Hi nobleresearcher,
Thank you for another interesting question.
http://www.geology.wisc.edu/~pbrown/g410/tidal/tidal.html
"Tidal energy works from the power of changing tides. Tidal changes in
sea level can be used to generate electricity, by building a dam
across a costal bay or estuary with large differences between low and
high tides. The high tides allow emense amounts of water to rush into
the bay. The gates of the dam then shut when water level is at its
maximum height. Holes in the bottom of the dam let water (at great
speed and pressure) to rush past turbines. The flow of water generates
enough power to turn the turbines which creates electricity. The
entire process repeats with each high tide.
ECONOMICS
"It is very possible to harness energy from the tides but technology
is not yet commercially available therefore makes this energy source
not cost competative. It is necessary when selecting a site to asses
economic feasibility. On average, the estimated cost to construct and
run a tidal power facility with an average annual out put of 1085 MW
(annual out put of 3423 GW) would total about 1.2 billion dollars not
including opporational costs and maintenance (this cost exceeds that
of coal and oil). The benifits derived from inclusion of a tidal power
plant are due to the cost of the fuels saved. (Roger H. Charlier 1982)
Primary role for tidal power which would make it economically
feassible:
replace fossil fuels
replace nuclear generated energy
reduce oil needs by one-half
save 3 million barrels of oil
save 330,000 tons of coal
save 90.8 tons of uranium
DISSADVANTAGES
not yet economically feasible
problems with transportation of hydroelectricity
ADVANTAGES
renewable resource
no pollution
produced 24 hours a day and 365 days a year
peak output coincides with peak energy demand
water is a free resource
highly efficient (coal/oil efficiency = 30%, tidal power efficiency = 80%)
technology not developed"
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How Tidal Power Plants Work
http://inventors.about.com/library/inventors/bltidalplants.htm
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Tidal Energy
http://www.eere.energy.gov/RE/ocean_tidal.html
"Tidal energy traditionally involves erecting a dam across the opening
to a tidal basin. The dam includes a sluice that is opened to allow
the tide to flow into the basin; the sluice is then closed, and as the
sea level drops, traditional hydropower technologies can be used to
generate electricity from the elevated water in the basin. Some
researchers are also trying to extract energy directly from tidal flow
streams.
The energy potential of tidal basins is large - the largest facility,
the La Rance station in France, generates 240 megawatts of power.
Tidal energy systems can have environmental impacts on tidal basins
because of reduced tidal flow and silt buildup."
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Tidal Energy
http://library.thinkquest.org/26366/text/alternative/tidal.html?tqskip1=1
What is tidal energy?
"Tidal energy is the utilization of the sun and moon's gravitational
forces - as the tide is the result of their influences. Like other
alternative energies, tidal energy is not really anything new.
Something called a tide mill existed nine hundreds years ago. The
difference between the tide mill and today's tidal power plant is the
size of the unit and the amount of energy generated. To utilize tidal
energy, people have to build a barrage (a barrier) with gates of some
kind at the opening of a bay or a river system to create an estuary (a
big basin). The gates create differences in the water levels between
the estuary and the ocean, therefore enabling the generation of
electricity. For example, when the tide falls, the receding water
retreats back to the ocean by passing through a turbine located in the
barrage; generating electricity. Electricity can also be generated
when the open gate lets water flow into the estuary during peak
periods of high tide. This is commonly called the barrage technique.
What are the advantages of tidal energy?
The major advantage of tidal energy is its economical benefits. For
example, tidal energy does not require any fuel. Tides rise and fall
every day in a very consistent pattern. Another benefit is the
economic life of a tidal power plant. A plant is expected to be in
production for 75 to 100 years, in comparison with the 35 years of a
conventional fossil fuel plant. Besides the economical factors, tidal
energy is clean and renewable, unlike fossil fuels.
What are the disadvantages of tidal energy?
The altering of the ecosystem at the bay is the biggest drawback of
tidal power. Damages like reduced flushing, winter icing and erosion
can change the vegetation of the area and disrupt the balance. Similar
to other ocean energies, tidal energy has several prerequisites that
make it only available in a small number of regions. For a tidal power
plant to produce electricity effectively (about 85% efficiency ), it
requires a basin or a gulf that has a mean tidal amplitude (the
differences between spring and neap tide) of 7 meters or above. It is
also desirable to have semi-diurnal tides where there are two high and
low tides everyday."
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Tidal Energy
http://riri.essortment.com/tidalenergy_rdrx.htm
"Even though tidal energy is beneficial to the economy and the
environment, the power provided would be on a small scale. Apparently,
"a barrage will only provide power for about 10 hours a day, so power
for the other 14 hours must be provided by other means".
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http://news.bbc.co.uk/2/hi/uk_news/england/devon/2992996.stm
(click on first image for more pictures)
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Best regards,
tlspiegel |
