Tidal Energy and Sea Wave Power
3 min read · Energy Atlas Editorial
Tidal power plants use ebb-tide energy from turbines in the dam enclosing a tidal basin, while tidal stream generators are turbines anchored to the seabed.
Tidal Energy
Tidal barrage power plants exploit the difference in water level between the sea and a basin created by a barrage. Water flowing between the sea and the basin passes through turbines to generate electricity. Depending on the design, electricity can be generated during the ebb tide, the flood tide or in both directions. Examples of operating tidal barrage power plants can be found in South Korea, France, Russia and China.
Just as in the case of large dams, tidal barrages can have a significant impact on their environment. Damming an estuary or bay can affect fish migration, ship traffic and natural sediment transport.
An alternative approach is to harness tidal currents directly using tidal stream generators.
Tidal stream generators (TSG), also known as tidal energy converters (TEC), extract kinetic energy directly from tidal currents without the need for a barrage. They may be mounted on the seabed or installed on floating structures and are particularly suitable for locations with strong tidal currents, such as straits and channels.
Tidal energy drove tidal mills as early as the 15th century. A tidal power project with a proposed capacity of up to 87 GW has been considered for Penzhin Bay in Russia. However, no such power plant is currently under construction. On August 4, 2011, South Korea began operating the world's largest tidal barrage power plant. The Sihwa plant has an installed capacity of 254 MW, surpassing the 240 MW La Rance tidal power plant in France, which had previously been the world's largest.
Wave Power
Ocean waves are generated mainly by winds blowing over the sea surface. These winds are ultimately driven by uneven solar heating of the Earth's surface and atmosphere. As the wind blows over the ocean, part of its energy is transferred to the water, creating waves. Wave energy represents a large renewable energy resource, and technologies for harnessing it have been developed and tested in several countries, including the United Kingdom, Ireland, Norway, Denmark and Japan.
Many different types of wave energy converters have been developed, including point absorbers, attenuators, oscillating water columns, oscillating wave surge converters and overtopping devices. Although numerous prototypes and demonstration projects have been tested, wave power has not yet achieved widespread commercial deployment.
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