By Erin McGowan
and Jackie Vandewater
Primary Types of Ocean Power:
• Wave Power
Ocean Thermal Energy Conversion (OTEC)
Ocean Current Energy
• Early stages of development
• Not a lot is known about this specific type of
Wave Energy and Power
Wave Energy is captured directly from
surface waves or from pressure
fluctuations below the surface.
Wave Power uses devices to extract energy
directly from the surface motion of ocean waves
or from pressure fluctuations below the surface.
One way to harness wave energy is to bend or
focus the waves into a narrow channel,
increasing their power and size.
The waves can then be channeled into a catch basin
or used directly to spin turbines.
Another way to harness wave energy is with an
Oscillating Water Column (OWC) that
generates electricity from the wave-driven rise
and fall of water in a cylindrical shaft or pipe.
The rising and falling water drives air into and out of
the top of the shaft, powering an air-driven turbine.
Wave power involves conversion devices
that bob up and down with passing swells.
Float devices can generate electricity from
the bobbing action of a floating object.
The object can be mounted to a floating
raft or to a device fixed on the ocean floor.
These types of devices can power lights and
whistles on buoys.
The generation of electricity from tides is similar to
hydroelectric generation, except that tidal water
flows in two directions.
The simplest generating system for tidal plants
involves a dam, known as a barrage, across an
Sluice gates on the barrage
allow the tidal basin to fill on the
incoming high tides and to
empty through the turbine system
on the ebb tide (outgoing tide).
Tidal fences can also harness the energy in
A tidal fence has vertical axis turbines
mounted within a fence structure, called a
caisson, that completely blocks a channel,
forcing all of the water through it.
Unlike barrage stations, tidal fences can be
used in unconfined basins, such as in a
channel between the mainland and a nearby
offshore island, or between two islands.
Tidal turbines are a new technology that
can be used in many tidal areas.
Tidal turbines are basically wind turbines that
can be located wherever there is strong
tidal flow, as well as in river estuaries.
Since water is about 800 times as dense as
air, tidal turbines will have to be much
sturdier than wind turbines.
They will be heavier and more expensive to build,
but will be able to capture more energy.
Ocean Thermal Energy
OTEC has the potential to produce more
energy than tidal, wave, and wind energy
The OTEC systems can be open or closed.
In an open system, the steam is turned into
fresh water, and new surface water is
added to the system.
A transmission cable carries the electricity to the
Ocean Thermal Energy
In a closed system, an evaporator turns
warm surface water into steam under
This steam spins a turbine generator to
Water pumps bring cold deep water
through pipes to a condenser on the
The cold water condenses the steam, and
the closed cycle begins again.
Development of Innovations
Ocean Energy still needs to undergo much more
development before it can be implemented in
Wave Energy is the most developed type of Ocean Energy
The Pelamis by Ocean Power Delivery of Scotland
PowerBuoy by Ocean Power Technologies
Aquabuoy by AquaEnergy
Wave Dragon by Wave Dragon, Inc.
La Rance, France
Verdant Power – water turbines
OTEC: only experimental plants, no large operations
Ocean Energy Implementation
India’s West Coast
New Jersey, Hawaii, Spain, Portugal, Oregon,
Washington, British Columbia, South Africa
2005 – 2006
Mostly funded through
John McCarthy (left) & John Keating (right) of OceanEnergy Limited with the
OceanEnergy Pioneer Award 2008 pictured with Eoin Sweeney (Head of the
Ocean Energy Development Unit (OEDU, Sustainable Energy Ireland) at the
EnergyOcean Conference which took place in Galveston, Texas, June 2008.
Are Citizens Using the
Issues with energy efficiency, engineering and
Nations and developed countries
Some small nations
Not always connected to grid
Wildlife and habitat to
erosion, navigation hazards
and commercial fishing
Maine’s Ocean Energy Progress
“FERC grants nine tidal
energy permits in Maine”
9 of 14 companies
Untapped before 2005
Gulf of Maine
Analysis of the Innovation
Not leading alternative energy source
Technology must catch up
Not all states have access to a body of water
Address environmental concerns
10 years, give or take
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