tidal energynew

8/6/2019 Tidal Energynew

http://slidepdf.com/reader/full/tidal-energynew 1/34

Tidal Energy

Rajarshi Sikdar1PI07EE071



Introduction

Recent economic reforms have transformed India into

the second fastest growing economy in the world.However India¶s fast economic growth comes with agrowing demand for energy. India has been said to bethe 6th largest consumer of oil and 3rd largestconsumer of coal. Not just India, countries around arebecoming more and more power hungry. This has led

to the fast depletion of conventional power sources.Conventional power sources also add to the pollutionand lead to global warming. So the need of the houris harness renewable sources of energy which are fastreplenishing and non pollutant.



WHAT IS TIDAL POWER? WHAT IS TIDAL POWER?

Tidal Power is the generation of electricalTidal Power is the generation of electricalpower through the harnessing of the ebbpower through the harnessing of the ebb

and flow of the tides.and flow of the tides.

Tidal Energy is sustainable, clean, reliable,Tidal Energy is sustainable, clean, reliable,widely distributed, and can offer significantwidely distributed, and can offer significantbenefits to many marine nations. Tidalbenefits to many marine nations. TidalEnergy can be captured in an efficient andEnergy can be captured in an efficient andcostcost--effective way.effective way.



HistorySince 1958, man has been harnessingthe power of tides to produceelectricity. But harnessing tides hasbeen going around since prehistorictimes. Historically, tide mills havebeen used, both in Europe and on theAtlantic coast of North America. The

earliest occurrences date from theMiddle Ages, or even from RomanTimes.



WorkingA barrage, which is in fact a huge dam, is built across ariver estuary or bay. This barrage has gates in it whichallow the water to flow into the barrage with theincoming tide. These gates are then closed when the tidebegins to go back out. This water which is now trapped

inside the barrage is now called a µhydrostatic head¶. Thegreater the head the more power can be generated fromthe out flowing water. There are other gates within thebarrage which are now opened; these gates containhydro-electric generators, very similar to the ones usedin Hydropower. These generators are now turned by theout flowing water and power is generated. The tidalrange has to be sufficient in order for this to be apractical means to generate power. This range should bein excess of 5 metres otherwise the power generated isnot sufficient.



Vertical Axis Type:



Horizontal Axis Type:



Barrages: It makes use of thepotential energy in the difference in

height (orhead

) between high andlow tides. Barrages are essentiallydams across the full width of a tidalestuary, and suffer from very high

civil infrastructure costs, a worldwideshortage of viable sites, andenvironmental issues.



Barrage Type:



Pros and Cons of Tidal Stream Can generate same amount of power

as wind with smaller blades moving

slower due to density of water Usually less expensive than barrage

Relatively new technology

Don¶t get the funneling effect of barrages



Types of Turbines used: Bulb Turbine

A type of hydroturbine in which the

entire generator ismounted inside thewater passageway asan integral unit withthe turbine. Theseinstallations can offersignificant reductionsin the size of thepowerhouse



Straflo Turbine

Straflo turbines are axial

turbines with the generatoroutside of the water channel



Tubular Turbine

Tubular turbine is widely usedin hydro power stations withthe head of 2-30 meters. Theblades are fixed or can beadjusted manually. Theefficient turbine of this kindcan process a large quantity of water flow which passesunimpeded. Since the tubular

type requires less space thanother turbines, a saving in civilcosts is realized due to asmaller powerhouse.



Helical TurbinesThe blades are shaped like the threads of a screwwhich run over a cylinder. Due to the shape of theblades a reaction thrust is exerted on the turbinewhich means that the turbine can rotate faster than

what the normal flowing speed of water would make itto spin at, had there been no reaction thrust.

The requisite feature of this turbine is that the axis of rotation should be at right angles to the direction of flow of current. This means that for a given setup theturbine will rotate in the same direction even if theflow of water is reversed in direction. Since this isexactly what happens in case of tides and tidalcurrents, it is ideal for use in such situations.



Schematic view of a HelicalSchematic view of a Helical

TurbineTurbine



Other Possibilities: Tidal Fence

Completely blocks a channel so asthe tide rises, water is forcedthrough the styles to turn them.The advantage of a tidal fence is

that all the electrical equipment(generators and transformers)can be kept high above the water.Also, by decreasing the cross-section of the channel, current

velocity through the turbines issignificantly increasedCan be used between islands orbetween a mainland and an islandas opposed to only across themouth of a confined bay.



Water

Wheel

Where the shoreline hassuitable topography, cliff-

mounted oscillating watercolumn (OWC) generatorscan be installed. The OWCworks on a simple principle.As an incoming wave causesthe water level in the unit'smain chamber to rise (seediagram), air is forced up afunnel which houses aWell's counter-rotatingturbine.



Tapered Channel

Its concept is similar to that of traditionalhydroelectric devices. Waves feed through

tapered channel into reservoir and arethen fed through a turbine. Kinetic energyof the moving wave is changed to potentialenergy as water is collected in thereservoir.



Floating Devices

The ³Salter ´Duck was developedin the 1970s and generateselectricity by bobbing up and

down with the waves. It canproduce energy extremelyefficiently.



Generation of Grid and Regrowth of

Coral Reefs1) Power for the Grid1) Power for the Grid



ReRe--growth of Coral Reefs Usinggrowth of Coral Reefs Using

Biorock Technology:Biorock Technology:

Biorock shore protectionBiorock shore protectionproject at Ihuru Island,project at Ihuru Island,

Maldives, turned aMaldives, turned aseverely eroding beachseverely eroding beachinto 15 meters (50into 15 meters (50feet) growth in a fewfeet) growth in a fewyearsyears



Biorock reef in front of Biorock reef in front of the beach usesthe beach useselectricity to grow solidelectricity to grow solid

limestone rock on alimestone rock on asteel frame and to growsteel frame and to growcorals. This slows downcorals. This slows downwaves, causes sand towaves, causes sand to

settle, and attracts fish.settle, and attracts fish.



Tidal energy can grow Biorock reefs toTidal energy can grow Biorock reefs toprotect whole islands from sea levelprotect whole islands from sea level

rise, while restoring their coral reefsrise, while restoring their coral reefsand fisheries.and fisheries.

Biorock¶s technology has been provenBiorock¶s technology has been provenin field tests in more than 20in field tests in more than 20Caribbean, Pacific, Indian Ocean, andCaribbean, Pacific, Indian Ocean, andSoutheast Asian countries.Southeast Asian countries.



World Map of the Distribution of World Map of the Distribution of

Tidal EnergyTidal Energy



Application Small-scale tidal plants can be used

for grinding purposes.

The barrage can be used fortransportation.

The main application is generation of power.



Advantages No pollution

Renewable resource

More efficient than wind because of the density of water

Predictable source of energy vs. wind and solar

Electrification of isolated communitiesElectrification of isolated communities

Generation for the gridGeneration for the grid

ReRe--growth of coral reefs using mineral accretiongrowth of coral reefs using mineral accretiontechnologytechnology

Substitution of imported petroleum used to generateSubstitution of imported petroleum used to generate

electricityelectricity Generation of hydrogen for fuel cells from theGeneration of hydrogen for fuel cells from the

electrolysis of water from tidal currents that doelectrolysis of water from tidal currents that do

not need to be in close proximity to endnot need to be in close proximity to end--users.users.



Disadvantages Presently costly

Expensive to build and maintain A 1085MW facility could cost as much as 1.2

billion dollars to construct and run

Technology is not fully developed Barrage style only produces energy for

about 10 hours out of the day Barrage style has environmental affects

Water is not replenished, it cannot flowaway so any dirt or pollution lingersaround the coast much longer



Environmental Effects Turbidity

Salinity

Sediment movement Effect on fishes



Why India is not using tidalenergy though it has a long

coast line?

Despite its advantages, Tidal Energy is notwidely used in India because;

It is not a prominent source and its

installation cost is high. Seasonal Tidal formation.

Most importantly, it is extremely site specific,requires mean tidal differences greater than4 m, and also favourable topographicalconditions, such as estuaries or certain typesof bays in order to bring down costs of dams,etc.



What is there in store for future?



Conclusion Tidal Energy is sustainable, clean, andTidal Energy is sustainable, clean, and

reliable.reliable.

Tidal Energy is widely distributed and canTidal Energy is widely distributed and can

offer significant benefits to many coastaloffer significant benefits to many coastalnations.nations.

Tide Energy can be captured in a practical,Tide Energy can be captured in a practical,efficient, costefficient, cost--effective way.effective way.

Tidal Energy deserves to be included on theTidal Energy deserves to be included on thelist of sources of sustainable energylist of sources of sustainable energysupported and funded by CSD, GEF, UNDP,supported and funded by CSD, GEF, UNDP,IEA, UNIDO, CDM, etc.IEA, UNIDO, CDM, etc.



THANK YOU

tidal energynew

Documents