Current TechnologiesThere are a number of different types of hydrokinetic generators currently in use. Follow the links to see a brief explanation for and examples of each. Tubine Type|Ribbon Type|Bouy Type|Biomimicry TypeTurbine TypeThe first thing that comes to mind (possibly after traditional dams) when most people think of hydrokinetic generators is the turbine type. Analogous to the wind turbine, they operate with relatively simple mechanics making them easy to build. Some disadvantages of this type include problems they cause the environment and problems the environment causes them. Because of the rotating blades they can harm fish and other underwater biota. They are also more likely to cause disturbances to the water column such as resuspension of sediment. The rotation also makes them more difficult to seal against the corrosive effects of sea water, and can allow macrophytes to become entwined, slowing or preventing the rotation and thus rendering the turbine useless. The optimum coastal environment for the turbine type of generator includes dam spillways (as in Minnesota), streams or forced running water situations. Please click on the thumbnail images below to view examples of turbine-type generators. Wave Dragon Hydro Green Energy Free Flow Power |........|
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Wave Dragon 
The Wave Dragon works by ramping the waves up to a reservoir above a turbine. This increased head forces the water to run through the turbine more quickly than it otherwise would, increasing the power output. Images courtesy of http://www.wavedragon.net/index.php Hydro Green Energy
Image courtesy of http://www.hgenergy.com/technology.html 
Hydro Green Energy’s Hydrokinetic Turbine Array is a product that is significantly more scalable than other generator types because of its array setup. This makes it much more widely applicable. Images and product specifications courtesy of http://www.hgenergy.com/technology.html Free Flow PowerFree Flow Power’s Turbine Generator works by rotating a magnet to generate the electric current. Two sizes are planned, to generate 10kW each. The 1m diameter model requires 3m/s stream velocity, and the 2m diameter model requires 2m/s. One major advantage of this generator is that it is designed to be retrofitted to existing structures implanted in flowing streams, thereby reducing start-up costs for switching to hydropower through this method. 
Image courtesy of Images courtesy of << http://free-flow-power.com/index.php?id=10 Ribbon TypeRibbon type generators, more accurately called attenuating wave energy converters, are huge long tubes that flex with the wave motion. The two main products under this category are the Pelamis and the Anaconda, each collecting the wave energy through a different principle. These generators are essentially 150-200 meter long submerged or semi-submerged tubes, with diameter of three to seven meters. The most efficient installation of these generators is in an array of about 40 arranged to occupy about a square kilometer about one to five miles offshore. A ‘wave farm’ of this sort would be expected to generate about 30MW. Because the installations are so large and being submerged or semi-submerged reduces their visibility, these wave farms may present a navigation hazard, but that has not stopped a number of countries around the world investing in these applications. Please click on the thumbnail images below to view examples of turbine-type generators. Pelamis |.........| Anaconda |
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PelamisThe Pelamis is a large steel tube articulated into sections. As the joints bend with the wave motion, the generator uses hydraulic rams in the joints to pressurize a fluid which is then pumped through hydraulic motors which drive electrical generators to produce the desired electricity. The steel body is 150m long and 3.5m in diameter. For more information about the Pelamis, please visit http://www.pelamiswave.com 
Image courtesy of Images courtesy of http://www.pelamiswave.com/media/pelamisbrochure.pdf AnacondaThe Anaconda is a long, closed rubber tube filled with seawater. As long ocean swells pass along the Anaconda, energy is dispersed laterally along the wave crests, pinching the rubber tube and creating a bulge. The bulge then grows in energy as it travels along the tube until it forces the water inside it into the duckbill valves covering the turbine located at the end. For a model 150m long and 7m in diameter placed in an area with 2m high waves, the Anaconda can generate 250kW of energy. For more information about the Anaconda, please visit http://www.checkmateuk.com/seaenergy/system.html. 
Image courtesy of Images courtesy of http://www.checkmateuk.com/seaenergy/system.html To view some very interesting videos of the Anaconda in action, please visit http://www.checkmateuk.com/seaenergy/images/anacondaw.wmv . Bouy TypeThe Buoy type hydrokinetic generators all capitalize on basically the same principles to derive useable energy from wave motion. They have a stable mooring and a float that moves relative to the mooring. The motion of the float is generated by the rising and falling water levels of ocean waves. This differential motion is converted to energy. Because of the range of motion they require, most buoy type generators are designed to do best in water depths of about 50 – 70 meters. Wave farms of 50-200 buoys would be the optimal application for this type of generator to reduce the ratio of power lost in transmitting to shore. There are several companies producing Buoy type generators. Please click the thumbnails to be redirected to the various Buoy generator websites. These are worth exploring, and include videos and diagrams demonstrating the operation of a buoy type generator. 
Biomimicry TypeThe biomimicry type generators were modeled after the natural movement principles of biological organisms. In addition to the efficient capture of energy from the waves, these types have been touted as being environmentally friendly in that their more ‘natural’ motion allows them to operate more in harmony with the biota surrounding their installation. There are several examples of this kind of generator. Please click the thumbnail images below for more information about each.  |
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The StingrayThe Stingray operates along the same principles as the wings of an airplane allowing the flow of water to oscillate the fin arm up and down while the fin keeps its orientation with regards to the direction of flow. The oscillating motion is what the electricity is generated from.
To see a video of the Stingray in action, please visit http://www.bwea.com/marine/devices2.html Image courtesy of Images courtesy of http://news.bbc.co.uk/2/hi/uk_news/scotland/2254701.stm The bioWaveBioPower Systems’ bioWave wave power generator is based on the buoyancy and motion of aquatic plants. It sways with the wave about an axis which turns that motion into energy. The design incorporates a gage which allows the bioWAVE to lock down flat against the ocean floor should the wave energy increase to damaging levels such as during a storm
To see a video of the Stingray in action, please visit http://www.biopowersystems.com/technologies.php Image courtesy of Images courtesy of www.biopowersystems.com/technologies.php The bioSTREAMBioPower Systems’ bioSTREAM tidal power generator is based on tail motion of fish such as tuna and sharks. Like the Stingray, the fin maintains its orientation relative to the water motion, but oscillates the fin arm to generate energy.
To see a video of the Stingray in action, please visit http://www.biopowersystems.com/biostream.php Image courtesy of Images courtesy of http://www.biopowersystems.com/biostream.php |