Tidal and Wave Energy

TIDA TIDAL L AND AND WAVE ENERGY

PRESENTED BY, GROUP 4

TIDAL ENERGY

TIDAL ENERGY

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Tides are generated through a combination of forces exerted by the gravitational pull of the sun and the moon and the rotation of the earth. The relative motion of the three bodies produces different tidal cycles which affect the range of the tides.

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Energy can be extracted extrac ted from tides by creating a reservoir or basin behind a barrage and then passing tidal waters through turbines in the barrage to generate electricity. electricity.

Tidal energy is extremely site specific requires mean tidal differences greater than 4 meters and also favorable topographical conditions, such as estuaries or certain types of bays in order to bring down costs of dams etc.

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Although not yet widely used, tidal power has potential for  future electricity generation. Tides are more predictable than wind energy and solar power.

Among sources of renewable energy, tidal power has traditionally suffered from relatively high cost and limited availability of sites with sufficiently high tidal ranges or flow velocities, thus constricting its total availability .

However, many recent technological developments and improvements, both in design (e.g. dynamic tidal  power, tidal lagoons) and turbine technology (e.g. new axial turbines, cross flow turbines), indicate that the total availability of tidal power may be much higher than previously assumed, and that economic and environmental costs may be brought down to competitive levels.

PROCESS OF ENERGY GENERATION

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Tidal energy is produced through the use of  tidal energy generators. These large underwater  turbines are placed in areas with high tidal movements, and are designed to capture the kinetic motion of the ebbing and surging of 

ocean tides in order to produce electricity. Tidal power has great potential for future power and electricity generation because of the massive size of the oceans.

Because the Earth’s tides are caused  by the tidal forces due to gravitational interaction with the Moon and Sun, and the Earth’s rotation, tidal power is practically inexhaustible and classified as a renewable energy source.

IMPORTANT PROJECTS

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The first in-stream tidal current generator in North America (Race Rocks Tidal Power Demonstration Project) was installed at Race Rocks on southern Vancouver Island in September  2006. The next phase in the development of this tidal current generator will be in Nova Scotia .

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Only a few tidal energy sites are in operation around the world. Larger sites include the White Sea in Russia and the Rance River in France (the largest site in the world). Smaller tidal power plant have been built in Canada, such as the site at Annapolis Royal in Nova Scotia, and several in Norway. Together they have a total capacity of less than 250 MW. However, the potential for tidal energy is immense; potential global tidal power exceeds 450 terawatts, most of it in Asia and North America

ADVANTAGES & DISADVANTAGES

 ADVANTAGES 

Tidal power belongs to renewable energy sources meaning it cannot be depleted like fossil fuels can. Tidal forces have their origin in the gravitational interaction with the Moon and Sun, meaning that we could harness tidal power as long as Moon and Sun continue to exist .

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The efficiency of tidal power. Tidal power belongs to the most efficient energy sources by having efficiency of  approximately 80%, this is much better efficiency as compared to other more popular renewable energy sources such as solar and wind.

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Tides are predictable, and this predictability is also one of the advantages that tidal power has over other energy sources  because rise and fall of tides are much more cyclic than random weather patterns. This predictability gives us knowledge when the tides will be in and out.

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Tidal power on larger scale could even lead to reduced import of foreign fuels and improve our energy security  because we wouldn't have to rely so much on expensive foreign fuel import to satisfy our growing energy demand .

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Barrages and small dams used to harness tidal power  could protect coastal areas or ship ports from dangerous tides during a stormy weather 

DISADVANTAGES 

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Tidal power plants are connected with high upfront costs needed for construction , and therefore lack cost-competitiveness on global energy market.

Tidal power is intermittent source of energy that can only produce electricity during tidal surges which is in average around 10 hours each day . This means that in order for tidal power to be considered as a reliable source of energy needs to  be accompanied with some effective energy storage solution.

 Tidal

power plants could lead to environmental damage in some cases as the frames of the turbines have potential to disrupt the movement of large marine animals. Also, the construction of tidal power plant can disrupt fish migration in the oceans.

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more a theoretic source of energy, limited in real life to just a few prototype projects because technology has  just started developing and needs big funds and plenty of scientific research before reaching the commercial character

SUITABLITY TO INDIA

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Since India is surrounded by sea on three sides, its  potential to harness tidal energy has been recognized  by the Government of India.

A British tidal energy company, Atlantis Resources, is expected to set up a tidal power plant with the capacity to generate over 250 MW in the Gulf of  Kutch or Khambhat.

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India’s first attempt to harness tidal power for  generating electricity would be in the form of a three MW plant proposed at the Durgaduani creek in Sundarbans delta of West Bengal.

The Gulf of Kutch and Gulf of Cambay in Gujarat and Gangs delta in the Sunder bans, the world’s largest mangrove, are the three sites identified as potential areas for tidal power generation .

WAVE ENERGY 

INTRODUCTION •

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Wave energy is captured directly from surface waves or from pressure fluctuations below the surface. Wave power systems convert the motion of  the waves into usable mechanical energy which in lump can be used to generate electricity. Waves are caused by wind blowing on the surface of the water.

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In 2008, the first experimental wave farm was opened in Portugal, at the Aguçadoura Wave Park . Ocean waves are caused by the wind as it blows across the sea. Waves are a powerful source of energy. The problem is that it's not easy to harness this energy and convert it into electricity in large amounts. Thus, wave power stations are rare.

PROCESS OF ENERGY GENERATION

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Wave energy is produced when electricity generators are placed on the surface of the ocean. The energy  provided is most often used in desalination plants, power plants and water pumps . Energy output is determined by wave height, wave speed, wavelength, and water density . To date there are only a handful of experimental wave generator plants in operation around the world.

WAVE ENERGY TECHNIQUES … •

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There are several methods of getting energy from waves. One of them works like a swimming pool wave machine in reverse.

At a swimming pool, air is blown in and out of a chamber beside the pool, which makes the water outside bob up and down, causing waves . At a wave power station, the waves arriving cause the water in the chamber to rise and fall , which means that air is forced in and out of the hole in the top of the chamber.

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We place a turbine in this hole, which is turned by the air rushing in and out. The turbine turns a generator. A problem with this design is that the rushing air can be very noisy, unless a silencer is fitted to the turbine.

The noise is not a huge problem anyway, as the waves make quite a bit of noise themselves

 ADVANTAGES AND DISADVANTAGES

 ADVANTAGES WAVE ENERGY  •

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Renewable: The best thing about wave energy is that it will never run out. There will always be waves crashing upon the shores of nations, near the populated coastal regions. The waves flow back from the shore, but they always return. Unlike fossil fuels, which are running out, in some places in the world, just as quickly as people can discover them. Environment Friendly: Also unlike fossil fuels, creating  power from waves creates no harmful byproducts such as gas, waste, and pollution. The energy from waves can be taken directly into electricity-producing machinery and used to power  generators and power plants nearby

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Abundant and Widely Available :Another benefit to using this energy is its nearness to places that can use it. Lots of big cities and harbors are next to the ocean and can harness the  power of the waves for their use. Coastal cities tend to be well populated, so lots of people can get use from wave energy  plants. Easily Predictable : The biggest advantages of wave power as against most of the other alternative energy sources is that it is easily predictable and can be used to calculate the amount that it can produce. The wave energy is consistent and proves much  better than other sources which are dependent on wind or sun exposure.

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Less Dependency on Foreign Oil Cos : Dependence on foreign companies for fossil fuels can be reduced if energy from wave power can be extracted up to its maximum. Not only it will help to curb air pollution but can also provide green jobs to millions of people.

No Damage to Land : Unlike fossil fuels which cause massive damage to land as they can leave large holes while extracting energy from them , wave power does not cause any damage to earth. It is safe, clean and one of the preferred method to extract energy from ocean.

Disadvantages •

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Suitable to Certain Locations : The biggest disadvantage to getting your energy from the waves is location. Only power   plants and towns near the ocean will benefit directly from it. Because of its source, wave energy is not a viable power  source for everyone. Landlocked nations and cities far from the sea have to find alternate sources of power, so wave energy is not the clean energy solution for everyone. Source of Disturbance for Private and Commercial Vessels : it disturbs commercial and private vessels.

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Effect on marine Ecosystem : As clean as wave energy is, it still creates hazards for some of the creatures near it. Large machines have to be put near and in the water to gather energy from the waves. These machines disturb the seafloor, change the habitat of near-shore creatures (like crabs and starfish) and create noise that disturbs the sea life around them. There is also a danger of  toxic chemicals that are used on wave energy platforms spilling and polluting the water near  them. Weak Performance in Rough Weather : The performance of  wave power drops significantly during rough weather. They must withstand rough weather.

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Noise and Visual pollution : Wave energy generators may  be unpleasant for some who live close to coastal regions. They look like large machines working in the middle of the ocean and destroy the beauty of the ocean. They also generate noise  pollution but the noise is often covered by the noise of waves which is much more than that of wave generators. Wavelength : Wind power is highly dependent on wavelength i.e. wave speed, wave length, wavelength and water density. They require a consistent flow of powerful waves to generate significant amount of wave power. Some areas experience unreliable wave behavior and it becomes unpredictable to forecast accurate wave power and therefore cannot be trusted as reliable energy source.

IMPORTANT PROJECTS

Wave Power Project - Lysekil •

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The goal of the Wave Power Project Lysekil is to test a new concept to generate electricity from the motions of sea waves under realistic circumstances and over a longer period of time. The research area is situated on the west coast of Sweden, about 1 nautical mile (2 km) west of the Islandsberg peninsula in the municipality of Lysekil .

The concept is based on a system of unique piston driven generators. A so-called linear generator is standing protected on the seabed and is driven, via a rope, by a buoy on the surface. Several generators can be combined into groups, some 20-100 m beneath the surface and can further be combined into groups using standard cables on the seabed.

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With the help of power electronics , the generated alternating power is converted into direct current, which is then brought to land by means of standard cables and connected to the power grid through a DC/AC converter. This system with buoy, rope and generator is expected to be cheap, sturdy, environmentally benign, and to be able to cope with the extreme conditions at sea.

WAVE ENERGY IN INDIA

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In India the research and development activity for exploring wave energy started at the Ocean Engineering Centre, Indian Institute of  Technology, Madras in 1982. Primary estimates indicate that the annual wave energy potential along the Indian coast is  between 5 MW to 15 MW per meter.