Μπιζάκης ΓιώργοςΠαπαμιχαήλ ΜάριοςΠαναγιωτόπουλος Αθανάσιος

Waves in energyWaves in energy Ocean Wave EnergyOcean Wave Energy Ocean wave energy is captured directly from surface Ocean wave energy is captured directly from surface

waves or from pressure fluctuations below the waves or from pressure fluctuations below the surface.surface.

Waves are caused by the wind blowing over the surface of Waves are caused by the wind blowing over the surface of

the ocean. In many areas of the world, the wind blows with the ocean. In many areas of the world, the wind blows with

enough consistency and force to provide continuous waves. enough consistency and force to provide continuous waves.

There is tremendous energy in the ocean waves. There is tremendous energy in the ocean waves. Wave Wave

power devicespower devices extract energy directly from the surface extract energy directly from the surface

motion of ocean waves or from pressure fluctuations below motion of ocean waves or from pressure fluctuations below

the surface.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 TechnologiesOcean Wave Energy Technologies

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

scales. scales.

Wave technologies have been designed to be installed in Wave technologies have been designed to be installed in nearshorenearshore, , offshoreoffshore, and , and

far offshorefar offshore locations. The OCS Alternative Energy Programmatic EIS is concerned locations. The OCS Alternative Energy Programmatic EIS is concerned

primarily with offshore and far offshore wave technologies. Offshore systems are primarily with offshore and far offshore wave technologies. Offshore systems are

situated in deep water, typically of more than 40 meters (131 feet).situated in deep water, typically of more than 40 meters (131 feet).

While all wave energy technologies are intended to be installed While all wave energy technologies are intended to be installed at or near the at or near the

water's surfacewater's surface, they differ in their orientation to the waves with which they are , 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 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 energy forms, usually electricity. The following wave technologies have been the

target of recent development.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.

AttenuatorsAttenuators are long multisegment floating structures are long multisegment floating structures oriented parallel to the direction of the waves. The differing oriented parallel to the direction of the waves. The differing

heights of waves along the length of the device causes flexing heights of waves along the length of the device causes flexing where the segments connect, and this flexing is connected to where the segments connect, and this flexing is connected to

hydraulic pumps or other converters.hydraulic pumps or other converters.

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

Environmental Environmental Considerations Considerations

Potential environmental considerations for the development of wave energy include the Potential environmental considerations for the development of wave energy include the

following: following:

Positive or negative impacts on marine habitat (depending on the nature of additional Positive or negative impacts on marine habitat (depending on the nature of additional

submerged surfaces, above-water platforms, and changes in the seafloor); 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 Toxic releases from leaks or accidental spills of liquids used in those systems with working

hydraulic fluids; hydraulic fluids;

Visual and noise impacts (device-specific, with considerable variability in visible freeboard Visual and noise impacts (device-specific, with considerable variability in visible freeboard

height and noise generation above and below the water surface); height and noise generation above and below the water surface);

Conflict with other sea space users, such as commercial shipping and recreational boating; Conflict with other sea space users, such as commercial shipping and recreational boating;

TsunamoTsunamo A tsunami (Japanese: A tsunami (Japanese: 津波津波 , lit. "harbor wave";[1] Japanese pronunciation: [tsɯnami], lit. "harbor wave";[1] Japanese pronunciation: [tsɯnami]

English pronunciation: /tsuːˈnɑːmi/ English pronunciation: /tsuːˈnɑːmi/ tsoo-NAH-meetsoo-NAH-mee or /suːˈnɑːm or /suːˈnɑːmii/ / soo-NAH-meesoo-NAH-mee[2]) is a [2]) is a

series of water waves (also called a tsunami wave train[3]) caused by the series of water waves (also called a tsunami wave train[3]) caused by the

displacement of a large volume of a body of water, usually an ocean, though it can displacement of a large volume of a body of water, usually an ocean, though it can

occur in large lakes. Tsunamis are a frequent occurrence in Japan; approximately occur in large lakes. Tsunamis are a frequent occurrence in Japan; approximately

195 events have been recorded.[4] Owing to the immense volumes of water and the 195 events have been recorded.[4] Owing to the immense volumes of water and the

high energy involved, tsunamis can devastate coastal regions.high energy involved, tsunamis can devastate coastal regions.

Earthquakes, volcanic eruptions and other underwater explosions (including Earthquakes, volcanic eruptions and other underwater explosions (including

detonations of underwater nuclear devices), landslides and other mass movements, detonations of underwater nuclear devices), landslides and other mass movements,

mteorite ocean impacts or similar impact events, and other disturbances above or mteorite ocean impacts or similar impact events, and other disturbances above or

below water all have the potential to generate a tsunami.below water all have the potential to generate a tsunami.

The Greek historian Thucydides was the first to relate tsunami to submarine The Greek historian Thucydides was the first to relate tsunami to submarine

earthquakes,[5][6] but the understanding of a tsunami's nature remained slim until earthquakes,[5][6] but the understanding of a tsunami's nature remained slim until

the 20th century and is the subject of ongoing research. Many early geological, the 20th century and is the subject of ongoing research. Many early geological,

geographical, and oceanographic texts refer to tsunamis as "seismic sea waves.“geographical, and oceanographic texts refer to tsunamis as "seismic sea waves.“

Some meteorological conditions, such as deep

depressions that cause tropical cyclones, can

generate a storm surge, called a

meteotsunami, which can raise tides several

metres above normal levels. The displacement

comes from low atmospheric pressure within

the centre of the depression. As these storm

surges reach shore, they may resemble

(though are not) tsunamis, inundating vast

areas of land

BibliographyBibliography Wikipedia.orgWikipedia.org

http://ocsenergy.anl.gov/guide/wave/index.cfmhttp://ocsenergy.anl.gov/guide/wave/index.cfm