[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2013/05/EW-05-28-16-Tidal-Power.mp3|titles=EW 05-28-16 Tidal Power]
The energy we use in the modern world comes from many sources. Virtually all of it turns out to originate from the sun, including fossil fuels, solar power, wind power, hydroelectric power, and wave power, or from radioactivity, including both nuclear power and geothermal energy.
The one real exception is tidal power. Tidal power draws energy from the orbital interactions between the earth and the moon.
There are ways to extract energy from the difference in height between high and low tides through the use of strategically placed dams and tidal barriers. However, the real focus for tidal power is on tidal stream generators.
Tidal stream generators make use of the currents that flow as a result of the changing tides by drawing energy from these currents in much the same way that wind turbines draw energy from air currents. Because water is 800 times denser than air, these underwater tidal turbines need only spin at a tenth of the speed of wind turbines to generate the same amount of energy. And unlike wind or solar power, tidal power is very predictable. However, despite these inherent advantages, tidal power is only practical in certain locations around the world where the tides are big enough.
One place where tidal power offers great promise is in the United Kingdom, where there are estimates that tides could provide 12-20% of that country’s electrical needs. As a result, there is lots of active development of this green power with the first large systems coming on line over the next few years.
Here in the U.S., tidal power is also being developed in Cobscook Bay in Maine, with the testing of a pilot system as I speak.
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Web Links
Current Builds Behind Tidal Energy Take-off
Wave and tidal energy: part of the UK’s energy mix
https://www.gov.uk/wave-and-tidal-energy-part-of-the-uks-energy-mix
Photo, taken on July 30, 2007, courtesy of Kevin McManus via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY, with partial support from the Field Day Foundation.