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Ocean Wave Energy

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					Ocean Wave Energy
Ocean wave energy is captured directly from surface waves or from pressure fluctuations
below the surface.

Waves are caused by the wind blowing over the surface of the ocean. In
many areas of the world, the wind blows with enough consistency and force
to provide continuous waves. There is tremendous energy in the ocean
waves. Wave power devices extract energy directly from the surface
motion of ocean waves or from pressure fluctuations below the surface.

Wave power varies considerably in different parts of the world, and wave
energy can't be harnessed effectively everywhere. Wave-power rich areas of the world
include the western coasts of Scotland, northern Canada, southern Africa, Australia, and
the northwestern coasts of the United States.

Ocean Wave Energy Technologies

A variety of technologies have been proposed to capture the energy from waves. Some of
the more promising designs are undergoing demonstration testing at commercial scales.

Wave technologies have been designed to be installed in nearshore, offshore, and far
offshore locations. The OCS Alternative Energy Programmatic EIS is concerned
primarily with offshore and far offshore wave technologies. Offshore systems are situated
in deep water, typically of more than 40 meters (131 feet).

While all wave energy technologies are intended to be installed at or near the water's
surface, they differ in their orientation to the waves with which they are interacting and
in the manner in which they convert the energy of the waves into other energy forms,
usually electricity. The following wave technologies have been the target of recent
development.

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 nearshore; 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.

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.
Rendition
of a Wave
Farm Made
Up of
Permanent
Magnet
Linear
Generator                  Point Absorber Wave Energy
Buoys                      Farm




                          Animation of Point Absorber Operation
                             (Quicktime required)
Attenuators are long multisegment floating structures oriented parallel to
the direction of the waves. The differing heights of waves along the length
of the device causes flexing where the segments connect, and this flexing is
connected to hydraulic pumps or other converters.

                                  Animation of Attenuator Device Operation Attenuator
                                      (Macromedia Flash Player Required) Wave
                                                                           Energy
                                                                           Device
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.

Environmental Considerations                               "Wave Dragon" Prototype
                                                           Overtopping Device
Potential environmental considerations for the
development of wave energy include the following:

 Positive or negative impacts on marine habitat (depending on the nature of additional
submerged surfaces, above-water platforms, and changes in the seafloor);
 Toxic releases from leaks or accidental spills of liquids used in those systems with
working hydraulic fluids;
 Visual and noise impacts (device-specific, with considerable variability in visible
freeboard height and noise generation above and below the water surface);
 Conflict with other sea space users, such as commercial shipping and recreational
boating;

				
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posted:2/1/2012
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Description: Basic Science and Electronic Devices