Tidal Energy (Non Conventional Energy Source)

This PPT contains the basic information about the Tidal Energy, which is the method of electricity generation using Tides at sea caused due to the gravitational pull of Moon on Earth. It is a part of non conventional method of electricity generation.

1. Tidal Energy

2. Introduction
•Tidesarethewavescausedduetothe
gravitationalpullofthemoonandalso
sun(thoughitspullisverylow).
•Theriseiscalledhightideandfalliscalledlow
tide.
•Thisbuildingupandrecedingofwaveshappens
twiceadayandcausesenormousmovementof
water.

3. Tidal energy
•Tidalenergyistheutilizationofthevariationsin
sealevelcausedprimarilybythegravitational
effectsofthemoon,combinedwiththerotation
oftheEarth.

4. History
•Tidal power buildings were built as early as the
9th Century throughout Europe.
•This building was built in Ohalo, Portugal circa
1280.

5. How does Tidal Energy Works ?
•TidalTurbines:Tidalturbinesusesimilartechnologyto
windturbines,althoughtheirbladesaremuchshorter
andstronger.Soagoodwaytothinkofthemisas
underwaterwindmills.
•TidalBarrages:Tidalbarragesareverysimilartothe
Damsinhydroelectricplants,exceptthattheyaremuch
largerastheyarebuiltacrossanestuaryorbay.
•TidalLagoons:TidalLagoonsaresimilartobarragesbut
haveamuchlowercostandimpactontheenvironment.

6. Application
•Tidalenergyisderivedfromthemotionofthe
Earth-Moonsystem.Duetotherotationof
earth,thebulgesoftidesarealwaysaheadofthe
positiononearthrightunderthemoon.
•Thegravitationalforcebetweenthisportionof
waterandmoongeneratesatorquethat
deceleratestherotationofearth.
•Ontheotherhand,thisforcehelpstoaccelerate
theorbitalmovementofmoonaroundearth.

7. •Asaconsequence,withoutotherinterference,
therotationalperiodofearthwillfinallybeequal
totheorbitalperiodofmoon.
•Theutilizationoftidalenergy,whichwill
inevitablyreducethetidalcurrents,takes
advantageoftheangulardynamicenergyof
earthinthesimilarway.

8. Different Generator Types
•Tidal Fences
•Tidal Lagoons
•Tidal Turbines

9. Tidal Fences
•Tidalfencesarecomposedof
individual,verticalaxisturbines
whicharemountedwithinthefence
structure,knownasacaisson.
•Kindoflikegiantturnstyleswhich
completelyblockachannel,forcing
allofthewaterthroughthem.
•Unlikebarragetidalpowerstations,
tidalfencescanalsobeusedin
unconfinedbasins,suchasinthe
channelbetweenthemainlandand
anearbyoffshoreisland,or
betweentwoislands.

10. Tidal Fences (cont.)
•Sincetheydonotrequire
floodingofthebasin,tidal
fenceshavemuchlessimpact
ontheenvironment,andare
significantlycheapertoinstall.
•Unlikebarragegenerators,
tidalfenceshavetheadvantage
ofbeingabletogenerate
electricityoncetheinitial
modulesareinstalled.
•Sinceacaissonstructureis
stillrequired,whichcan
disruptthemovementoflarge
marineanimalsandshipping,
therearestillecological
concerns

11. •“A2.2GWtidalfence
usingtheDavisturbine,
wasbeingplannedforthe
SanBernadinoStraitin
thePhilippinestobe
constructedbytheBlue
Energycompany.The
project,estimatedtocost
$US2.8Billionis
unfortunatelyonhold
due to political
instability”
accordingtoMichael
MaseraBlueEnergy
spokesman.”
Davis Hydro Turbine
Tidal Fences (cont.)

12. Tidal Lagoons
•Tidallagoonsareanadaptationofthe
barragesystem.Similartostandard
barragemodels,tidallagoonsretaina
headpondandgeneratepowervia
conventionalhydro-turbines.
•Thedifferenceisthattheconventional
barragedesignsexploitthenatural
coastlinetominimizebarragelength.
However,thisentailsblockingthe
estuaryregardlessofhowdeepitis.
Thisraisethecostsconsiderably.
•However,alagoon,foralowcostcan
prettymuchbebuiltanywherethat
thereisahightidalrange.
•Thelagoonhasrelativelylittlevisual
impact,asitisbelowthehighwater
tidemarkandappearslikeanormal
seawallatlowtide.

13. Tidal Lagoons (cont.)
•Thelagooncanbebuiltusinglooseaggregatesfoundinquarriesor
demolishedstructures.Thisrubblewouldbe‘dumped’untilan
impoundwallwascomplete.Asanyaggregatecanbeused,itis
possibletorestrictconstructioncostsbyimplementingthecheapest
materialsavailable
•Thisconstructiontechniquealsohastheaddedbenefitofcreatingan
artificialreef.Aswell,acalmwaterlakewouldbecreatedinthe
middlewheresmallerfishandbirdscouldflourish
•Migratingfishcanswimaroundunimpededandwithoutthedanger
ofsluicesornegotiatingturbines.
•TidalElectricisplanningtotesttheconceptinSwanseaBaywitha
relativelysmall30MWoutputplant.
•DesignbeingimplementedinChinainthefuture.
•“TheChinesegovernmenthasexpresseditsenthusiasticsupportof
TidalElectric’sambitious300MWoffshoretidallagooninthewaters
nearthemouthoftheYaluRiverbysigninganagreementpledgingto
cooperatewiththedevelopment.At300MW,theprojectwouldbe
thelargesttidalpowerprojectintheworld,toppingthecapacityof
the240MWFrenchtidalpowerplantinLaRance.“

14. •Proposedshortlyaftertheoilcrisisof
the1970s,tidalturbineshaveonly
becomerealityinthelastdecade,
whena10-15kW'proofofconcept'
turbinewasoperatedonLochLinnhe.
Resemblingawindturbine,tidal
turbinesoffersignificantadvantages
overbarrageandfencetidalsystems,
includingreducedenvironmental
effects.
•Tidalturbinesutilizetidalcurrents
thataremovingwithvelocitiesof
between2and3m/s(4to6knots)to
generatebetween4and13kW/m2.
Fastmovingcurrent(>3m/s)can
causeunduestressonthebladesina
similarwaythatverystronggaleforce
windscandamagetraditionalwind
turbinegenerators,whilstlower
velocitiesareuneconomic.
Tidal Turbines

15. TidalTurbines(cont.)
•Tidalturbinesoffersignificant
advantagesoverbarrageandfence
tidalsystems(andotherrenewable
energysources):
•Highenergyintensity:A1MWtidal
turbinecanaccessfivetotentimesas
muchenergypersquaremeterofrotor
thana1MWwindturbine,resultingina
smallerandpotentiallylowercost
machine.
•Minimalenvironmentalimpact:tidal
turbinesarevisibleenoughtobe
avoidedbymarinersbuttheyhavea
lowvisualimpactontheseascape,they
producenopollutionornoiseandtheir
slowmovingrotorswhichturnatless
thanonerevolutioninfourseconds(15
rpm)areconsideredunlikelytoharm
marinelife.
•Highenergyreturnonenergy
invested:tidalturbinesshouldoffer
fasterenergypaybackthanmostother
renewables.

16. Future Expansion of Tidal Turbines
•TidalFarms.Setsofupto
hundredsoftidalturbines
workinginconjunction.
•Potentialforgiga-wattsofpower
•MarineCurrentTurbine(MCT)
createdSeaFlow(300kW),is
followingupwithSeaGen
(1MW),whichwillexpandtoa5
turbinetidalfarmthatwill
provide5MW.
•The Norwegian company,
HammerfestStrom,believes
thattheywillhavetheirfirst
tidalfarmofover20second
generationdevicesoperational
beforetheendof2008.This
wouldbethe3rdphaseoftheir
'BlueConcept'projectand
wouldresultinatidalfarmthat
wouldproduce10MW of
renewableelectricity.

17. Conclusions
•Tidal power is a renewable, potentially zero emission (during
operation) energy source.
•Tides have the advantage of being completely predictable, unlike
solar and wind power.
•Different types of Tidal Generators suit different areas and energy
needs.
•There are environmental concerns that need to be addressed when
developing this technology further.

18. Advantages
•Itisaninexhaustiblesourceofenergy.
•2)Tidalenergyisenvironmentfriendlyenergy
anddoesn'tproducegreenhousegases.
•3)As71%ofEarth’ssurfaceiscoveredbywater,
thereisscopetogeneratethisenergyonlarge
scale.
•4)Wecanpredicttheriseandfalloftidesas
theyfollowcyclicfashion.

19. •5)Efficiencyoftidalpowerisfargreateras
comparedtocoal,solarorwindenergy.Its
efficiencyisaround80%.
•6)Althoughcostofconstructionoftidalpoweris
highbutmaintenancecostsarerelativelylow.

20. Disadvantages
•1)Costofconstructionoftidalpowerplantis
high.
•2)Thereareveryfewideallocationsfor
constructionofplantandtheytooarelocalized
tocoastalregionsonly.
•3)Intensityofseawavesisunpredictableand
therecanbedamagetopowergenerationunits.
4)Influencesaquaticlifeadverselyandcan
disruptmigrationoffish.

21. •5) The actual generation is for a short period of
time. The tides only happen twice a day so
electricity can be produced only for that time.
•6) Frozen sea, low or weak tides, straight
shorelines, low tidal rise or fall are some of the
obstructions.