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The Age of Undersea Windmills Begins
Mar 16, 2006 Harry Valentine EnergyPulse.com
An announcement was made during late February in
Bermuda advising that construction was to begin on
an undersea windmill installation that will provide
up to 10% of Bermuda's electricity. This project will
be the first commercial application of a technology
that can generate electrical power ocean currents.
It is a concept that has been debated, researched
and debated over several years. Unlike tidal power
stations that can only generate power for up to 10-hours
per day, installations like the proposed Bermuda project
could generate power throughout the day.
The installation at Bermuda may be the "proof of
concept" and the basis upon which larger and more
powerful versions of this technology may be developed.
There are numerous other locations around the world
where prevailing ocean conditions would favour larger
installations that have higher generation capacity.
While the construction and installation cost of the
technology may be high, its operating cost over long-term
is expected to be comparable to that of shore-based
hydroelectric installations. Several favourable locations
where undersea windmills may be installed actually
lie outside of heavily traveled commercial shipping
lanes. Some of the locations would include:
Strait of Florida:
The Gulf Stream flows from the Gulf of Mexico and
a portion of it flows into the 12-mile wide channel
entrance to the channel that lies between Key Largo
and the southeast tip of Florida. This channel gently
converges over 15-miles to a width of 2-miles and
water depth is less than 150-ft. The current at this
point in the channel may be strong enough to enable
undersea windmills to generate an estimated 10-megawatts
of electric power that may mainly be used in the Florida
Keys.
Bahamas:
A portion of the Gulf Stream flows from Florida
Strait into the Northwest Providence Channel of the
Bahamas and through the 30-mile wide entrance to Little
Bahama Bank that lies between Grand Bahama and Great
Abaco Islands. The Gulf Stream and Equatorial Current
merge in this region and flow into the Atlantic through
a 2-mile wide exit between Little Abaco and Great
Abaco Islands and also through an 8-mile wide exit
that lies between Little Abaco and Grand Bahama Islands.
Undersea windmills capable of generating over 100-megawatts
of electric power may be installed at these exists
that are less than 150-ft in depth.
Trinidad and Tobago:
A portion of the South Equatorial Current diverges
to the northwest along the Brazilian coast toward
the islands of Trinidad and Tobago. These islands
form an angle that captures a band of ocean current
that is 80-miles wide and within a distance of 20-miles,
the band of current converges into the 20-mile wide
channel that lies between the 2-islands. This causes
a strong ocean current to flow through the channel
where the water depth is less than 150-ft near Trinidad
and less than 600-ft near Tobago. At the present time
electricity on these islands is generated using natural
gas and diesel. In the long-term future, a "farm"
of large undersea windmills that could be installed
in the channel near Tobago and generate up to 1000-megawatts
of power.
Indonesia:
As the Equatorial Counter Current moves eastward
across the Indian Ocean, the 45-degree angle of the
Sumatra coastline will deflect a wide band of ocean
current toward the 45-mile wide entrance to Sunda
Strait that lies between Sumatra and Java. The strait
is 80-miles long and converges to a width of 10-miles
near its exist. The water depth rises from over 6000-ft
in the Indian Ocean (200-miles to the east) to under
150-ft at the narrowest point in the strait. The converging
strait would assure that a fast current would flow
through undersea windmills located at the narrowest
point. These units may need to be built to a restricted
height so as to allow ships with deep keels to pass
overhead. Alternatively, special shipping lanes may
be implemented in Sunda Strait so as allow the maximum
height of windmills to operate there.
Indonesia may have a potential of over 2000-megawatts
of tidal electric power, much of which could be sold
to Singapore where power stations consume expensive
natural gas to produce power. A portion of the Indonesian
tidal power may be used to generate hydrogen that
would be sold to markets in Japan, China, Hong Kong
and possibly Singapore. If the Government of Indonesia
is willing, private investors could finance the installation
of ocean power conversion systems around Indonesia.
New Zealand:
There are two sites around New Zealand's South Island
where undersea windmills may be installed. The angle
formed by South Island and Stewart Island captures
a 70-mile wide band of the West Wind Drift Ocean Current
and forces it to converge into the 20-mile wide Foveaux
Strait. The water depth changes rapidly from under
600-ft outside the strait to under 150-feet in the
strait. The combined convergence of width and depth
causes a strong current to flow in the strait where
a "farm" of undersea windmills may be installed and
generate up to 1000-megawatts of power.
A portion of the West Wind Drift merges with the
East Australian Current and is deflected to flow in
a northeasterly direction along the 500-mile west
coast of New Zealand's South Island and into the 60-mile
wide (north - south distance) entrance to Cook Strait.
Twice a day an eastward-moving band of tidal rise
from the Tasman Sea that is 450-miles wide would combine
with this ocean current. The converging angle made
by New Zealand's two main islands would funnel the
tidal rise into the entrance of Cook Strait that further
converges to a width of 12-miles at its narrowest
point.
For power to be generated in Cook Strait, undersea
windmills may need to be installed between Cape Jackson
and Kapiti Island where the water depth is less than
600-feet. This channel may be made narrower by building
breakwaters and shallower by depositing rocks and
boulders on the channel floor. The reduced width and
depth of the flow of water would increase the speed
of the current that would flow through the artificially
narrowed channel where up to 2000-megawatts of electric
power could be generated. A designated shipping channel
may have to be implemented in Cook Strait at a future
time if power from the ocean is to be generated there.
This power generation would be complimented by New
Zealand's high capacity for hydraulic energy storage.
Australia:
The West Wind Drift Ocean Current moves eastward
along the southern coast of Australia and into Bass
Strait. The angle that of southwest coast of the State
of Victoria deflects a 165-mile band of this ocean
current into the 40-mile wide channel between Cape
Otway and King Island. The sea floor also rises over
120-miles from a depth of over 6000-ft outside the
channel to under 600-ft in the channel. This combined
convergence of width and height would assure that
a strong tidal current would flow in this channel
where in the distant future, a "farm" of undersea
windmills may be installed between King Island and
Cape Otway and generate some 3,000-megawatts of power
from the ocean current.
Other Sites:
There a numerous other suitable straits and channels
around the world where the combination of ocean currents,
ocean tides, changes in ocean depth and converging
coastlines (wide entrance and narrow exit) allow undersea
windmills to be installed to generate power. The list
of such sites would include:
- Tsugaru-kaikyo channel between Hokkaido and Honshu
in Japan;
- Muskeget Channel between Martha's Vinyard and
Nantucket Island, USA;
- The deeper channel in Strait of Dover (below depth
of ships’ keels);
- The entrance to the Strait of Gibraltar (below
depth of ships' keels);
- Dardenelles, Turkey (below depth of ships' keels);
- Strait of Bab el Mandeb (below depth of ships’
keels);
- The channel between St Vincent Gulf and Encounter
Bay, Australia;
- The channel between Fraser Island and Eastern
Australia;
- The channel between New Britain and Papua New
Guinea
Technology:
Submersible windmills are being installed in rivers
such as the Hudson River near New York City. Bi-directional
undersea windmills are being tested for future use
at ocean inlets where power would be generated from
the twice-daily change in ocean tides. As the technology
develops in the future, larger undersea windmills
with much greater generation capacity will appear.
Power generation from undersea windmills will be more
consistent than power generation from land-based windmills.
The ocean tides and currents are more reliable than
prevailing winds and ocean water has 870-times the
density of air. Undersea power generation technology
is likely to become more viable in the long-term future
and may do so in the absence of special tax breaks
and subsidies from governments. The pioneering installation
in Bermuda may be the forerunner of a technology that
will serve the economic needs of many nations in the
long-term future.
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