Tidal energy

Pages: 6 (1286 mots) Publié le: 27 mars 2011
Tidal energy
what is tidal energy?

It's a form of hydropower that converts the energy of tides into electricity.
First utilisation : the Middle Ages
The first tidal power plant started operation in 1966.
Not yet very used but tidal power has a big potentiel for future electricity generation
inconvénient : there are few sites with sufficiently high tidal ranges ( 16 feet ) or flowvelocities

Tidal energy is produced through the use of tidal energy generators. These large underwater turbines are placed in areas with high tidal movements, and are designed to capture the kinetic motion of the ebbing and surging of ocean tides in order to produce electricity. Tidal power has great potential for future power and electricity generation because of the massive size of the oceans. Thesearticles explore the potential energy of tidal power technologies.
Tidal power can be classified into three generating methods:
1. Tidal Barrages

A tidal barrage is built across an estuary.
When the tide goes in and out, the water flows through tunnels in the dam.
the dam is used to capture the energy from masses of water moving in and out of a bay or river due to tidal forces.
Turbinesare placed in these tunnels to capture the energy as the water flows in and out.
Turbines installed in the barrage wall generate power as water flows in and out of the estuary basin, bay, or river

2.Tidal stream generator
Tidal stream generators (TSGs) make use of the kinetic energy of moving water to power turbines, in a similar way to wind turbines that use moving air. This method isgaining in popularity because of the lower cost and lower ecological impact compared to tidal barrages.

A tidal stream generator (TSG) is a machine that extracts energy from moving masses of water, or tides. These machines function very much like underwater wind turbines, hence are also sometimes referred to as tidal turbines.

TSGs are the cheapest and the least ecologically damaging among thethree main forms of tidal power generation.
3.Dynamic tidal power
Dynamic tidal power (or DTP) exploits an interaction between potential and kinetic energies in tidal flows. It proposes that very long dams (for example: 30–50 km length) be built from coasts straight out into the sea or ocean, without enclosing an area. Tidal phase differences are introduced by the dam, leading to a significantwater level differential (at least 2–3 meters) in shallow coastal seas featuring strong coast-parallel oscillating tidal currents such as found in the UK, China and Korea. Each dam would generate power at a scale of 6 - 15 GW.

Dynamic tidal power or DTP is the newest technique of tidal power generation. It involves creating large dam-like structure extending from the coast straight to the ocean,with a perpendicular barrier at the far end, forming a large 'T' shape.

This long T-dam interferes with coast-parallel oscillating tidal waves which run along the coasts of continental shelves, containing powerful hydraulic currents (common in e.g. China, Korea, and the UK).

Dynamic tidal power or DTP is a new and untested method of tidal power generation. It would involve creatinglarge dam-like structure extending from the coast straight to the ocean, with a perpendicular barrier at the far end, forming a large 'T' shape.
This long T-dam would interfere with coast-parallel oscillating tidal waves which run along the coasts of continental shelves, containing powerful hydraulic currents (common in e.g. China, Korea, and the UK).[1][2][3][4]
The concept was invented and patented in1997 by Dutch coastal engineers Kees Hulsbergen and Rob Steijn.[5

A DTP dam is a long dam of 30 to 60 km which is built perpendicular to the coast, running straight out into the ocean, without enclosing an area. The horizontal acceleration of the tides is blocked by the dam. In many coastal areas the main tidal movement runs parallel to the coast: the entire mass of the ocean water accelerates...
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