varshab_sessionvii_29dec2006

8/3/2019 VarshaB_SessionVII_29dec2006

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Canyouimaginelifewithoutlights,fans,cars,computersandtelevision,oroffetchingwaterfromthewellorriver?Thisiswhatlifewouldhavebeenlikehadmannot

discoveredtheusesofenergy.

Weuseenergytodowork.Energyisthecapacitytodowork.Whether wedophysicalwork,mentalworkormechanicalwork,energyisalwaysinuse.Everychangeinvolvesenergy.Energyisallaroundus.Ourenergycomesfromthefoodweeat.Food,thereforemusthave

energy.Energyisnotmatter.Noonehaseverseenortastedorsmelledenergy.Butthisdoesntmeanthatenergydoesntexist.Abodypossessingenergyiscapable

ofdoing

work.


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Sourceswhichhaveaccumulatedinnatureoveraverylongtimeandcannotbereplacedveryquickly.

Thenonrenewablesourcesofenergyincludecoal,petroleumandnaturalgas.

Theyarealsocalledconvectionalsourcesofenergy. Sinceittakesmillionsofyearsfortheseresourcesto

developinsidetheearth,theyaregettingexhausted

fast. Ifwecontinueusingthefossilfuelsatthepresent

rate,wewillexhaustthemwithin50100years.

Theneedforustodevelopbetterandsafesourcesof

energyisperhapsthegreatestnow.


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Sourcesofenergywhichcanbeusedagainagainandarenotexhaustible.

Theexamplesaresun,water,windandbiomass. Suchsourcesofenergyarefreelyavailableandare

freeofcost.

They

don

t

pollute

the

environment. Weshouldprefertherenewablesourcesofenergybecause:

Theyareavailableinplenty.

Theyareavailablefreeofcost. Theydontpolluteair Theyarenotexhaustible.

Meansand

ways

to

harness

the

renewable

sources

ofenergymoreefficientlyhavetobedeveloped.


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Water power, or hydropower, furnishes about7% of the worlds commercial energy out ofwhich 4% is used in the US

Where water flows from a high place to a lowerone, the energy of the falling water can becaptured and used to produce other forms of

energy. Most water power is used to generate electricpower.

Water power supplies energy without pollutionand without using up the water in the process.

But costly dams and other structures arerequired to harness water power.


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Solar energy is used throughout the world toperform various small jobs. People capture this type of energy with various

devices that change the suns energy into heat

or electrical energy. Flat-plate collectors convert solar energy intoheat energy to heat water and the air inside thebuildings.

Solar cells, also called photovoltaic cells, convertsolar energy into electrical energy. Solar power can provide a clean and almost

unlimited source of energy. but it is thinlydistributed over a wide area and must becollected and concentrated to produce energy.

In addition, darkness and bad weather interruptthe supply of sunlight.


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Photovoltaiccells Inaphotovoltaic

cell,lightexciteselectronstomovefromonelayertoanotherthroughsemiconductive

silicon

materials.

Thisproducesanelectriccurrent.


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SolarHome Inthissolarhomein

Corrales,NewMexico,aflatplatesolarcollector(lowerright)

providesenergy

to

heatwaterpumpedbythewindmill.Thewaterisstoredinlargedrumsonthesideofthehome.


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Tidal energy comes from the energy of water as itflows from high tide to low tide.This energy can be captured by closing a bay with a

dam. As the tide rises, the bay fills with water. Athigh tide, the dam is closed to hold the water thewater in the bay. At low tide, the stored water isreleased through a turbine to generate electricpower.The chief disadvantage of tidal power plants isthat they can produce energy only during falling

tides.Also, the plants can be built in few places.


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Biomass is a renewable energy resource derivedfrom the carbonaceous waste of various human andnatural activities

It is derived from numerous sources, including theby-products from the timber industry, agriculturalcrops, raw materials from the forest, major partsof household waste and wood.

Biomass does not add carbon dioxide to theatmosphere as it absorbs the same amount ofcarbon in growing as it releases when consumed as a

fuel. Its advantage is that it can be used to generate

electricity with the same equipment or power plantsthat are now burning fossil fuels.


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Geothermal power is generated wherever watercomes in contact with hot rocks below the earths

surface. The rocks give off heat that makes the water hot

enough to turn in to steam.

Power companies can drill wells and pump the hotwater or steam to the surface, where it can beused to generate energy.

In areas where no underground water or steamexists naturally, engineers can pump water intothe ground to be heated by hot rocks.

Bolivia, Iceland, New Zealand, and the united

states have developed geothermal power plants.


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Geothermal energy plant Geothermalenergyplants

generateelectricityandheatbyharnessingtheheatenergycontainedwithintheearth.Theearthtransfersitsenergytodeep

lyingcirculatingwater,whichtheplantsaccesswithwellsandpumps.Geothermalenergyis

attractivebecause

it

creates

almostnoenvironmentalpollution.However,thenumberofsiteswheregeothermalenergycanbeeconomicallyextractedislimited.


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Wind power is the conversion of wind energy intomore useful forms, usually electricity using windturbines.

Most modern wind power is generated in the formof electricity by converting the rotation of turbineblades into electrical current by means of anelectrical generator.

Wind power is used in large scale wind farms fornational electrical grids as well as in small individualturbines for providing electricity to rural

residences or grid-isolated locations. Wind energy is ample, renewable, widelydistributed, clean, and mitigates the greenhouseeffect if used to replace fossil-fuel-derived

electricity.
http://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Wind_farmshttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/Mitigation_of_global_warminghttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Mitigation_of_global_warminghttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/Wind_farmshttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind


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WindFarm Theseturbinesare

partofawindfarmlocatednearLakeBenton,Minnesota.

Thisregion

is

one

ofthemostproductivewind

energysites

in

the

MidwesternUnitedStates.


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Nuclear energy provides about 6% of thecommercial energy used in the world.

Today, energy comes from fission- that is, the

splitting of atomic nuclei of certain elements,especially uranium.

But scientists hope eventually to produce

nuclear energy from fusion, the combining ofatomic nuclei.

Nuclear fusion produces the heat and light of

the sun and other stars, and the explosiveforce of the hydrogen bomb.

However, fusion devices have yet to produce

usable amounts of energy.


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Since energy resources are limited, we must use

the available energy with utmost care and notwaste it. Judicious and economical use can help in

overcoming the energy crisis. The wise and economic use of energy resources is

called conservation of energy. We should use more of renewable sources of

energy as they are available in plenty and theydont pollute the environment.


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varshab_sessionvii_29dec2006

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