Ocean energy is replenished by the sun and through tidal
influences of the moon and sun gravitational forces
Near-surface winds induce wave action and cause windblown currents at about 3% of the wind speed
Tides cause strong currents into and out of coastal basins
Ocean surface heating by some 70% of the incoming
sunlight adds to the surface water thermal energy, causing
expansion and flow
Wind energy is stronger over the ocean due to less drag,
although technically, only seabreezes are from ocean energy
Causes Of Waves
Gravitational attraction of sun and moon
Category Of Ocean Waves
Deep Water Waves
Shallow Water waves
Deep Water Waves
Waves do NOT interact with the seafloor.
Orbits of the water molecules are circular
Shallow Water Waves
Waves DO interact with the seafloor.
Orbits of the water molecules become elliptical.
Ocean Wave Energy Converted
Distance from shore—Wave energy devices may
convert wave power at the shoreline, near to the shore
(defined as shallow water where the depth is less than
one half of the wavelength ), or offshore.
Bottom mounted or floating – Wave energy devices
may be either bottom –mounted or floating.
Devices Used To Generate the
Oscillating water column
This is a bottom –mounted or floating structure that
absorbs energy in all direction .
The power take off system may take off number of
forms depending on the displaces.
Pressure differences on the top of float set the upper
floater into motion.
Oscillating Water Column
At the shoreline this could be a cave with a blow
hole and on air turbine/generator in the blow hole that
and chamber developed.
Wave entered and exit the chamber, the water column
moves up and down and act like a piston.
The air is channeled through a turbine/generator to
The head of collected water turns the turbine it flow back out
to sea and turbine are coupled to produce electricity.
Floating structure arms to focus the wave energy. It
has both ramp and reservoir so that as wave arrive
This is a floating reservoir structure with a ramp, over which
the waves topple and hydro turbine/generating through which
the water returns to the sea.
Attenuator structure that is oriented parallel to the
wave. This is called a linear absorber.
The structure is composed of multiple section in pitch
& yaw related to each other.
This motion is used to pressurize a hydraulic piston
arrangement & turn a hydraulic turbine/ generator to
Properties of Ocean Waves
An ocean wave is an undulation of the sea surface.
Progressive waves move across the sea surface.
Standing waves oscillate about a fixed point
Wave energy are:
Free renewable energy
More profitable that wind energy
Renewable but not profitable.
This marginal system show that the sea is a vast space
whose resources are not exploited.
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