Tidal energy harnesses the predictable power of ocean tides and currents to generate electricity through various methods like tidal barrages and tidal turbines. Tidal barrages capture energy by trapping water behind large dams during high tide, then releasing it to spin turbines during low tide. Tidal turbines resemble underwater windmills that spin to generate power from tidal currents. While tidal energy is renewable and predictable, methods like barrages can impact local ecosystems and transportation.

1. Tidal Energy

2. What is Tidal Energy?
 Tidal Energy is a form of hydropower that
creates forms of energy by converting the energy
of the incoming and outgoing tides.
 Tidal energy is a reliable source of power because
of its predictability, tide cycles are always known
as opposed to the inconsistent power of the wind
and sun.
 The stronger the tide, either in water level height
or current strength, the greater the potential for
power generation.

3. Methods of Harnessing Energy
from The Tides
 There are multiple methods of obtaining energy from
the changing tides and each has their own set of
advantages and disadvantages.
 Depending on the location, one particular method
could be more appropriate than another

4.  A barrage would be used in an estuary with a large
fluctuation between high and low tide
 Wave methods would be used farther out in the sea if
there is a particular area with large waves.
 Underwater turbines are useful if there are strong
underwater currents

5. Tidal energy
Wave energy
What is ocean wave energy
Energy harnessed from waves is an
alternative energy source that has been
in use for centuries. The kinetic energy
(movement) exists in the moving waves
of the ocean. There is tremendous
energy in the ocean waves. Ocean wave
energy is captured directly from surface
waves or from pressure fluctuations
below the surface.

6. Tidal energy
Wave energy
•depends on the waves – variable energy supply
•needs a suitable site, where waves are consistently strong
•some designs are noisy
•the energy is free – no fuel is •mist be able to withstand very rough weather
costly to develop
needed and no waste is produced •visual impact if above water or on shore
•not expensive to operate and can disturb or disrupt marine life – including changes in the
distribution and types of marine life near the shore
maintain •poses a possible threat to navigation from collisions due to
•can produce a significant amount the low profile of the wave energy devices above the water,
making them undetectable either by direct sighting or by
of energy. radar
•may interfere with mooring and anchorage lines with
commercial and sport-fishing
•may degrade scenic ocean front views from wave energy
devices located near or on the shore, and from onshore
overhead electric transmission lines.

7. Tidal energy Wave energy
Wave-Energy Conversion Devices
Wave power devices extract energy While all wave energy technologies
directly from the surface motion are intended to be installed at or near
of ocean waves or from pressure the water's surface, they differ in their
fluctuations below the surface. orientation to the waves with which
they are interacting and in the
A variety of technologies have
manner in which they convert the
been proposed to capture the
energy of the waves into other energy
energy from waves.
forms, usually electricity. The
Wave technologies have been
following wave technologies have
designed to be installed in near
been the target of recent
shore, offshore, and far offshore
development.
locations.
Terminator Point
Oyster Attenuators Overtopping
devices absorber
devices

8. Tidal energy Wave energy
Wave-Energy Conversion Devices
Aquamarine Power is the owner and
developer of Oyster, the world’s
largest working hydro-electric wave
energy converter. Oyster has been
designed to harness the abundant
natural energy found in near shore waves
and convert it into sustainable zero-
emission electricity.
Oyster is a simple mechanical hinged
flap connected to the seabed at around
10m depth. Each passing wave moves the
flap, driving hydraulic pistons to deliver
high pressure water via a pipeline to an
onshore electrical turbine. Multiple
Oyster devices are designed to be
deployed in utility-scale wave farms
typically of 100MW or more.
Oyster will combine high efficiency and
survivability with low cost operations,
maintenance and manufacture to

9. Tidal energy
Wave energy
Wave-Energy Conversion Devices
Terminator devices extend
perpendicular to the direction of wave
travel and capture or reflect the power of
the wave. These devices are typically
onshore or near shore; however, floating
versions have been designed for offshore
applications. The oscillating water
column is a form of terminator in which
water enters through a subsurface
opening into a chamber with air trapped
above it. The wave action causes the
captured water column to move up and
down like a piston to force the air though
an opening connected to a turbine.
Potential wave energy extraction
technology.

10. Tidal energy Wave energy
Wave-Energy Conversion Devices
A point absorber is a floating
structure with components that move
relative to each other due to wave action
(e.g., a floating buoy inside a fixed
cylinder). The relative motion is used to
drive electromechanical or hydraulic
energy converters.

11. Tidal energy Attenuators are long
Wave energy multisegment floating structures
oriented parallel to the direction of
Wave-Energy Conversion Devices the waves. The differing heights of
waves along the length of the device
causes flexing where the segments
Pelamis : connect, and this flexing is connected
to hydraulic pumps or other
World’s First converters.
Commercial Wave
Energy Project
The wave energy converter
shown is a semi-submerged,
The device is a long, tubular articulated structure composed
Structure which floats on the of cylindrical sections linked by
surface of the ocean and converts hinged joints. These structures
incoming waves from all directions can also be aligned in a row, one

12. Tidal energy Wave energy
Wave-Energy Conversion Devices
Overtopping devices have
reservoirs that are filled by
incoming waves to levels above the
average surrounding ocean. The
water is then released, and gravity
causes it to fall back toward the
ocean surface. The energy of the
falling water is used to turn hydro
turbines. Specially built seagoing
vessels can also capture the energy
of offshore waves. These floating
platforms create electricity by
funneling waves through internal
turbines and then back into the sea.

13. Tidal Barrage
•A special kind of dam called a "barrage" is used to capture the
power of the tides.
•As high tide comes in, gates in the barrage are opened. The rush
of water rotates the turbines at the sides of these gates.
•When the tide is fully in, the gates are closed, and the water is
trapped until low tide.
•At low tide, the water within the barrage is higher than the water
beyond.
•The gates are reopened, and water rushes back toward the ocean.
The torrent of water again turns the wheels of the turbines.
•Therefore, the turbines generate electricity during the surge of
both high and low tides and make this system on harnessing
energy a very productive one.

14. Tidal Barrage Pros Vs. Cons
• Clean, renewable energy. • Costs of building is
• Good for the environment. tremendous.
• Once installed, little • Only provides power when the
maintenance. tide is going in and out
(around 10 hours per day)
• Power is free once barrage is
built. • Affects transportation in the
waterway.
• Tides are very reliable and
• Affects wild life in the area
easy to predict.
• Maximum energy is limited to
• Cost of technology is likely to
2.5 terawatts. Total amount of
fall
tidal dissipation or the friction
• Sustainable measured by slowing of the
lunar orbit.

15. Barrage Diagram

16. Bay of Fundy Tidal Project
• A possible project site
close to here is the Bay
of Fundy.
• A Barrage is planned to
be built in the minas
basin just off the coast
of Nova Scotia.
• The Bay of Fundy has
the highest tides in the
world making this a
desirable location for
this project.

17. •Tidal Turbines are an alternative way to conserve energy using tidal
currents
•They are very close in concept to using a windmill under the sea, river, or
ocean
• Water currents turn the turbines, which activates a generator that
produces electricity
•The blades are designed for bi-directional flow , so they turn regardless of
which way the tide is moving
•They usually spin between 10 and 20 times
per minute

18. •Northern Ireland's Strangford Narrows – this is a green electricity
generator that relies on the changing tide to produce power for about
1000 homes
•It is the worlds largest ever tidal turbine
•New York City’s East River has six 35 kilowatt turbines will produce
enough energy to provide for a supermarket and a parking garage
•They can be as close as six feet from the surface and they are 16 foot,
rotors that spin with the tidal change Northern Ireland’s Strangford Narrows
East River Turbines

19. •Tidal dams restrict fish
migration and cause silt build
•They produce no up which affects tidal basin
atmospheric waste ecosystems in negative ways
•It does not need fuel to run •People are working on more
•Although it is expensive to fish friendly turbines, yet it is
hard to prevent all fish from
build, it is not expensive to
avoiding these turbines. This
maintain means that there are some fish
•All the tides of the rivers, killings from the use of
seas, and oceans are turbines
predictable so one can know •There are only about 40 high
when the most energy will be flow areas on Earth where
produced these turbines would work to
• It is completely renewable their highest potential

20. Bibliography
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pollution." Air Pollution, Science and Society. New York: Facts On
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= AIR0013&SingleRecord=True (accessed March 1, 2010).
• Nichols, C. Reid, and Robert G. Williams. "tidal power plant."
Encyclopedia of Marine Science. New York: Facts On File, Inc., 2008.
Science Online. Facts On File, Inc.
http://www.fofweb.com/activelink2.asp?ItemID=WE40&SID=5&iPin
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• William K. Fox, "Energy sources", in AccessScience@McGraw-Hill,
http://www.accessscience.com, DOI 10.1036/1097-8542.233000
• George G. Adkins, "Tidal power", in AccessScience@McGraw-Hill,
http://www.accessscience.com, DOI 10.1036/1097-8542.696700