Btech IIIrd year

Electrical Engineering

Made By:-

Amit Kumar Sharma

Manish Dhiman

Gulzar Ahmed

Mohd. Jasif Qureshi

Submitted To:-

Mr. B.S. Jha Sir

Overview of Tidal Generation

- Tides

- Types of Tides

- History of Tidal Power

- Generation of Tidal Energy

Generating Methods of Tidal Energy

- Tidal stream generator

- Tidal barrage

- Dynamic tidal power

- Tidal lagoon

Tidal Turbines

Types Of Turbines

Present Tidal Power Plants in the World

Environmental Concerns

Advantages

What Is Tide??

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.

Some shorelines experience almost two equal high tides and two low tides each day, called a semi-diurnal tide. Some locations experience only one high and one low tide each day, called a diurnal tide. Some locations experience two uneven tides a day, or sometimes one high and one low each day; this is called a mixed tide.

Types Of Tides

According to the height of the tide - High tide: when the sea water reaches its greatest height

within the tide cycle. - Low tide: when the sea water reaches its lowest height

within the tide cycle.

According to the lunar phase- Spring tides During the full moon and new moon phases, the Moon

and the Sun are aligned and their effects combined, producing the spring tides. On the tide tables we can see the high tidal coefficient of the tides when both celestial bodies are aligned.

There is a proven increase in the activity of fish during spring tides, above all if these coincide with sunrise or sunset, and these are the most propitious days for fishing.

- Neap tides

During waxing and waning moons, on the contrary, the effects are detracted, thereby obtaining tides of less amplitude (lower tidal coefficient), called neap tides.

The movement on the seabed tends to be less and this normally results in days that are less propitious for fishing than days with spring tides.

History Of Tidal Power

787: simple technique of a waterwheel by the Spanish, French, and British

1966: “La Rance” tidal power plant went in operation.

2001: British Parliament states “the world can no longer neglect the massive potential of wave and tidal energy”

2002: Large investments in research and prototypes spark proposals in Turkey, China, and United States; among others

Generation of Tidal Energy: -

Tidal power is taken from the Earth'soceanic tides; tidal forces are periodicvariations in gravitational attractionexerted by celestial bodies.

These forces create correspondingmotions or currents in the world's oceans.Due to the strong attraction to theoceans, a bulge in the water level iscreated, causing a temporary increase insea level. When the sea level is raised,water from the middle of the ocean isforced to move toward the shorelines,creating a tide.

This occurrence takes place in anunfailing manner, due to the consistentpattern of the moon’s orbit around theearth. The magnitude and character ofthis motion reflects the changingpositions of the Moon and Sun relative tothe Earth, the effects of Earth's rotation,and local geography of the sea floor andcoastlines.

Generating Methods: -

Tidal Steam Generator: -

Tidal stream generators (or TSGs) make use of the kinetic energy of movingwater to power turbines, in a similar way to wind turbines that use wind topower turbines. Some tidal generators can be built into the structures ofexisting bridges, involving virtually no aesthetic problems. Land constrictionssuch as straits or inlets can create high velocities at specific sites, which can becaptured with the use of turbines. These turbines can be horizontal, vertical,open, or ducted and are typically placed near the bottom of the water column.

Tidal Barrage: -Tidal barrages make use of the potential energy in the difference in heightbetween high and low tides. When using tidal barrages to generate power, thepotential energy from a tide is seized through strategic placement of specializeddams. When the sea level rises and the tide begins to come in, the temporaryincrease in tidal power is channeled into a large basin behind the dam, holdinga large amount of potential energy. With the receding tide, this energy is thenconverted into mechanical energy as the water is released through largeturbines that create electrical power through the use of generators. Barrages areessentially dams across the full width of a tidal estuary.

Dynamic Tidal Power: -Dynamic tidal power (or DTP) is an untried but promising technology thatwould exploit an interaction between potential and kinetic energies in tidalflows. It proposes that very long dams (for example: 30–50 km length) be builtfrom coasts straight out into the sea or ocean, without enclosing an area. Tidalphase differences are introduced across the dam, leading to a significant water-level differential in shallow coastal seas – featuring strong coast-paralleloscillating tidal currents such as found in the UK, China, and Korea.

Tidal Lagoon: -A newer tidal energy design option is to construct circular retaining wallsembedded with turbines that can capture the potential energy of tides. Thecreated reservoirs are similar to those of tidal barrages, except that the locationis artificial and does not contain a preexisting ecosystem.

Tidal Turbines: -

• Proposed shortly after the oil crisis ofthe 1970s, tidal turbines have onlybecome reality in the last decade, when a10-15kW 'proof of concept' turbine wasoperated on Loch Linnhe. Resembling awind turbine, tidal turbines offersignificant advantages over barrage andfence tidal systems, including reducedenvironmental effects.

• Tidal turbines utilize tidal currents thatare moving with velocities of between 2and 3 m/s (4 to 6 knots) to generatebetween 4 and 13 kW/m2. Fast movingcurrent (>3 m/s) can cause undue stresson the blades in a similar way that verystrong gale force winds can damagetraditional wind turbine generators,whilst lower velocities are uneconomic.

Types of Turbines: -

Bulb Type

Rim Type

Tubular Type

•In systems with a bulb turbine, water flowsaround the turbine, making access formaintenance difficult, as the water must beprevented from flowing past the turbine.

•Rim turbines reduce these problems as thegenerator is mounted in the barrage, at rightangles to the turbine blades. Unfortunately, it isdifficult to regulate the performance of theseturbines and it is unsuitable for use in pumping.

•Tubular turbines have been proposed for usesome UK projects. In this configuration, theblades are connected to a long shaft andorientated at an angle so that the generator issitting on top of the barrage.

Present Tidal Power Plants In world: -Station Capacity (MW) Country

Annapolis Royal Generating Station 20 Canada

Jiangxia Tidal Power Station 3.2 China

Kislaya Guba Tidal Power Station 1.7 Russia

Rance Tidal Power Station 240 France

Sihwa Lake Tidal Power Station 254 South Korea

Strangford Lough SeaGen 1.2 United Kingdom

Uldolmok Tidal Power Station 1.5 South Korea

Environmental Concerns: -

Tidal power generation can offer significant advantages, including improved transportation due to the development of traffic or rail bridges across estuaries and reduced greenhouse gas emissions by utilizing tidal power in place of fossil fuels.

However there are also some significant environmental disadvantages which make tidal power, particularly barrage systems less attractive than other forms of renewable energy.

Potentially the largest disadvantage of tidal power is the effect a tidal station has on the plants and animals which live within the estuary. As very few tidal barrages have been built, very little is understood about the full impact of tidal power systems on the local environment. What has been concluded is that the effect due to a tidal barrage is highly dependent upon the local geography and marine ecosystem.

Wales have been caught in tidal generators. Fish may move through sluices safely, but when these are closed, fish will

seek out turbines and attempt to swim through them. Also, some fish will be unable to escape the water speed near a turbine and will be sucked through.

Advantages : - Apart from the initial installation cost, tidal power is

free. Tidal energy produces no greenhouse gases or any

other kind of pollution. It requires no fuel. Electricity is produced reliably. Not expensive to maintain. Tides are totally predictable, enabling us to calculate

when we can generate more, and at times when the generation is low, shift the load to some other source of electricity generation.

Offshore turbines and vertical-axis turbines are not extremely expensive to build and do not have a large environmental impact.