a viable alternative to the |
| | + | conventional sources. Therefore, global effort is on to tap energy |
| | + | in concentrated form from the non-conventional sources. |
| | | | |
| | + | |
| | + | When solar radiation strikes the earth’s |
| | + | atmosphere, some of it is reflected by dust particles and clouds, |
| | + | some of it is absorbed by carbon dioxide, water vapour, ozone layer |
| | + | and the remaining reaches the earth’s surface. Most of the |
| | + | ultraviolet radiation is absorbed by the ozone layer. Some infrared |
| | + | radiation is absorbed by the ozone layer. Some infrared radiation is |
| | + | absorbed by clouds, carbon dioxide and water vapour. The amount of |
| | + | radiation, reaching the earth, thus may vary with the presence of |
| | + | clouds, humidity, the latitude- the position of the place north or |
| | + | south of equator, the time of year, the time of day and other |
| | + | factors. An idea of the magnitude of energy reaching the earth’s |
| | + | surface falling on an area equal to the size of the tennis court per |
| | + | day is roughly equal to the energy obtained from 135 litres of petrol |
| | + | or 180 kg of coal. |
| | | | |
| − | For example, a block is lying at rest on a table.
| |
| − | It is pushed and it acquires a uniform velocity. Now the block has
| |
| − | acquired some energy (kinetic energy, as we will define shortly).
| |
| − | While the cause of the change in the state was a force (the push), it
| |
| − | has resulted in the body acquiring a change in energy.
| |
| − |
| |
| | | | |
| − | We can see that there are two ways of describing
| + | === Harnessing Solar Energy === |
| − | this (and for that matter, any) process. One is to study the cause
| + | |
| − | (the force) and the other is to examine the change in energy.
| + | Solar energy can be harnessed in five ways: |
| | | | |
| | | | |
| − | == Understanding Kinetic Energy ==
| + | # using solar panels |
| | + | # solar thermal |
| | + | # concentrated solar power |
| | + | # solar nanowires and |
| | + | # By using photosynthetic and biological processes. |
| | | | |
| − | If an object is moved from rest to a uniform
| + | However, |
| − | velocity, horizontally, it has acquired kinetic energy. Conversely,
| + | before solar energy can be successfully utilized, two major problems |
| − | if an object is moving with a velocity ‘v’ and has to be stopped,
| + | need to be solved. '''Firstly''' |
| − | work needs to be done. Let us understand this mathematically.
| + | solar energy is highly diffused; that is, it is thinly spread over |
| | + | the earth’s surface and so one needs to concentrate it, '''secondly''', |
| | + | solar energy has to be stored for us during night or on a very cloudy |
| | + | day. |
| | | | |
| | | | |
| | + | When sunlight concentrated by a convex lens is |
| | + | made to fall on a piece of paper, it burns. The problem of |
| | + | concentrating solar energy may be solved through the use of different |
| | + | types of reflectors for focusing sunlight. Reflectors are used in |
| | + | solar cookers and solar ovens. The simplest of these reflectors is a |
| | + | single reflector provided in hot-box type of solar cookers. It is a |
| | + | sheet of polished looking glass or aluminized plastic hinged to one |
| | + | side of the box which reflects solar radiation into the cooker and |
| | + | heats it. In a solar oven, several reflectors are provided on all |
| | + | sides of a box. Curved mirrors, parabolic reflectors and Fresnel |
| | + | lenses are also used in solar cookers. |
| | | | |
| − | | + | |
| | + | === Solar Thermal Power Generation === |
| | + | |
| | + | Generally two approaches are followed in this |
| | + | method of power generation |
| | | | |
| | | | |
| − | Let us say an object of mass ‘m’ is moving
| + | (1)sunlight reflected from several mirrors |
| − | with a velocity ‘v’ and is brought to rest by a retarding force
| + | arranged in an array is focused on a single heat exchanger in a solar |
| − | over a distance ‘s’
| + | furnace; and |
| | | | |
| | | | |
| − | The
| + | (2)a large number of cylindrical reflectors in a |
| − | acceleration = v<sup>2</sup>/ 2s
| + | solar farm focus solar radiation on long pipes carrying a gas which |
| | + | collects the heat. A good example of the solar furnace approach is |
| | + | the tower concept. Sunlight is focused on to a boiler mounted on the |
| | + | top of a tower located near the centre of the field of mirrors to |
| | + | produce a high temperature for driving a steam turbine. Another |
| | + | similar plant system used arrays of heliostat-guided mirrors to focus |
| | + | sunlight into a cavity-type boiler near the ground to produce steam |
| | + | for a steam turbine electric power plant. Sunlight striking the |
| | + | mirrored faces of the heliostat modules is reflected and concentrated |
| | + | in the cavity of the heat exchanger. |
| | | | |
| | | | |
| − | The force required = m x a
| + | In contrast to the solar furnace approach, in the |
| | + | solar farm, parabolic cylindrical concentrators or other types of |
| | + | concentrators are used to focus sunlight on to a central pipe |
| | + | surrounded by an evacuated quartz envelope. Heat collected by a |
| | + | fluid(nitrogen or helium) flowing through these pipes may be stored |
| | + | at a temperature over 500 degree Celsius in a molten salt. This heat |
| | + | may then be used to drive steam turbines for the generation of |
| | + | electricity |
| | | | |
| | | | |
| − | = m x v<sup>2</sup>/ | + | === Photovoltaic Power Generation === |
| − | 2s
| |
| − | | |
| | | | |
| − | Work done =
| + | [[Image:Energy%20for%20KOER_html_m4d95859e.gif]]Unlike |
| − | force x displacement
| + | the solar thermal systems discussed above, solar cells offer a very |
| − | | + | attractive means for direct conversion of sunlight into electricity |
| − |
| + | with high reliability and low maintenance. The disadvantages, |
| − | = (m x v<sup>2</sup>/
| + | however, are high cost and difficulty of storing large amounts of |
| − | 2s) x s
| + | electricity as compared with the relative ease of storing heat for |
| − | | + | later use. The working of a solar cell depends upon the phenomenon |
| − |
| + | of photo electricity; that is, the liberation of electrons by light |
| − | = ½ m v<sup>2</sup>
| + | falling on a body. Though this phenomenon has been known for a long |
| − | | + | time, its application to semiconductors such as silicon has proved to |
| − |
| + | be of great use. The principle of solar cells is simple. When light |
| − | This is the expression of the kinetic energy that
| + | waves strike a semi-conductor material with energy sufficient to |
| − | the object had. | + | dislodge an electron from a fixed position in the material and make |
| | + | it move freely in the material, a vacant electron position or ‘hole’ |
| | + | is created in the material. The hole acts a positive charge and can |
| | + | move if a neighbouring electron leaves its site to fill the hole |
| | + | site. A current is created if the electron-hole pairs are separated |
| | + | by voltage in the cell material. Such an intrinsic voltage may be |
| | + | created by adding small amounts of impurities or dopants to the pure |
| | + | material or by joining two semiconductor materials. When impurities |
| | + | such as phosphorous are introduced into silicon, it becomes |
| | + | electron-rich and is referred to as ‘n-type’ silicon. On the |
| | + | other hand, impurities such as boron give rise to ‘p-type’ |
| | + | silicon with excess of holes. When these two oppositely charged |
| | + | semiconductors (one electron rich and the other electron-deficient) |
| | + | are in contact, free charge leaks across the common boundary and |
| | + | becomes fixed as ions in the region adjacent to the boundary. At the |
| | + | interface, the fixed (but opposite) ions create an electric field |
| | + | that sends free electrons one way and free holes the other. |
| | | | |
| | | | |
| − | If this object is a car and it was brought to rest
| + | In the dark, no current flows in the solar cell. |
| − | by braking, the kinetic energy was lost as heat energy due to
| + | But when it is illuminated, a current will flow as long as the cell |
| − | friction (braking) between the road and the car tires. The total
| + | is illuminated and can supply electricity to an external load. |
| − | energy remains conserved; it merely moves from one form to another.
| |
| | | | |
| | | | |
| − | == Understanding Potential Energy ==
| + | The |
| | + | best and most efficient solar cells are constructed from high purity |
| | + | silicon. This type of cell has already been used very successfully |
| | + | for providing electrical power in spacecraft. The overall efficiency |
| | + | of photovoltaic cells is around 11 percent. But their cost has |
| | + | prevented their use for large-scale generation |
| | + | |
| | | | |
| − | If an object is lifted from the ground to a
| + | === Conversion into Electrical Energy === |
| − | certain height, work has been done in moving it and this is stored in
| |
| − | the object as potential energy. If the object is dropped, it will
| |
| − | fall to the ground with a velocity and will acquire kinetic energy.
| |
| − | | |
| | | | |
| − | | + | The conversion of solar energy into electricity |
| − | | + | can be achieved via two routes: |
| | | | |
| | | | |
| − | There are a few important points to keep in mind
| + | (1) solar energy is |
| − | with respect to potential energy:
| + | used to boil water which can then be used to generate electricity |
| | + | (solar thermal power generation) |
| | | | |
| | | | |
| − | * It is also useful to think of potential energy in terms of change in energy level with respect to a zero. The surface of the earth has been arbitrarily assumed to be at zero potential energy.
| + | (2) direct conversion of solar energy into |
| − | * Potential energy can be more usefully understood and described as potential for energy. When a body has potential energy, it has the capacity to do work. When a spring is compressed, work has been done on it. If it is released, the spring can do work. The potential (for) energy that it has allows the spring to do work.
| + | electricity using solar cells. |
| − | * The potential for energy is with respect to a zero defined for a system. The potential energy is, therefore, always to be referred to in terms of a system. The potential energy of the object-earth system was changed when it was lifted to a height ‘h’.
| |
| − |
| |
| − | If an object of mass ‘m’ is raised to a height
| |
| − | ‘h’, work has been done.
| |
| | | | |
| | | | |
| − | Work done = m x g xh
| + | === Wind Energy === |
| − | | |
| | | | |
| − | = mgh
| + | Wind is produced by |
| | + | temperature differences in the air. This is true both of a gentle |
| | + | evening breeze as well as a roaring hurricane. The main driving |
| | + | force behind the wind system of the earth’s atmosphere is the |
| | + | temperature difference between the tropics and the polar regions. |
| | + | This temperature difference arises due to the fact that the tropical |
| | + | regions of the earth are much warmer than the polar regions. Wind |
| | + | energy is the energy of air in motion and has been used for ages for |
| | + | driving sail boats, for grinding grain and pumping water. |
| | | | |
| | | | |
| − | This is stored in the object as potential energy | + | Today it is also used |
| − | and when the object falls, gets converted into kinetic energy. In | + | for generating electric power. When air is blown on wind vane, a |
| − | this particular case, the potential energy is referred to as
| + | child’s common toy, starts rotating. This idea is used in making |
| − | gravitational potential energy.
| + | the windmill which is nothing but a big wind vane. Wind energy is |
| | + | inexhaustible and is therefore a permanent source of energy as there |
| | + | will always be winds. According to an estimate, about 175 to 220 |
| | + | thousand trillion watt hours per year of wind energy can be produced |
| | + | globally, This is a very promising figure as it is about 2.7 times |
| | + | the total energy used on the earth today. |
| | | | |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m2c2c5733.gif]]
| + | === Hydroelectric Power === |
| − | | |
| | | | |
| − | == Potential Energy – Kinetic energy changes during free fall ==
| + | Running water is an |
| − |
| + | easily available source of energy. It is available free and does not |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_6ddeba61.gif]]
| + | pollute the environment. Running water can be used to burn a turbine |
| | + | generator to produce electricity and is the basis of the |
| | + | hydroelectric plant. Water is stored in a reservoir behind a dam. |
| | + | When water flows from a height, it turns big turbines to generate |
| | + | electricity. |
| | | | |
| | | | |
| − | == Conservation of energy ==
| + | [[Image:Energy%20for%20KOER_html_cb7184a.jpg]]<br> |
| − |
| + | ''Srisailam |
| − | The key idea here is that the total energy of the
| + | Dam across the Krishna River'' |
| − | system is conserved. Potential energy can be converted into kinetic
| |
| − | energy and vice versa. But the total energy remains unchanged.
| |
| | | | |
| − |
| + | The gravitational potential emergy of the water is converted |
| − | In more general terms, the law of conservation of
| + | into kinetic energy that powers the turbines to produce electricity. |
| − | energy states that energy can neither be created nor destroyed; but
| + | There are a number of hydroelectric power plants in India; the Bhakra |
| − | can be transformed from one form to another.
| + | Nangal dam in punkab, Damodar valley Project in West Bengal, Hirakud |
| | + | Project and Kosi Project in Bihar and the Nagarjunasagar project in |
| | + | Andhra Pradesh to name a few. These projects produce a very |
| | + | significant percentage of the total electricity generated in our |
| | + | country. However, large dams also have a high degree of |
| | + | environmental impact in terms of flooding and silting of the rivers. |
| | + | The environmental costs of the dams must be weighed against the |
| | + | benefits of the dams. |
| | | | |
| | | | |
| − | Suppose a cart is rolling across a floor and
| + | === Ocean energy === |
| − | strikes a box at rest on the floor. As a result of the collision,
| |
| − | the box will slide a certain distance across the floor before coming
| |
| − | to rest because of friction. The sliding box has moved against the
| |
| − | frictional force has therefore done a certain amount of work. The
| |
| − | box moved and did work because energy was supplied to it by the
| |
| − | moving cart. The energy that an object possesses by virtue of its
| |
| − | motion is called '''Kinetic energy'''. The more massive the object
| |
| − | is and the faster it moves, the greater is its KINETIC ENERGY.
| |
| − | | |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_2a51c40a.jpg]] A
| + | Tides are the raising |
| − | bullet fired from a gun for example can piece through the body
| + | and filling of the ocean level due to the moon’s gravitational pull |
| − | because it moves with a very high speed although its mass is not very
| + | which can be easily seen along the seashore. It is possible to |
| − | large. If an object is lifted to a height, it acquired another form
| + | extract energy from these tides and the main requirement for |
| − | of energy called '''potential energy'''. An object can also possess
| + | harnessing tidal energy is that the difference between the high tide |
| − | potential energy. An object can also possess potential energy if it
| + | and the low tide should be large, at least a few metres. The first |
| − | is put under strain. Then it has energy stored in it because of the | + | ever tidal powered electric generating plant was set up on River |
| − | work done to bring it in that condition. In a time piece, the main
| + | Rance in France, to harness the power tides in the English Channel |
| − | spring, for example, once wound keeps unwinding and driving the
| + | which rise to as much as 14 metres at this location. By opening |
| − | clockwork mechanism for many hours. Here the coiled spring has
| + | gates as the tide rises and then closing them at high tide, a |
| − | energy stored in it because of the work done on it while winding.
| + | 23-square kilometers pool is formed behind the Rance river dam. As |
| − | | + | the tide falls, the trapped water is allowed to flow out, driving 24 |
| − |
| + | electricity generating turbines of 13MW capacity each for total |
| − | So far we have discussed two forms of energy
| + | average power output of 310MW. |
| − | KINETIC ENERGY and POTENTIAL ENERGY. Both can manifest themselves in
| |
| − | other ways.
| |
| − | | |
| − |
| |
| − | The molecule in every bit of matter solid, liquid
| |
| − | or gas are in a continual state of motion. This random motion of
| |
| − | molecules(or atoms) constitute an internal KINETIC ENERGY or Thermal
| |
| − | energy that an object possesses even though the object as a whole
| |
| − | may not be in motion. Thermal energy is thus manifestation of the
| |
| − | motion of the molecules of a substance. A change in the thermal
| |
| − | energy of an object can be brought about by supplying heat to the
| |
| − | object. For example, by repeatedly hitting a block of metal with a
| |
| − | hammer, its atoms are caused to move rapidly, thereby raising the
| |
| − | thermal energy of the metal block which as a result becomes hot.
| |
| | | | |
| | | | |
| − | When petrol burns or when dynamite explodes for
| + | It is estimated that |
| − | example the potential energy stored in these substances is converted
| + | the total global potential for tidal power is only2 percent of the |
| − | into heat or KINETIC ENERGY.
| + | world’s potential hydroelectric capacity. Besides, it involves |
| | + | very high initial cost and the output is variable. |
| | | | |
| | | | |
| − | == Key vocabulary == | + | === Energy from waves === |
| − |
| |
| − | == Additional web resources == | |
| − | | |
| − | = Forms of energy =
| |
| | | | |
| − | We have discussed two forms of energy, viz,
| + | Unlike the tides which |
| − | Kinetic energy and potential energy. But energy occurs in various
| + | exhibit a regular but long periodic variability, waves keep the ocean |
| − | forms such as electrical energy, heat energy, solar energy tidal
| + | water in continual motion. The vertical rise and fall of the |
| − | energy hydro energy, geothermal energy and so on. All these forms of
| + | successive waves can be used to produce energy. India’s first wave |
| − | energy fall under the two categories of energy kinetic and potential.
| + | energy project has gone on stream at vizhinjam near Trivandrum. The |
| − | | + | 150-MW project implemented by the Wave Energy Group attached to the |
| − |
| + | Ocean Engineering Centre, IIT, Madras, in association with the state |
| − | Potential energy is the stored energy and the
| + | Harbour Engineering department. This project works works on the |
| − | energy of position. Chemical energy, nuclear energy, stored
| + | principle of an oscillating water column, which drives an air |
| − | mechanical energy and Gravitational energy come under potential
| + | turbine. The turbine is so designed that it rotates in one |
| − | energy.
| + | direction, irrespective of the direction of air flow. It is a |
| | + | multipurpose scheme and floats on the sea bed. From the ecological |
| | + | and environment points of view too, it is the best as the unit hardly |
| | + | leaves any waste. The biggest advantage of the project is that power |
| | + | generation is possible throughout the year, though not uniformly. |
| | | | |
| − |
| + | |
| − | <u>'''Chemical energy'''</u>''': C'''hemical
| |
| − | energy is the energy stored in the bonds of atoms and molecules.
| |
| − | | |
| − |
| |
| | {| border="1" | | {| border="1" |
| | |- | | |- |
| | | | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m44e5e465.jpg]] | + | [[Image:Energy%20for%20KOER_html_m550953e9.jpg]]<br> |
| | | | |
| | | | |
| | | | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_76425964.jpg]] | + | [[Image:Energy%20for%20KOER_html_m44b8741.jpg]]<br> |
| | | | |
| | | | |
| − | | | + | |} |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m2c5971ce.jpg]]
| + | === Energy from Ocean Thermal Gradients === |
| − | | |
| | | | |
| − | |}
| + | [[Image:Energy%20for%20KOER_html_m533a134.jpg]][[Image:Energy%20for%20KOER_html_196bef2b.jpg]]The |
| − | <u>Examples,
| + | heat contained in the ocean waters heated by the sun can be converted |
| − | Biomass, petroleum, natural gas, propane and coal are stored chemical
| + | into electricity by utilizing the difference in temperature between |
| − | energy.</u>
| + | the surface water can be used to heat some low-boiling organic liquid |
| | + | such as ammonia or propane, the vapours of which are allowed to |
| | + | expand through a turbine which can run a generator. The vapours |
| | + | leaving a turbine are channeled into a condenser located in the low |
| | + | temperature water zone, much below the water surface. The condensed |
| | + | liquid is pumped into a boiler evaporator to start the cycle afresh. |
| | | | |
| | | | |
| − | | + | The expected efficiency |
| − | | + | of such a system is about 2 percent. The amount of energy available |
| | + | from ocean thermal gradients is enormous, and is replenished |
| | + | continuously. |
| | | | |
| | | | |
| − | <u>Nuclear
| + | === Geo thermal energy === |
| − | energy</u>: Nuclear energy is the energy stored | |
| − | in the nucleus of an atom. It is the energy that holds the nucleus
| |
| − | together. Example , nucleus of an uranium atom.
| |
| − | | |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m9e8921d.jpg]][[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m4db0caad.jpg]][[:]]
| + | We are |
| − | | + | living between two great sources of energy- the sun up in the sky, |
| − |
| + | and hot rocks beneath the earth’s surface. The interior of the |
| − | | + | earth is extremely hot. As one goes deep into the earth the |
| − | | + | temperature increases. The earth has very hot materials in and below |
| | + | the crust. As some places this hot material |
| | + | comes quite close to the surface, or even out of the surface in |
| | + | the form of volcanic eruptions. In places where it comes close to |
| | + | the surface, underground water often gets heated |
| | + | and produces steam and hot water which comes out as hot springs and |
| | + | geysers. The areas in which such conditions exist are known as |
| | + | geothermal regions. Infrared photography of the ground from |
| | + | satellites like IRS-1 has played an important role in locating the |
| | + | geothermal regions. |
| | | | |
| | | | |
| − | | + | [[Image:Energy%20for%20KOER_html_m224b8bc5.jpg]]After |
| − | | + | locating a geothermal region, a bore is drilled through the rock to |
| | + | tap the heat. In many places steam under high pressure comes out |
| | + | straight from the borehole and can be used to drive turbines |
| | + | directly. Where steam is not available, cold water is pumped down |
| | + | through one hole and heated water and steam produced pumped out of |
| | + | another. The hot water or steam produced can be used to run a turbine |
| | + | or to heat housed and offices. Geo thermal energy is used for space |
| | + | heating where the temperature goes down to 30 to 35 degrees below the |
| | + | freezing point, for poultry farming, mushroom cultivation and |
| | + | pashmina-wool processing which need a warmer climate. |
| | | | |
| | | | |
| − | | + | Although at first |
| − | | + | glance, geothermal energy seems very promising, geothermal sources |
| | + | are, in reality, far from being pollution free. Underground steam |
| | + | contains hydrogen sulphide gas and minerals which can poison fish and |
| | + | other forms of aquatic life in streams and rivers. |
| | | | |
| | | | |
| − | <u>'''Stored mechanical energy'''</u>: Stored
| + | = Energy storage = |
| − | mechanical energy is the energy stored in the objects by the
| |
| − | application of a force. Compressed springs and stretched rubber
| |
| − | bands are examples of stored mechanical energy.
| |
| − | | |
| | | | |
| − | <u>'''Gravitational
| + | We have seen that whatever the source of energy, |
| − | energy: '''</u>It is
| + | all of these are converted into electrical energy for use. This |
| − | the energy of place or position. Water in a reservoir behind a | + | brings to focus the need for energy storage and distribution. |
| − | hydropower dam is an example of gravitational potential energy. When
| |
| − | the water is released to spin the turbine it becomes kinetic energy.
| |
| | | | |
| | | | |
| − | kinetic energy is energy in motion. It is the
| + | One of the problems associated with the generation |
| − | motion of waves, electrons, atoms , molecules and substances. Radiant
| + | of electricity from various is that the demand for power fluctuates. |
| − | energy, thermal energy, motion, sound and electrical energy come | + | During the day, the power requirements, especially for commercial |
| − | under kinetic energy.
| + | purposes, are much greater than during night time. If there was some |
| | + | way to store electrical energy, the generating plant could be |
| | + | operated at full capacity during the night, storing up energy to be |
| | + | released when the demand increases. |
| | | | |
| | | | |
| − | <u>'''Radiant energy: '''</u>It is the
| + | == Concept flow == |
| − | electromagnetic energy that travels in travels in transverse waves.
| |
| − | Radiant energy includes visible light, x-rays, gamma rays and radio
| |
| − | waves. Solar energy is an example of radiant energy.
| |
| − | | |
| | | | |
| − | <u>'''Thermal energy: '''</u>Thermal energy or
| + | Some of the key ideas in energy storage are: |
| − | heat energy is the internal energy in substances. It is the vibration
| |
| − | of atoms and molecules within substances. Geothermal energy is an
| |
| − | example of thermal energy.
| |
| | | | |
| | | | |
| − | <u>'''Sound: '''</u>It is the movement of energy
| + | # All forms of energy are used to generate electrical energy |
| − | through substances in longitudinal (compression/rarefaction) waves.
| + | # Generation, storage and transmission of electrical energy is involved in meeting energy demands |
| − | | + | # There are two different approaches for storing electricity energy, depending upon whether this storage is for small-scale or large-scale purposes. |
| | | | |
| − | <u>'''Electrical energy: '''</u>It is the
| + | === Small-scale storage === |
| − | movement of electrons. Lightning and electricity are examples of
| |
| − | electrical energy.
| |
| − | | |
| | | | |
| − | We have seen that energy occurs in various forms.
| + | [[Image:Energy%20for%20KOER_html_m7a21910d.jpg]][[Image:Energy%20for%20KOER_html_bb112d6.png]]For |
| − | These different forms of energy can be converted from one form to
| + | small-scale storage of electricity, batteries and fuel cells offer |
| − | another.
| + | the best course. An electric battery consists of one or more electric |
| | + | cells which are devices for producing electric directly from the |
| | + | chemical reactions. Electricity made in this way is much more |
| | + | expensive than that made by mechanical generators but batteries being |
| | + | compact and portable, are a better choice for many applications |
| | + | Cells are generally of two types; primary cells and secondary cells. |
| | | | |
| | | | |
| − | * For example, when we switch on an electric light firstly, we can see the transfer of electrical energy from the power plant to our home, and then the conversion of electric energy into heat energy, part of it into visible light. This light energy is not destroyed but it is absorbed by the walls, ceiling and floor and other objects, finally to be converted into heat.
| + | One good example of a primary cell is a voltaic |
| − | * electric energy → heat energy+ light energy
| + | cell which consists of copper |
| − | * In power plant, chemical energy stored in fossil fuels such as coal, oil or gas is converted into heat energy in the boiler by combustion. This heat energy changes water from liquid state to steam. This heat energy of steam is converted in part, into mechanical energy in the steam turbine. This mechanical energy is then converted into electrical energy in the generator. From the generator it is transferred by the electric cables to various points where it can be used for further transfer to homes and industries etc.,
| |
| − | * Chemical energy → heat energy → steam energy → mechanical energy electrical energy → light energy+ heat energy+ mechanical energy+ etc.,
| |
| − | * In the running of a car the chemical energy hidden in the explosive mixture of petrol vapour and air is converts by the spark into heat energy. The heat energy, in turn is converted in part, into mechanical energy of motion of the pistons in the cylinders. The mechanical energy of the pistons is transferred to the drive shaft and from there to the wheels to move the car.
| |
| − | * Chemical energy → heat energy → mechanical energy
| |
| − | * All biological processes throughout the domain of living things can also be shown to be energy conversion processes. The digestion of food is a combination of rather complicated processes but what it amounts to is the transformation of chemical energy locked in the food into heat energy to keep the body warm, and into mechanical energy to enable the body to do work by moving its various parts or itself as a whole besides synthesizing some compounds. There is also some conversion into electrical energy to establish communication between various parts of the body through the nervous system.
| |
| − | * Chemical energy → heat energy + mechanical energy + electrical energy
| |
| − | * In all the above examples energy is converted from one to another, but the total energy in any energy conservation process always remains constant; that is energy can neither be created nor destroyed. This is the law of conservation of energy.
| |
| − |
| |
| − | == Key vocabulary ==
| |
| − |
| |
| − | # Vibration-Any regularly repeated to and fro motion
| |
| − | # Law of conservation-A physical law that some property of a system remains constant throughout a series of changes
| |
| − |
| |
| − | == Additional web resources ==
| |
| − |
| |
| − | 1)
| |
| − | [[http://www.youtube.com/watch?v=VJfIbBDR3e8]]
| |
| | | | |
| | | | |
| − | 2)
| + | and zinc metal plated dipped in a solution of |
| − | [[http://www.youtube.com/watch?v=f9kJwtayTJI]]
| + | sulphuric acid which acts as an electrolyte. The electrolyte |
| − | | + | contains positive and negative ions but is overall electrically |
| − |
| + | neutral. Zinc tends to dissolve in the solution more easily than |
| − | = Power, energy units and conversions =
| + | does copper. In solution it forms positive zinc ions leaving |
| − |
| + | electrons behind on the zinc plate. This gives zinc plate a negative |
| − | One important aspect of the processes producing or
| + | charge with respect to copper plate and so, when an electric circuit |
| − | using or/and converting energy from one form to another is the rate
| + | is completed at the terminals of the cell, the electrons flow to the |
| − | at which this is done. For example, two persons perform equal
| + | copper plate giving rise to a current. This cell becomes dead when |
| − | amounts of work by lifting identical boxes from the ground level and
| + | the solution becomes saturated with zinc so that no more of it wants |
| − | keeping them on a shelf .One of them does this rapidly while the
| + | to dissolve. To revive the cell one has just to replace the |
| − | other does it slowly. Although the total work done by each person is | + | electrolyte sulphuric acid, this can be continued so long as zinc is |
| − | the same, the two persons work at different power levels. The faster | + | present but when the zinc is gone, the cell is permanently dead. The |
| − | working person converts his body’s chemical energy into work at a
| + | principal disadvantage of the primary cell is its short life. |
| − | more rapid rate than the slowly working person
| + | Obviously it would be more useful to have a cell which could be |
| | + | restored to its original condition once it had discharged all its |
| | + | available form of energy. Fortunately it is possible to do so with |
| | + | some types of cells. Such cells are called secondary cells and a set |
| | + | of them is called a storage battery because it enables charges |
| | + | produced by other means to be stored for later use. In a storage |
| | + | battery electricity is stored where chemical changes take place which |
| | + | can be reversed to release the stored electrical energy. A typical |
| | + | storage battery takes a few hours to charge and can then be used as a |
| | + | source of energy. |
| | | | |
| | | | |
| − | Power is the rate at which work is done or energy
| + | These batteries find use in the fabrication of |
| − | is used or supplied and may therefore be calculated by dividing the
| + | uninterrupted power supplies for continuous operation of costly |
| − | work done (or energy used or supplied) in the process by the time
| + | equipment, computers and other strategic gadgets. Here the batteries |
| − | taken by the process. Energy or work is measured in Joules (J) and
| + | are coupled with an oscillator which converts this D.C supply from |
| − | time is measured is seconds (s) and so the unit of power is the '''joule
| + | this battery to A. C. at higher voltage and frequency. |
| − | per second (J/s),''' This unit is given the special name '''WATT (W)'''
| |
| − | where
| |
| | | | |
| | | | |
| − | 1watt =1 J/s
| + | === Large scale storage === |
| − | | |
| | | | |
| − | 1000watt =1
| + | For meeting the large energy requirements of homes |
| − | kilowatt=1kw
| + | and industry, storage batteries are impractical. To meet the |
| | + | requirements of varying demands, electricity generation is increased |
| | + | or decreased and in many cases, there is a transmission and |
| | + | distribution company that manages this kind of scheduling. |
| | | | |
| | | | |
| − | 1000,000 watt =1megawatt=1MW
| + | = Nuclear energy = |
| − | | |
| | | | |
| − | 1,000,000,000watt =1gigawatt=1GW
| + | We have seen how different sources of energy are |
| | + | used to generate steam and hence the mechanical energy to produce |
| | + | electricity. These sources can be renewable or non-renewable. Yet |
| | + | another source that has been used to generate electrcity is nuclear |
| | + | energy, the atomic energy is used in the generation of energy. In |
| | + | this section, we will understand the atomic structure and the source |
| | + | of energy in the atom. |
| | | | |
| | | | |
| − | 1,000,000,000,000watt =1terawatt=TW
| + | == Concept flow == |
| − | | |
| | | | |
| − | A commercial unit energy that we often hear about | + | # Atoms consist of protons, neutrons and electrons. Different atoms and nuclei have different levels of stability. Atoms occur in more than one configuration due to difference in their nuclear structure and these different configurations are called isotopes. |
| − | on out electricity bills is the '''kilowatt hours (kwh).'''
| + | # A vast amount of energy is available within the nucleu and nuclear reaction processes release this energy. Nuclear energy so produced is used in the place of coal or gas to heat water and produce steam. A nuclear reaction occurs when uranium atoms split intosmaller particles in a chain reaction that produces a large amount of heat. |
| − | 1kilowatt hour is the energy used or supplied when 1kw power is used
| + | # Chemical reactions, such as burning, involve the release of energy mainly due to exchange or transfer of electrons whereas nuclear energy involves the release of energy from within the nucleus of the atoms. |
| − | or supplied for one hour. '''1kwh is equal to 3.6 million joules''' | |
| − | | |
| | | | |
| − | == Energy Units and conversions == | + | === Atoms === |
| | | | |
| − | The basic unit for the measurement of energy in
| + | All matter is made up of different naturally |
| − | the metric system is the joule, but there are also other units in
| + | occurring elements, each possessing physical and chemical properties |
| − | common usage. The kilowatt hour is usually used to describe
| + | distinct from the other. These smallest entities into which these |
| − | electrical energy. The '''calorie''' which is defined as the amount
| + | elements can be divided are called atoms. Atoms are made up of three |
| − | of heat energy required to raise the temperature of 1g of water
| + | still smaller particles-positively charged protons, negatively |
| − | through 1degree Celsius, is the unit primarily used to measure heat
| + | charged electrons and electrically neutral neutrons. The relatively |
| − | and also to describe the energy content of foodstuf
| + | heavy protons and neutrons constitute the tiny nucleus. This is |
| | + | surrounded by moving electrons and overall the orbit is electrically |
| | + | neutral and is about ten to the power of 5 times the size if the |
| | + | nucleus. The number of orbiting electrons is always equal to the |
| | + | number of protons so that the net electrical charge of the atom is |
| | + | Zero. |
| | | | |
| | | | |
| − | == Additional web resources ==
| + | Atoms of a particular element always contain the |
| − |
| + | same number of protons and there is a scale of elements, going from |
| − | # www.sciencejoywagon.com/'''physics'''zone/05'''work'''-'''energy'''/ -
| + | the atoms of hydrogen which have only one proton, helium atoms which |
| − |
| + | have two protons, lithium atoms which have three protons, and so on |
| − | = Sources of energy - conventional =
| + | all way up to very large atoms such as uranium, which has 92 protons. |
| − |
| + | The number of protons is therefore, important because it identifies |
| − | Firewood has been the major source of energy
| + | the element to which the atom belongs. Thus any atom which contains, |
| − | during most of man’s history and it continued to remain the most
| + | say 17 protons must be chlorine; uranium atoms always contain 92 |
| − | important fuel until the middle of nineteenth century. Firewood is
| + | protons, and so on. The atomic number of an element is the same as |
| − | obtained from the forests and is primarily used for heating and
| + | the number of protons in the nucleus. |
| − | cooking. The other fuel which has been traditionally used here is
| |
| − | animal dung cakes. The animal dung mainly consists of undigested
| |
| − | plant material which on drying, gives a product that readily burns.
| |
| − | One of the disadvantages of both firewood and animal dung cakes as
| |
| − | fuels is that they give a lot of smoke on burning. By contrast,
| |
| − | charcoal prepared by burning wood in insufficient supply of air is a
| |
| − | clean fuel and gives negligible smoke on burning. Till a few years
| |
| − | ago, charcoal was a major source of energy in urban areas. It has
| |
| − | now been largely replaced by the liquid and gaseous fuels such as
| |
| − | kerosene and petroleum gas.
| |
| | | | |
| | | | |
| − | The industrial revolution in Europe around the
| + | [[Image:Energy%20for%20KOER_html_m2a27ed59.gif]]Along |
| − | middle of the nineteenth century led to search for other fuels to
| + | with the protons in the atomic nucleus there are also the |
| − | meet the increasing energy demands. The discovery of coal, followed
| + | electrically neutral particles called neutrons. The number of |
| − | by oil and natural gas fulfilled these demands to a large extent and
| + | neutrons in the nucleus tends to increase with number of protons. |
| − | these fuels since then have been the primary sources of world’s
| + | For instance, in the helium atom ( which has two protons) there are |
| − | energy. All these chemical fuels-coals, oil and natural gas- are
| + | two neutrons, lithium (which has three protons) has four neutrons, |
| − | derived from the slow decay of living organisms such as trees, algae
| + | uranium (which has 92 protons) has 146 neutrons, and so on. The |
| − | and small marine animals for millions of years and are therefore | + | protons and neutrons in a nucleus are bound together by immensely |
| − | known as fossil fuels. The fossil fuels are being consumed at an
| + | strong forces, called nuclear forces which counteract the |
| − | appreciable rate. The fossil fuels are being consumed at an
| + | electrostatic forces of repulsion acting between the protons. In |
| − | appreciable rate. Although their new deposits continue to be
| + | very large atoms, such as uranium and plutonium, the binding nuclear |
| − | discovered, the world reserves of these fuels are not limited.
| + | forces are only slightly stronger than the repulsive forces between |
| − | Further, these energy sources take millions of years to form and
| + | the large number of protons; such nuclei are unstable and can be made |
| − | therefore fossil fuels are also known as non-renewable sources of
| + | to undergo fission- split into two or more fragments releasing |
| − | energy. These fuels once exhausted cannot be replaced quickly when
| + | nuclear energy. |
| − | exhausted. Hence these are also called as exhaustible resources.
| |
| − | | |
| − |
| |
| − | == Formation of fossil fuels ==
| |
| − |
| |
| − | Fossil fuels-coal, oil and natural gas-are the
| |
| − | result of decomposition of living matter. Coal is obtained from dead
| |
| − | plant matter which consists primarily of carbon, hydrogen and oxygen.
| |
| | | | |
| | | | |
| − | On dry land, this matter rots away by bacterial
| + | === Isotopes === |
| − | action in presence of atmospheric oxygen to form carbon dioxide and
| |
| − | water. But in swampy locations, the dead plant matter is covered
| |
| − | with water and is, therefore, protected from the oxidising action of
| |
| − | air. Instead, it is attacked by bacteria which do not require free
| |
| − | oxygen in order to live. In the process oxygen and hydrogen of the
| |
| − | dead plant matter gradually escape and the residue, therefore,
| |
| − | becomes richer and richer in carbon. The end product of the
| |
| − | bacterial action is a soggy, carbon-rich substance called peat.
| |
| − | | |
| | | | |
| − | Over long periods of time the peat is covered
| + | The atomic weight of an element is expressed as |
| − | with sand, silt and clay. As peat gets compressed and heated further
| + | the sum of the number of protons and neutrons. Atoms of the same |
| − | due to geological changes, more gases are forced out and therefore
| + | element can differ from one another by having a different number of |
| − | the proportion of carbon continues to increase. In this way, peat is | + | neutrons in their nuclei. For example, uranium (which has 92 |
| − | gradually converted into various forms of coal such as lignite,
| + | protons) can have either 143 or 146 neutrons. These two forms of |
| − | bituminous coal and anthracite.
| + | uranium have the same chemical but slightly different physical |
| | + | properties. Atoms of the same element which exist in different forms |
| | + | as a result of having different numbers of neutrons in their nuclei |
| | + | are called isotopes. The first of the two uranium isotopes described |
| | + | above is called uranium-235, and the second, uranium-238. |
| | + | Uranium-238 is heavier than uranium-235. Similarly there are three |
| | + | isotopes of hydrogen, namely hydrogen (one proton only), deuterium or |
| | + | heavy hydrogen ( one proton and one neutron), and tritium ( one |
| | + | proton and two neutrons). |
| | | | |
| | | | |
| − | In contrast to coal, the raw material in the
| + | Atoms of the same element always contain the same |
| − | formation of oil and natural gas consists mainly of marine organisms,
| + | number of protons in their nuclei. The number of protons is balanced |
| − | mostly plants that grow near the surface of the sea. When these
| + | by an equal number of electrons to make the atom electrically |
| − | organisms die and accumulate in basins, where the water is stagnant,
| + | neutral. It is the number of orbiting electrons that determines the |
| − | they are also protected from atmospheric oxidation. The dead marine
| + | chemical properties of an element. When atoms combine with other to |
| − | matter is decomposed by anaerobic bacteria. Oxygen, nitrogen and
| + | form molecules, there is rearrangement of the outermost electrons in |
| − | other elements escape leaving mainly compounds of carbon and hydrogen
| + | the orbit ( also called valence electrons). In this process, energy |
| − | called hydrocarbons. The accumulating covering layer of sediments
| + | can be stored or released so that is some reactions ( burning for |
| − | provides heat and pressure that convert the hydrocarbon material into
| + | example) heat energy is released. Thus atoms of carbon ( coal, on |
| − | droplets of liquid oil and bubbles of natural gas. As more
| + | combination with atoms of oxygen from the air to form carbon dioxide |
| − | sedimentary deposits are laid down over periods of time, the pressure
| + | in the process of burning, release energy. |
| − | increases and the oil and gas are forced into nearby porous sand or
| |
| − | sandstone. Gradually the oil and gas migrate upward through the sand
| |
| − | and they then either escape to the surface or are trapped beneath
| |
| − | layers of clay stone. This migration process separates the oil from
| |
| − | underground water because water molecule readily adhere to sand
| |
| − | whereas oil molecules do not. Thus the oil tends to collect in the
| |
| − | pore spaces of sandy rocks beneath roof rocks with natural gases on
| |
| − | the top.
| |
| | | | |
| | | | |
| − | == Processing of coal and petroleum == | + | === Principle of Nuclear Fission === |
| | | | |
| − | Coal, which is essentially pure carbon, is chiefly
| + | [[Image:Energy%20for%20KOER_html_m4cc0b6df.jpg]]Isotopes |
| − | used as a combustion fuel. The reaction of carbon with atmospheric
| + | of certain very heavy atoms, for example, uranium-235 and |
| − | oxygen to produce carbon dioxide is an exothermic reaction that
| + | plutonium-239, are so unstable that they can be made to split |
| − | releases about 7,840 kilocalories/kg of carbon and this reaction is
| + | (fission) when hit by a neutron. When this happens, a very large |
| − | responsible for the heat energy derived from burning coal. Burning
| + | amount of energy is released. This process is known as nuclear |
| − | of coal produces large quantities of fly ash and noxious gases such | + | fission. In this process, the mass of the two smaller atoms ( |
| − | as a sulphur dioxide and related compounds which cause atmospheric
| + | collectively known as fission products) plus the mass of the two or |
| − | pollution. Coal is therefore converted into a cleaner fuel, coke, by
| + | three neutronsa that are produced, is slightly less than the mass of |
| − | heating crushed coal to high temperatures in the absence of air.
| + | the original uranium-235 or plutonium-239 atom plus the bombarding |
| | + | neutron. Thus, in the process of nuclear fission, some matter is |
| | + | lost and converted into energy. According to Einstein’s famous |
| | + | equation, even a small amount of matter is equivalent to a very large |
| | + | amount of energy. Thus the nuclear fission of uranium-235 contained |
| | + | in 1 tonne of natural uranium is equivalent in electricity output to |
| | + | the burning of approximately 20,000 tonnes of coal. Natural uranium |
| | + | contains only 0.7 percent of uranium-235. |
| | | | |
| | | | |
| − | Coal can also be converted into liquid and gaseous
| + | == Fission Nuclear Reactors == |
| − | fuels which can partially replace the fuels derived from petroleum.
| + | |
| | + | A nuclear reactor is a device in which the nuclear |
| | + | fission process is carried out under controlled conditions. The |
| | + | basic fuel of a nuclear reactor is uranium, obtained from ores such |
| | + | as pitchblende. Natural uranium is a mixture of two isotopes, |
| | + | uranium-235 and uranium 238, present in the ratio of 0.7:99. Only |
| | + | the comparatively rare isotope uranium-235 undergoes nuclear fission. |
| | | | |
| | | | |
| − | Unlike coal and natural gas which can be used
| + | There are two types of nuclear reactors: |
| − | directly as fuels without processing, petroleum or crude oil is not
| |
| − | directly usable. The name ‘petroleum’ is derived from the Latin
| |
| − | words ''petra'' meaning ‘rock’ and ''oleum''
| |
| − | meaning ‘oil’. Therefore, it means rock oil, to distinguish it
| |
| − | from animal or vegetable oils. Petroleum, also often called crude
| |
| − | oil, is a mixture of hundreds of hydrocarbon compounds together with
| |
| − | small amounts of compounds of other elements. The exact composition
| |
| − | of a crude depends upon many factors such as its age and the types of
| |
| − | organisms from which it is formed. So, every deposit of crude oil
| |
| − | is a unique mixture whose exact composition differs even from
| |
| − | deposits separated from it vertically or horizontally by a few metres
| |
| − | of rock. Natural gas is normally associated with crude oil. It is a
| |
| − | mixture of gaseous hydrocarbons, mainly methane and ethane. The
| |
| − | non-hydrocarbon compounds present in crude oil are mainly compounds
| |
| − | of sulphur, nitrogen and oxygen. Other elements present in very
| |
| − | small amounts include vanadium, nickel, chlorine, arsenic and lead.
| |
| | | | |
| | | | |
| − | === Detection of Oil === | + | # '''Thermal reactors''' use uranium as fuel and have moderators to slow down neutrons. They are called thermal reactors because they use slow-moving or thermal neutrons. |
| | + | # '''Fast breed reactors: '''Since 99.3 percent of natural uranium is uranium-238 and since this isotope cannot undergo fission, thermal reactors are able to use a very small proportion of natural uranium. However, fast reactors are able to convert this otherwise unusable uranium-238 into a new element, plutonium-239, which can then be fissioned to liberate energy. Fast breeder reactors do not need a moderator as fast neutrons used. |
| | + | |
| | + | === Thermal reactors === |
| | | | |
| − | The method generally used for locating oil | + | The core of a thermal has five components. Uranium dioxide pellets are |
| − | deposits is the seismic survey. Shock waves generated by surface
| + | packed in long metal tubes known as fuel elements. A nuclear reactor |
| − | explosive charges travel through rock layers and are reflected back
| + | contains several tones of uranium in thousands of fuel elements. |
| − | by various geological structures and possible locations where oil
| + | Periodically, the used-up fuel elements are taken out and new fuel |
| − | might be trapped can be found. To find whether oil is really present
| + | elements put in. The most commonly used moderators used moderators |
| − | and whether it can be economically extracted, it is necessary to | + | are water, heavy water, and graphite. |
| − | drill a well.
| |
| | | | |
| | | | |
| − | === Extraction and refining of Oil ===
| + | Control rods are used to control the rate of the |
| − |
| + | nuclear chain reaction. They are made of boron which readily absorbs |
| − | Once the oil has been found by drilling the well,
| + | neutrons. When these rods are lowered into the core (containing fuel |
| − | the next step is to operate the well; that is, to raise the oil to | + | elements and the moderator), that absorb most of the neutrons and so |
| − | the surface. After extraction, the oil is usually transported to a | + | there can be no chain reaction. This effectively shuts down the |
| − | refinery through pipelines. From offshore platforms, the oil is
| + | reactor. As they are pulled out progressively, neutrons are |
| − | sometimes transported to the shore in large tankers. The natural gas
| + | available to split uranium atoms, thus releasing more neutrons. The |
| − | produced in the process is also transported by large pipelines.
| + | further the control rods are pulled out, the larger is the number of |
| | + | fissions in the core and more heat is produced. |
| | + | |
| | + | |
| | + | Since the uranium fuel as well as the fission |
| | + | products are intensely radioactive, a very thick steel-and-concrete |
| | + | shield is required to prevent the escape of any radiation from the |
| | + | core. Indian reactors usually have double shielding to further |
| | + | minimize any risk. |
| | | | |
| | | | |
| − | Crude oil is processed in a refinery by fractional
| + | To remove the heat produced by nuclear fission in |
| − | distillation. This process involves heating the crude oil in a tall
| + | the fuel elements, a coolant is used which circulates through spaces |
| − | tower so that various components are distilled out of it and can be
| + | between the fuel elements, Indian reactors, which use natural |
| − | trapped at various levels in the tower. In this process the use is
| + | uranium as fuel, use heavy water as coolant, but reactors using |
| − | made of the fact that the different hydrocarbon compounds in the
| + | enriched uranium (in which the percentage of uranium-235 is raised by |
| − | crude have different boiling points and hence can be separated at its
| + | complex processes) use ordinary water as coolant. The heated coolant |
| − | boiling point. The lightest compounds such as gases which have low
| + | coming out of the core transfers the heat exchanger to boil water and |
| − | boiling points rise to the top and the heavier oils with higher
| + | raise steam which is then used to run a turbine generator to generate |
| − | boiling points are collected lower down.
| + | electricity. |
| | | | |
| | | | |
| − | The various fractions may then be further
| + | === Fast breed reactors === |
| − | processed by cracking or refining, both of which involve the use of
| + | |
| − | catalysts-substances which facilitate the chemical reactions without
| + | Thermal reactors are able to release energy from |
| − | themselves undergoing any change. Catalytic cracking, often called
| + | the small proportion of uranium-235 contained in the natural uranium. |
| − | cat-cracking, is a means of breaking down the heavier distillates to
| + | They are, however, unable to use the uranium-238 which constitutes |
| − | form lighter compounds.
| + | 99.3 percent of natural uranium. The significance of fast reactors |
| | + | is that they are able to convert Uranium-238 into plutonium-239 in |
| | + | significant quantities, so that much into plutonium-239 in |
| | + | significant quantities, so that much more energy can be extracted |
| | + | from natural uranium than is possible with thermal reactors. |
| | | | |
| | | | |
| − | The various fractions obtained after refining are
| + | There are two important features of fast breeder |
| − | used for different purposes The gas fraction, like natural gas, is
| + | reactors. Firstly, there is no moderator. The neutrons given off in |
| − | used chiefly as a fuel for heating. Petrol is used in spark ignition
| + | the fission reaction are not slowed down. ( It is for this reason |
| − | internal combustion engines that require a fairly volatile fuel.
| + | that this type of reactor is known as a fast reactor. |
| − | Kerosene is used as a lighting and cooking fuel in villages, and also
| |
| − | in tractors and jet engines. Diesel is used in diesel engines.
| |
| | | | |
| | | | |
| − | === Biomass Energy ===
| + | Secondly, the fuel elements of fast reactors |
| − |
| + | contain a mixture of plutonium-239 and uranium-238. Plutonium is |
| − | Fossil fuels are derived from plants, trees and
| + | placed in the centre of the core, whereas the uranium-238 is located |
| − | animals that lives millions of years ago. It took the remains of
| + | in a blanket surrounding the plutonium core. Two processes take |
| − | these organisms millions of years of burial under tremendous pressure
| + | place simultaneously in these reactors: |
| − | and the internal heat to turn into coal, oil, or gas that we use as
| |
| − | fuel today. We cannot get fossil fuels from the plant and animal
| |
| − | waste that we produce today. But they, too form a substantial source
| |
| − | of energy in the form of biomass. Biomass means the waste material
| |
| − | and dead parts of living objects. It includes garbage, industrial
| |
| − | waste, crop residue, sewage and plant waste such as dead leaves and
| |
| − | wood. These wastes can be both wet and dry. Wet wastes are in the
| |
| − | form of animal excreta or domestic and industrial residues. Dry
| |
| − | wastes refers to leaves, wood, paper, straw, fruit skin and others.
| |
| − | There are two ways of using biomass as a source of energy. One is to
| |
| − | burn the dry biomass directly to produce heat and generate steam.
| |
| − | Another method is to convert this biomass into gaseous fuels called
| |
| − | biogas by fermentation.
| |
| | | | |
| | | | |
| − | The raw material used for the production of
| + | (i)Plutonium-239 (originally produced from some of |
| − | biogas is cow dung mixed with water which is taken in an insulated,
| + | the uranium-238 atoms) in thermal reactors is fissioned, producing |
| − | air-tight container called digester. In the digester, bacteria break
| + | heat which is removed by the coolant. Since the heat produced in the |
| − | the raw material into simpler chemicals by a process known as | + | core is very large, the coolant used in a fast reactor is liquid |
| − | anaerobic decomposition. Other bacteria then convert the chemicals
| + | sodium. |
| − | into a biogas for fuel. The gas consists of mainly methane and is
| |
| − | drawn out through a gas outlet pipe.
| |
| | | | |
| | | | |
| − | Wet wastes from household and industries too can
| + | (ii)A significant proportion of uranium-238 is |
| − | be used to produce methane gas. Wastes may be dumped in deep pits.
| + | converted into plutonium in the blanket. In fact more plutonium is |
| − | Wells are then drilled down into the waste. A pipeline is then
| + | bred in the blanket than is fissioned in the core, and for this |
| − | drilled down into the waste. A pipeline is then to recover the gas
| + | reason, fast reactors are known as fast breeder reactors. |
| − | produced by the natural decomposition of the material.
| + | Plutonium-239 atoms are created when uranium-238 atoms absorb fast |
| | + | moving neutrons. |
| | | | |
| | | | |
| − | === Direct conversion of heat to electricity === | + | === Spent fuel === |
| | | | |
| − | The most convenient usable form of energy is
| + | In both thermal and fast reactors, the spent fuel |
| − | electricity. In the conventional thermal power
| + | elements contain three types of material: (i)highly radioactive |
| − | | + | fission products; (ii)large amounts of unused uranium-238, known as |
| − |
| + | ‘depleted’ uranium; and (iii) a certain among of plutonium. By |
| − | Generation systems, heat energy from combustion of
| + | reprocessing the fission products from spent fuel, the plutonium and |
| − | fuel is used to boil water to produce steam. The kinetic energy of | + | depleted uranium can be fabricated into new fuel elements for fast |
| − | steam is converted into mechanical energy in a steam turbine.
| + | reactors. By repeated processes through fast reactors followed by |
| − | Finally, the mechanical energy of turbine is converted into
| + | reprocessing, it is possible to extract much more energy than when |
| − | electricity in generators. These stages involve various losses and
| + | using only thermal reactors. 1 tonne of natural uranium fissioned in |
| − | therefore the overall efficiency of these plants is never more than
| + | a thermal reactor is equivalent to about 20,000 tonnes of coal. Used |
| − | 40 percent. It is, however, possible to cut short the above energy
| + | in fast reactors, however, 1 tonne of natural uranium is equivalent |
| − | conversion stages and convert heat from the combustion of fuels
| + | to about 1,000,000 tonnes of coal. |
| − | directly into electricity using a magneto-hydro dynamic generator,
| |
| − | popularly known as MHD generator, which works on the basic phenomenon
| |
| − | of electromagnetic induction. | |
| − | | |
| − |
| |
| − | == Key vocabulary ==
| |
| − |
| |
| − | == Additional web resources ==
| |
| − |
| |
| − | # www.technologystudent.com/energy1/less4.htm - [[Cached]] - [[Similar]]
| |
| − | # [[http://video.nationalgeographic.com/video/player/environment/energy-environment/alternative-energy.html]]
| |
| − |
| |
| − | = Sources of energy - Non conventional =
| |
| − |
| |
| − | The conventional sources of energy discussed in
| |
| − | the previous chapter are exhaustible and cannot be quickly replaced | |
| − | when exhausted. It takes millions of years for these sources to be
| |
| − | formed from the decay of living organisms. These sources are,
| |
| − | therefore, also known as non-renewable sources of energy. In
| |
| − | contrast, we have another class of the sources such as the sun, wind,
| |
| − | waves, tides, and geothermal heat which are inexhaustible. These
| |
| − | sources of energy are, therefore, known as renewable sources of
| |
| − | energy. A major problem in harnessing these sources of energy is
| |
| − | that the energy released by them is highly diffused as compared with
| |
| − | the energy obtained from fossil fuels or nuclear fuels. Nature
| |
| − | provides some concentration of the sun’s energy in the form of wind
| |
| − | and waves. The gradients set up in the atmosphere by solar heating
| |
| − | turn some of its energy into the movement of large masses of air,
| |
| − | thereby providing wind energy. This wind, in turn, whips up the
| |
| − | waves in the sea which at places can provide highly concentrated
| |
| − | energy. But none of these sources of energy in their natural form
| |
| − | can as yet provide a viable alternative to the conventional sources.
| |
| − | Therefore, global effort is on to tap energy in concentrated form
| |
| − | from the non-conventional sources.
| |
| | | | |
| | | | |
| − | == Solar energy == | + | === Nuclear Fusion === |
| | | | |
| − | The source of energy most readily available to us
| + | What is happening inside the sun? |
| − | in the sun. Solar energy has several advantages over the other
| |
| − | energy sources. It is inexhaustible; it is free from any pollution
| |
| − | and unlike fossil fuels, transformation of solar energy does not
| |
| − | produce any toxic by-products.
| |
| | | | |
| | | | |
| − | Sunlight is a mixture of light of various
| + | [[Image:Energy%20for%20KOER_html_m413290ce.jpg]]The |
| − | wavelengths which we can see as the visible colours-violet, indigo,
| + | sun consists mainly of hydrogen gas. The atoms of hydrogen under |
| − | blue, green, yellow, orange and red, wavelengths each of different
| + | tremendous pressure at the centre of the sun, come together and fuse |
| − | energy. Investigations with sophisticated detectors, more sensitive | + | to for helium nucleus along with the liberation of tremendous energy |
| − | than our eyes, indicate that besides visible radiation in sunlight,
| + | in the form of heat and light. It this energy which maintains its |
| − | there are two other types of radiations, namely, infrared and
| + | temperature and makes the sun shine. In this process again, like in |
| − | ultraviolet radiations. These radiations, however, cannot be seen.
| + | nuclear fission, mass is converted into energy. This is also the |
| − | Ultraviolet radiation has more energy than infrared radiation.
| + | principle on which the hydrogen bomb is based. Since the various |
| − | Ultraviolet radiation causes sunburns. It also helps in making
| + | reactions taking place inside the sun occur at very high |
| − | vitamin D in our skin. Infrared radiation, on the other hand, warms
| + | temperatures, they are called thermonuclear reactions. The sun, |
| − | our body; that is why we feel warmer in sunlight.
| + | therefore, may be considered as a thermonuclear furnace where |
| | + | hydrogen atoms are continuously being fused into helium atoms. Mass |
| | + | lost during these fusion reactions Is converted into energy. |
| | | | |
| | | | |
| − | When solar radiation strikes the earth’s
| + | There are several possible reactions in which |
| − | atmosphere, some of it is reflected by dust particles and clouds,
| + | light atoms can fuse to form heavier nuclei and release energy, but |
| − | some of it is absorbed by carbon dioxide, water vapour, ozone layer
| + | the one which the scientists which have been trying to accomplish is |
| − | and the remaining reaches the earth’s surface. Most of the | + | the thermonuclear reaction involving deuterium and tritium nuclei and |
| − | ultraviolet radiation is absorbed by the ozone layer. Some infrared
| + | not hydrogen nuclei. This is due to the fact that though ordinary |
| − | radiation is absorbed by the ozone layer. Some infrared radiation is
| + | hydrogen is the raw material for the thermonuclear process in the |
| − | absorbed by clouds, carbon dioxide and water vapour. The amount of
| + | sun, its reaction rate is quite slow. Reactions involving deuterium |
| − | radiation, reaching the earth, thus may vary with the presence of
| + | nuclei or deuterium and tritium nuclei are more efficient. Fusion of |
| − | clouds, humidity, the latitude- the position of the place north or
| + | two nuclei of deuterium of deuterium forms a tritium and a hydrogen |
| − | south of equator, the time of year, the time of day and other
| + | nuclei while the fusion of a deuterium and a tritium nuclei forms a |
| − | factors. An idea of the magnitude of energy reaching the earth’s
| + | helium nucleus with two protons and two neutrons. |
| − | surface falling on an area equal to the size of the tennis court per
| |
| − | day is roughly equal to the energy obtained from 135 litres of petrol
| |
| − | or 180 kg of coal.
| |
| | | | |
| | | | |
| − | === Harnessing Solar Energy ===
| + | For the above reactions to take place, the |
| | + | colliding deuterium nuclei should have enormous speed. This is made |
| | + | possible by heating the particles to a few hundred million degrees. |
| | + | Remember, much below this temperature, the atoms are already stripped |
| | + | of their electrons. Thus they form a mixture of positively charged |
| | + | ions and electrons known as plasma. |
| | + | |
| | | | |
| − | Solar energy can be harnessed in five ways:
| + | If one can fuse all the nuclei in 1 gram of |
| | + | deuterium, it would yield 100,000 kWh of energy. A complete fission |
| | + | of an equivalent amount of uranium, on the other hand will give |
| | + | 25,000kWh. |
| | | | |
| | | | |
| − | # using solar panels
| + | === Fusion Reactors === |
| − | # solar thermal
| |
| − | # concentrated solar power
| |
| − | # Solar nanowires and
| |
| − | # By using photosynthetic and biological processes.
| |
| | | | |
| − | However,
| + | Despite its tremendous potential there are many |
| − | before solar energy can be successfully utilized, two major problems
| + | technical problems in building a practical fusion reactor. One major |
| − | need to be solved. '''Firstly'''
| + | problem is the confinement and control of plasma at more than a |
| − | solar energy is highly diffused; that is, it is thinly spread over
| + | hundred million degrees so that thermonuclear energy could be made |
| − | the earth’s surface and so one needs to concentrate it, '''secondly''', | + | available at a steady rate. One very successful method to confine |
| − | solar energy has to be stored for us during night or on a very cloudy
| + | the plasma in a magnetic field. |
| − | day.
| |
| | | | |
| | | | |
| − | When sunlight concentrated by a convex lens is
| + | Among other alternatives being tried for |
| − | made to fall on a piece of paper, it burns. The problem of
| + | harnessing nuclear fusion is one by using lasers. A laser is a |
| − | concentrating solar energy may be solved through the use of different
| + | highly powerful beam of coherent beam of coherent light which can be |
| − | types of reflectors for focusing sunlight. Reflectors are used in
| + | focused on a very small spot. In this method, called inertial |
| − | solar cookers and solar ovens. The simplest of these reflectors is a
| + | fusion, pellets of deuterium-tritium fuel are rapidly compressed and |
| − | single reflector provided in hot-box type of solar cookers. It is a
| + | heated by bombardment with laser beams, resulting in a series of |
| − | sheet of polished looking glass or aluminized plastic hinged to one
| + | miniature thermonuclear explosions and production of energy. |
| − | side of the box which reflects solar radiation into the cooker and
| + | |
| − | heats it. In a solar oven, several reflectors are provided on all
| |
| − | sides of a box. Curved mirrors, parabolic reflectors and Fresnel
| |
| − | lenses are also used in solar cookers.
| |
| − | | |
| | | | |
| − | === Heating for House and buildings ===
| + | One of the most serious problems in the nuclear |
| − |
| + | fusion process is the fact that large amounts of tritium is only |
| − | One of the most promising applications of solar | + | weakly radioactive, its chemical behavior is exactly the same as |
| − | energy during the last few decades has been the heating and cooling
| + | ordinary hydrogen and it can readily enter into organic substances. |
| − | of residential and commercial buildings. Typical home solar heating
| + | Control of tritium will be one of the major problems in the operation |
| − | system is shown schematically in the fig. Solar radiation falls on a
| + | of the fusion reactors. |
| − | collector which is placed on the south facing slope of the roof.
| |
| − | Heat from the hot water is used to heat air. When heat is required
| |
| − | in the house , a fan forces warm air throughout the house. If the
| |
| − | water temperature in the reservoir is not sufficiently high to
| |
| − | provide adequate heating, auxiliary electrical heating may be used to
| |
| − | heat the water. During extremely cold conditions, especially on
| |
| − | cloudy days, a large amount of auxiliary heating is required.
| |
| − | Therefore, on an average, about one-third to one half of the
| |
| − | necessary heat could be supplied by solar radiation. Solar therefore
| |
| − | offers the possibility of substantial savings in fuel costs.
| |
| | | | |
| | | | |
| − | === Conversion into Electrical Energy ===
| + | There are many advantages of fusion power. The |
| − |
| + | fuel supply is plentiful and relatively inexpensive. |
| − | The | |
| − | conversion of solar energy into electricity can be achieved via two
| |
| − | routes:
| |
| | | | |
| | | | |
| − | (1)solar
| + | The world’s oceans constitute an inexhaustible |
| − | energy is used to boil water which can then be used to generate
| + | source of the primary fuel deuterium in the form of water; about one |
| − | electricity (solar thermal power generation)
| + | molecule out of every 3,000 water molecules contains an atom of |
| | + | deuterium. The products of fusion reactions are either stable |
| | + | isotopes or they are only weakly radioactive. Radioactivity will |
| | + | also be produced by the neutrons released in the reactions when they |
| | + | are captured in the materials of the reactor. |
| | | | |
| | | | |
| − | (2)direct
| + | Further, fusion reactors do not produce air |
| − | conversion of solar energy into electricity using solar cells.
| + | pollutants that contribute to acid rain or global warming. Despite |
| − | | + | these advantages, however, immense difficulties are yet to be |
| − |
| + | overcome before energy generation can become feasible on a large |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_25b465a0.jpg]][[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_521ac395.jpg]]
| + | scale. |
| | | | |
| − | === Solar Thermal Power Generation ===
| |
| | | | |
| − | Generally two approaches are followed in this
| + | The process of nuclear fission involves the |
| − | method of power generation
| + | splitting of a heavy nucleus while the nuclear fusion is the joining |
| | + | together of lighter atoms to form heavier ones. Both the processes, |
| | + | however, release tremendous amounts of energy. |
| | | | |
| | | | |
| − | (1)sunlight reflected from several mirrors
| + | = Energy and the environment = |
| − | arranged in an array is focused on a single heat exchanger in a solar
| |
| − | furnace; and
| |
| − | | |
| | | | |
| − | (2)a large number of cylindrical reflectors in a
| + | Modern society cannot exist without the production |
| − | solar farm focus solar radiation on long pipes carrying a gas which
| + | and utilization of energy. Every month we have to pay direct charges |
| − | collects the heat. A good example of the solar furnace approach is
| + | for use of electricity. Oil and gas in our homes and for the petrol |
| − | the tower concept. Sunlight is focused on to a boiler mounted on the | + | used in our cars. And there are also indirect charges that we pay |
| − | top of a tower located near the centre of the field of mirrors to
| + | for the energy used in manufacturing processes and for the |
| − | produce a high temperature for driving a steam turbine. Another
| + | transportation of the goods that we buy. In addition to these |
| − | similar plant system used arrays of heliostat-guided mirrors to focus
| + | charges, we pay also in terms of the effects that energy production |
| − | sunlight into a cavity-type boiler near the ground to produce steam
| + | and energy utilization have on our world in terms of environment |
| − | for a steam turbine electric power plant. Sunlight striking the | + | pollution. Environmental pollution may be defined as the unfavorable |
| − | mirrored faces of the heliostat modules is reflected and concentrated
| + | alteration of our surroundings. It may not be possible to estimate |
| − | in the cavity of the heat exchanger.
| + | monetary losses or many of the side effects associated with energy |
| | + | production and energy utilization. What is the value of the health |
| | + | impairment, for example, caused by the cars exhaust fumes? What value |
| | + | do we place on the destruction of farmland and pollution of water |
| | + | caused by strip mining for coal? What value is associated with the |
| | + | loss of seaside beaches because of oil pills washing ashore? As a |
| | + | matter of fact, as long as we continue to produce and utilize energy, |
| | + | we will have to pay for these undesirable side effects. How much are |
| | + | we willing to pay? |
| | | | |
| | | | |
| − | In contrast to the solar furnace approach, in the
| + | == Concept flow == |
| − | solar farm, parabolic cylindrical concentrators or other types of
| |
| − | concentrators are used to focus sunlight on to a central pipe
| |
| − | surrounded by an evacuated quartz envelope. Heat collected by a
| |
| − | fluid(nitrogen or helium) flowing through these pipes may be stored
| |
| − | at a temperature over 500 degree Celsius in a molten salt. This heat
| |
| − | may then be used to drive steam turbines for the generation of
| |
| − | electricity
| |
| − | | |
| | | | |
| − | === Photovoltaic Power Generation === | + | # Uncontrolled energy consumption places a strain on the environment |
| | + | # Mining for coal and drilling for petroleum leads to destruction of land, pollution and habitat loss |
| | + | # What are the ecological costs of oil spills, health lost and other such effects? |
| | + | # There needs to be a judicious use of energy |
| | + | |
| | + | === Threats from Fossil fuels === |
| | + | |
| | + | Most of the energy that is generated throughout |
| | + | the world at present is derived from the burning of fossil |
| | + | fuels-coal, natural gas and petroleum products. There are numerous |
| | + | environment problems associated with the extraction, transportation |
| | + | and utilization of fossil fuels. |
| | + | |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m4d95859e.gif]] Unlike
| + | The most plentiful fuel source in the world is |
| − | the solar thermal systems discussed above, solar cells offer a very | + | coal. The highest quality coal(anthracite generally occurs |
| − | attractive means for direct conversion of sunlight into electricity
| + | sufficiently far underground to require high-cost deep-mining |
| − | with high reliability and low maintenance. The disadvantages,
| + | techniques. Further, anthracite generally contains a very high |
| − | however, are high cost and difficulty of storing large amounts of
| + | percentage of sulphur and it cannot be used as a fuel without |
| − | electricity as compared with the relative ease of storing heat for
| + | expensive treatment to remove sulphur. Consequently in recent years, |
| − | later use. The working of a solar cell depends upon the phenomenon
| + | there has been increased interest in the mining of lower quality but |
| − | of photo electricity; that is, the liberation of electrons by light | + | relatively sulphur-free coal that lies close to the surface. |
| − | falling on a body. Though this phenomenon has been known for a long
| + | Strip-mining techniques are used for the extraction of this coal. |
| − | time, its application to semiconductors such as silicon has proved to
| + | Strip mining for coal causes serious and continuing environmental |
| − | be of great use. The principle of solar cells is simple. When light
| + | problems. One of the most serious problems associated with the |
| − | waves strike a semi-conductor material with energy sufficient to
| + | strip-mining of coal is the huge amount of land that is torn up in |
| − | dislodge an electron from a fixed position in the material and make
| + | the process. Unless rehabilitation measures are taken, the area |
| − | it move freely in the material, a vacant electron position or ‘hole’
| + | adjoining the strip mined land can suffer from landslides, erosion |
| − | is created in the material. The hole acts a positive charge and can
| + | and sedimentation. |
| − | move if a neighbouring electron leaves its site to fill the hole
| |
| − | site. A current is created if the electron-hole pairs are separated
| |
| − | by voltage in the cell material. Such an intrinsic voltage may be
| |
| − | created by adding small amounts of impurities or dopants to the pure
| |
| − | material or by joining two semiconductor materials. When impurities
| |
| − | such as phosphorous are introduced into silicon, it becomes
| |
| − | electron-rich and is referred to as ‘n-type’ silicon. On the
| |
| − | other hand, impurities such as boron give rise to ‘p-type’
| |
| − | silicon with excess of holes. When these two oppositely charged
| |
| − | semiconductors (one electron rich and the other electron-deficient)
| |
| − | are in contact, free charge leaks across the common boundary and | |
| − | becomes fixed as ions in the region adjacent to the boundary. At the
| |
| − | interface, the fixed (but opposite) ions create an electric field
| |
| − | that sends free electrons one way and free holes the other.
| |
| | | | |
| | | | |
| − | In the dark, no current flows in the solar cell.
| + | Unlike coal, the extraction of oil does not |
| − | But when it is illuminated, a current will flow as long as the cell
| + | desecrate the land the way the strip-mining does. However, the most |
| − | is illuminated and can supply electricity to an external load. | + | serious environmental problem associated with oil-well drilling |
| | + | occurs at offshore sites. Because of the many technical difficulties |
| | + | inherent in offshore drilling, if a rupture occurs or if the drilling |
| | + | opens a crack in the rock that contains the oil deposit, a major |
| | + | leakage of oil into the water can occur before the damage is repaired |
| | + | or the crack is sealed. The release of large amounts of oil into the |
| | + | water can be injurious to the marine life. When the oil spreads over |
| | + | water, the diffusion of oxygen into water is inhibited. This affects |
| | + | the respiration of fish and other marine life. Oil pollution of sea |
| | + | causes either problems too. Oil is pushed to the shore by the water |
| | + | currents and winds, thereby spoiling the beaches. |
| | | | |
| | | | |
| − | The best and most efficient solar cells are
| + | === Combustion of fuel === |
| − | constructed from high purity silicon. This type of cell has already
| |
| − | been used very successfully for providing electrical power in
| |
| − | spacecraft. The overall efficiency of photovoltaic cells is around
| |
| − | 11 percent. But their cost has prevented their use for large-scale
| |
| − | generation
| |
| − | | |
| | | | |
| − | === Power from space ===
| + | The burning of fossil fuels releases a variety of |
| − |
| + | noxious gases and particulate matter into the atmosphere. The major |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_28a8f203.jpg]]A
| + | contributors to this atmospheric pollution are coal and oil and |
| − | new concept of placing a large array of solar powered photovoltaic
| + | natural gas by far is the least offensive of the fossil fuels , One |
| − | devices on manmade earth-circling satellites and transmitting the
| + | of the major problems with coal and oil is the presence of sulphur. |
| − | power to earth has been proposed and is receiving increasing
| + | Depending upon the source, the sulphur content can be up to several |
| − | attention as a potential energy resource for the next century. The
| + | percent and upon combustion several oxides (particularly sulphur |
| − | idea is that solar panels put up in space would receive on the
| + | dioxide) are produced. When sulphur dioxide is released into the |
| − | ground. And this energy would be available round the clock. The
| + | atmosphere, it combines with water vapour and forms sulphuric acid. |
| − | energy thus tapped may be transmitted to the earth in a sufficiently
| + | It is this sulphuric acid which is injurious to plant and animal |
| − | narrow microwave beam using a transmitting antenna. On the earth the
| + | life. It has been found that atmospheric sulphuric acid eating the |
| − | energy beam may be received by a receiving antenna and converted into
| + | limestone facings of many monuments and public buildings in urban |
| − | commercial frequency electric power.
| + | life. Sulphur dioxide is believed to cause cough, shortness of |
| − | | + | breath and spasm of the larynx. It can cause acute irritation to the |
| − |
| + | membranes of the eyes resulting in excessive flow tears and redness. |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_56745c9d.jpg]]
| + | When absorbed by plants beyond a certain level the plants cells |
| − | | + | become inactive and are killed, resulting in tissue collapse and |
| − | === Biological conversion of Solar energy ===
| + | drying of leaves. Sulphur dioxide is also known to interfere with |
| − |
| + | the respiratory and photosynthesis in plants. |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_2c8b489d.jpg]]
| |
| − | | |
| | | | |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_77206083.jpg]] | + | [[Image:Energy%20for%20KOER_html_m798592ab.gif]]The |
| − | | + | burning of petrol in internal combustion engines is the major source |
| | + | of carbon monoxide, nitrogen dioxides and hydrocarbons in the |
| | + | atmosphere. In addition, there are large quantities of lead which |
| | + | are released into the atmosphere from high octane petrol used in |
| | + | cars. All these pollutants and the products of the photochemical |
| | + | reactions they undergo in presence of sunlight contribute to the |
| | + | noxious known as smog. There seems at present no escape from the |
| | + | health hazards of smog until some effective way is found to remove |
| | + | the pollutants from the vehicular exhaust gases. |
| | | | |
| | | | |
| − | Photosynthesis in plants is a biological process
| + | ==== Combustion of fuel - Effects of carbon Dioxide and carbon Monoxide: ==== |
| − | by which they convert solar energy into sugars and starches, which
| + | |
| − | are energy-rich compounds. Fast growing trees having high
| + | The consumption of oxygen and the |
| − | photosynthetic efficiency can therefore be harvested and burned to
| + | formation of carbon dioxide are necessary consequences of every |
| − | raise steam and generate electricity as in a thermal power station.
| + | combustion process. One may think that this may deplete the world’s |
| − | Such an ‘energy plantation’ would be a renewable resource and
| + | supply of oxygen and thus upset the oxygen-carbon dioxide balance |
| − | economical means of harnessing solar energy. However, the average
| + | that is necessary for plant and animal life. |
| − | efficiency of solar energy conversion in these plants is about 1
| |
| − | percent and the overall efficiency of conversion of sunlight into
| |
| − | electricity would be about 0.3 percent as compared to 10 percent for
| |
| − | solar cells.
| |
| | | | |
| | | | |
| − | == Wind Energy ==
| + | Carbon dioxide molecules strongly absorb heat |
| − |
| + | radiations emitted from the surface of the earth heated by the sun. |
| − | Wind is produced by
| + | By holding back this energy in the earth’s atmosphere, carbon |
| − | temperature differences in the air. This is true both of a gentle
| + | dioxide reduces the heat lost by the earth to space. This is called |
| − | evening breeze as well as a roaring hurricane. The main driving
| + | ‘greenhouse effect’ and because of this, it is argued, the |
| − | force behind the wind system of the earth’s atmosphere is the
| + | continued burning of fossil fuels will result in a steady increase in |
| − | temperature difference between the tropics and the Polar Regions. | + | the earth’s surface temperature. However, an increasing in the |
| − | This temperature difference arises due to the fact that the tropical
| + | temperature of the earth’s surface and lower atmosphere has the |
| − | regions of the earth are much warmer than the Polar Regions. Wind
| + | compensating effect of increasing evaporation and cloudiness. |
| − | energy is the energy of air in motion and has been used for ages for
| + | Because clouds reflect some of the incident sunlight, increases in |
| − | driving sail boats, for grinding grain and pumping water.
| + | cloudiness tend to decrease the surface temperature. Further, the |
| | + | release of particulate matter into the atmosphere from fuel burning |
| | + | increases the number of condensation sites around which water |
| | + | droplets can form. The result is an increase in the amount of rain, |
| | + | hail and thunderstorms which lead to the lowering of the temperature. |
| | + | The amount of carbon dioxide is regulated by the presence of the |
| | + | ocean waters which 60 times as much carbon dioxide as does the |
| | + | atmosphere and absorbs a large fraction of the carbon dioxide |
| | + | released by the burning of fuels. Also, the increased level of |
| | + | carbon dioxide in the atmosphere actually stimulates a more rapid |
| | + | growth of plants. This increased utilization of carbon dioxide |
| | + | further reduces the atmospheric excess. Thus the role of carbon |
| | + | dioxide in influencing the world’s climate is quite a complex one. |
| | | | |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_59310382.jpg]]Today
| + | Carbon monoxide is another pollutant produced by |
| − | it is also used for generating electric power. When air is blown on
| + | burning of fossil fuel. It is usually produced when there is |
| − | wind vane, a child’s common toy, starts rotating. This idea is
| + | insufficient oxygen for burning. It is released into the atmosphere |
| − | used in making the windmill which is nothing but a big wind vane.
| + | mainly from automobile exhaust gases. But it does not so far |
| − | Wind energy is inexhaustible and is therefore a permanent source of
| + | constitute a serious environmental problem. |
| − | energy as there will always be winds. According to an estimate,
| + | |
| − | about 175 to 220 thousand trillion watt hours per year of wind energy
| |
| − | can be produced globally, This is a very promising figure as it is
| |
| − | about 2.7 times the total energy used on the earth today.
| |
| − | | |
| | | | |
| − | == Hydroelectric Power == | + | === Thermal pollution === |
| | | | |
| − | Running water is an
| + | The term ‘thermal pollution' basically refers to |
| − | easily available source of energy. It is available free and does not
| + | the detrimental effects of discharges of unwanted heat into the |
| − | pollute the environment. Running water can be used to burn a turbine
| + | environment. All electricity generating plants produce electricity |
| − | generator to produce electricity and is the basis of the
| + | by driving huge turbine generators with steam. The steam is |
| − | hydroelectric plant. Water is stored in a reservoir behind a dam.
| + | condensed in a cooling system and is cycled back to the heating unit |
| − | When water flows from a height, it turns big turbines to generate
| + | for reuse. The cooling system can be water that is pumped from some |
| − | electricity. There are a number of hydroelectric power plants in
| + | nearby reservoir and discharged back into it, or it can be a cooling |
| − | India; the Bhakra Nangal dam in punkab, Damodar valley Project in
| + | tower in which the heat is dissipated into the atmosphere. Both |
| − | West Bengal, Hirakud Project and Kosi Project in Bihar and the
| + | cause thermal pollution. If the heated water is discharged into a |
| − | Nagarjunasagar project in Andhra Pradesh to name a few. These
| + | static reservoir, such as a lake, the effect can be even more |
| − | projects produce a very significant percentage of the total
| + | severe. The thermal is generated by the energy producer as well as |
| − | electricity generated in our country.
| + | the energy user. Almost all of the energy we use is eventually |
| | + | converted into heat. Most of this waste is dissipated into the air |
| | + | where it contributes to the general atmospheric heating. |
| | | | |
| | | | |
| − | === Ocean energy === | + | === Effects of Nuclear Radiations === |
| | | | |
| − | Tides are the raising
| + | Nuclear reactors, unlike the other sources of |
| − | and filling of the ocean level due to the moon’s gravitational pull
| + | power, offer a lot of advantage. Nuclear reactors generate |
| − | which can be easily seen along the seashore. It is possible to
| + | electrical power without the smoke and fumes that are characteristic |
| − | extract energy from these tides and the main requirement for
| + | of fossil fuel-burning plants. Also the mining of uranium produces |
| − | harnessing tidal energy is that the difference between the high tide
| + | much less degradation of the countryside than the mining of fossil |
| − | and the low tide should be large, at least a few metres. The first
| + | fuels, particularly coal. Nuclear reactors, therefore, offer the |
| − | ever tidal powered electric generating plant was set up on River
| + | prospect of long term relatively clean power. However, nuclear |
| − | Rance in France, to harness the power tides in the English Channel
| + | reactors have their own peculiar set of disadvantages, mainly |
| − | which rise to as much as 14 metres at this location. By opening
| + | associated with the production of radioactive materials. Some |
| − | gates as the tide rises and then closing them at high tide, a
| + | radioactive waste is released into the environment both gases into |
| − | 23-square kilometers pool is formed behind the Rance river dam. As
| + | the atmosphere and in the form of low activity waste such as tritium |
| − | the tide falls, the trapped water is allowed to flow out, driving 24 | + | in cooling water. |
| − | electricity generating turbines of 13MW capacity each for total
| |
| − | average power output of 310MW.
| |
| | | | |
| | | | |
| − | It is estimated that
| + | All radioactive substances emit harmful |
| − | the total global potential for tidal power is only2 percent of the | + | radiations, some of which can cause cancer in man and animals and |
| − | world’s potential hydroelectric capacity. Besides, it involves
| + | damage the genetic material of the cell, producing long term harmful |
| − | very high initial cost and the output is variable.
| + | effects in living organisms. However, modern nuclear reactors are |
| | + | quite safe. An individual living near a nuclear reactor is exposed |
| | + | much less to its emitted radiation than what one gets from X-rays and |
| | + | natural sources. |
| | + | |
| | + | |
| | + | = Energy and the future = |
| | + | |
| | + | The worldwide demand for energy is increasing day |
| | + | by day. The increasing use of modern means of transport-cars, buses, |
| | + | trains, aero planes , ships, etc., the rapid rise in the overall |
| | + | industrialization; the tremendous growth in population, particularly |
| | + | in the last 40 years, are some of the factors that have led to a |
| | + | tremendous spurt in mankind’s energy requirements. |
| | | | |
| | | | |
| − | === Energy from waves === | + | === Need for Judicious Use of energy === |
| | | | |
| − | Unlike the tides which
| + | It follows therefore that mankind has to adopt a |
| − | exhibit a regular but long periodic variability, waves keep the ocean
| + | judicious approach towards consumption of energy sources to ensure |
| − | water in continual motion. The vertical rise and fall of the
| + | that these are not depleted too fast. This approach needs to be |
| − | successive waves can be used to produce energy. India’s first wave
| + | supplemented by optimum utilization of our natural sources. We have, |
| − | energy project has gone on stream at vizhinjam near Trivandrum. The
| + | for example, reserves of billions of tones of coal spread across the |
| − | 150-MW project implemented by the Wave Energy Group attached to the
| + | Bihar, West Bengal and Orissa region. This coal may not be of the |
| − | Ocean Engineering Centre, IIT, Madras, in association with the state
| + | best quality, but coal mining in this area can always be stepped up |
| − | Harbour Engineering department. This project works works on the
| + | to meet our energy requirements. In India, technology used is coal |
| − | principle of an oscillating water column, which drives an air
| + | mining and handling after it is mined is still primitive where |
| − | turbine. The turbine is so designed that it rotates in one
| + | mechanical wheels are used in open pit mining. Any improvement in |
| − | direction, irrespective of the direction of air flow. It is a
| + | material handling system can lead to a saving of a lot of coal which |
| − | multipurpose scheme and floats on the sea bed. From the ecological
| + | is otherwise lost'''.''' |
| − | and environment points of view too, it is the best as the unit hardly
| |
| − | leaves any waste. The biggest advantage of the project is that power
| |
| − | generation is possible throughout the year, though not uniformly.
| |
| − | | |
| − |
| |
| − | {| border="1"
| |
| − | |-
| |
| − | |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m550953e9.jpg]]
| |
| | | | |
| | | | |
| − | |
| + | One source of energy which has remained |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m44b8741.jpg]]
| + | underutilized is the hydroelectric energy. The subcontinent has many |
| − | | + | large rivers with substantial hydroelectric potential, much of which |
| − |
| + | still remains unutilized. These can be tapped to provide energy |
| − | |}
| + | which is clean, renewable and cheap. Large numbers of small |
| − | === Energy from Ocean Thermal Gradients ===
| + | hydroelectric power projects across the country over the country over |
| − |
| + | small rivers could also yields a fair amount of energy. |
| − | The heat contained in | |
| − | the ocean waters heated by the sun can be converted into electricity
| |
| − | by utilizing the difference in temperature between the surface water
| |
| − | can be used to heat some low-boiling organic liquid such as ammonia | |
| − | or propane, the vapours of which are allowed to expand through a
| |
| − | turbine which can run a generator. The vapours leaving a turbine are
| |
| − | channeled into a condenser located in the low temperature water zone,
| |
| − | much below the water surface. The condensed liquid is pumped into a
| |
| − | boiler evaporator to start the cycle afresh. The expected efficiency
| |
| − | of such a system is about 2 percent. The amount of energy available
| |
| − | from ocean thermal gradients is enormous, and is replenished
| |
| − | continuously.
| |
| | | | |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m533a134.jpg]][[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_196bef2b.jpg]]
| + | Wind energy has a tremendous scope as alternative |
| | + | source of energy not only in India but the entire region stretching |
| | + | from Afghanistan to Vietnam. Wind electric generators are at present |
| | + | operating successfully in many parts of India. Windmills are also |
| | + | being used for pumping water and this use of windmills should be |
| | + | encouraged. If India develops a system whereby windmills and |
| | + | generators could be manufactured on a large scale, it will really be |
| | + | a tremendous boon to the rural economy of this vast region. Wind |
| | + | energy is a non-polluting, cheap, renewable source of energy. |
| | | | |
| − | == Geo thermal energy ==
| |
| | | | |
| − | We are
| + | A substantial portion of our energy requirements |
| − | living between two great sources of energy- the sun up in the sky,
| + | is met by firewood. It necessitates felling of trees, resulting in |
| − | and hot rocks beneath the earth’s surface. The interior of the
| + | deforestation, soil erosion, and floods. To prevent this and to |
| − | earth is extremely hot. As one goes deep into the earth the
| + | maintain the stability of forest reserves a massive afforestation |
| − | temperature increases. The earth has very hot materials in and below
| + | programme is necessary. The use of firewood as fuel must be avoided |
| − | the crust. As some places this hot material comes quite close to the
| + | as far as possible by encouraging the use of biogas plants. Benefits |
| − | surface, or even out of the surface in the form
| + | accruing from biogas plants are immense and manifold. Biogas plant |
| − | of volcanic eruptions. In places where it comes close to the
| + | generate but only substantial economic gains to the country but also |
| − | surface, underground water often gets heated and
| + | help up gradation of the environment. As India is dependent on |
| − | produces steam and hot water which comes out as hot springs and
| + | imported oil for meeting its energy requirements, it would be prudent |
| − | geysers. The areas in which such conditions exist are known as
| + | to reduce the consumption of petroleum products. These are primarily |
| − | geothermal regions. Infrared photography of the ground from
| + | used for road and rail transport. The industry uses a large quantity |
| − | satellites like IRS-1 has played an important role in locating the
| + | of petroleum products both as raw material and also as fuel. There is |
| − | geothermal regions.
| + | tremendous scope for reducing the consumption of diesel and petrol in |
| | + | cars, trucks and two wheelers by more efficient engine design and |
| | + | maintenance. |
| | | | |
| | | | |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m224b8bc5.jpg]]After
| + | It is indeed a good news that India has vast |
| − | locating a geothermal region, a bore is drilled through the rock to
| + | reserves of natural gas which is a very clean source of energy. The |
| − | tap the heat. In many places steam under high pressure comes out
| + | Bombay High oilfields contain very large quantities of gas which at |
| − | straight from the borehole and can be used to drive turbines
| + | present are flared or burnt. Only recently are efforts being made to |
| − | directly. Where steam is not available, cold water is pumped down
| + | utilize natural gas commercially, for generating power and production |
| − | through one hole and heated water and steam produced pumped out of
| + | of fertilizer. Especially in the north east. The Dutch and the |
| − | another. The hot water or steam produced can be used to run a turbine
| + | British have found vast reserves of offshore natural gas and in the |
| − | or to heat housed and offices. Geo thermal energy is used for space
| + | process have developed new technology to utilize it. |
| − | heating where the temperature goes down to 30 to 35 degrees below the
| |
| − | freezing point, for poultry farming, mushroom cultivation and
| |
| − | pashmina-wool processing which need a warmer climate.
| |
| | | | |
| | | | |
| − | Although at first
| + | === Minimizing Wastage === |
| − | glance, geothermal energy seems very promising, geothermal sources
| |
| − | are, in reality, far from being pollution free. Underground steam
| |
| − | contains hydrogen sulphide gas and minerals which can poison fish and
| |
| − | other forms of aquatic life in streams and rivers.
| |
| − | | |
| | | | |
| − | == Key vocabulary ==
| + | Not only have we to adopt a judicious approach to |
| − |
| + | using our energy sources, we have also to lay a great stress on |
| − | # Radiation-In general the emission of energy from a source, either as waves or as moving particles.
| + | prevention of wastage. Even a casual look at our day-today |
| − | # Quartz-The most abundant mineral, consisting of crystalline silicon dioxide and having diverse physical properties and uses.
| + | activities reveals that energy is wasted in many ways. Careless |
| − | # Semiconductor-A material, such as Silicon or germanium, that has a resistivity midway between that of conductors and that of insulators.
| + | habits, like leaving the lights and fans on when no one is round, |
| − |
| + | keeping the car or scooter engine on while gossiping with a friend on |
| − | == Additional web resources ==
| + | the road, etc. contribute to wastage of energy. We have to know |
| − |
| + | about the various ways in which energy is wasted at home and in |
| − | 1)
| + | industries, and then develop-and encourage others to develop-proper |
| − | [[http://news.discovery.com/tech/five-ways-harness-solar.html]]
| + | design and also ensure that all machinery is kept well maintained and |
| − | | + | in proper running condition. This helps save a lot of energy. With |
| − |
| + | the impending energy crisis facing mankind, saving ‘every bit of |
| − | 2)
| + | energy ‘ is of great importance. This saved energy can then be put |
| − | [[http://www.youtube.com/watch?v=0OkqJw1oTMk]]
| + | to some useful ‘use’ in future. WE must remember energy saved is |
| | + | energy produced. |
| | | | |
| | | | |
| − | # [[http://www.youtube.com/watch?v=tSBACzRE3Gw&feature=related]] 4)[[www.indiacore.com/.../kssidhu-non-]][[conventional]][[-]][[energy]][[-]][[resources]][[.pdf]]
| + | = Evaluation: = |
| − | # [[http://www.darvill.clara.net/altenerg/geothermal.htm]]
| |
| | | | |
| − | 6)
| + | # What is work?When do we say that work is done? |
| − | [[http://solarwaterheater.20m.com/RenewableEnergyVideo.html]]
| + | # What are kinetic and potential energy? |
| − | | + | # What are the different forms of energy? |
| | + | # What is power? |
| | + | # What are the units of energy? |
| | + | # What are fossil fuels?How are they formed? |
| | + | # What are the different steps to process the petroleum? |
| | + | # What is Biomass energy? How it is generated? |
| | + | # What are the different sources of non -conventional energy? |
| | + | # What are the different ways of harnessing solar energy? |
| | + | # Name the different non conventional sources of energy. |
| | + | # Name the different storage devices. |
| | + | # What are isotopes? Name some isotopes. |
| | + | # Draw the diagrams of the nuclear reactors-thermal and fast breed |
| | + | # How are fossil fuels threatening us? |
| | + | # What are the effects of Carbon Dioxide and Carbon Monoxide? |
| | + | # How are nuclear radiations affect out environment? |
| | + | # What is the need for judicious use of available energy? |
| | + | # List some steps to minimize energy wastage |
| | | | |
| − | 7)[[www.physics.wisc.edu/~himpsel/wires.html]]
| + | = Additional web resources = |
| − | | |
| | | | |
| − | = Energy storage = | + | # [[http://www.youtube.com/watch?v=8J_z3_3pue0]] |
| − |
| + | # [[Image:Energy%20for%20KOER_html_m145a4ee8.gif]][[Image:Energy%20for%20KOER_html_mb374f76.gif]][[http://www.youtube.com/watch?v=sOa7EpJf89I&feature=related]] |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m7a21910d.jpg]]One | + | # [[http://www.youtube.com/watch?v=S0TurHQp_AE&feature=related]] |
| − | of the problems associated with the generation of electricity from
| + | # web.mit.edu/8.02t/www/materials/modules/ReviewD.pdf – This review document summarizes the law of conservation of energy very clearly |
| − | various is that the demand for power fluctuates. During the day, the
| + | # [[http://www.youtube.com/watch?v=f9kJwtayTJ]] |
| − | power requirements, especially for commercial purposes, are much
| + | # [[http://www.youtube.com/watch?v=VJfIbBDR3e8]] |
| − | greater than during night time. If there was some way to store
| + | # [[http://www.youtube.com/watch?v=f9kJwtayTJI]] |
| − | electrical energy, the generating plant could be operated at full
| + | # [[www.sciencejoywagon.com/physicszone/05work-energy/]] |
| − | capacity during the night, storing up energy to be released when the
| + | # [[www.technologystudent.com/energy1/less4.html]] |
| − | demand increases.
| + | # [[http://video.nationalgeographic.com/video/player/environment/energy-environment/alternative-energy.html]] |
| − | | + | # [[http://news.discovery.com/tech/five-ways-harness-solar.html]] |
| − |
| + | # [[http://www.youtube.com/watch?v=0OkqJw1oTMk]] |
| − | There are two different approaches for storing
| + | # [[http://www.youtube.com/watch?v=tSBACzRE3Gw&feature=related]] |
| − | electricity energy, depending upon whether this storage is for
| + | # [[www.indiacore.com/.../kssidhu-non-conventional-energy-resources.pdf]] |
| − | small-scale or large-scale purposes.
| + | # [[http://www.darvill.clara.net/altenerg/geothermal.html]] |
| − | | + | # [[http://solarwaterheater.20m.com/RenewableEnergyVideo.html]] |
| − |
| + | # uw.physics.wisc.edu/~himpsel/wires.html |
| − | == Small-scale storage ==
| + | # hyperphysics.phy-astr.gsu.edu/hbase/nucene/'''fission'''.html |
| − |
| + | # phet.colorado.edu/en/simulation/'''nuclear'''-'''fission''' |
| − | For small-scale storage of electricity, batteries
| + | # www.whatis'''nuclear'''.com/articles/nuc'''reactor'''.html |
| − | and fuel cells offer the best course. An electric battery consists
| + | # [[http://www.youtube.com/watch?v=SePyzzRiE5U]] |
| − | of one or more electric cells which are devices for producing
| + | # [[http://www.youtube.com/watch?v=e-0Jf-zuG4s]] |
| − | electric directly from the chemical reactions. Electricity made in
| + | # [[http://www.youtube.com/watch?v=zDGcD8Ix9Ek]] |
| − | this way is much more expensive than that made by mechanical
| + | # [[www.whatisnuclear.com/articles/nucreactor.html]] |
| − | generators but batteries being compact and portable, are a better
| + | # [[www.westinghouse]][[nuclear.com/.../WhatIsNuclearEnergy.shtm]] |
| − | choice for many applications Cells are generally of two types;
| + | # [[www.indianuclearenergy.net]] |
| − | primary cells and secondary cells.
| + | # '''video.nationalgeographic.com/video/.../energy.../alternative-energy.html ''' |
| − | | + | # ''en.wikipedia.org/wiki/'''''''Waste'''''''_minimisation'' - [[Cached]] – [[Similar]] |
| − |
| + | # www.youtube.com/watch?v=FBTXQV7GKow |
| − | One good example of a primary cell is a voltaic
| + | # ''www.streetdirectory.com/.../''''energy''''-''''crisis-in-india''''-aouac.html'' - [[Cached]] – [[Similar]] |
| − | cell which consists of copper and zinc metal plated dipped in a
| |
| − | solution of sulphuric acid which acts as an electrolyte. The
| |
| − | electrolyte contains positive and negative ions but is overall
| |
| − | electrically neutral. Zinc tends to dissolve in the solution more
| |
| − | easily than does copper. In solution it forms positive zinc ions
| |
| − | leaving electrons behind on the zinc plate. This gives zinc plate a
| |
| − | negative charge with respect to copper plate and so, when an electric
| |
| − | circuit is completed at the terminals of the cell, the electrons flow
| |
| − | to the copper plate giving rise to a current. This cell becomes dead
| |
| − | when the solution becomes saturated with zinc so that no more of it
| |
| − | wants to dissolve. To revive the cell one has just to replace the
| |
| − | electrolyte sulphuric acid, this can be continued so long as zinc is
| |
| − | present but when the zinc is gone, the cell is permanently dead. The
| |
| − | principal disadvantage of the primary cell is its short life.
| |
| − | Obviously it would be more useful to have a cell which could be
| |
| − | restored to its original condition once it had discharged all its
| |
| − | available form of energy. Fortunately it is possible to do so with
| |
| − | some types of cells. Such cells are called secondary cells and a set
| |
| − | of them is called a storage battery because it enables charges
| |
| − | produced by other means to be stored for later use. In a storage
| |
| − | battery electricity is stored where chemical changes take place which
| |
| − | can be reversed to release the stored electrical energy. A typical
| |
| − | storage battery takes a few hours to charge and can then be used as a
| |
| − | source of energy.
| |
| − | | |
| − |
| |
| − | These batteries find use in the fabrication of
| |
| − | uninterrupted power supplies for continuous operation of costly
| |
| − | equipment, computers and other strategic gadgets. Here the batteries
| |
| − | are coupled with an oscillator which converts this D.C supply from
| |
| − | this battery to A. C. at higher voltage and frequency.
| |
| − | | |
| − |
| |
| − | == Large scale storage ==
| |
| − |
| |
| − | For meeting the large energy requirements of homes
| |
| − | and industry, storage batteries are impractical. '''Key
| |
| − | vocabulary'''
| |
| − | | |
| − |
| |
| − | # Electrolyte-A liquid containing positive and negative ions, that conducts electricity by the flow of those charges | |
| − |
| |
| − | = Nuclear power =
| |
| − |
| |
| − | == Atoms ==
| |
| − |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m4cc0b6df.jpg]]All
| |
| − | matter is made up of different naturally occurring elements, each
| |
| − | possessing physical and chemical properties distinct from the other.
| |
| − | These smallest entities into which these elements can be divided are
| |
| − | called atoms. Atoms are made up of three still smaller
| |
| − | particles-positively charged protons, negatively charged electrons
| |
| − | and electrically neutral neutrons. The relatively heavy protons and
| |
| − | neutrons constitute the tiny nucleus. This is surrounded by moving
| |
| − | electrons and overall the orbit is electrically neutral and is about
| |
| − | ten to the power of 5 times the size if the nucleus. The number of
| |
| − | orbiting electrons is always equal to the number of protons so that
| |
| − | the net electrical charge of the atom is Zero.
| |
| − | | |
| − |
| |
| − | Atoms of a particular element always contain the
| |
| − | same number of protons and there is a scale of elements, going from
| |
| − | the atoms of hydrogen which have only one proton, helium atoms which
| |
| − | have two protons, lithium atoms which have three protons, and so on
| |
| − | all way up to very large atoms such as uranium, which has 92 protons.
| |
| − | The number of protons is therefore, important because it identifies
| |
| − | the element to which the atom belongs. Thus any atom which contains,
| |
| − | say 17 protons must be chlorine; uranium atoms always contain 92
| |
| − | protons, and so on. The atomic number of an element is the same as
| |
| − | the number of protons in the nucleus.
| |
| − | | |
| − |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m2a27ed59.gif]]
| |
| − | Along with the protons in the atomic nucleus there are also the
| |
| − | electrically neutral particles called neutrons. The number of
| |
| − | neutrons in the nucleus tends to increase with number of protons.
| |
| − | For instance, in the helium atom ( which has two protons) there are
| |
| − | two neutrons, lithium (which has three protons) has four neutrons,
| |
| − | uranium (which has 92 protons) has 146 neutrons, and so on. The
| |
| − | protons and neutrons in a nucleus are bound together by immensely
| |
| − | strong forces, called nuclear forces which counteract the
| |
| − | electrostatic forces of repulsion acting between the protons. In
| |
| − | very large atoms, such as uranium and plutonium, the binding nuclear
| |
| − | forces are only slightly stronger than the repulsive forces between
| |
| − | the large number of protons; such nuclei are unstable and can be made
| |
| − | to undergo fission- split into two or more fragments releasing
| |
| − | nuclear energy.
| |
| − | | |
| − |
| |
| − | == Isotopes ==
| |
| − |
| |
| − | The atomic weight of an element is expressed as
| |
| − | the sum of the number of protons and neutrons. Atoms of the same
| |
| − | element can differ from one another by having a different number of
| |
| − | neutrons in their nuclei. For example, uranium (which has 92
| |
| − | protons) can have either 143 or 146 neutrons. These two forms of
| |
| − | uranium have the same chemical but slightly different physical
| |
| − | properties. Atoms of the same element which exist in different forms
| |
| − | as a result of having different numbers of neutrons in their nuclei
| |
| − | are called isotopes. The first of the two uranium isotopes described
| |
| − | above is called uranium-235, and the second, uranium-238.
| |
| − | Uranium-238 is heavier than uranium-235. Similarly there are three
| |
| − | isotopes of hydrogen, namely hydrogen (one proton only), deuterium or
| |
| − | heavy hydrogen ( one proton and one neutron), and tritium ( one
| |
| − | proton and two neutrons).
| |
| − | | |
| − |
| |
| − | Atoms of the same element always contain the same
| |
| − | number of protons in their nuclei. The number of protons is balanced
| |
| − | by an equal number of electrons to make the atom electrically
| |
| − | neutral. It is the number of orbiting electrons that determines the
| |
| − | chemical properties of an element. When atoms combine with other to
| |
| − | form molecules, there is rearrangement of the outermost electrons in
| |
| − | the orbit ( also called valence electrons). In this process, energy
| |
| − | can be stored or released so that is some reactions ( burning for
| |
| − | example) heat energy is released. Thus atoms of carbon ( coal, on
| |
| − | combination with atoms of oxygen from the air to form carbon dioxide
| |
| − | in the process of burning, release energy.
| |
| − | | |
| − |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m798592ab.gif]]Chemical
| |
| − | reactions, such as burning, involve the release of energy mainly due
| |
| − | to exchange or transfer of electrons whereas nuclear energy involves
| |
| − | the release of energy from within the nucleus of the atoms.
| |
| − | | |
| − |
| |
| − | == Principle of Nuclear Fission ==
| |
| − |
| |
| − | Isotopes of certain very heavy atoms, for example,
| |
| − | uranium-235 and plutonium-239, are so unstable that they can be made
| |
| − | to split (fission) when hit by a neutron. When this happens, a very
| |
| − | large amount of energy is released. This process is known as nuclear
| |
| − | fission. In this process, the mass of the two smaller atoms (
| |
| − | collectively known as fission products) plus the mass of the two or
| |
| − | three neutrons that are produced, is slightly less than the mass of
| |
| − | the original uranium-235 or plutonium-239 atom plus the bombarding
| |
| − | neutron. Thus, in the process of nuclear fission, some matter is
| |
| − | lost and converted into energy. According to Einstein’s famous
| |
| − | equation, even a small amount of matter is equivalent to a very large
| |
| − | amount of energy. Thus the nuclear fission of uranium-235 contained
| |
| − | in 1 tonne of natural uranium is equivalent in electricity output to
| |
| − | the burning of approximately 20,000 tonnes of coal. Natural uranium
| |
| − | contains only 0.7 percent of uranium-235.
| |
| − | | |
| − |
| |
| − | == Nuclear Reactors == | |
| − |
| |
| − | A nuclear reactor is a device in which the nuclear
| |
| − | fission process is carried out under controlled conditions. The
| |
| − | basic fuel of a nuclear reactor is uranium, obtained from ores such
| |
| − | as pitchblende. Natural uranium is a mixture of two isotopes,
| |
| − | uranium-235 and uranium 238, present in the ratio of 0.7:99. Only
| |
| − | the comparatively rare isotope uranium-235 undergoes nuclear fission.
| |
| − | | |
| − |
| |
| − | There are two types of nuclear reactors:
| |
| − | | |
| − |
| |
| − | # '''Thermal reactors''' use uranium as fuel and have moderators to slow down neutrons. They are called thermal reactors because they use slow-moving or thermal neutrons.
| |
| − | # '''Fast breed reactors: '''Since 99.3 percent of natural uranium is uranium-238 and since this isotope cannot undergo fission, thermal reactors are able to use a very small proportion of natural uranium. However, fast reactors are able to convert this otherwise unusable uranium-238 into a new element, plutonium-239, which can then be fissioned to liberate energy. Fast breeder reactors do not need a moderator as fast neutrons used.
| |
| − |
| |
| − | '''Thermal reactors: '''The core of
| |
| − | a thermal has five components.
| |
| − | Uranium dioxide pellets are packed in long metal tubes known as fuel
| |
| − | elements. A nuclear reactor contains several tones of uranium in
| |
| − | thousands of fuel elements. Periodically, the used-up fuel elements
| |
| − | are taken out and new fuel elements put in. The most commonly used
| |
| − | moderators used moderators are water, heavy water, and graphite.
| |
| − | | |
| − |
| |
| − | Control rods are used to control the rate of the
| |
| − | nuclear chain reaction. They are made of boron which readily absorbs
| |
| − | neutrons. When these rods are lowered into the core (containing fuel
| |
| − | elements and the moderator), that absorb most of the neutrons and so
| |
| − | there can be no chain reaction. This effectively shuts down the
| |
| − | reactor. As they are pulled out progressively, neutrons are
| |
| − | available to split uranium atoms, thus releasing more neutrons. The
| |
| − | further the control rods are pulled out, the larger is the number of
| |
| − | fissions in the core and more heat is produced.
| |
| − | | |
| − |
| |
| − | Since the uranium fuel as well as the fission
| |
| − | products are intensely radioactive, a very thick steel-and-concrete
| |
| − | shield is required to prevent the escape of any radiation from the
| |
| − | core. Indian reactors usually have double shielding to further
| |
| − | minimize any risk.
| |
| − | | |
| − |
| |
| − | To remove the heat produced by nuclear fission in
| |
| − | the fuel elements, a coolant is used which circulates through spaces
| |
| − | between the fuel elements, Indian reactors, which use natural
| |
| − | uranium as fuel, use heavy water as coolant, but reactors using
| |
| − | enriched uranium (in which the percentage of uranium-235 is raised by
| |
| − | complex processes) use ordinary water as coolant. The heated coolant
| |
| − | coming out of the core transfers the heat exchanger to boil water and
| |
| − | raise steam which is then used to run a turbine generator to generate
| |
| − | electricity.
| |
| − | | |
| − |
| |
| − | == Fast breed reactors ==
| |
| − |
| |
| − | Thermal reactors are able to release energy from
| |
| − | the small proportion of uranium-235 contained in the natural uranium.
| |
| − | They are, however, unable to use the uranium-238 which constitutes
| |
| − | 99.3 percent of natural uranium. The significance of fast reactors
| |
| − | is that they are able to convert Uranium-238 into plutonium-239 in
| |
| − | significant quantities, so that much into plutonium-239 in
| |
| − | significant quantities, so that much more energy can be extracted
| |
| − | from natural uranium than is possible with thermal reactors.
| |
| − | | |
| − |
| |
| − | There are two important features of fast breeder
| |
| − | reactors. Firstly, there is no moderator. The neutrons given off in
| |
| − | the fission reaction are not slowed down. ( It is for this reason
| |
| − | that this type of reactor is known as a fast reactor.
| |
| − | | |
| − |
| |
| − | Secondly, the fuel elements of fast reactors
| |
| − | contain a mixture of plutonium-239 and uranium-238. Plutonium is
| |
| − | placed in the centre of the core, whereas the uranium-238 is located
| |
| − | in a blanket surrounding the plutonium core. Two processes take
| |
| − | place simultaneously in these reactors:
| |
| − | | |
| − |
| |
| − | (i)Plutonium-239 (originally produced from some of
| |
| − | the uranium-238 atoms) in thermal reactors is fissioned, producing
| |
| − | heat which is removed by the coolant. Since the heat produced in the
| |
| − | core is very large, the coolant used in a fast reactor is liquid
| |
| − | sodium.
| |
| − | | |
| − |
| |
| − | (ii)A significant proportion of uranium-238 is
| |
| − | converted into plutonium in the blanket. In fact more plutonium is
| |
| − | bred in the blanket than is fissioned in the core, and for this
| |
| − | reason, fast reactors are known as fast breeder reactors.
| |
| − | Plutonium-239 atoms are created when uranium-238 atoms absorb fast
| |
| − | moving neutrons.
| |
| − | | |
| − |
| |
| − | === Spent fuel ===
| |
| − |
| |
| − | In both thermal and fast reactors, the spent fuel
| |
| − | elements contain three types of material: (i)highly radioactive
| |
| − | fission products; (ii)large amounts of unused uranium-238, known as
| |
| − | ‘depleted’ uranium; and (iii) a certain among of plutonium. By
| |
| − | reprocessing the fission products from spent fuel, the plutonium and
| |
| − | depleted uranium can be fabricated into new fuel elements for fast
| |
| − | reactors. By repeated processes through fast reactors followed by
| |
| − | reprocessing, it is possible to extract much more energy than when
| |
| − | using only thermal reactors. 1 tonne of natural uranium fissioned in
| |
| − | a thermal reactor is equivalent to about 20,000 tonnes of coal. Used
| |
| − | in fast reactors, however, 1 tonne of natural uranium is equivalent
| |
| − | to about 1,000,000 tonnes of coal.
| |
| − | | |
| − |
| |
| − | == Nuclear Fusion ==
| |
| − |
| |
| − | What is happening inside the sun?
| |
| − | | |
| − |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_m413290ce.jpg]]The
| |
| − | sun consists mainly of hydrogen gas. The atoms of hydrogen under
| |
| − | tremendous pressure at the centre of the sun, come together and fuse
| |
| − | to for helium nucleus along with the liberation of tremendous energy
| |
| − | in the form of heat and light. It this energy which maintains its
| |
| − | temperature and makes the sun shine. In this process again, like in
| |
| − | nuclear fission, mass is converted into energy. This is also the
| |
| − | principle on which the hydrogen bomb is based. Since the various
| |
| − | reactions taking place inside the sun occur at very high
| |
| − | temperatures, they are called thermonuclear reactions. The sun,
| |
| − | therefore, may be considered as a thermonuclear furnace where
| |
| − | hydrogen atoms are continuously being fused into helium atoms. Mass
| |
| − | lost during these fusion reactions Is converted into energy.
| |
| − | | |
| − |
| |
| − | The process of nuclear fission involves the
| |
| − | splitting of a heavy nucleus while the nuclear fusion is the joining
| |
| − | together of lighter atoms to form heavier ones. Both the processes,
| |
| − | however, release tremendous amounts of energy.
| |
| − | | |
| − |
| |
| − | There are several possible reactions in which
| |
| − | light atoms can fuse r form heavier nuclei and release energy, but
| |
| − | the one which the scientists which have been trying to accomplish is
| |
| − | the thermonuclear reaction involving deuterium and tritium nuclei and
| |
| − | not hydrogen nuclei. This is due to the fact that though ordinary
| |
| − | hydrogen is the raw material for the thermonuclear process in the
| |
| − | sun, its reaction rate is quite slow. Reactions involving deuterium
| |
| − | nuclei or deuterium and tritium nuclei are more efficient. Fusion of
| |
| − | two nuclei of deuterium of deuterium forms a tritium and a hydrogen
| |
| − | nuclei while the fusion of a deuterium and a tritium nuclei forms a
| |
| − | helium nucleus with two protons and two neutrons.
| |
| − | | |
| − |
| |
| − | For the above reactions to take place, the
| |
| − | colliding deuterium nuclei should have enormous speed. This is made
| |
| − | possible by heating the particles to a few hundred million degrees.
| |
| − | Remember, much below this temperature, the atoms are already stripped
| |
| − | of their electrons. Thus they form a mixture of positively charged
| |
| − | ions and electrons known as plasma.
| |
| − | | |
| − |
| |
| − | If one can fuse all the nuclei in 1 gram of
| |
| − | deuterium, it would yield 100,000 kWh of energy. A complete fission
| |
| − | of an equivalent amount of uranium, on the other hand will give
| |
| − | 25,000kWh.
| |
| − | | |
| − |
| |
| − | === Fusion Reactors ===
| |
| − |
| |
| − | Despite its tremendous potential there are many
| |
| − | technical problems in building a practical fusion reactor. One major
| |
| − | problem is the confinement and control of plasma at more than a
| |
| − | hundred million degrees so that thermonuclear energy could be made
| |
| − | available at a steady rate. One very successful method to confine
| |
| − | the plasma in a magnetic field.
| |
| − | | |
| − |
| |
| − | Among other alternatives being tried for
| |
| − | harnessing nuclear fusion is one by using lasers. A laser is a
| |
| − | highly powerful beam of coherent beam of coherent light which can be
| |
| − | focused on a very small spot. In this method, called inertial
| |
| − | fusion, pellets of deuterium-tritium fuel are rapidly compressed and
| |
| − | heated by bombardment with laser beams, resulting in a series of
| |
| − | miniature thermonuclear explosions and production of energy.
| |
| − | | |
| − |
| |
| − | One of the most serious problems in the nuclear
| |
| − | fusion process is the fact that large amounts of tritium is only
| |
| − | weakly radioactive, its chemical behavior is exactly the same as
| |
| − | ordinary hydrogen and it can readily enter into organic substances.
| |
| − | Control of tritium will be one of the major problems in the operation
| |
| − | of the fusion reactors.
| |
| − | | |
| − |
| |
| − | There are many advantages of fusion power. The
| |
| − | fuel supply is plentiful and relatively inexpensive.
| |
| − | | |
| − |
| |
| − | The world’s oceans constitute an inexhaustible
| |
| − | source of the primary fuel deuterium in the form of water; about one
| |
| − | molecule out of every 3,000 water molecules contains an atom of
| |
| − | deuterium. The products of fusion reactions are either stable
| |
| − | isotopes or they are only weakly radioactive. Radioactivity will
| |
| − | also be produced by the neutrons released in the reactions when they
| |
| − | are captured in the materials of the reactor.
| |
| − | | |
| − |
| |
| − | Further, fusion reactors do not produce air
| |
| − | pollutants that contribute to acid rain or global warming. Despite
| |
| − | these advantages, however, immense difficulties are yet to be
| |
| − | overcome before energy generation can become feasible on a large
| |
| − | scale.
| |
| − | | |
| − |
| |
| − | == Additional web resources ==
| |
| − |
| |
| − | ''1)
| |
| − | hyperphysics.phy-astr.gsu.edu/hbase/nucene/'''''''fission'''''''.html''
| |
| − | - [[Cached]]
| |
| − | - [[Similar]]
| |
| − | | |
| − |
| |
| − | ''2)
| |
| − | phet.colorado.edu/en/simulation/'''''''nuclear'''''''-'''''''fission'''''
| |
| − | - [[Cached]]
| |
| − | - [[Similar]]
| |
| − | | |
| − |
| |
| − | ''3)
| |
| − | www.whatis'''''''nuclear'''''''.com/articles/nuc'''''''reactor'''''''.html''
| |
| − | - [[Cached]]
| |
| − | - [[Similar]]
| |
| − | | |
| − |
| |
| − | ''4)
| |
| − | ''[[http://www.youtube.com/watch?v=SePyzzRiE5U]]
| |
| − | | |
| − |
| |
| − | ''5)
| |
| − | ''[[http://www.youtube.com/watch?v=e-0Jf-zuG4s]]
| |
| − | | |
| − |
| |
| − | ''6)
| |
| − | ''[[http://www.youtube.com/watch?v=zDGcD8Ix9Ek]]
| |
| − | | |
| − |
| |
| − | ''7)
| |
| − | www.whatis'''''''nuclear'''''''.com/articles/nuc'''''''reactor'''''''.html''
| |
| − | - [[Cached]]
| |
| − | - [[Similar]]
| |
| − | | |
| − |
| |
| − | ''8)
| |
| − | www.westinghouse'''''''nuclear'''''''.com/.../WhatIs'''''''NuclearEnergy'''''''.shtm''
| |
| − | - [[Cached]]
| |
| − | – [[Similar]]
| |
| − | | |
| − |
| |
| − | ''9)
| |
| − | www.india'''''''nuclearenergy'''''''.net/''
| |
| − | - [[Cached]]
| |
| − | - [[Similar]]
| |
| − | | |
| − |
| |
| − | = Energy and the environment =
| |
| − |
| |
| − | Modern society cannot exist without the production
| |
| − | and utilization of energy. Every month we have to pay direct charges
| |
| − | for use of electricity. Oil and gas in our homes and for the petrol
| |
| − | used in our cars. And there are also indirect charges that we pay
| |
| − | for the energy used in manufacturing processes and for the
| |
| − | transportation of the goods that we buy. In addition to these
| |
| − | charges, w pay also in terms of the effects that energy production
| |
| − | and energy utilization have on our world in terms of environment
| |
| − | pollution. Environmental pollution may be defined as the unfavorable
| |
| − | alteration of our surroundings. It may not be possible to estimate
| |
| − | monetary losses or many of the side effects associated with energy
| |
| − | production and energy utilization. What is the value of the health
| |
| − | impairment, for example, caused by the cars exhaust fumes? What value
| |
| − | do we place on the destruction of farmland and pollution of water
| |
| − | caused by strip mining for coal? What value is associated with the
| |
| − | loss of seaside beaches because of oil pills washing ashore? As a
| |
| − | matter of fact, as long as we continue to produce and utilize energy,
| |
| − | we will have to pay for these undesirable side effects. How much are
| |
| − | we willing to pay?
| |
| − | | |
| − |
| |
| − | == Threats from Fossil fuels ==
| |
| − |
| |
| − | Most of the energy that is generated throughout
| |
| − | the world at present is derived from the burning of fossil
| |
| − | fuels-coal, natural gas and petroleum products. There are numerous
| |
| − | environment problems associated with the extraction, transportation
| |
| − | and utilization of fossil fuels.
| |
| − | | |
| − |
| |
| − | The most plentiful fuel source in the world is
| |
| − | coal. The highest quality coal(anthracite generally occurs
| |
| − | sufficiently far underground to require high-cost deep-mining
| |
| − | techniques. Further, anthracite generally contains a very high
| |
| − | percentage of sulphur and it cannot be used as a fuel without
| |
| − | expensive treatment to remove sulphur. Consequently in recent years,
| |
| − | there has been increased interest in the mining of lower quality but
| |
| − | relatively sulphur-free coal that lies close to the surface.
| |
| − | Strip-mining techniques are used for the extraction of this coal.
| |
| − | Strip mining for coal causes serious and continuing environmental
| |
| − | problems. One of the most serious problems associated with the
| |
| − | strip-mining of coal is the huge amount of land that is torn up in
| |
| − | the process. Unless rehabilitation measures are taken, the area
| |
| − | adjoining the strip mined land can suffer from landslides, erosion
| |
| − | and sedimentation.
| |
| − | | |
| − |
| |
| − | Unlike coal, the extraction of oil does not
| |
| − | desecrate the land the way the strip-mining does. However, the most
| |
| − | serious environmental problem associated with oil-well drilling
| |
| − | occurs at offshore sites. Because of the many technical difficulties
| |
| − | inherent in offshore drilling, if a rupture occurs or if the drilling
| |
| − | opens a crack in the rock that contains the oil deposit, a major
| |
| − | leakage of oil into the water can occur before the damage is repaired
| |
| − | or the crack is sealed. The release of large amounts of oil into the
| |
| − | water can be injurious to the marine life. When the oil spreads over
| |
| − | water, the diffusion of oxygen into water is inhibited. This affects
| |
| − | the respiration of fish and other marine life. Oil pollution of sea
| |
| − | causes either problems too. Oil is pushed to the shore by the water
| |
| − | currents and winds, thereby spoiling the beaches.
| |
| − | | |
| − |
| |
| − | == Combustion of fuel ==
| |
| − |
| |
| − | The burning of fossil fuels releases a variety of
| |
| − | noxious gases and particulate matter into the atmosphere. The major
| |
| − | contributors to this atmospheric pollution are coal and oil and
| |
| − | natural gas by far is the least offensive of the fossil fuels , One
| |
| − | of the major problems with coal and oil is the presence of sulphur.
| |
| − | Depending upon the source, the sulphur content can be up to several
| |
| − | percent and upon combustion several oxides (particularly sulphur
| |
| − | dioxide) are produced. When sulphur dioxide is released into the
| |
| − | atmosphere, it combines with water vapour and forms sulphuric acid.
| |
| − | It is this sulphuric acid which is injurious to plant and animal
| |
| − | life. It has been found that atmospheric sulphuric acid eating the
| |
| − | limestone facings of many monuments and public buildings in urban
| |
| − | life. Sulphur dioxide is believed to cause cough, shortness of
| |
| − | breath and spasm of the larynx. It can cause acute irritation to the
| |
| − | membranes of the eyes resulting in excessive flow tears and redness.
| |
| − | When absorbed by plants beyond a certain level the plants cells
| |
| − | become inactive and are killed, resulting in tissue collapse and
| |
| − | drying of leaves. Sulphur dioxide is also known to interfere with
| |
| − | the respiratory and photosynthesis in plants.
| |
| − | | |
| − |
| |
| − | The burning of petrol in internal combustion
| |
| − | engines is the major source of carbon monoxide, nitrogen dioxides and
| |
| − | hydrocarbons in the atmosphere. In addition, there are large
| |
| − | quantities of lead which are released into the atmosphere from high
| |
| − | octane petrol used in cars. All these pollutants and the products of
| |
| − | the photochemical reactions they undergo in presence of sunlight
| |
| − | contribute to the noxious known as smog. There seems at present no
| |
| − | escape from the health hazards of smog until some effective way is
| |
| − | found to remove the pollutants from the vehicular exhaust gases.
| |
| − | | |
| − |
| |
| − | '''Effects of carbon Dioxide and carbon Monoxide:
| |
| − | '''
| |
| − | | |
| − |
| |
| − | The consumption of oxygen and the
| |
| − | formation of carbon dioxide are necessary consequences of every
| |
| − | combustion process. One may think that this may deplete the world’s
| |
| − | supply of oxygen and thus upset the oxygen-carbon dioxide balance
| |
| − | that is necessary for plant and animal life.
| |
| − | | |
| − |
| |
| − | Carbon dioxide molecules strongly absorb heat
| |
| − | radiations emitted from the surface of the earth heated by the sun.
| |
| − | By holding back this energy in the earth’s atmosphere, carbon
| |
| − | dioxide reduces the heat lost by the earth to space. This is called
| |
| − | ‘greenhouse effect’ and because of this, it is argued, the
| |
| − | continued burning of fossil fuels will result in a steady increase in
| |
| − | the earth’s surface temperature. However, an increasing in the
| |
| − | temperature of the earth’s surface and lower atmosphere has the
| |
| − | compensating effect of increasing evaporation and cloudiness.
| |
| − | Because clouds reflect some of the incident sunlight, increases in
| |
| − | cloudiness tend to decrease the surface temperature. Further, the
| |
| − | release of particulate matter into the atmosphere from fuel burning
| |
| − | increases the number of condensation sites around which water
| |
| − | droplets can form. The result is an increase in the amount of rain,
| |
| − | hail and thunderstorms which lead to the lowering of the temperature.
| |
| − | The amount of carbon dioxide is regulated by the presence of the
| |
| − | ocean waters which 60 times as much carbon dioxide as does the
| |
| − | atmosphere and absorbs a large fraction of the carbon dioxide
| |
| − | released by the burning of fuels. Also, the increased level of
| |
| − | carbon dioxide in the atmosphere actually stimulates a more rapid
| |
| − | growth of plants. This increased utilization of carbon dioxide
| |
| − | further reduces the atmospheric excess. Thus the role of carbon
| |
| − | dioxide in influencing the world’s climate is quite a complex one.
| |
| − | | |
| − |
| |
| − | Carbon monoxide is another pollutant produced by
| |
| − | burning of fossil fuel. It is usually produced when there is
| |
| − | insufficient oxygen for burning. It is released into the atmosphere
| |
| − | mainly from automobile exhaust gases. But it does not so far
| |
| − | constitute a serious environmental problem.
| |
| − | | |
| − |
| |
| − | == Thermal pollution ==
| |
| − |
| |
| − | The term ‘thermal pollution' basically refers to
| |
| − | the detrimental effects of discharges of unwanted heat into the
| |
| − | environment. All electricity generating plants produce electricity
| |
| − | by driving huge turbine generators with steam. The steam is
| |
| − | condensed in a cooling system and is cycled back to the heating unit
| |
| − | for reuse. The cooling system can be water that is pumped from some
| |
| − | nearby reservoir and discharged back into it, or it can be a cooling
| |
| − | tower in which the heat is dissipated into the atmosphere. Both
| |
| − | cause thermal pollution. If the heated water is discharged into a
| |
| − | static reservoir, such as a lake, the effect can be even more
| |
| − | severe. The thermal is generated by the energy producer as well as
| |
| − | the energy user. Almost all of the energy we use is eventually
| |
| − | converted into heat. Most of this waste is dissipated into the air
| |
| − | where it contributes to the general atmospheric heating.
| |
| − | | |
| − |
| |
| − | == Effects of Nuclear Radiations ==
| |
| − |
| |
| − | Nuclear reactors, unlike the other sources of
| |
| − | power, offer a lot of advantage. Nuclear reactors generate
| |
| − | electrical power without the smoke and fumes that are characteristic
| |
| − | of fossil fuel-burning plants. Also the mining of uranium produces
| |
| − | much less degradation of the countryside than the mining of fossil
| |
| − | fuels, particularly coal. Nuclear reactors, therefore, offer the
| |
| − | prospect of long term relatively clean power. However, nuclear
| |
| − | reactors have their own peculiar set of disadvantages, mainly
| |
| − | associated with the production of radioactive materials. Some
| |
| − | radioactive waste is released into the environment both gases into
| |
| − | the atmosphere and in the form of low activity waste such as tritium
| |
| − | in cooling water.
| |
| − | | |
| − |
| |
| − | All radioactive substances emit harmful
| |
| − | radiations, some of which can cause cancer in man and animals and
| |
| − | damage the genetic material of the cell, producing long term harmful
| |
| − | effects in living organisms. However, modern nuclear reactors are
| |
| − | quite safe. An individual living near a nuclear reactor is exposed
| |
| − | much less to its emitted radiation than what one gets from X-rays and
| |
| − | natural sources.
| |
| − | | |
| − |
| |
| − | = Energy and the future =
| |
| − |
| |
| − | The worldwide demand for energy is increasing day
| |
| − | by day. The increasing use of modern means of transport-cars, buses,
| |
| − | trains, aero planes , ships, etc., the rapid rise in the overall
| |
| − | industrialization; the tremendous growth in population, particularly
| |
| − | in the last 40 years, are some of the factors that have led to a
| |
| − | tremendous spurt in mankind’s energy requirements. Since all this
| |
| − | energy has to come from the energy sources available on this planet,
| |
| − | scientists have calculated that the world’s present known stocks of
| |
| − | fossil fuels may not last for more than a 100 years or so.
| |
| − | | |
| − |
| |
| − | == Need for Judicious Use of energy ==
| |
| − |
| |
| − | It follows therefore that mankind has to adopt a
| |
| − | judicious approach towards consumption of energy sources to ensure
| |
| − | that these are not depleted too fast. This approach needs to be
| |
| − | supplemented by optimum utilization of our natural sources. We have,
| |
| − | for example, reserves of billions of tones of coal spread across the
| |
| − | Bihar, West Bengal and Orissa region. This coal may not be of the
| |
| − | best quality, but coal mining in this area can always be stepped up
| |
| − | to meet our energy requirements. In India, technology used is coal
| |
| − | mining and handling after it is mined is still primitive where
| |
| − | mechanical wheels are used in open pit mining. Any improvement in
| |
| − | material handling system can lead to a saving of a lot of coal which
| |
| − | is otherwise lost'''.'''
| |
| − | | |
| − |
| |
| − | One source of energy which has remained
| |
| − | underutilized is the hydroelectric energy. The subcontinent has many
| |
| − | large rivers with substantial hydroelectric potential, much of which
| |
| − | still remains unutilized. These can be tapped to provide energy
| |
| − | which is clean, renewable and cheap. Large numbers of small
| |
| − | hydroelectric power projects across the country over the country over
| |
| − | small rivers could also yields a fair amount of energy.
| |
| − | | |
| − |
| |
| − | Wind energy has a tremendous scope as alternative
| |
| − | source of energy not only in India but the entire region stretching
| |
| − | from Afghanistan to Vietnam. Wind electric generators are at present
| |
| − | operating successfully in many parts of India. Windmills are also
| |
| − | being used for pumping water and this use of windmills should be
| |
| − | encouraged. If India develops a system whereby windmills and
| |
| − | generators could be manufactured on a large scale, it will really be
| |
| − | a tremendous boon to the rural economy of this vast region. Wind
| |
| − | energy is a non-polluting, cheap, renewable source of energy.
| |
| − | | |
| − |
| |
| − | A substantial portion of our energy requirements
| |
| − | is met by firewood. It necessitates felling of trees, resulting in
| |
| − | deforestation, soil erosion, and floods. To prevent this and to
| |
| − | maintain the stability of forest reserves a massive afforestation
| |
| − | programme is necessary. The use of firewood as fuel must be avoided
| |
| − | as far as possible by encouraging the use of biogas plants. Benefits
| |
| − | accruing from biogas plants are immense and manifold. Biogas plant
| |
| − | generate but only substantial economic gains to the country but also
| |
| − | help up gradation of the environment. As India is dependent on
| |
| − | imported oil for meeting its energy requirements, it would be prudent
| |
| − | to reduce the consumption of petroleum products. These are primarily
| |
| − | used for road and rail transport. The industry uses a large quantity
| |
| − | of petroleum products both as raw material and also as fuel. There is
| |
| − | tremendous scope for reducing the consumption of diesel and petrol in
| |
| − | cars, trucks and two wheelers by more efficient engine design and
| |
| − | maintenance.
| |
| − | | |
| − |
| |
| − | It is indeed a good news that India has vast
| |
| − | reserves of natural gas which is a very clean source of energy. The
| |
| − | Bombay High oilfields contain very large quantities of gas which at
| |
| − | present are flared or burnt. Only recently are efforts being made to
| |
| − | utilize natural gas commercially, for generating power and production
| |
| − | of fertilizer. Especially in the north east. The Dutch and the
| |
| − | British have found vast reserves of offshore natural gas and in the
| |
| − | process have developed new technology to utilize it.
| |
| − | | |
| − |
| |
| − | == Minimizing Wastage ==
| |
| − |
| |
| − | Not only have we to adopt a judicious approach to
| |
| − | using our energy sources, we have also to lay a great stress on
| |
| − | prevention of wastage. Even a casual look at our day-today
| |
| − | activities reveals that energy is wasted in many ways. Careless
| |
| − | habits, like leaving the lights and fans on when no one is round,
| |
| − | keeping the car or scooter engine on while gossiping with a friend on
| |
| − | the road, etc. contribute to wastage of energy. We have to know
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| − | about the various ways in which energy is wasted at home and in
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| − | industries, and then develop-and encourage others to develop-proper
| |
| − | design and also ensure that all machinery is kept well maintained and
| |
| − | in proper running condition. This helps save a lot of energy. With
| |
| − | the impending energy crisis facing mankind, saving ‘every bit of
| |
| − | energy ‘ is of great importance. This saved energy can then be put
| |
| − | to some useful ‘use’ in future. WE must remember energy saved is
| |
| − | energy produced.
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| − | | |
| − |
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| − | | |
| − | | |
| − | | |
| − |
| |
| − | == Additional web resources ==
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| − |
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| − | '''1)video.nationalgeographic.com/video/.../energy.../alternative-energy.html
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| − | '''
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| − | | |
| − |
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| − | 2)
| |
| − | ''en.wikipedia.org/wiki/'''''''Waste'''''''_minimisation''
| |
| − | - [[Cached]]
| |
| − | - [[Similar]]
| |
| − | | |
| − |
| |
| − | 3) www.youtube.com/watch?v=FBTXQV7GKow
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| − | | |
| − |
| |
| − | ''4)
| |
| − | www.streetdirectory.com/.../''''energy''''-''''crisis-in-india''''-aouac.html''
| |
| − | - [[Cached]]
| |
| − | - [[Similar]]
| |
| − | | |
| − |
| |
| − | = Activities =
| |
| − |
| |
| − | Winding
| |
| − | the main spring of the time piece, once wound keeps unwinding and
| |
| − | driving the clockwork mechanism for many hours. The energy stored in
| |
| − | the coiled spring is potential energy.
| |
| − | | |
| − |
| |
| − | In
| |
| − | a catapult, the rubber band is stretched and make the pebble let go.
| |
| − | Energy is stored (potential) when the rubber is in stretched
| |
| − | condition. When it is released, it is this stored energy that is
| |
| − | converted into the kinetic energy which makes the pebble go far and
| |
| − | fast. potential energy.
| |
| − | | |
| − |
| |
| − | = Evaluation =
| |
| − |
| |
| − | # What is work?When do we say that work is done?
| |
| − | # What are kinetic and potential energy?
| |
| − | # What are the different forms of energy?
| |
| − | # What is power?
| |
| − | # What are the units of energy?
| |
| − | # What are fossil fuels?How are they formed?
| |
| − | # What are the different steps to process the petroleum?
| |
| − | # What is Biomass energy? How it is generated?
| |
| − | # What are the different sources of non -conventional energy?
| |
| − | # What are the different ways of harnessing solar energy?
| |
| − | # Name the different non conventional sources of energy.
| |
| − | # Name the different storage devices.
| |
| − | # What are isotopes? Name some isotopes.
| |
| − | # Draw the diagrams of the nuclear reactors-thermal and fast breed
| |
| − | # How are fossil fuels threatening us?
| |
| − | # What are the effects of Carbon Dioxide and Carbon Monoxide?
| |
| − | # How are nuclear radiations affect out environment?
| |
| − | # What is the need for judicious use of available energy?
| |
| − | # List some steps to minimize energy
| |
| − |
| |
| − | = Additional Information =
| |
| − |
| |
| − | Energy requirements for various
| |
| − | Activities
| |
| − | | |
| − |
| |
| − | '''( in kilocalories/hour)'''
| |
| − | | |
| − |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_79ae7f48.gif]]
| |
| − | | |
| − | | |
| − |
| |
| − | Light work
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| − | Moderate work
| |
| − | | |
| − |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_79ae7f48.gif]]Sitting
| |
| − | 19 Shoe making 80-115
| |
| − | | |
| − |
| |
| − | Writing
| |
| − | 20 Sweeping 85-110
| |
| − | | |
| − |
| |
| − | Standing relaxed 20 Dusting
| |
| − | 110
| |
| − | | |
| − |
| |
| − | Typing 16-40 Washing
| |
| − | 125-215
| |
| − | | |
| − |
| |
| − | Typing quickly 55 Charring
| |
| − | 80-160
| |
| − | | |
| − |
| |
| − | Sewing 30-90 Metal
| |
| − | working 120-140
| |
| − | | |
| − |
| |
| − | Dressing and
| |
| − | Carpentering 150-180
| |
| − | | |
| − |
| |
| − | Undressing
| |
| − | 33 House painting 145-240
| |
| − | | |
| − |
| |
| − | Drawing 40-50 Walking
| |
| − | 130-
| |
| − | | |
| − |
| |
| − | Violin playing 40-50
| |
| − | | |
| − |
| |
| − | Tailoring 50-85
| |
| − | | |
| − |
| |
| − | Ironing 60
| |
| − | | |
| − |
| |
| − | Washing dishes 60
| |
| − | | |
| − |
| |
| − | Book binding 45-90
| |
| − | | |
| − |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_36b949c8.gif]]
| |
| − | | |
| − | | |
| − |
| |
| − | Hard work
| |
| − | Very Hard work
| |
| − | | |
| − |
| |
| − | [[File:Energy_Resource_Material_Subject_Teacher_Forum_September_2011_html_3c3aa152.gif]]Polishing
| |
| − | 175 Stone masonry 350
| |
| − | | |
| − |
| |
| − | Joiner work 195 Sawing wood
| |
| − | 420
| |
| − | | |
| − |
| |
| − | Blacksmithing 275-350 Coal mining
| |
| − | 320
| |
| − | | |
| − |
| |
| − | Riveting 275 Running
| |
| − | 800-1,000
| |
| − | | |
| − |
| |
| − | Marching 280-400 Climbing 400-900
| |
| − | | |
| − |
| |
| − | Cycling 180-600 Walking very
| |
| − | quickly 570
| |
| − | | |
| − |
| |
| − | Rowing 120-600 Rowing very
| |
| − | quickly 1,240
| |
| − | | |
| − |
| |
| − | Swimming 200-700 Running very
| |
| − | quickly 1,240
| |
| − | | |
| | | | |
| − | Skiing 500-9[[File:50
| + | <br> |
| | + | <br> |
| | | | |
| | | | |
| − | Wrestling 1,000
| + | [[Image:Energy%20for%20KOER_html_m798592ab.gif]]<u>Keywords |
| | + | – Work, Energy, Power, Kinetic Energy, Potential Energy, Law of |
| | + | Conservation of Energy, Thermodynamics, Biomass, Fossil Fuel, |
| | + | Combined Cycle Power Generation</u> |
