The document discusses tidal energy and its generation. It describes how tides are caused by gravitational forces from the sun and moon. Tidal energy can be harnessed using in-stream devices, barrages, or lagoons. Barrages use the potential energy difference between high and low tides to power turbines. Lagoons have self-contained structures to harness tidal energy at a lower cost than barrages. Tidal energy is a renewable source with predictable tides, but construction can be costly and disrupt aquatic ecosystems.

1. Tidal Energy
Arpan Deyasi
Dept of ECE, RCCIIT, Kolkata, India
Course: EI605D
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What is Tide?
Tide is the rising and falling of Earth’s
ocean surface due to gravitational
attractive forces of Sun and Moon,
along with Earth’s rotation effect
What is Tidal Force?
It is the vectorial difference
between the gravitational
force of Earth and Moon

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Tidal Wave
building up and receding of waves happened twice a day,
i.e., two high tides and two low tides during each period
of Earth’s rotation
Time interval between consecutive low and high tide is 6.207 hr

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SPRING Tide
Sun
New moonFull moon
Earth
Solar tide Lunar tide
When gravitational attraction of Sun and Moon combines,
then tide is called ‘SPRING’

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NEAP Tide
When gravitational attraction of Sun and Moon work
orthogonally, then tide is called ‘NEAP’
Earth
Solar tide
Lunar tide
Sun

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Tidal Energy Generation
1. In-stream Device: KE of moving water is utilized into
power the turbines
shorter and stronger blades, work as underwater windmills
The set-up can be gradually scaled-up in the form of array
It has lower potential costs
It has higher ecological impacts

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Tidal Energy Generation
2. Barrages: It’s a type of bigger hydroelectric plant built
at the bay
Uses PE difference between high and low tides
Higher cost of installation
Larger ecological impacts

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Tidal Energy Generation
3. Lagoon : It’s a type of small barrage built at lower cost
Self-contained structures
Combination of ebb and flood
Cost and potential impact are lower than barrage

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WorkingprincipleofBarrage

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Working principle of Barrage
Consists of turbines, sluice gates, barrage iself
Operates during Ebb and Flood
Barrage holds water back during high tide
Sluice gate let the water flow whenever required
Turbine and generator produce electricity

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Ebb & Flood

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Ebb generation
Basin is filled with incoming high tide current
Sluice gates are closed
When outside water level is low enough, gates are opened
so that water can flows out, thorough turbines

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Flood generation
Basin is emptied with low tide
Sluice gates are closed
When water level is outside is high enough, gates are opened to
allow water flow inside, through turbines

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SINGLE BASIN TIDAL ENERGY SYSTEM
Power house is situated at the
mouth of single basin
Hydraulic turbine only
operates during discharge of
water from basin during ebb
tide. During high tidal basin
is again filled.
Power generation is
intermittent.
It cannot meet peak power
demands .

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DOUBLE BASIN TIDAL ENERGY SYSTEM
System has two basins at two
different levels and sluice
gates are provided in the
dam.
Upper basin is filled during
high tide and lower basin is
emptied during low tide.
Therefore, it creates a
permanent head for turbine
to operate continuously.
Power generation is
continuous.
The peak power demands can
be met by pumping water by
other means from lower
basin to upper basin.

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Uses of Tidal Energy
Tidal Electricity generation
Mechanical crushing of grains in grain mills
Tidal barrage can be used to store energy

17. Advantages of Tidal Energy
Longevity of equipment is relatively large
Inexhaustible source of energy
No greenhouse gas emission
Can be generated at large scale as 75% of earth is covered by water
Rise and fall of tides are predictable owing to their cyclic fashion
Efficiency is higher than coal, solar or wind
After installation, maintenance cost is relatively low
Fuel is not required for operation
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18. Disadvantages of Tidal Energy
Electro-magnetic emissions disrupt aquatic eco-system
High construction costs
Less sites available for construction costs, associated with
expensive transmission costs
Unpredictable sea-wave can destruct power generation units
Frozen sea, weak tides, straight shorelines, low tidal waves
cause obstructions
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References
1. Non conventional Energy, A. V. Desai, New Age International
Publishers Ltd.
2. Renewable energy resources and emerging technologies, D.P.
Kothari, Prentice Hall of India Pvt. Ltd.
3. Er. R K Rajput, Non-Conventional Energy Sources and Utilisation
(Energy Engineering), S. Chand Publishing
4. B.H Khan, Non Conventioanl Energy Resources, Tata McGraw-Hill
Education