Tidal Electricity (Tidal Power)

Tidal electricity, or tidal power, is an alternative form of energy which is generated by harnessing the kinetic energy of tides. It is anticipated, that the tidal power will become one of the major source of electricity in the future. It is estimated that 64,000 MWe (megawatt electrical) can be produced, if the complete oceanic tidal power is tapped.

Tide mills, mills which were run by the rise and falls in tide, were used in the coastal regions of Europe and the United States in the past. It was basically the utilization of kinetic energy of the waves to produce power. Today, this process has advanced to become one of the most inexpensive and reliable sources of power in the world.

Generation of tidal electricity is slightly similar to generation of hydroelectricity. A tidal range of 7 m is required to generate tidal power. A huge dam, called a barrage, is constructed across the full width of the river estuary. It is recommended, to chose a site where the bay has a narrow opening, as this will reduce the cost of construction of the barrage. The water flows through the tunnels within the dam, when it enters the estuary during the high tide and flows out during the low tide. This flow and ebb of the tide rotates the turbines to produce electricity. Depending on the design of the barrage electricity can be generated on either ebb side, the side from which the water goes out, flood side, the side from which the water fills in or both the sides.

Tidal lagoons are similar to barrages, but they don't cover the entire mouth of the estuary. They are cheaper compared to barrages. In yet another method, tidal fences built in the water channelize the water through them. This process rotates the turbines to generate electricity. Tidal streams are similar to the wind turbines on land. These underwater turbines are rotated by the waves. Because of their low cost and comparatively lesser ecological issues, they are preferred over barrages.

Advantages of Tidal Electricity

• This source of energy doesn't generate waste or harmful emissions.
• It is an inexpensive source of power.
• As tides are predictable, the power generated from them is more reliable than other sources such as wind energy.
• The structures built to tap tidal energy can also act as protective barriers for the coastline in case of storm.
• It is a renewable source of energy.
• Utilization of tidal power will lessen the use of nuclear power, which is costly and involves a lot of risk.

Disadvantages of Tidal Electricity

• These structures block the water outlet affecting the salinity levels of the water, as there is less exchange of water between the inland water source and the sea.
• The underwater life is threatened by the construction of tidal turbines.
• Fish, like Salmon, migrate upstream to lay eggs. These structures block their migratory route.
• The fish in the area where these turbines are located, die due to the exposure to turbines.
• Although, it is an inexpensive source of power, the initial investment is very high because the construction of the mammoth structures require high capital.

In future, more techniques of deriving kinetic energy of oceans will be introduced, to generate cheaper power. It is assumed that the coastal areas of Alaska and Washington have great tidal power potential. Tapping the kinetic energy of ocean currents, like gulf stream, is planned in order to enhance tidal power generation. If these plans are brought into action, then it would be possible to sustain the increasing demand of power consumption throughout the world.