10-05-2012, 03:29 PM
Tidal Power Energy
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Introduction
It’s a plain fact that we are in a world where almost 80 percent of the demanding
energy is furnished by sources such as natural gas, coal, or oil, which are quickly
being depleted as well as being environmentally unfriendly. We have also developed
some destructive processes such as the nuclear power plants, which would also be a
sword of Damocles of all human beings. Luckily, we have already realized the
importance of making an enormous change in our way of life and our way of using
the energy, so looking for renewable resources to substitute current ones is much
urgent for us. Tidal power is classified as a renewable energy source, because tides are
caused by the orbital mechanics of the solar system and are considered inexhaustible
within a human timeframe. Energy from tidal power is also a form of pollution free
energy, which has a lot of potential. Though these potentials have not been fully
realised yet, we can’t deny the advantage of such kind of a renewable energy. This
paper gives some basic introductions of tidal power and the basic principle of how
tidal generator works, and it also focuses on the development of tidal power energy of
the world.
Background
As we all know that, Electricity and heat energy are essential in our life. However,
most of them come from traditional sources of energy such as coal, oil, gas and
nuclear power. The extraction and use of these fuels are causing many environmental
problems of the world, such as climate change, the ozone layer destruction and so
forth. The combustion of fossil fuels created an excess of carbon dioxide, Scientist
across the world agrees that we must reduce our use of fossil fuels in the years to
come, or we will create devastating effects in nature. An acceptable power generation
technology must be mechanically sound, environmentally acceptable, and
economically profitable in order to become a real alternative for builders of new
capacity. An energy policy for a sustainable future will be based on a high level of
energy efficiency and greater use of renewable energy, preferably in an energy mix. I
choose tidal power as my target is because it is such the renewable energy source by
which we can solve the serious problems: it produces no waste and pollution, what is
more important, it is totally free to use. It is absolutely possible that tidal power will
be one of the most popular sources of power in future and become an attractive option
for power companies looking for renewable source power, but unwilling to accept the
risks involved in experimenting with unproven technologies. China is the country that
has built the most tidal power stations in the world, and tidal power energy is no
doubt playing a more and more important role in China’s energy consumption
process.
History
Tidal energy is one of the oldest forms of energy used by humans. Indeed, tide mills,
in use on the Spanish, French and British coasts, date back to 787 A.D. but it is likely
that there were predecessors lost in the anonymity of prehistory. Tide mills consisted
of a storage pond, filled by the incoming (flood) tide through a sluice and emptied
during the outgoing (ebb) tide through a water wheel. The tides turned waterwheels,
producing mechanical power to mill grain and power was available for about two to
three hours, usually twice a day.
The power requirements of the industrialized world dwarf the output of the early tidal
barrages and it was not until the 1960’s that the first commercial-scale modern-era
tidal power plant was built, near St. Malo, France. The hydro mechanical devices such
as the paddlewheel and the overshot waterwheel have given way to highly-efficient
bulb-type hydroelectric turbine/generator sets. The tidal barrage at St. Malo uses
twenty-four 10-megawatt low-head bulb-type turbine generator sets. Installed in 1965,
the barrage has been functioning without missing a tide for more than 37 years.
After that, more and more commercial-scale tidal barrage was put in service in France,
Canada, Switzerland, UK, China and so forth.
Why there are tides
Tides are caused principally by the gravitational pull of the moon on the world’s
oceans. The sun also plays a minor role, not through its radiant energy but in the form
of its gravitational pull, which exerts small additional effect on tidal rhythms. And the
rotation of the earth is also a factor in the production of tides.