Chapter 1_Sources of Energy

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Thermal Engg.

CHAPTER 1 Sources of Energy

• Man has needed and used energy at an increasing rate for his sustenance. Energy

utilization increases due to rapid growth in industrialization. Economic development ofany country depends on the energy sources.

• So energy is the primary and most universal measure of all kinds of work for human

beings and nature and closely related with energy utilization.

• Everything that happens in the world is the expression of flow of energy in one of its

form.

Classification of Various Sources of EnergyConventional OR Non Renewable Non Conventional ORRenewable Energy Sources Energy Sources1. This source of energy can be produced from 1. This source of energy can be

produced from

fossil fuels such as coal natural gas petroleum sun wind falling water sea waves etc.

oil uranium etc.!. They are exhausted and limited as they cannot !. They can never be exhausted and

therefore be renewed. are renewable.". Energy density is high. ". Energy density is low.#. $ost of generation high. They are very #. $ost of generation is low. They are

lessexpensive to be maintained stored and expensive due to local availabilityand easytransmitted as they are carried over long to maintain.

distances through transmission grid and lines.%. They cause pollution when used as they emit %. They are generally pollution free.

smoke and ash.

Non Renewable Energy Sources

Thermal Energy

&uclear Energy

'ydraulic Energy

Renewable Energy Sources

Solar Energy

(ind Energy

)io Energy

'ydro Energy

*eothermal Energy

+cean Energy Or (ave and Tidal Energy

Conventional OR Non Renewable Energy SourcesFOSSIL FUELS

• ,ossil ,uels consist of deposits of once living organisms. The organic matter takes

centuries to form.• ,ossil ,uels principally consist of carbon and hydrogen bonds.

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Thermal Engg.

• There are three types of fossil fuels coal or solid fuel li-uid fuel or oil and gaseous fuel

or natural gas.

• ,ossil fuels are the main fuel for the thermal power.

• There is a fear that they will get exhausted eventually in the next centurary.

Solid Fuels:

• These are

&atural Solid ,uels eg. (ood peat coal / lignite anthrasite and bituminous coals0depending on the relative proportions of fixed carbon moisture and volatile matter.

rtificial Solid ,uels eg. (ood charcoal coke and pulverized coal etc.

Liquid Fuels:

• They are crude petroleum and various oily residues obtained in distilling petroleum

shale oil and coal tar.

• These fuels have more advantages over solid fuels.

• $rude oil is extracted from oil production wells drilled either on2shore or off shore.

• 3t is then refined in refineries to obtain petrol diesel kerosene furnace oil lubricating

oil paraffin asphalt tar etc.

• 3t consists of a mixture of gases li-uids and solid hydrocarbon with small amount of

nitrogen and sulphur compound.

Gaseous Fuels:

Advantages of Gaseous Fuels

• 3t can be produced at a central location and clean gas can be distributed over a wide

area.• &uisance of smoke production and ash disposal eliminated at point of fuel utilization.

• *reater control of variation in demand conditions of combustion and nature of flame

and heating atmosphere possible.

• *reater economy by use of efficient heat exchanger methods possible.

• *aseous fuels re-uire far less excess air for complete combustion.

isadvantages of Gaseous Fuels

• 4ower produced with gaseous fuels is less when compared to solid and li-uid fuels.

• s its specific volume is high gaseous fuel containers are much larger than those for

li-uid fuels. 'ence they are li-uefied by moderate compression at normal temperatureand stored in tank or cylinder.

Natural Gas

• 3t is the only gas occurring in nature.

• 3t contains 56 to 768 methane rest are propane butane heavier and more complex

hydrocarbons carbon dioxide nitrogen and some helium. lso methane is agreenhouse gas with a global warming potential approximately # times that of carbondioxide.

• &atural gas may be used as

9i-uefied &atural *as 09&*:

$ompressed &atural *as 0$&*:

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Thermal Engg.

Li!uefied Natural Gas "LNG#

• 3t is stored as a super cooled 0cryogenic: li-uid.

• The temperature re-uired to condense 9&* depends on its precise composition but it is

typically between 21!6;$ and 21<6;$.

• The advantage of 9&* is that it offers an energy density comparable to petrol and diesel

fuels extending range and reducing refuelling fre-uency.

• The disadvantage is the high cost of cryogenic storage on vehicles and the ma=or

infrastructure re-uirement of 9&* dispensing stations production plants andtransportation facilities.

Co$%ressed Natural Gas "CNG#

• $&* is stored on the vehicle in high pressure tanks at !6 to !% M4a pressure 0!66 to

!%6 bar:.

• 3t is lighter than air and thus will normally dissipate in the case of a leak giving it a

significant safety advantage over gasoline or 94*.• s it does not li-uefy even under high pressure it has a lower energy density.

Li!uefied &etroleu$ Gas or Autogas "L&G#

• 3t is produced as a by product of natural gas processing and petroleum refining.

• 3t consists mainly of propane propylene butane and butylene in various mixtures.

• The components of 94* are gases at normal temperatures and pressures and hence it

can evaporate and therefore stored in pressurized steel bottles.

• 3t can vary widely in composition leading to variable engine performance and cold

starting performance.

• 94* is heavier than air and thus will flow along floors and tend to settle in low spotssuch as basements. Such accumulations can cause explosion hazards.

3n general the chemical energy of fuel is converted into heat energy by the combustion ofthe fuel. This heat energy produced is utilized for the production of mechanical energy which can be converted into electrical energy for many applications such as in

3nternal $ombustion 03$: Engines

$ooking purposes

To generate electricity in thermal power plant.

THERA! ENERG" SO#RCES $THERA! PO%ER P!ANT&• Steam is important working fluid which can be used for producing mechanical energy in

thermal power plant.

• Steam can be generated by using any type of fuel such as coal oil or gas. The type of

fuel used depends upon the availability of the fuel in a particular country.

'OR(ING OF )*ER+AL &O'ER &LAN)

• Steam is generated in the boiler of the thermal power plant using the heat of the fuel

burned in the combustion chamber.

• The steam generated is passed through steam turbine where part of its thermal energy

is converted into mechanical energy which is further used for generating electric power.

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Thermal Engg.

• The steam coming out of the steam turbine is condensed in the condenser and the

condensate is supplied back to the boiler with the help of the feed pump and the cycle isrepeated.

FUNC)ION

• )oiler / 3t is used to generate steam.

• $ondenser 2 3t is used to condense the steam coming out of steam turbine at low

pressure.

• Steam Turbine / 3T is used to convert part of heat energy of steam into mechanical

energy.

• ,eed 4ump / 3t is used to raise the pressure of the condensate from the condenser

pressure 06.61% bar: to boiler pressure 0!66 bar:.

• +ther $omponents Economiser Superheater and Steam ,eed 'eaters / Steam from

different points of turbine is fed to the heaters to heat the condensate to a highertemperature and to increase the overall efficiency of the thermal power plant.

A,AN)AGES OF )*ER+AL &O'ER &LAN) • The fuel used is -uite cheap.

• 9ess initial cost as compared to other generating plants.

• 3t can be installed at any place irrespective of the existence of coal.

• The coal is transported to the site of the plant by rail or road.

• 3t re-uires less space as compared to hydro power plants.

• $ost of generation is less than that of diesel power plants.

ISA,AN)AGES OF )*ER+AL &O'ER &LAN)

• 3t pollutes the atmosphere due to production of large amount of smoke and fumes.

• 3t is costlier in running cost as compared to hydroelectric plants.

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Thermal Engg.

N#C!EAR ENERG" SO#RCES $N#C!EAR PO%ER P!ANT&

• 3n nuclear reactor for reaction to occur it re-uires a very heavy elemental isotope

typically some form of uranium or plutonium and other a very light >free neutron?.

• The light particle collides with the heavy particle which splits into two or three pieces.This reaction is called fission.

• This fission produces a ton of energy in the form of both kinetic energy and

electromagnetic radiation.

• These new pieces includes two new nuclei 0 by products: some photons 0gamma rays:

but also some more free neutrons. These newly produced free neutrons zoom aroundand smack into more uranium or plutonium isotope which in turn produces more energyand more free neutrons and it keeps going as a nuclear fission chain reaction.

'OR(ING OF NUCLEAR &O'ER &LAN)

• 3n nuclear power plants the boiler of steam or thermal power plant is replaced by

nuclear reactor. The nuclear fission reaction heat is used either for steam generation orheating the working fluid.

• The heat in the nuclear reactor is used by steam turbine which is converted to

mechanical energy and it is further used for generating electric power.

• (ater from rivers can be used for condensing the steam in the condenser provided it is

available throughout the year.

• 3f not then a cooling tower is generally used.

• 3n this case the same is used again and again for condensing the steam.

• The warm water coming out of condenser after absorbing the heat of exhaust steam is

passed through the cooling tower where it is cooled in the current of air.

• This cold water is again passed through the condenser.

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Thermal Engg.

A,AN)AGES OF NUCLEAR &O'ER &LAN)

• 3t needs less area compared to thermal plant of e-ual capacity.

• The weight of nuclear fuel re-uired is negligible in comparison to the coal re-uired for

thermal plant of e-ual capacity. This totally eliminates the problem of transport and

storage of fuel.

• 3t produces valuable isotopes which are used for different purposes.

ISA,AN)AGES OF NUCLEAR &O'ER &LAN)

• The waste from the nuclear reactor and reprocessing systems is extremely radioactive.

Therefore its disposal is one of the ma=or problems as it is highly in=urious to humananimal and plant life.

• &uclear 4ower plants can be used only as base load plants. They are not suitable to

take variable load 0or peak load plant: as reactor cannot be controlled easily and -uicklyto respond to load changes.

A&&LICA)IONS OF NUCLEAR &O'ER &LAN)

• 3t is used to generate electricity for civilian consumption.

• They are also used on sea2going vessels where they provide both electricity and

mechanical power for propulsion.

• The ma=or application of the atomic battery power plant is on space satellites that have a

substantial long2term demand for electricity that cannot be met through other meanssuch as solar panels.

• Enriching uranium for fission reactors creates an isotope known as depleted uranium

which the merican military uses in the manufacture of both armour and ammunition

due to its extremely high density. 0by products:.

H"'RA#!(C ENERG" SO#RCES $H"'RO PO%ER P!ANT&

• ,or utilising the energy available in water a dam is built to collect the rain water in a

reservoir which provides a higher level as well as storage.

• This water having a higher potential energy is used to run the prime mover 0water

turbine: under the natural head available at the site.

'OR(ING OF *-RO &O'ER &LAN)

• The potential energy of water is first converted into kinetic energy in a nozzle as it falls

through a head of '.

• This kinetic energy is utilised to run the water turbine0mechanical power: and this is

further converted into electrical energy as the water turbine drives the generator.

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Thermal Engg.

A,AN)AGES OF *-RO &O'ER &LAN)

• The working cost of this system is less than other type of power generation system as

no fuel is used.

• 'ydro power is fuelled by water so it?s a clean fuel source. 3t does not pollute the air like

power plants that burn fossil fuels such as coal or natural gas.

• +nce a dam is constructed electricity can be produced at a constant rate.• 3t electricity is not needed the sluice gates can be shut stooping electricity generation.

• The lake?s water can be used for irrigation purposes.

ISA,AN)AGES OF *-RO &O'ER &LAN)

• The capital investment is generally high.

• 'ydro power plants can be impacted by draught. (hen water is not available the hydro

power plants cannot produce electricity.

• 'ydro power facilities impact the local environment and may compete with other uses

for the land. 'umans flora and fauna may lose their natural habitat.

SO!AR ENERG"

• Solar energy refers to the direct use of the energy contained in the sunlight.

• Solar energy is available as long as the sun shines but its intensity depends on weather

conditions and geographic location.

• The earth and its atmosphere receive continuously 1.<x161< ( of radiation from the sun.

• The surface receives about #<8 of the total solar energy that reaches the earth. +nly

this amount is usable.

• The density of sunlight falling on earth?s surface is considerably low and therefore it

cannot be used directly for power generation.

• $onverting the sun?s radiant energy to heat is the most common and well developedsolar conversion technology today.

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Thermal Engg.

• The various solar thermal collectors used are

,lat 4late $ollectors

4arabolic $oncentration $ollector

A,AN)AGES OF SOLAR ENERG-

• Solar energy is unlimited and it is free clean renewable energy. The sun keeps coming

back every day. The solar energy landing on the earth in one day is enough to power theplanet for a year.

• 3t is pollution free.

• 3t can be converted into heat or light.

ISA,AN)AGES OF SOLAR ENERG-

• Sun does not shine consistently.

• Most of the solar energy falls on remote areas would therefore re-uire some means of

transportation to be useful to the industrialized nations.

• Solar energy is a diffuse source. To harness it we must concentrate it into an amountand form that we can use such as heat and electricity.

• Expensive to install though plants and panels are getting cheaper.

A&LICA)IONS OF SOLAR ENERG-

• @+MEST3$

Solar water heater

'eating and cooling of residential buildings

Solar $ookers

Solar distillation on a small community scale

• 3&@CSTB39 &@ *B3$C9TCB9

(ater 4umping

@ryers

Salt 4roduction by evaporation of sea water

Solar ,urnaces

• 4+(EB

Solar 4onds

Solar Electric 4ower *eneration

4hoto voltaic cell which convert it into light energy

)io $onversion and (ind energy which are indirect source of solar energy

)lat Plate Collectors

• ,lat plate collectors are used typically for temperature re-uirements upto <%;$.

• These collectors are of two basic types based on the heat transfer fluid

9i-uid Type where heat transfer fluid may be water mixture of water and antifreeze oil etc.0 used for water heating:

ir Type where heat transfer medium is air 0used mainly for drying and space heatingre-uirements:.



Thermal Engg.

• The basic elements of flat plate collectors are

*lazing2 one or more covers of transparent material like glass plastics etc.

bsorber2 a plate with tubes or passages attached to it for the passage of a working fluid.The absorber plate is usually painted black.

Tubes2 to facilitate the flow of heat transfer fluid.

3nsulation2 to minimize heat loss from the back and the sides.

$ontainer2 box or casing.

'OR(ING OF FLA) &LA)E COLLEC)OR• The solar radiation falls on absorber plate after coming through one or more transparent

glass covers. The absorbed radiation is partly transferred to a li-uid flowing through tube which is fixed to absorber plate. The remaining is lost by convection and radiation.

• The transparent cover helps in reducing the losses by convection and re2radiation while

thermal insulation on bottom and the side helps in reducing the conduction heat loss.

• The li-uid absorbs heat and decreases in density thus flowing to the top. s the water

heats up to <%;$ to 166;$ these collectors are used only for domestic purposes.

• The li-uid like ,reon can be used to generate power as it boils at lower temperatures.

The flat plate collectors can achieve a temperature of 1#6;$ with booster mirror.

Cylin*rical Parabolic Concentrating Collectors

'OR(ING OF C-LINRICAL &ARA.OLIC CONCEN)RA)ING COLLEC)OR

• They are typically used for temperatures above 166;$. it consists of a concentrator and

a receiver 0absorber:.

• The concentrator is a mirror reflector having the shape of a cylindrical parabola. The sun

rays incident on concentrator are focused on axis where it is absorbed on the surface ofabsorber tube or receiver and transferred to the fluid flowing through it.

• The absorber tube is a concentric glass cover which helps in reducing convective and

radiative losses to the surrounding. The concentrators can be rotated so that the sun

rays always focus on absorber tube. This movement is called tracking. s the fluid

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Thermal Engg.

temperature obtained is about "66;$ it can be used to generate steam that drives powerconversion subsystem producing electricity.

SO!AR %ATER HEATER

• There are basically two types of water heating systems.

• &atural $irculation or 4assive Solar System 0Thermosyphon:

They are simple in design and low cost

Their application is usually limited to non freezing climates although they may also bedesigned with heat exchangers for mild freezing climates.

• ,orced $irculation or ctive Solar System

They are used in freezing climates and for commercial and industrial process heating.

'OR(ING OF SOLAR 'A)ER *EA)ER

• The solar radiation falling on flat plate collector is received and absorbed by the water

flowing through the tubes.

• s water gets heated in the collector it rises to the tank and the cooler water from the

tank moves to the bottom of the collector setting up a natural circulation loop. 3t is alsocalled a thermosyphon loop.

• This process of heating water continues during the day and hot water is collected in the

storage tank. The storage tank is provided with insulation to avoid heat loss to thesurrounding atmosphere.

• check valve provided to the inlet of the storage tank to prevent back circulation of

water and loss of heat in night.• Since this water heater does not use a pump it is a passive water heater. ,or the

thermosyphon to work the storage tank must be located higher than the collector at least6." metres.

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Thermal Engg.

PHOTVO!TA(C CE!!S

• 4hotovoltaic conversion is the direct conversion of sunlight into electricity at the atomic

level with no intervening heat engines.

• Some materials exhibit a property known as the photoelectric effect that causes them to

absorb photons of light and release electrons. (hen these free electrons are capturedan electric current result that can be used as electricity.

• The photoelectric effect was first noted by )ec-uerel in 1"7 when light was incident on

an electrode in an electrolyte solution. 3n 17%# researchers at B$ and )ell 9aboratoriesbuilt first photovoltaic module of p and n types of semiconductors.

'OR(ING OF &*O)O,OL)AIC CELL

• 4hotovoltaic cell or solar cells are made of semiconductor materials such as silicon.

• thin semiconductor wafer is specially treated to form an electric field positive on one

side and negative on the other.

• (hen light energy strikes the solar cells electrons are knocked loose from the atoms in

the semiconductor material. 3f electrical conductors are attached to the positive and

negative sides forming an electrical circuit the electrons can be captured in the form ofan electric current ie electricity.

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Thermal Engg.

• number of solar cells electrically connected to each other and mounted in a support

structure or frame is called a photovoltaic module. The current produced is directlydependent on how much light strikes the module.

• Multiple modules can be wired together to form an array. 3n general the larger the area

of a module or array the more electricity that will be produced.

• 4hotovoltaic modules and arrays produces direct2current 0@$: electricity.

• They can b connected in both series and parallel electrical arrangements to produce any

re-uired voltage and current combinations.

A&&LICA)IONS OF &*O)O,OL)AIC CELL

• $alculators

• (atches

• (ater 4umping

• Bemote )uildings

• $ommunications

• Satellites and Space Fehicles

SO!AR '(ST(!AT(ON

• There is an important need for clean pure drinking water in many developing countries.

+ften water sources contain dissolved salts and harmful bacteria and therefore cannotbe used for drinking. 3n addition there are many coastal locations where sea water isabundant but potable water is not available.

• @istillation is one of many processes that can be used for water purification. This

re-uires an energy input as heatG solar radiation can be the source of energy. 3n thisprocess water is evaporated thus separating water vapour from dissolved matter which

is condensed as pure water.

'OR(ING OF SOLAR IS)ILA)ION

• 3t consists of a blackened basin containing saline water at a shallow depth over which a

transparent air tight cover completely closes the space above the basin.

• The incident solar radiation is transmitted through the transparent cover and is absorbed

as heat by a black surface 0basin: in contact with the water to be distilled.

• The water is thus heated and gives off water vapour. The vapour condenses on the

transparent cover which is at a lower temperature because it is in contact with theambient air and runs down into a gutter from where it is fed to a storage tank.

•Efficiencies of !%8 are typical. @aily output as a function of solar irradiation is greatest inthe early evening when the feed water is still hot but when outside temperatures arefalling.

1!



Thermal Engg.

%in* Energy

• (ind energy is basically harnessing 0controlling: of wind power to produce electricity.

• The kinetic energy of the wind is converted to electrical energy. (hen solar radiation

enters the earth?s atmosphere different regions of the atmosphere are heated to differentdegrees because of earth?s curvature.

• This heating is higher at the e-uator and lowest at the poles.

• Since air tends to flow from warmer to cooler regions this causes winds and it is these

airflows that are harnesses in windmills and wind turbines to produce power.

A,AN)AGES OF 'IN ENERG-

• This energy is the least expensive renewable energy source.

• +nce the wind turbine is built the energy it produces does not cause green house gases

or other pollutants. Moreover wind is its fuel source which is clean.

• lthough wind turbines can be very tall each takes up only a small plot of land. This

means that the land below can be used. This is especially the case in agricultural areasas farming can still continue.

• Bemote areas that are not connected to the electricity power grid can use wind turbinesto produce their own supply.

• (ind turbines are available in a range of sizes which means a vast range of people and

businesses can use them.

ISA,AN)AGES OF 'IN ENERG-

• The strength of wind is not constant and it varies from zero to storm force.

• (ind turbines are noisy.

• 9arge area is needed for small power generation.

A&&LICA)IONS OF 'IN ENERG-

• (ind mills are used to produce electricity.• 3t is used for grinding and pumping water for irrigation of farms.

1"



Thermal Engg.

• 3t is also used for sailing of ships.

)-&ES OF 'IN )UR.INES

• The basic wind energy conversion device is the wind turbine.

• lthough various designs and configuration exist these turbines are generally grouped

into two types.

Vertical Axis Wind Turbines3n which the axis of rotation is vertical with respect to the ground 0and roughly perpendicularto the wind stream:.Examples

@arrieus Fertical xis (ind Turbines or Eggbeater (ind Mill

*iromill

'elical )lades (ind Turbine

$yclo Turbine

Savonius (ind Turbine

ori!ontal Axis Wind Turbines3n which the axis of rotation is horizontal with respect to the ground 0and roughly parallel tothe wind stream:.Examples

Multiblade (ind turbine

Sail Type (ind Mill

4ropeller Type (ind Mill

'OR(ING OF 'IN )UR.INE

• (ill turbines consists of a blade or rotor which converts the energy in the wind to

rotational shaft energy and transfers its to gearbox and a generator.

• tower is used to support the rotor gearbox and generator and other e-uipments

including controls electrical cables ground support e-uipments and interconnectione-uipment.

1#



Thermal Engg.

Geot+er,al Energy

• *eothermal energy is heat from within the earth. 3t is generated in the earth?s core

almost #666 miles beneath the earth?s surface.

• The double2layered core is made up of very hot magma surrounding a solid iron centre.

Fery high temperatures are continuously produced inside the earth by the slow decay ofradioactive particles. This process is natural in all rocks.

• This heat in the form of steam is continuously produced deep within the earth.

• 3t is renewable energy source because water is perforated again and again by rainfall.

'OR(ING OF GEO)*ER+AL &O'ER &LAN)

• The steam is tapped from the natural storage through a drilled well and then supplied to

the turbine passing through the separator where most of the dirt carried by steam isremoved.

• The steam coming out of the turbine is condensed in the condenser and discharged over

the ground with the help of the pump.• The same condensate may again be pumped into the ground to get converted into

steam.

A,AN)AGES OF GEO)*ER+AL &O'ER &LAN) • 3t involves low running costs since it saves 68 over fossil fuels and no fuel is used to

generate the power.

• )eing the renewable source it has helped in reducing global warming and pollution.

ISA,AN)AGES OF GEO)*ER+AL &O'ER &LAN)

• The installation cost is high.

• The sites can run out of steam over a period of time due to drop in temperature or if too

much water is in=ected to cool the rocks.

• 3t is only suitable for regions where temperatures below the earth are -uite high and can

produce steam over a long period of time.

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Thermal Engg.

Ti*al an* %ave Energy

• Tide of the sea is used for running the water turbine. The ocean tides contain large

amount of potential energy which is used for power generation.

• Tidal power is predictable and relies on the gravitational pull of the moon and the sun to

create currents in the oceans.

• @ue to the contours of the earth?s surface there is une-ual heating of the earth from the

sun which generates wind.

• This wind blowing over water makes ocean waves.

• (ave power refers to the energy of ocean waves and the capture of that energy to do

useful work.

'OR(ING OF )IAL &O'ER &LAN)

• @uring the high tide period the water flows from sea into the tidal basin through the

water turbine as the level of tide is more than the water level in the tidal basin. Thisoperates the turbine and ultimately the generator.

• @uring the low tide period the water flows from tidal basin to sea as the water level in thebasin is more than that of the tide in the sea. @uring this period also the flowing waterturns turbine and generates the power.

• The generation of power stops only when sea level and tidal level are e-ual.

A,AN)AGES OF 'A,E ENERG-

• (aves are free and will not run out so the cost is in building the power station.

• (ave power does not produce green house gases.

ISA,AN)AGES OF 'A,E ENERG- • (aves can be big or small so you may not always be able to generate electricity.

• Hou need to find a way of transporting the electricity from the sea onto the land.

• &ot many people have tired to generate electricity this way yet so the e-uipment is

expensive.

A,AN)AGES OF )IAL ENERG-

• Tides are free once the power station has been built and will not run out.

• &o green house gases are produced when we make the electricity.

ISA,AN)AGES OF )IAL ENERG-

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Thermal Engg.

• Hou may need to build a large wall called a dam to make the water flow through the

generators. This may not be good for plants and animals that live nearby.

• The tides only happen twice a day so can only produce electricity for that time.

• 3nitial high capital cost.

-io,ass Energy

• )iomass refers to all organic matter generated through photosynthesis and other

biological processes.

• The ultimate source of this renewable biomass is the inexhaustible solar energy which is

captured by plants through photosynthesis.

• 3t includes matter like wood herbaceous plants algae a-uatic plants and residues like

straw husks cow dung saw dust human excreta etc.

A&&LICA)ION

• 3t is directly used for cooking and agricultural growth.• The sugarcane leftover pulp after extracting =uice is used for producing electricity.

• 3t is also used for mechanical applications and pumping of water.

-iogas Plant

• )iogas is generated from cow dung human waste animal excreta particularly dairy

cattle pig and sheep etc.

• 3t consists of 568 methane and rest carbon dioxide.

• 3t is clean safe and efficient fuel.

• 3t is used for cooking and lighting.

)-&ES OF .IOGAS &LAN)S

• )ag Type 4ortable @igester

• ,ixed @ome 4lants

• ,loating @rum 4lants

'OR(ING OF .IOGAS &LAN)

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Thermal Engg.

• The plant consists of two parts. The digester which is a well containing the animal waste

in the form of slurry and the dome which floats on the slurry and serves as the gasholder.

• The digester is below ground level. vertical partition wall divides it into two e-ual parts

and serves to direct the flow of the slurry.

• Two pipe lines leads to digester bottom2 one for feeding slurry and other to remove the

spent slurry called sludge which comes out after it has undergone fermentation.• The sludge contains nitrogen phosphorous and potassium which acts as excellent

fertilizers.

• The diameter of digester ranges from 1.! m to 5 m and depth from " to 5 m.

• The gas generation process occurs in two stages. 3n first stage the complex organic

substances contained in the waste are acted upon by a certain kind of bacteria calledacid former and are broken up into small chain simple acids. 3n second stage theseacids are acted upon by another kind of bacteria which completes fermentation.

• @ue to fermentation reaction the density of slurry decreases and it moves up and flow

into second chamber and then into the sludge. The gas liberated during the process is

collected in the dome.

A,AN)AGE OF .IOGAS &LAN)

• 3t converts natural organic waste into fertilizer which is free from harmful synthetic

chemicals.

• 3t is eco2friendly energy production. The calorific value of biogas is e-ual to that of half

litre of diesel oil. 3t is capable of replacing wood hard coal kerosene etc.

• 3t helps considerable workload reduction in rural areas.

• 3t significantly lowers the green house effects on the earth?s atmosphere.

ISA,AN)AGE OF .IOGAS &LAN) • ,ormation of sulphurous compounds can lead to odour.

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Thermal Engg.

-io 'iesel

• )io diesel is a renewable fuel derived from vegetable oils such as soybean oil corn oil

sunflower oil cotton seed oil rubber seed oil etc.

• 3t is refined into fuel which can be burned in diesel engines and buses.

• 3t can also be made by combining alcohol with vegetable oil or recycled cooking greases

or oils 0eg yellow grease:.

• 3t can be used as an additive to reduce vehicle emissions 0typically !68: or in its pure

form 0)3++: as a renewable alternative fuel for diesel engines.

A,AN)AGES OF .IO IESEL

• 3t is renewable and clean burning fuel.

• 3t has high lubricity and fuel efficiency.

• 3t emits very low green house gases.

• 3t is bio gradable non toxic non hazardous non flammable.

)uel Cells

• fuel cell is a device that generates electricity by a chemical reaction. Every fuel cell has

two electrodes one positive and one negative called anode and cathode respectively.The reaction that produces electricity takes place at the electrodes.

• Every fuel cell also has an electrolyte which carries electrically charged particles from

one electrode to the other and a catalyst which speeds the reaction at the electrodes.

• 'ydrogen is the basic fuel along with oxygen. ,uel cells generate electricity with very

little pollution as much of the hydrogen and oxygen used ultimately combines to formharmless by product ie water.

• The main types of fuel cells are

lkaline ,uel $ells 0,$:

@irect Methanol ,uel $ells0 @M,$:

17

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Thermal Engg.

Molten $arbonate fuel $ells0M$,$:

4hosphoric cid ,uel $ells04,$:

4olymer Electrolyte Membrane ,uel $ells 04EM,$:

Solid +xide ,uel $ells0S+,$:

CHAPTER 1 SO#RCES O) ENERG".uestions )ro, Previous -oar* Pa/ers

1. (hat are conventional 0non renewable: and non conventional 0renewable: sources ofenergyI *ive examples of each.@ec !667 0#:+B 9ist out renewable and non renewable sources of energy. May !61!@ec !66 0!:+B @ifferentiate between renewable and non renewable source of energy. @ec!61! 0#:

!. State the fuels used in following types of power plants Thermal and &uclear @ec!611 0!:

". @raw a sketch of thermal power plant and explain its workingI State two application of

it. May !6160#:

#. @raw labeled sketch with working of nuclear power plant. State applications of it. May !61! May !667

0#:%. Explain use of hydraulic energy to generate electricity.

May !611 0#:5. @escribe the working principle of tidal power plant with suitable sketch. @ec !611 May

!611 0#:<. State advantages and disadvantages of solar energy. @ec !611 May !611

May !616 0#:. @raw a sketch of solar water heater and describe its working in brief.

!6



Thermal Engg.

@ec 1! May !611 @ec !660#:

+B @raw a labeled sketch of solar water heater. State any two advantages of solarenergy.

May !667

0#:7. Explain the use of solar energy to generate electricity with neat sketch. May

!66 0#:+B Explain photovoltaic cell working with a diagram. (rite its two applications. @ec!667 0#:

16.State various types of wind mills. May !660!:

11.@escribe the working principle of wind mill. @ec !6110#:

1!.(hat do you mean by geothermal energy sourceI Explain how this can be used.@ec !667 0#:

1".State advantages and disadvantages of tidal energy. @ec !61!May !667@ec !66 0#:

1#.@raw a labeled sketch of )iogas plant. State its advantages. May!66 0#:@raw a labeled sketch of )io2gas plant. State two applications of the same. @ec!66 0#:

1%.*ive advantages of $oncentric $ollectors. May !6110!:

15. Explain the working of solar distillation plant. @ec!61! 0#:

1<.(hat is biogas and bio massI State its applications. May!61! 0#:

!1

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Chapter 1_Sources of Energy

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