Marine Current Turbines
Posted: Thu Apr 23, 2009 1:48 pmMarine Current Turbines Ltd (MCT) is a UK-based company which is developing tidal stream generators.
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The technology developed by MCT works much the same as a submerged windmill, driven by the flow of water rather than air. Tidal flows are more predictable than air flows both in time and maximum velocity and it is therefore possible to bring designs closer to the theoretical maximum. The turbines have a patented feature by which they can take advantage of the reversal of flow every 6 hours and generate on both flow and ebb of the tide. The tips of the blades are well below the surface so will not be a danger to shipping or be vulnerable to storms.
Because the blades are relatively slow moving (15 rpm)and there are only two, it is considered unlikely that there will be adverse environmental impacts on fish or other aquatic life, and a monitoring project has been set up in the Strangford Lough project to confirm this.
Two approaches are being followed, one for relatively shallow waters, up to 30 metres (98 ft), and the other for deeper waters. In shallow waters, the turbines are suspended on a tower which extends above the surface of the water and enables the turbines to be lifted clear of the water for maintenance purposes. But since the number of sites around the world where this is possible is finite, they are also developing fully submersed systems which will take advantage of larger scale, but will also be able to be brought to the surface for maintenance.
The technology under development by MCT is known as “SeaGen” and consists of twin axial flow rotors of 15m to 20m in diameter (the size depending on local site conditions), each driving a generator via a gearbox much like a hydro-electric turbine or a wind turbine. These turbines have a patented feature by which the rotor blades can be pitched through 180o in order to allow them to operate in bi-direction flows – that is on both the ebb and the flood tides. The twin power units of each system are mounted on wing-like extensions either side of a tubular steel monopile some 3m in diameter and the complete wing with its power units can be raised above sealevel to permit safe and reliable maintenance.
SeaGen was the first full-scale tidal flow power station to be connected to the grid to produce electricity for consumption. It was due to be installed in 2007 but delays with the installation barge meant that it was not installed until March 2008 after being modified extensively to permit the use of a crane barge rather than a jackup as originally planned.
It produced electricity on 14 July 2008. However, subsequently a computer problem caused damage to one of the rotors and procuring a replacement took until towards the end of October 2008. However SeaGen was able to operate using just its good rotor through the summer of 2008 and that rotor was operated at full rated power of 600kW for many hours. After replacement of the damaged rotor SeaGen delivered its full rated power of 1.2MW for the first time on 18 December 2008 - believed to be the first time a "wet renewable energy system" has delivered in excess of 1MW.
http://www.youtube.com/watch?v=0eKLvCJn ... PL&index=3
http://www.youtube.com/watch?v=lzc9-V9D ... playnext=1
Sources: and
[align=center]
[/align]
The technology developed by MCT works much the same as a submerged windmill, driven by the flow of water rather than air. Tidal flows are more predictable than air flows both in time and maximum velocity and it is therefore possible to bring designs closer to the theoretical maximum. The turbines have a patented feature by which they can take advantage of the reversal of flow every 6 hours and generate on both flow and ebb of the tide. The tips of the blades are well below the surface so will not be a danger to shipping or be vulnerable to storms.
Because the blades are relatively slow moving (15 rpm)and there are only two, it is considered unlikely that there will be adverse environmental impacts on fish or other aquatic life, and a monitoring project has been set up in the Strangford Lough project to confirm this.
Two approaches are being followed, one for relatively shallow waters, up to 30 metres (98 ft), and the other for deeper waters. In shallow waters, the turbines are suspended on a tower which extends above the surface of the water and enables the turbines to be lifted clear of the water for maintenance purposes. But since the number of sites around the world where this is possible is finite, they are also developing fully submersed systems which will take advantage of larger scale, but will also be able to be brought to the surface for maintenance.
The technology under development by MCT is known as “SeaGen” and consists of twin axial flow rotors of 15m to 20m in diameter (the size depending on local site conditions), each driving a generator via a gearbox much like a hydro-electric turbine or a wind turbine. These turbines have a patented feature by which the rotor blades can be pitched through 180o in order to allow them to operate in bi-direction flows – that is on both the ebb and the flood tides. The twin power units of each system are mounted on wing-like extensions either side of a tubular steel monopile some 3m in diameter and the complete wing with its power units can be raised above sealevel to permit safe and reliable maintenance.
SeaGen was the first full-scale tidal flow power station to be connected to the grid to produce electricity for consumption. It was due to be installed in 2007 but delays with the installation barge meant that it was not installed until March 2008 after being modified extensively to permit the use of a crane barge rather than a jackup as originally planned.
It produced electricity on 14 July 2008. However, subsequently a computer problem caused damage to one of the rotors and procuring a replacement took until towards the end of October 2008. However SeaGen was able to operate using just its good rotor through the summer of 2008 and that rotor was operated at full rated power of 600kW for many hours. After replacement of the damaged rotor SeaGen delivered its full rated power of 1.2MW for the first time on 18 December 2008 - believed to be the first time a "wet renewable energy system" has delivered in excess of 1MW.
http://www.youtube.com/watch?v=0eKLvCJn ... PL&index=3
http://www.youtube.com/watch?v=lzc9-V9D ... playnext=1
Sources: and