TIDAL POWER PLANT

                   

   Tidal power, also called tidal energy, is a form of  hydropower that converts the energy of tides  into electrical energy.In tidal plant  power of the rise and fall of the sea level or tidal power, can be harnessed to generate electricity.Tidal power 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.The tides contain energy that can be harnessed to produce electricity. Two types of tidal energy can be extracted. kinetic energy can be harnessed from the ebbing and surging tides. potential energy can be harnessed from differences in the high and low tides. Using tidal currents remains the primary method of generating electricity.Tidal energy is the utilization of the variations in sea level caused primarily by the gravitational effects of the moon, combined with the rotation of the Earth.

                                               Types of Tidal Plants

Tidal Fences: Tidal fences block a channel, forcing water to go through it and turning its turbines to generate electricity.
Barrage Tidal Plants: Barrage tidal plants are the most common type of tidal plant. A dam or barrage is installed, usually where there is a narrow water channel, with gates and turbines at certain points. As water flow through the turbines, they turn a generator that produces electricity.
Tidal Turbines: Tidal turbines work like an underwater wind turbine, using the tides to turn blades and generate electricity.

                                 Working of Barrage Tidal Plants

A huge dam (called a “barrage”) is built across a river estuary. When the tide goes in and out, the water flows through tunnels in the dam.

The ebb and flow of the tides can be used to turn a turbine, or it can be used to push air through a pipe, which then turns a turbine. Large lock gates, like the ones used on canals, allow ships to pass.

If one was built across the Severn Estuary, the tides at Weston-super-Mare would not go out nearly as far – there’d be water to play in for most of the time.

But the Severn Estuary carries sewage and other wastes from many places (e.g. Bristol & Gloucester) out to sea.

There are 3 main parts to a barrage tidal plant. These include: Barrage: the barrage acts much like a dam, holding back water to be later released.

Sluice Gates: the sluice gates allow water to flow through the turbine.
Turbine: the turbine spins as the water flows through it, which in turn rotates an electricity-producing generator.

When the tide falls, water behind the barrage is held in the estuary. The water is then released, flowing seaward turning a turbine and generator, which creates electricity. Later, when the tide rises, it will be held back in the barrage and then released back into the estuary, flowing through another turbine and allowing the electricity-producing process to be repeated.

Advantages

• Does not generate emmissions or wastes

• Uses an abundant, inexpensive fuel source (water) to generate power

• Electricity is reliably generated (tides are predictable)

• May protect coastline against damage from high storm tides and provide a ready-made road bridge

                                            Disadvantages

• Expensive to construct

• Power is often generated when there is little demand for electricity

• Limited construction locations

• Barrages may block outlets to open water. Although locks can be installed, this is often a slow and expensive process.

• Barrages affect fish migration and other wildlife- many fish like salmon swim up to the barrages and are killed by the spinning turbines. Fish ladders may be used to allow passage for the fish, but these are never 100% effective. Barrages may also destroy the habitat of the wildlife living near it

• Barrages may affect the tidal level – the change in tidal level may affect navigation, recreation, cause flooding of the shoreline and affect local marine life