Wave/Tidal Energy
by: Karina Ayala, Rachael Carleson
Williams, Lidya Makonnen, Terrell
Stevenson
Wave Energy
• Offshore systems are situated in
WHAT IS IT?
deep water, typically of more than
• Wave power devices extract
40 meters (131 feet). Sophisticated
energy directly from surface
mechanisms—like the Salter
Duck—use the bobbing motion of
waves or from pressure
the waves to power a pump that
fluctuations below the
creates electricity. Other offshore
surface.
devices use hoses connected to
• Energy extracted from the
floats that ride the waves. The rise
waves is stored in generators.
and fall of the float stretches and
• Wave energy can be
relaxes the hose, which pressurizes
converted into electricity
the water, which, in turn, rotates a
through both offshore and
turbine.
onshore systems.
•Oscillating water column
The oscillating water column consists of a partially submerged concrete or steel
structure that has an opening to the sea below the waterline. It encloses a column of
air above a column of water. As waves enter the air column, they cause the water
column to rise and fall. This alternately compresses and depressurizes the air
column. As the wave retreats, the air is drawn back through the turbine as a result
of the reduced air pressure on the ocean side of the turbine.
HOW DOES IT WORK?
1. Wave capture chamber set into rock face.
2. Tidal power forces water into chamber.
3. Air alternately compressed and
decompressed and decompressed by
"oscillating water column".
4. Rushes of air drive the Wells Turbine,
creating power.
•TAPCHAN
Tapered channel system, consists of a tapered channel, which feeds into a reservoir
constructed on cliffs above sea level. The narrowing of the channel causes the waves to
increase in height as they move toward the cliff face. The waves spill over the walls of
the channel into the reservoir and the stored water is then fed through a turbine.
• The TAPCHAN systems
overcome the issue of
power on demand, as the
reservoir is able to store
energy until it is
required.
•Pendulor device
The pendulor wave-power device consists of a rectangular box,
which is open to the sea at one end.
A flap is hinged over the
opening and the action of
the waves causes the flap
to swing back and forth.
The motion powers a
hydraulic pump and a
generator.
Main Advantages
• This is a non-polluting source of energy
• Wave turbines are relatively quiet to operate and do not affect wild
life.
Main Disadvantages
• Wave energy requires a consistent supply of powerful waves
to fuel a community's electrical needs, but waves are not
consistent.
• Spills or accidental leaks caused by hydraulic fluids in the
system could also potentially harm marine life.
Tidal Energy
WHAT IS IT?
• Tides of water caused by the
Moon and Sun, in
combination with Earth's
rotation.
• Practically inexhaustible and
it is classified as a renweable
resource.
• For tidal differences to be
harnessed into electricity the
difference between high and
low tides must be at least 16
feet.
• There are only about fourty
sites on the earth with tidal
ranges of this magnitude.
Tidal power
technologies
include the
following...
Barrage or dam
A barrage or dam is typically used to convert tidal energy into
electricity by forcing the water through turbines, activating a
generator.
Gates and turbines are
installed along the dam.
When the tides produce an
adequate difference in the
level of the water on opposite
sides of the dam, the gates
are opened. The water then
flows through the turbines.
The turbines turn an electric
generator to produce
electricity.
Tidal fence
Tidal fences look like giant turnstiles. They can reach across channels between small
islands or across straits between the mainland and an island.
A tidal fence has vertical
axis turbines mounted in a
fence. All the water that
passes is forced through
the turbines. They can be
used in areas such as
channels between two
landmasses.
Tidal turbine
Tidal turbines look like wind turbines. They are arranged underwater in
rows, as in some wind farms.
• Ideal locations for tidal turbine farms are close to shore
in water depths of 65.5–98.5 feet.
• Turbines were submerged in the East River to generate
electricity from rapid tidal currents in New York City in
2007
Main Advantages
• It is predictable.
• No waste or pollution
• It is very cheap to maintain.
Main Disadvantages
• Building cost is expensive.
• Disrupts migration of creatures
in the ocean
• Only produces power for only
about 10 hours a day.
THE
END...
SOURCES
• http://www.energysavers.gov/
• http://www.rise.org
• http://www.technologyreview.com/energy/
• http://en.wikipedia.org/wiki/Tidal_power
• http://en.wikipedia.org/wiki/Wave_power