KAUTILYA INSTITUTE OF TECHNOLOGY & ENGINEERING,JAIPUR

Session 2008-12

Seminar Report

ON

(TIDAL ENERGY)

Presented on

DATE-31March,2012

Submitted To- Submmited By-Prof.B.K.GRAG PUSHPENDRA SINGH (Dean Mechanical Depatment) Roll No.08EKTME044

MECHANICAL ENGINEERING DEPARTMENT

KAUTILYA INSTITUTE OF TECHNOLOGY & ENGINEERING

SITAPURA INDUSTRIAL AREA ,JAIPUR

Website: www.kautilya.net

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PREFACE

This seminar report has been prepared as per the requirement of the syllabus of

Mechanical engineering course structure under which the students are required to

prepare seminar for final year. My job during the preparation of this project report

was to get knowledge about “TIDAL ENERGY” and its various generating

methods.

It was a great experience for me that to get exposed to the professional set up.

During seminar, we had very knowledgably experience. We found in this project

that we gain a lot of knowledge in Mechanical field.

Now we take opportunity to present report and sincerely hope that it will be as

much knowledge enhancing to the readers as it was to use during the field work of

project and compilation of the report.

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ACKNOWLEDGMENT

I am deeply indebted to many people for the successful completion of this report. I

would like to take this opportunity and go on record to thank them for their help

and support.

I am deeply indebted to the Kautilya Institute Of Technology & Engg. for all the

pains and trouble they have gone through on my behalf and all the support they

continue to provide me with.

I express my deep sense of gratitude and sincere feelings of obligation to my guide

faculty Prof. R.K. Agarwal (KITE) who helped in overcoming difficulties and

who imparted me the necessary conceptual knowledge.

I would also like to thanks Prof. B.K Grag (Dean of Mechanical) who have

directly or indirectly extend their kind co-operation and support by guiding me

systematically and methodically in completion of the report. I wish to express my

greatness to all my friends and teachers for their helpful input, insightful

comments, steadfast love and support. Thank You for being there for me every

time.

Pushpendra Singh Shekhawat

(4th year B. Tech., VIII sem)

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CERTIFICATE

This is to certify that Pushpendra Singh Shekhawat (4th year B. Tech.

Mechanical, VIII Sem.), is a student of Kautilya Institute of Technology and

Engineering, Jaipur (2008-12) batch.

He has done his seminar on “TIDAL ENERGY” under my guidance Prof.

B.K.Garg (Dean of Mechanical Department).

The work is only for academic purpose. I am fully satisfied with his work and

recommend its acceptance in the partial fulfilment of the requirement for the

award of KITE course.

(Prof. B. K. Garg Sir)

(Dean of Mechanical Department)

Place: Jaipur (Raj.)

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INDEX

Tidal Energy

Generation of tidal energy

Generating methods

1. Tidal stream generator

2. Tidal barrage

3. Dynamic tidal power

Advantages

Disadvantages

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Tidal Energy

Gravitational forces between the moon and, the sun and earth cause the rhythmic

rising and lowering of ocean waters around the world that result in tide

waves.Tidal power, also called tidal energy, is a form of hydropower that

converts the energy of tides into useful forms of power - mainly electricity.

Fig1. Spring and Neap tide

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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.Historically, tide mills have been used, both in

Europe and on the Atlantic coast of North America. The earliest occurrences date

from the Middle Ages, or even from Roman times.[1][2]The world's first large-scale

tidal power plant (the Rance Tidal Power Station) became operational in 1966.

Generation of tidal energy

Tidal power is extracted from the Earth's oceanic tides; tidal forces are periodic

variations in gravitational attraction exerted by celestial bodies. These forces

create corresponding motions or currents in the world's oceans..

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Fig2. Variation of tide over a day

The magnitude and character of this motion reflects the changing positions of the

Moon and Sun relative to the Earth, the effects of Earth's rotation, and local

geography of the sea floor and coastlines

Tidal power is the only technology that draws on energy inherent in the orbital

characteristics of the Earth–Moon system, and to a lesser extent in the Earth–Sun

system. Other natural energies exploited by human technology originate directly or

indirectly with the Sun, including fossil fuel, conventional hydroelectric, wind,

biofuel, wave and solar energy. Nuclear energy makes use of Earth's mineral

deposits of fissionable elements, while geothermal power taps the Earth's internal

heat, which comes from a combination of residual heat from planetary accretion

(about 20%) and heat produced through radioactive decay (80%).

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Fig3. Turbine under the water

A tidal generator converts the energy of tidal flows into electricity. Greater tidal

variation and higher tidal current velocities can dramatically increase the potential

of a site for tidal electricity generation.

Because the Earth's tides are ultimately 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 resource. Movement of tides causes a loss of

mechanical energy in the Earth–Moon system: this is a result of pumping of water

through natural restrictions around coastlines and consequent viscous dissipation

at the seabed and in turbulence. This loss of energy has caused the rotation of the

Earth to slow in the 4.5 billion years since its formation. During the last

620 million years the period of rotation of the earth (length of a day) has increased

from 21.9 hours to 24 hours;[4] in this period the Earth has lost 17% of its rotational

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energy. While tidal power may take additional energy from the system, the effect

is negligible and would only be noticed over millions of years.

Generating methods

Tidal stream generator

Tidal barrage

Dynamic tidal power

Tidal stream generator

A tidal stream generator, often referred to as a tidal energy converter (TEC) is

a machine that extracts energy from moving masses of water, in particular tides,

although the term is often used in reference to machines designed to extract energy

from run of river or tidal estuarine sites. Certain types of these machines function

Fig4.Tidal stream generator

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very much like underwater wind turbines, and are thus often referred to as tidal

turbines. They were first conceived in the 1970s during the oil crisis.

Tidal stream generators are the cheapest and the least ecologically damaging

among the three main forms of tidal power generation.

Similarity to wind turbines

Tidal stream generators draw energy from water currents in much the same way as

wind turbines draw energy from air currents. However, the potential for power

generation by an individual tidal turbine can be greater than that of similarly rated

wind energy turbine. The higher density of water relative to air (water is about 800

times the density of air) means that a single generator can provide significant

power at low tidal flow velocities compared with similar wind speed. Given that

power varies with the density of medium and the cube of velocity, it is simple to

see that water speeds of nearly one-tenth of the speed of wind provide the same

power for the same size of turbine system; however this limits the application in

practice to places where the tide moves at speeds of at least 2 knots (1 m/s) even

close to neap tides. Furthermore, at higher speeds in a flow between 2 to 3 metres

per second in seawater a tidal turbine can typically access four times as much

energy per rotor swept area as a similarly rated power wind turbine.

Tidal barrage

A tidal barrage is a dam-like structure used to capture the energy from masses of

water moving in and out of a bay or river due to tidal forces. Instead of damming

water on one side like a conventional dam, a tidal barrage first allows water to

flow into a bay or river during high tide, and releasing the water back during low

tide. This is done by measuring the tidal flow and controlling the sluice gates at

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key times of the tidal cycle. Turbines are then placed at these sluices to capture

the energy as the water flows in and out.

.

Fig.5 The Rance Tidal Power Station, a tidal barrage in France.

Tidal barrages are among the oldest methods of tidal power generation, with

projects being developed as early as the 1960s, such as the 1.7 megawatt Kislaya

Guba Tidal Power Station in Kislaya Guba, Russia.

Dynamic tidal power

Dynamic tidal power or DTP is a new and untested method of tidal power

generation. It would involve creating large dam-like structure extending from the

coast straight to the ocean, with a perpendicular barrier at the far end, forming a

large 'T' shape.

This long T-dam would interfere with coast-parallel oscillating tidal waves which

run along the coasts of continental shelves, containing powerful hydraulic currents

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(common in e.g. China, Korea, and the UK). The concept was invented and

patented in 1997 by Dutch coastal engineers Kees Hulsbergen and Rob Steijn.

Fig.6 Top-down view of a DTP dam. Blue and dark red colors indicate low and high tides, respectively.

A DTP dam is a long dam of 30 to 60 km which is built perpendicular to the coast,

running straight out into the ocean, without enclosing an area. The horizontal

acceleration of the tides is blocked by the dam. In many coastal areas the main

tidal movement runs parallel to the coast: the entire mass of the ocean water

accelerates in one direction, and later in the day back the other way. A DTP dam is

long enough to exert an influence on the horizontal tidal movement, which

generates a water level differential (head) over both sides of the dam. The head

can be converted into power using a long series of conventional low-head turbines

installed in the dam.

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Benefits

A single dam can accommodate over 1 GW (1000 MW) of installed capacity, with

a capacity factor of about 30%, for an estimated annual power production of each

dam of about 4.6 TWh .To put this number in perspective, an average European

person consumes about 6800 kWh per year, so one DTP dam could supply energy

for about 6.76 hundred thousand Europeans. If two dams are installed at the right

distance from one another (about 200 km apart), they can complement one another

to level the output (one dam is at full output when the other is not generating

power). Dynamic tidal power doesn't require a very high natural tidal range, so

more sites are available and the total availability of power is very high in countries

with suitable conditions, such as Korea, China, and the UK (the total amount of

available power in China is estimated at 80 - 150 GW).

Advantages

It reduces the dependence upon fossil fuels

Tidal and wave energy is free, renewable, and clean source of energy

It produces clean electricity, with no production of greenhouse gas or

pollution.

Tidal and wave energy generation and consumption creates no liquid or

solid pollution

Highly efficient resource (compared with coal and oil at 30%, tidal power

efficiency is about 80%)

Energy capturing and conversion mechanism may help protect the shoreline

Energy capturing and conversion mechanism has little visual impact

About 60 billion watts of energy from tides can be used for electricity

generation

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Tides are active 24 hours a day, 365 days a year

Tidal power is a renewable source of energy.

It produces energy for free, once the initial costs are recovered.

Disadvantages

It is not cost effective because fossil-fuel power stations do not pay for the

cost of their carbon emissions to the planet. This will change as fossil fuel is

valued at its real price.

It leads to the displacement of wild life habitats.

It can only be used where there is suitable tidal flow or wave motion. So it

can not be used inland.

It only produces electricity during tidal surges.

Barrage systems require salt resistant parts and lots of maintenance.

The frames of the turbines can disrupt the movement of large marine

animals and ships through the channels on which the barrage is built.

The barrage systems have the disadvantages of disrupting fish migration and

killing fish passing through the turbines, therefore, there is also the risk of

destruction of ecosystem that rely on the coming and going of tides.

The ecosystem is disrupted during the construction of building the tidal

fence. this affects the fishes and also the fishermen who depends their life

on it.

Fossil fuels can be moved to just about anyplace to create energy on the

spot. This is what allows a car to work while moving.

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