ENERGY PORTION READING MATERIAL FOR EES

UNIT 1

Contents

List of Figures iv

List of Table v

1 Classi�cation of various energy sources 1

1.1 Introduction: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Primary and Secondary Energy: . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3 Commercial Energy and Non Commercial Energy: . . . . . . . . . . . . . . . 3

1.4 Renewable and Non-Renewable Energy: . . . . . . . . . . . . . . . . . . . . . 4

1.5 Conventional and Non-conventional Energy sources: . . . . . . . . . . . . . . 5

2 Energy Scenario: 6

2.1 Global Primary Energy Reserves: . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.1 Coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.2 Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.3 Natural gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.2 Indian Energy Scenario: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.2.1 Coal and Lignite: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.2.2 Petroleum and natural gas: . . . . . . . . . . . . . . . . . . . . . . . 8

2.2.3 Renewable energy sources : . . . . . . . . . . . . . . . . . . . . . . . . 9

2.2.4 Installed generating capacity of electricity : . . . . . . . . . . . . . . . 11

3 Basics of Energy 15

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2 Various Forms of Energy: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2.1 Potential Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

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3.2.1.1 Gravitational Energy . . . . . . . . . . . . . . . . . . . . . . 16

3.2.1.2 Elastic potential energy . . . . . . . . . . . . . . . . . . . . 16

3.2.1.3 Chemical energy . . . . . . . . . . . . . . . . . . . . . . . . 16

3.2.1.4 Electric potential energy . . . . . . . . . . . . . . . . . . . . 16

3.2.1.5 Nuclear Energy . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.2.2 Kinetic Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.2.2.1 Radiant Energy . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.2.2.2 Thermal Energy . . . . . . . . . . . . . . . . . . . . . . . . 19

3.2.2.3 Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.2.2.4 Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.2.2.5 Electrical Energy . . . . . . . . . . . . . . . . . . . . . . . . 20

3.2.3 Grades of Energy; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.2.3.1 High-Grade Energy . . . . . . . . . . . . . . . . . . . . . . . 20

3.2.3.2 Low-Grade Energy . . . . . . . . . . . . . . . . . . . . . . . 21

3.2.4 Basic Numerical to �nd units of power consumption . . . . . . . . . . 21

4 Bibliography 24

iii

List of Figures

1.1 Major primary and secondary sources . . . . . . . . . . . . . . . . . . . . . . 3

1.2 Renewable and Non renewable energy . . . . . . . . . . . . . . . . . . . . . . 4

2.1 Estimated reserves of Coal in India . . . . . . . . . . . . . . . . . . . . . . . 7

2.2 Estimated Reserves of Crude Oil in India . . . . . . . . . . . . . . . . . . . . 8

2.3 Estimated reserves of Natural Gas in India . . . . . . . . . . . . . . . . . . . 9

2.4 Sourcewise Estimated potential of renewable power in India . . . . . . . . . 10

2.5 Statewise Estimated potential of renewable power in India . . . . . . . . . . 10

2.6 Gas Pipeline Network of India . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.7 Coal �eld and lignite occourance of India . . . . . . . . . . . . . . . . . . . . 13

2.8 Nuclear power Reactors in operation and Construction . . . . . . . . . . . . 14

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List of Tables

v

Chapter 1

Classi�cation of various energy sources

1.1 Introduction:

Energy is the capacity of a physical system to perform work. Energy exists in several formssuch as heat, kinetic or mechanical energy, light, potential energy, electrical, or other forms.According to the law of conservation of energy, the total energy of a system remains constant,though energy may transform into another form. Two billiard balls colliding, for example,may come to rest, with the resulting energy becoming sound and perhaps a bit of heat atthe point of collision.

Energy, like mass, is a scalar physical quantity. The joule is the International System ofUnits (SI) unit of measurement for energy. It is a derived unit of energy, work, or amountof heat. It is equal to the energy expended (or work done) in applying a force of one newtonthrough a distance of one meter. However energy is also expressed in many other units suchas ergs, calories, British Thermal Units, kilowatt-hours and kilo calories for instance. Thereis always a conversion factor for these to the SI unit; for instance; one kWh is equivalent to3.6 million joules

Energy is one of the major inputs for the economic development of any country. In thecase of the developing countries, the energy sector assumes a critical importance in view ofthe ever increasing energy needs requiring huge investments to meet them. Energy can beclassi�ed into several types based on the following criteria:

•Primary and Secondary energy

•Commercial and Non commercial energy

•Renewable and Non-Renewable energy

1.2 Primary and Secondary Energy:

Primary energy sources are those that are either found or stored in nature. Common primaryenergy sources are coal, oil, natural gas, and biomass (such as wood). Other primary energy

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sources available include nuclear energy from radioactive substances, thermal energy storedin earth's interior, and potential energy due to earth's gravity. Primary energy is an energyform found in nature that has not been subjected to any conversion or transformation process.It is energy contained in raw fuels, and other forms of energy received as input to a system.Primary energy can be non-renewable or renewable.

Primary energy sources are transformed in energy conversion processes to more convenientforms of energy (that can directly be used by society), such as electrical energy, re�nedfuels, or synthetic fuels such as hydrogen fuel. In the �eld of energetics, these forms arecalled energy carriers and correspond to the concept of "secondary energy" in energy statis-tics. Energy carriers are energy forms which have been transformed from primary energysources. Electricity is one of the most common energy carriers, being transformed fromvarious primary energy sources such as coal, oil, natural gas, and wind.

The major primary and secondary energy sources are shown in Figure 1.1 Primary energysources are mostly converted in industrial utilities into secondary energy sources; for examplecoal, oil or gas converted into steam and electricity. Primary energy can also be used directly.Some energy sources have non-energy uses, for example coal or natural gas can be used as afeedstock in fertilizer plants.

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Figure 1.1: Major primary and secondary sources

1.3 Commercial Energy and Non Commercial Energy:

Commercial Energy:

The energy sources that are available in the market for a de�nite price are known as commer-cial energy. By far the most important forms of commercial energy are electricity, coal andre�ned petroleum products. Commercial energy forms the basis of industrial, agricultural,transport and commercial development in the modern world. In the industrialized countries,commercialized fuels are predominant source not only for economic production, but also formany household tasks of general population. Examples: Electricity, lignite, coal, oil, naturalgas etc.

Non-Commercial Energy:

The energy sources that are not available in the commercial market for a price are classi�ed asnon-commercial energy. Non-commercial energy sources include fuels such as �rewood, cattle

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dung and agricultural wastes, which are traditionally gathered, and not bought at a priceused especially in rural households. These are also called traditional fuels. Non-commercialenergy is often ignored in energy accounting. Example: Firewood, agro waste in rural areas;solar energy for water heating, electricity generation, for drying grain, �sh and fruits; animalpower for transport, threshing, lifting water for irrigation, crushing sugarcane; wind energyfor lifting water and electricity generation.

1.4 Renewable and Non-Renewable Energy:

Renewable energy is generally de�ned as energy that comes from resources which are natu-rally replenished on a human timescale. Renewable energy replaces conventional fuels in fourdistinct areas: electricity generation, hot water/space heating, motor fuels, and rural (o�-grid) energy services. Renewable energy is energy obtained from sources that are essentiallyinexhaustible. Examples of renewable resources include wind power, solar power, geothermalenergy, tidal power and hydroelectric power (See Figure 1.2). The most important featureof renewable energy is that it can be harnessed without the release of harmful pollutants.

A non-renewable resources of energy are resources that does not renew itself at a su�cientrate for sustainable economic extraction in meaningful human timeframes. An example iscarbon-based, organically-derived fuel. The original organic material, with the aid of heatand pressure, becomes a fuel such as oil or gas. Fossil fuels (such as coal, petroleum, andnatural gas), and certain aquifers are all non-renewable resources. Non-renewable energy isthe conventional fossil fuels such as coal, oil and gas, which are likely to deplete with time.

Figure 1.2: Renewable and Non renewable energy

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1.5 Conventional and Non-conventional Energy sources:

Conventional Energy

Energy that has been used from ancient times is known as conventional energy. The con-ventional sources of energy are generally non-renewable sources of energy, which are beingused since a long time. These sources of energy are being used extensively in such a waythat their known reserves have been depleted to a great extent.

At the same time it is becoming increasingly di�cult to discover and exploit their newdeposits. It is envisaged at known deposits of petroleum in our country will get exhaustedby the few decades and coal reserves are expected to last for another hundred years. Thecoal, petroleum, natural gas and electricity are conventional sources of energy.

Non- Conventional Energy

Non -Conventional resources are relatively newer as comapred to conventional ones. Thoesesources of energy are generally renewable. Examples are solar energy, wind energy, tidalenergy, wave, biomass, geothermal and energy from waste etc. These sources are abundantin nature. But emphasis of producing energy(electricty) from these sources have started inrecent times.

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Chapter 2

Energy Scenario:

2.1 Global Primary Energy Reserves:

2.1.1 Coal

Proven reserves are those reserves claimed to have a reasonable certainty (normally at least90% con�dence) of being recoverable under existing economic and political conditions, withexisting technology. Industry specialists refer to this as P90 (i.e., having a 90% certainty ofbeing produced). Proven reserves are also known in the industry as 1P

Proved recoverable coal reserves at end-2008 shows that the largest reserves are found in theUnited States(22.6%), Russia(14.4%), China(12.6%), Australia(8.9%) and India(7%). ByIEA the top 10 coal producers in 2011 were (Mt): China 3,576 (46%), United States 1,004(13 %), India 586 (8%), Australia 414 (5 %), Indonesia 376 (5 %), Russia 334 (4 %), SouthAfrica 253 (3 %), Germany 189 (2 %), Poland 139 (2 %) and Kazakhstan 117 (2 %).

2.1.2 Oil

Oil reserves are the amount of technically and economically recoverable oil. Reserves may befor a well, for a reservoir, for a �eld, for a nation, or for the world. Di�erent classi�cations ofreserves are related to their degree of certainty. Based on data from OPEC at the beginning of2013 the highest proved oil reserves including non-conventional oil deposits are in Venezuela(20% of global reserves), Saudi Arabia (18% of global reserves), Canada (13% of globalreserves), and Iran (9%).

2.1.3 Natural gas

There is some disagreement on which country has the largest proven gas reserves. Sourcesthat list Russia as having by far the largest proven reserves include the US CIA (47.6 trillion

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cubic meters), the Oil and Gas Journal (47.8 tcm), the US Energy Information Administra-tion (47.8 tcm), and OPEC (48.7 tcm). However, BP credits Russia with only 32.9 tcm,which would place it in second place, slightly behind Iran (33.1 to 33.8 tcm, depending onthe source).

World oil and gas reserves are estimated at just 45 years and 65 years respectively.Coal is likely to last a little over 200 year. (a pdf �le is shared with you for yourreference to see the overview of global energy scenario).

2.2 Indian Energy Scenario:

2.2.1 Coal and Lignite:

Coal deposits are mainly con�ned to eastern and south central parts of the country. Thestates of Jharkhand, Odisha, Chhattisgarh, West Bengal, Andhra Pradesh, Maharashtra andMadhya Pradesh account for more than 99% of the total coal reserves in the country. As on31.03.12 the estimated reserves of coal was around 293.5 billion tones, an addition of 7.64billion over the last year ( Table 1.1). The total estimated reserve of coal in India as on31.03.11 was around 285.86 billion tonnes.

The estimated reserve of lignite as on 31.03.12 was 41.96 billion tonnes against 40.91 billiontonnes as on 31.03.11

Figure 2.1: Estimated reserves of Coal in India

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2.2.2 Petroleum and natural gas:

The estimated reserves of crude oil in India as on 31.03.2012 stood at 759.59 million tonnes(MT).Geographical distribution of Crude oil indicates that the maximum reserves are in theWestern O�shore (44.46%) followed by Assam (22.71%), whereas the maximum reserves ofNatural Gas are in the Eastern O�shore (34.73%) followed by Western o�shore (31.62%).There was an increase of 0.29% in the estimated reserve of crude oil for the country as awhole during 2011-12. There was an increase of estimated Crude Oil reserves by 7.09% inAndhra Pradesh followed by Tamil Nadu (4.48%).

Figure 2.2: Estimated Reserves of Crude Oil in India

The estimated reserves of natural gas in India as on 31.03.2012 stood at 1330.26 billioncubic meters (BCM). In case of Natural Gas, the increase in the estimated reserves over thelast year was 4.08%. The maximum contribution to this increase has been from Cold BedMethane(CBM) (11.32%), followed by Tripura (8.95%).

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Figure 2.3: Estimated reserves of Natural Gas in India

2.2.3 Renewable energy sources :

There is high potential for generation of renewable energy from various sources- wind, solar,biomass, small hydro and cogeneration bagasse. The total potential for renewable powergeneration in the country as on 31.03.12 is estimated at 89774 MW (Table 1.3). This includeswind power potential of 49130 MW (54.73%), SHP (small-hydro power) potential of 15399MW (17.15%), Biomass power potential of 17,538 MW(19.54%) and 5000 MW (5.57%) frombagasse-based cogeneration in sugar mills.

The geographic distribution of the estimated potential reveals that Gujarat has the highestshare of about 13.91% (12,489 MW ), followed by Karnataka with 12.3% share (11,071 MW)and Maharashtra with 10.69% share (9,596 MW), mainly on account of wind power potential.

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Figure 2.4: Sourcewise Estimated potential of renewable power in India

Figure 2.5: Statewise Estimated potential of renewable power in India

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2.2.4 Installed generating capacity of electricity :

The total installed capacity for electricity generation in the country has increased from16,271 MW as on 31.03.1971 to 2,36,387 MW as on 31.03.2012, registering a compoundannual growth rate (CAGR) of 6.58%. There has been an increase in generating capacityof 29,861 MW over the last one year, which is 14.46% more than the capacity of last year.The highest rate of annual growth (18.91%) from 2010-11 to 2011-12 in installed capacitywas for Thermal power followed by Hydro Power (3.79%).

A pdf �le for India's Energy Scenario is attached for your reference.

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Figure 2.6: Gas Pipeline Network of India

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Figure 2.7: Coal �eld and lignite occourance of India

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Figure 2.8: Nuclear power Reactors in operation and Construction14

Chapter 3

Basics of Energy

3.1 Introduction

Energy is the ability to do work and work is the transfer of energy from one form to another.In practical terms, energy is what we use to manipulate the world around us, whether byexciting our muscles, by using electricity, or by using mechanical devices such as automobiles.Energy comes in di�erent forms - heat (thermal), light (radiant), mechanical, electrical,chemical, and nuclear energy.

3.2 Various Forms of Energy:

There are two types of energy - stored (potential) energy and working (kinetic) energy. Forexample, the food we eat contains chemical energy, and our body stores this energy until werelease it when we work or play.

3.2.1 Potential Energy

In physics, potential energy is energy stored in a system of forcefully interacting physicalentities . Potential energy is stored energy and the energy of position (gravitational). It existsin various forms.There are various types of potential energy, each associated with a particulartype of force. For example, the work of an elastic force is called elastic potential energy;work of the gravitational force is called gravitational potential energy; work of the Coulombforce is called electric potential energy; work of the strong nuclear force or weak nuclear forceacting on the baryon charge is called nuclear potential energy; work of intermolecular forces iscalled intermolecular potential energy. Chemical potential energy, such as the energy storedin fossil fuels, is the work of the Coulomb force during rearrangement of mutual positions ofelectrons and nuclei in atoms and molecules. Thermal energy usually has two components:the kinetic energy of random motions of particles and the potential energy of their mutualpositions.

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3.2.1.1 Gravitational Energy

Gravitational energy is the potential energy associated with gravitational force, as work isrequired to elevate objects against Earth's gravity. The potential energy due to elevatedpositions is called gravitational potential energy, and is evidenced by water in an elevatedreservoir or kept behind a dam. If an object falls from one point to another point inside agravitational �eld, the force of gravity will do positive work on the object, and the gravita-tional potential energy will decrease by the same amount.

3.2.1.2 Elastic potential energy

Elastic potential energy is the potential energy of an elastic object (for example a bow or acatapult) that is deformed under tension or compression (or stressed in formal terminology).It arises as a consequence of a force that tries to restore the object to its original shape, whichis most often the electromagnetic force between the atoms and molecules that constitute theobject. If the stretch is released, the energy is transformed into kinetic energy.

3.2.1.3 Chemical energy

Chemical energy is a form of potential energy related to the structural arrangement of atomsor molecules. This arrangement may be the result of chemical bonds within a molecule orotherwise. Chemical energy of a chemical substance can be transformed to other forms ofenergy by a chemical reaction. As an example, when a fuel is burned the chemical energy isconverted to heat, same is the case with digestion of food metabolized in a biological organ-ism. Green plants transform solar energy to chemical energy through the process known asphotosynthesis, and electrical energy can be converted to chemical energy through electro-chemical reactions. The similar term chemical potential is used to indicate the potential ofa substance to undergo a change of con�guration, be it in the form of a chemical reaction,spatial transport, particle exchange with a reservoir, etc.

3.2.1.4 Electric potential energy

An object can have potential energy by virtue of its electric charge and several forces relatedto their presence. There are two main types of this kind of potential energy: electrostaticpotential energy, electrodynamic potential energy (also sometimes called magnetic potentialenergy).

Electrostatic potential energy: In case the electric charge of an object can be assumedto be at rest, it has potential energy due to its position relative to other charged objects.The electrostatic potential energy is the energy of an electrically charged particle (at rest)in an electric �eld. It is de�ned as the work that must be done to move it from an in�nitedistance away to its present location, adjusted for non-electrical forces on the object. Thisenergy will generally be non-zero if there is another electrically charged object nearby.

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Magnetic potential energy: Magnetic potential energy is the form of energy related notonly to the distance between magnetic materials, but also to the orientation, or alignment,of those materials within the �eld. For example, the needle of a compass has the lowestmagnetic potential energy when it is aligned with the north and south poles of the Earth'smagnetic �eld. If the needle is moved by an outside force, torque is exerted on the magneticdipole of the needle by the Earth's magnetic �eld, causing it to move back into alignment.The magnetic potential energy of the needle is highest when it is perpendicular to the Earth'smagnetic �eld. Two magnets will have potential energy in relation to each other and thedistance between them, but this also depends on their orientation. If the opposite poles areheld apart, the potential energy will be the highest when they are near the edge of theirattraction, and the lowest when they pull together. Conversely, like poles will have thehighest potential energy when forced together, and the lowest when they spring apart.

3.2.1.5 Nuclear Energy

Nuclear potential energy is the potential energy of the particles inside an atomic nucleus.The nuclear particles are bound together by the strong nuclear force. Weak nuclear forcesprovide the potential energy for certain kinds of radioactive decay, such as beta decay.Nuclear particles like protons and neutrons are not destroyed in �ssion and fusion processes,but collections of them have less mass than if they were individually free, and this massdi�erence is liberated as heat and radiation in nuclear reactions (the heat and radiationhave the missing mass, but it often escapes from the system, where it is not measured).The energy from the Sun is an example of this form of energy conversion. In the Sun, theprocess of hydrogen fusion converts about 4 million tonnes of solar matter per second intoelectromagnetic energy, which is radiated into space.

3.2.2 Kinetic Energy

In physics, the kinetic energy of an object is the energy which it possesses due to its motion.It is de�ned as the work needed to accelerate a body of a given mass from rest to itsstated velocity. Having gained this energy during its acceleration, the body maintains thiskinetic energy unless its speed changes. The same amount of work is done by the body indecelerating from its current speed to a state of rest. In classical mechanics, the kineticenergy of a non-rotating object of mass m traveling at a speed v is 1/2mv2. In relativisticmechanics, this is only a good approximation when v is much less than the speed of light.

Energy occurs in many forms, including chemical energy, thermal energy, electromagneticradiation, gravitational energy, electric energy, elastic energy, nuclear energy, and rest energy.These can be categorized in two main classes: potential energy and kinetic energy.

Kinetic energy may be best understood by examples that demonstrate how it is transformedto and from other forms of energy. For example, a cyclist uses chemical energy provided byfood to accelerate a bicycle to a chosen speed. On a level surface, this speed can be main-tained without further work, except to overcome air resistance and friction. The chemical

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energy has been converted into kinetic energy, the energy of motion, but the process is notcompletely e�cient and produces heat within the cyclist.

The kinetic energy in the moving cyclist and the bicycle can be converted to other forms. Forexample, the cyclist could encounter a hill just high enough to coast up, so that the bicyclecomes to a complete halt at the top. The kinetic energy has now largely been convertedto gravitational potential energy that can be released by freewheeling down the other sideof the hill. Since the bicycle lost some of its energy to friction, it never regains all of itsspeed without additional pedaling. The energy is not destroyed; it has only been convertedto another form by friction. Alternatively the cyclist could connect a dynamo to one of thewheels and generate some electrical energy on the descent. The bicycle would be travelingslower at the bottom of the hill than without the generator because some of the energy hasbeen diverted into electrical energy. Another possibility would be for the cyclist to applythe brakes, in which case the kinetic energy would be dissipated through friction as heat.

Like any physical quantity which is a function of velocity, the kinetic energy of an objectdepends on the relationship between the object and the observer's frame of reference. Thus,the kinetic energy of an object is not invariant.

Spacecraft use chemical energy to launch and gain considerable kinetic energy to reachorbital velocity. In a perfectly circular orbit, this kinetic energy remains constant becausethere is almost no friction in near-earth space. However it becomes apparent at re-entry whensome of the kinetic energy is converted to heat. If the orbit is elliptical or hyperbolic, thenthroughout the orbit kinetic and potential energy are exchanged; kinetic energy is greatestand potential energy lowest at closest approach to the earth or other massive body, whilepotential energy is greatest and kinetic energy the lowest at maximum distance. Withoutloss or gain, however, the sum of the kinetic and potential energy remains constant.

Kinetic energy can be passed from one object to another. In the game of billiards, the playerimposes kinetic energy on the cue ball by striking it with the cue stick. If the cue ball collideswith another ball, it slows down dramatically and the ball it collided with accelerates to aspeed as the kinetic energy is passed on to it. Collisions in billiards are e�ectively elasticcollisions, in which kinetic energy is preserved. In inelastic collisions, kinetic energy isdissipated in various forms of energy, such as heat, sound, binding energy (breaking boundstructures).

Flywheels have been developed as a method of energy storage. This illustrates that kineticenergy is also stored in rotational motion.

Several mathematical descriptions of kinetic energy exist that describe it in the appropriatephysical situation. For objects and processes in common human experience, the formula ½mv²given by Newtonian (classical) mechanics is suitable. However, if the speed of the object iscomparable to the speed of light, relativistic e�ects become signi�cant and the relativisticformula is used. If the object is on the atomic or sub-atomic scale, quantum mechanicale�ects are signi�cant and a quantum mechanical model must be employed.

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3.2.2.1 Radiant Energy

Radiant energy is the energy of electromagnetic waves. The quantity of radiant energy maybe calculated by integrating radiant �ux (or power) with respect to time and, like all formsof energy, its SI unit is the joule. The term is used particularly when radiation is emittedby a source into the surrounding environment. Radiant energy may be visible or invisible tothe human eye. Radiant energy includes visible light, x-rays, gamma rays and radio waves.Solar energy is an example of radiant energy.

Because electromagnetic (EM) radiation can be conceptualized as a stream of photons, radi-ant energy can be viewed as the energy carried by these photons. Alternatively, EM radiationcan be viewed as an electromagnetic wave, which carries energy in its oscillating electric andmagnetic �elds.

When EM waves are absorbed by an object, the energy of the waves is converted to heat(or converted to electricity in case of a photoelectric material). This is a very familiare�ect, since sunlight warms surfaces that it irradiates. Often this phenomenon is associatedparticularly with infrared radiation, but any kind of electromagnetic radiation will warman object that absorbs it. EM waves can also be re�ected or scattered, in which case theirenergy is redirected or redistributed as well.

3.2.2.2 Thermal Energy

Thermal energy is the part of the total potential energy and kinetic energy of an object orsample of matter that results in the system temperature.It is represented by the variable Q,and can be measured in Joules.

The internal energy of a system, also often called the thermodynamic energy, includes otherforms of energy in a thermodynamic system in addition to thermal energy, namely formsof potential energy that do not in�uence temperature and do not absorb heat, such asthe chemical energy stored in its molecular structure and electronic con�guration, and thenuclear binding energy that binds the sub-atomic particles of matter.

Microscopically, the thermal energy may include both the kinetic energy and potential energyof a system's constituent particles, which may be atoms, molecules, electrons, or particlesin plasmas. It originates from the individually random, or disordered, motion of particlesin a large ensemble, as consequence of absorbing heat. In ideal monatomic gases, ther-mal energy is entirely kinetic energy. In other substances, in cases where some ofthermal energy is stored in atomic vibration, this vibrational part of the thermal energy isstored equally partitioned between potential energy of atomic vibration, and kinetic energyof atomic vibration.

Geothermal energy is an example of thermal energy.

Heat can be transferred through three modes between two objects having a temperaturedi�erence , viz: Conduction, Convection and Radiation

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3.2.2.3 Motion

The movement of objects or substances from one place to another is motion. Wind andhydropower are examples of motion.

3.2.2.4 Sound

Sound is the movement of energy through substances in longitudinal (compression/rarefac-tion) waves.Sound is produced when a force causes an object or substance to vibrate theenergy is transferred through the substance in a wave. Typically, the energy in sound is farless than other forms of energy.

Let's see this illustration. A vibrating drum in a disco transfers energy to the room assound. Kinetic energy from the moving air molecules transfers the sound energy to thedancers eardrums. Notice that Kinetic (movement) energy in the sticks is being transferredinto sound energy. Sound vibrations create sound waves which move through mediums suchas air and water before reaching our ears.

3.2.2.5 Electrical Energy

Electrical energy is the bulk �ow of charges ie: Electron, protons, ions. If electric energy isgenerated due to movement of charges then it is a form of Kinetic energy, like if we connecta light bulb by battery so light is generated due to �ow of current which makes it conversionof electric kinetic energy into light energy. But if an electric �eld is generated by a chargedparticle at rest due to which potential di�erence is created it is electrical potential energy.Lightning and electricity are examples of electrical energy. All AC DC current and appliancesare run by electrical kinetic energy.

3.2.3 Grades of Energy;

Energy can be classi�ed into two grades:

3.2.3.1 High-Grade Energy

Electrical and chemical energy are high-grade energy, because the energy is concentrated ina small space. Even a small amount of electrical and chemical energy can do a great amountof work. The molecules or particles that store these forms of energy are highly orderedand compact and thus considered as high grade energy. High-grade energy like electricity isbetter used for high grade applications like melting of metals rather than simply heating ofwater.

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3.2.3.2 Low-Grade Energy

Low-grade energy: Based on the thermodynamic concepts, an energy source can be calledas high-grade or low-grade, depending the ease with which it can be converted into otherforms. Thus electrical energy is called a high-grade energy, as it is very easy to convertalmost all of it into other energy forms such as thermal energy (say by using an electricalheater). Whereas, it is not possible to convert thermal energy completely into electricalenergy (typical e�ciencies of thermal power plants are around 30 percent), hence thermalenergy is called a low-grade energy. Naturally, high-grade energy sources are more expensivecompared to low-grade energy sources.

Heat is low-grade energy. Heat can still be used to do work (example of a heater boilingwater), but it rapidly dissipates. The molecules, in which this kind of energy is stored (airand water molecules), are more randomly distributed than the molecules of carbon in a coal.This disordered state of the molecules and the dissipated energy are classi�ed as low-gradeenergy.

3.2.4 Basic Numerical to �nd units of power consumption

Kilowatt (kW) (Active Power) :

kW is the active power or the work-producing part of apparent power.

Power Factor:

Power Factor (PF) is the ratio between the active power (kW) and apparent power (kVA)

When current lags the voltage like in inductive loads, it is called lagging power factor andwhen current leads the voltage like in capacitive loads, it is called leading power factor.

Inductive loads such as induction motors, transformers, discharge lamp, etc. absorb compar-atively more lagging reactive power (kVAr) and hence, their power factor is poor. Lower the

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power factor; electrical network is loaded with more current. It would be advisable to havehighest power factor (close to 1) so that network carries only active power which does realwork. PF improvement is done by installing capacitors near the load centers, which improvepower factor from the point of installation back to the generating station.

kilowatt hour (kWh)

Kilowatt-hour is the energy consumed by 1000 Watts in one hour. If 1kW (1000 watts) ofa electrical equipment is operated for 1 hour, it would consume 1 kWh of energy (1 unit ofelectricity).

For a company, it is the amount of electrical units in kWh recorded in the plant over a monthfor billing purpose. The company is charged / billed based on kWh consumption.

Example:

Q.1 A 3-phase AC induction motor (20 kW capacity) is used for pumping operation. Elec-trical parameter such as current, volt and power factor were measured with power analyzer.Find energy consumption of motor in one hour? (line volts. = 440 V, line current = 25amps and PF = 0.90). Ans.1 Energy consumption = 3 x 0.440 (kV) x 25(A) x0.90(PF) x 1(hour) = 17.15 kWh

Q.2 A 400 Watt mercury vapor lamp was switched on for 10 hours per day. The supply voltis 230 V. Find the power consumption per day? (Volt = 230 V, Current = 2 amps, PF =0.8)

Ans.2 Electricity consumption (kWh) = V x I x Cos x No of Hours = 0.230 x2 x 0.8 x 10 = 3.7 kWh or Units

Q.3 An electric heater of 230 V, 5 kW rating is used for hot water generation in an industry.Find electricity consumption per hour (a) at the rated voltage (b) at 200 V

Ans.3 (a) Electricity consumption (kWh) at rated voltage = 5 kW x 1 hour = 5kWh. (b) Electricity consumption at 200 V (kWh) = (200 / 230)2 x 5 kW x 1hour = 3.78 kWh.

• Q.4 A three phase,10 kW motor has the name plate details as 415 V, 18.2 amps and 0.9PF. Actual input measurement shows 415 V, 12 amps and 0.7 PF which was measuredwith power analyzer during motor running. Calculate the rated e�ciency of motor atfull load and motor loading.

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Chapter 4

Bibliography

All the data and material have been taken from BEE handbooks, Wikipedia and statisticsof govt. of India

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