2. HistoryHistory Sources differ, but its generallySources differ, but its generallyagreed that forms of tidalagreed that forms of tidalenergy were used as early asenergy were used as early asthe eighth century A.D.the eighth century A.D. The first recorded uses of tidalThe first recorded uses of tidalenergy were on Europeanenergy were on Europeancoasts.coasts. Early tidal mills sat on a pondEarly tidal mills sat on a pondfilled by the incoming tide thatfilled by the incoming tide thatwent through a sluice, andwent through a sluice, andemptied when the tide went outemptied when the tide went outthrough a water wheel.through a water wheel. The turning of the water wheelThe turning of the water wheelprovided power to mill grain.provided power to mill grain.
3. PresentPresent The newest technology of the source ofThe newest technology of the source oftidal energy is now used for electricity.tidal energy is now used for electricity. Now a days hydroelectric power isNow a days hydroelectric power isbecoming more common.becoming more common. It works by tidal waves going throughIt works by tidal waves going throughthe generator converting the energy ofthe generator converting the energy ofthe wave into power with out anythe wave into power with out anyharmful green house gases.harmful green house gases. There are many different ways ofThere are many different ways ofcreating tidal energy.creating tidal energy. One way is tidal generator.ThisOne way is tidal generator.Thismachine has special blades so nothingmachine has special blades so nothinggets caught.gets caught. Another type is a barrage witch isAnother type is a barrage witch isbecoming more common in rivers.becoming more common in rivers. The two big tidal power plants are nowThe two big tidal power plants are nowin France and Russia.in France and Russia.
5. TidalTurbinesTidalTurbinesTidal turbines use similar technology toTidal turbines use similar technology towind turbines, although their blades arewind turbines, although their blades aremuch shorter and stronger. (So a goodmuch shorter and stronger. (So a goodway to think of them is as underwaterway to think of them is as underwaterwindmills).windmills).Basically the water currents turn theBasically the water currents turn theturbines, which in turn activate aturbines, which in turn activate agenerator that produces electricity.generator that produces electricity.These systems work best where thereThese systems work best where thereare very strong tidal zones (Norwegianare very strong tidal zones (Norwegianand British coastlines.)and British coastlines.)The upfront cost of these tidal streamThe upfront cost of these tidal streamsystems is very high and also installationsystems is very high and also installationand maintenance is difficult.and maintenance is difficult.But it’s still cheaper and has lessBut it’s still cheaper and has lessenvironmental impact than any anotherenvironmental impact than any anothertidal system.tidal system.
6. TidalBarragesTidalBarrages Tidal barrages are very similar to the Dams inTidal barrages are very similar to the Dams inhydroelectric plants, except that they are muchhydroelectric plants, except that they are muchlarger as they are built across an estuary or bay.larger as they are built across an estuary or bay. The tidal range (difference between high and lowThe tidal range (difference between high and lowtide) needs to be in excess of five metres for thetide) needs to be in excess of five metres for thebarrage to be workable.barrage to be workable. As the tide comes in, water flows through the damAs the tide comes in, water flows through the daminto the basin.Then when the tide stops the gatesinto the basin.Then when the tide stops the gatesare closed, which traps the water in theare closed, which traps the water in thebasin/estuary.basin/estuary. As the tide goes out gates in the dam whichAs the tide goes out gates in the dam whichcontain turbines are then opened and the flowingcontain turbines are then opened and the flowingwater passes through the turbines, thuswater passes through the turbines, thusgenerating energy.generating energy. Tidal barrages have very high infrastructure costsTidal barrages have very high infrastructure costsand are very damaging on the local environment.and are very damaging on the local environment. Also construction of such dams is a very lengthyAlso construction of such dams is a very lengthyproject. A good example of this is the La Ranceproject. A good example of this is the La Rancebarrage in France which took over five years tobarrage in France which took over five years tobuild (it’s the largest tidal power station in thebuild (it’s the largest tidal power station in theworld.)world.)
7. TidalLagoonsTidalLagoons Tidal Lagoons are similar toTidal Lagoons are similar tobarrages but have a muchbarrages but have a muchlower cost and impact on thelower cost and impact on theenvironment.environment. They are self containedThey are self containedstructures cut off from thestructures cut off from therest of the sea.rest of the sea. It works in pretty much theIt works in pretty much thesame way as a tidal barragesame way as a tidal barrageas when the tide rises theas when the tide rises thelagoon fills and when it fallslagoon fills and when it fallsthe water is then releasedthe water is then releasedthrough the turbines.through the turbines.
8. HowitworksHowitworks Turbines are placed under the sea inTurbines are placed under the sea inareas which have high tidal movement.areas which have high tidal movement. These turbines are designed toThese turbines are designed tocapture the energy produced by thecapture the energy produced by thetidal movement and is thentidal movement and is thentransformed into electricity.transformed into electricity. The tide moves a huge amount of waterThe tide moves a huge amount of watertwice each day.twice each day. Although the energy supply is reliableAlthough the energy supply is reliableand plentiful, converting it into usefuland plentiful, converting it into usefulelectrical power is not easy.electrical power is not easy. There are eight main sites aroundThere are eight main sites aroundBritain where tidal power stationsBritain where tidal power stationscould usefully be built.could usefully be built. Only around 20 sites in the world haveOnly around 20 sites in the world havebeen identified as possible tidal powerbeen identified as possible tidal powerstations.stations.
9. CostCost It’s Very inexpensive in theIt’s Very inexpensive in thelong run.long run. Most of the cost comesMost of the cost comesfrom building it.from building it. It cost about 5-10 billionIt cost about 5-10 billiondollars.dollars. Most companies dont wantMost companies dont wantto invest because thereto invest because therearent immediate results.arent immediate results. 80% of kinetic energy from80% of kinetic energy fromthe waves can bethe waves can beconverted into usableconverted into usableenergyenergy
10. Advantagesvs.Advantagesvs.disadvantagesdisadvantages AdvantagesAdvantages The energy is freeThe energy is free- no fuel needed,- no fuel needed,no wasteno wasteproduced.produced. Most designs areMost designs areinexpensive toinexpensive tooperate andoperate andmaintain.maintain. Waves canWaves canproduce a greatproduce a greatdeal of energy.deal of energy. Tides areTides arepredictablepredictable There are minimalThere are minimalenvironmentalenvironmentalimpacts.impacts. DisadvantageDisadvantagess Depends on the waves – -Depends on the waves – -sometimes youll get loads ofsometimes youll get loads ofenergy, sometimes nothingenergy, sometimes nothing The actual construction isThe actual construction isvery expensivevery expensive Needs a suitable site, whereNeeds a suitable site, wherewaves are consistentlywaves are consistentlystrong.strong. Must be able to withstandMust be able to withstandvery rough weather.very rough weather. Disturbance or destructionDisturbance or destructionof marine lifeof marine life Degradation of scenic oceanDegradation of scenic oceanfront views from wavefront views from waveenergy devices located nearenergy devices located nearor on the shore, and fromor on the shore, and fromonshore overhead electriconshore overhead electrictransmission lines.transmission lines. The dams become unusableThe dams become unusableafter 50-100 yearsafter 50-100 years