Tidal energy, also known as tidal power, is a form of hydropower which converts the energy of sea tides into electricity. Tides are generated by the gravitational pull of the sun and the moon which creates currents in the sea.

The tide comes in twice and out twice every 24 hours, filling and emptying natural basins along the shoreline. The currents which flow in and out of these basins can be utilised by mechanical devices to produce electricity. At present there are two ways in which we can harness energy from the tide, the use of tidal stream and tidal range technology. Other technologies are also currently under development.

Tidal stream is the flow of water as the tide ebbs and floods (falls and rises) and this flow of water powers turbines which produce electricity and are best positioned where currents are strongest. These turbines generate energy from water currents in much the same way that wind turbines produce energy from air currents. However, as the density of water is 800 times greater than air, tidal stream turbines can be considerably smaller than wind turbines. Other tidal stream technologies include oscillating hydrofoils and floating devices.

Tidal range is the vertical distance between high and low tides. Tidal range technology converts tidal energy into electricity in a similar way to a hydroelectric power plant, only the dam is bigger and spans a tidal bay or river estuary. Gates and turbines are installed along a barrage or dam. When there is a sufficient difference in the height of water on either side of the dam the gates then open allowing the flow of water through the turbines which produces electricity.

It is estimated the UK has almost 50% of Europe’s tidal energy resources and around 64% of this is located in Scotland. In addition, Scotland also possesses approximately 25% of Europe’s tidal stream capacity, around 18GW (gigawatts). Up until now high costs have kept tidal energy from being utilised to its full potential. However, with the current rate of depletion of non-renewables and their associated costs, according to the Carbon Trust tidal energy is ready to become a significant and economically viable source of energy.

As we will always be able to rely on the coming and going of the tide, tidal energy is a reliable and predictable form of renewable power. It is estimated that between 15 - 20% of the UK’s electricity consumption will come from tidal and wave technologies in the future which will generate significant investment and jobs in Scotland.




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