SeaGen Making Underwater Tidal Electricity
One company may have found a commercial solution for generating electricity from offshore tides. On July 17, 2008 a SeaGen 1.2 MW tidal unit began producing power and feeding the electricity grid for Great Britain. The SeaGen (Sea Gen) is undergoing field trials in Strangford Lough in Northern Ireland and Marine Current Turbines Ltd (MCT) is the company behind the project. MCT's Managing Director, Martin Wright, says that the best way to grasp the technology concept behind the SeaGen is to "think of it as an underwater windmill".
The SeaGen consists of two massive underwater rotors, each having a diameter of between 15 to 20 metres. The rotors have a patented 180 degree pitch adjustment capability, allowing them to reverse direction and track the movement of the tide both inwards and outwards. One twin bladed SeaGen unit is capable of producing up to 1.2 MW of power for between 18-20 hours a day. SeaGen's are powered by the tidal force of water being passed by the rotors during inwards and outwards tidal flow.
The current costs of a SeaGen installed are £3.6 m for a 1.2 MW model (£3m/MW) which MCT says is about 30% more in cost than a conventional offshore wind turbine. These costs should reduce somewhat as the technology, production methods, and production volumes are improved. MCT is planning their first commercial tidal electricity generation farm off the coast of Anglesey in Wales at a size of 10.5 MW generation capacity.