TIDAL POWER MAY BE BEST

Why Tidal Power is Europe's Best Near-Term Ocean Energy Technology
Peter Ausmus, September 8, 2010 (Matter Network via Reuters)

"…[T]he world's largest tidal turbine…1 MW…will be installed off the coast of Scotland near Orkney…Scotland is the hot spot for tidal power in all of northern Europe, with the Pentland Firth often described as the "Saudi Arabia of tidal power." The U.K. and Ireland also feature among the best tidal sites in the world, because they are relatively close to people…[In] the U.S…95% of the nation's tidal resources [are] off the coast of remote Alaska…

"Tidal stream turbines…[look] like wind turbines placed underwater. Tidal projects comprise over 90 percent of today's marine kinetic capacity totals, but the vast majority of this installed capacity relies upon first generation "barrage" systems still relying upon storage dams… [A] 2009 [Pike Research] forecast shows…[tidal systems dominating] the near-term market for ocean energy technologies."

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"Tides result from the gravitational forces of the moon and sun interacting with oceans. (Because of its proximity to the earth, the moon actually exerts about twice as much influence on tidal patterns as the sun.) The ever-changing relationship between the moon, sun, and earth causes the ocean to rise and fall at regular ["semi-diurnal"] intervals…

"These tidal streams become concentrated pools of kinetic energy ideal for power generation, when passing through narrow channels, an inlet into a bay or other passages between two land masses. While the tidal resource is much less abundant than wave energy resources, its power density is greater. Most waves move at the pace of approximately one meter per second; tides typically move at least twice that speed at two meters per second. A doubling of the speed of tidal streams will result in eight times the amount of potential energy since power density is determined by the cube of water speed."

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"The Electric Power Research Institute has projected that a 100 MW tidal stream turbine project could generate power at a [market-competitive] cost of 6 to 9 cents per kilowatt hour…Tidal resources have the highest power density of any of the marine renewable technologies, hence the lowest cost estimates…[They] can be accurately predicted literally years in advance…

"…Tidal devices are typically sited below the ocean surface…can't be seen…[or] heard…[and will] not interfere with shipping or other maritime uses…While physics is on the side of tidal streams…experts estimate the wave resource to be two to three times the size of the world's tidal stream resource..."