GreeniacsArticles
Energy
Hydrokinetics
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Written by Elizabeth Jones
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| Thursday, 26 January 2012 | ||||||||||||||||||
Hydrokinetics![]() U.S. locations with the most wave and tidal electricity generation potential.3 Hydrokinectic power has several advantages among alternative forms of energy, including predictability, invisibility, the power density of water, and proximity:
Tidal Power 5 Due to these environmental impacts, there are only two commercial-sized barrages operating in the world. One is located in La Rance, France and the other is in Annapolis Royal, Nova Scotia, Canada. Both France and Nova Scotia are now experimenting with less disruptive technologies.8 ![]() Barrage located in La Rance, France.9 Tidal Fences: Tidal fences, also known as tidal reefs, can be used in many of the same places that tidal barrages are used.10 These fences have vertical axis turbines mounted on a fence that stretches across the width of a channel such that all the water that passes up and down stream is forced through the turbines.11 This technology is less expensive to install and less damaging to local ecosystems, although it can disrupt migration patterns of large marine animals. There is one tidal fence project currently planned for a strait in the Philippines.12 Tidal Turbines: Tidal turbines are basically underwater windmills that can be located anywhere there is strong tidal flow. However, unlike the millions of similar-looking windmills of the world, there are less than a dozen tidal turbine projects and few look alike.
Wave Power Oscillating Water Column: In a partially submerged oscillating water column the water level changes in relation to the rise and fall of waves. This creates a piston of sorts that drives air into a turbine to produce electricity.17 To see a video on this technology, click here. Point Absorber: Point absorbers use the vertical motion of waves to act as a pump that pressurizes seawater or some other internal fluid.18 Attenuator: An attenuator, or heave-surge device, is a segmented floating tube that is placed on the surface of the ocean. Waves bend the tube up and down or side to side at its segments, which pressurizes a hydraulic piston to power a generator.19
Overtopping Device: In these floating reservoirs, waves break over the walls of a device. This overtopping water generates pressure to turn a hydro turbine. 22Here in the United States some of these types of hydrokinetic power projects are taking off in Washington State23 and New York24. Estimates suggest that the amount of energy that could feasibly be captured from U.S. waves, tides, and river currents is enough to power over 67 million homes!25 Time will tell, though, if the price of hydrokinetic power comes down enough to really create a wave of change.26 1 Marine Foresight Panel Report, House of Commons, London. Office of Science and Technology. May 1997. 2 http://www1.eere.energy.gov/water/hydrokinetic/default.aspx 3 http://www.ucsusa.org/clean_energy/technology_and_impacts/ energy_technologies/how-hydrokinetic-energy-works.html 4 http://www.ucsusa.org/clean_energy/technology_and_impacts/ energy_technologies/how-hydrokinetic-energy-works.html 5 http://www.darvill.clara.net/altenerg/tidal.htm 6 http://www.eia.gov/kids/energy.cfm?page=hydropower_home-basics-k.cfm#top-container 7 Id. 8 http://cleantechnica.com/2008/07/28/france-plans-groundbreaking-tidal-power-experiment/ 9 http://en.wikipedia.org/wiki/File:Barrage_de_la_Rance.jpg 10 http://www.darvill.clara.net/altenerg/tidal.htm 11 http://www.eia.gov/kids/energy.cfm?page=hydropower_home-basics-k.cfm#top-container 12 http://www.eu-oea.com/index.asp?bid=425 13 http://cleantechnica.com/2008/07/17/world%E2%80%99s-first-commercial-scale-tidal- power-system-begins-feeding-electricity-to-the-grid/ 14 http://www.scientificamerican.com/article.cfm?id=turbine-that-rides-the-tide 15 http://cleantechnica.com/2011/03/17/wind-giant-iberdrola- worlds-biggest-tidal-scottishpower-renewables/ 16 http://www.washington.edu/news/articles/assessing-the-environmental-effects-of-tidal-turbines 17 http://www.ucsusa.org/clean_energy/technology_and_impacts/ energy_technologies/how-hydrokinetic-energy-works.html 18 Id. 19 Id. 20 http://www.scientificamerican.com/article.cfm?id=ocean-wave-tidal-power 21 http://www.aidea.org/AEA/PDF%20files/OceanRiverEnergy/6-22-2007EPRIprimer.pdf 22 http://www.leonardo-energy.org/wave-dragon 23 http://www.washington.edu/news/articles/assessing-the-environmental-effects-of-tidal-turbines 24http://sustainablecities.dk/en/city-projects/cases/new-york-leading-the-way-in-tidal-power 25http://www.ucsusa.org/clean_energy/technology_and_impacts/ energy_technologies/how-hydrokinetic-energy-works.html 26 http://sanfrancisco.cbslocal.com/2011/05/19/pge-abandons- plans-to-develop-wave-power-along-california-coast/
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| Last Updated ( Thursday, 26 January 2012 ) | ||||||||||||||||||
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