Strangford Lough SeaGen is the world's first large scale commercial tidal stream generator located in Strangford Lough. It is more powerful than any other tidal stream generator in the world. In 2007 Strangford Lough SeaGen became home to the world's first commercial tidal stream power station. The 1.2 megawatt underwater tidal electricity generator, part of Northern Ireland's Environment and Renewable Energy Fund scheme, takes advantage of the fast tidal flow in the lough which can be up to 4 m/s. Although the generator is powerful enough to power up to a thousand homes, the turbine has a minimal environmental impact, as it is almost entirely submerged, and the rotors turn slowly enough that they pose no danger to wildlife.

The first SeaGen generator was installed in Strangford Narrows between Strangford and Portaferry in Northern Ireland in April 2008 and was connected to the grid in July 2008. It generates 1.2 MW for between 18 and 20 hours a day while the tides are forced in and out of Strangford Lough through the Narrows. Interestingly, Strangford Lough was also the site of the very first known tide mill in the world, the Nendrum Monastery mill where remains dating from 787 have been excavated.

Since June 2008 a tidal energy device called Evopod has been tested in Strangford Lough near the Portaferry Ferry landing. The device is a 1/10 scale prototype and is being monitored by Queens University Belfast. The device is a semi submerged floating tidal turbine and is moored to the seabed via a buoy mounted swivel so that it always maintains optimum heading into the direction of the tidal flow. The scale device is not grid connected and dissipates the small amount of power it generates as heat into the sea.

Technology

SeaGen generator weights 300 tonnes. It consists of twin axial-flow rotors of 16 metres (52 ft) in diameter, each driving a generator through a gearbox like a hydro-electric or wind turbine. These turbines have a patented feature by which the rotor blades can be pitched through 180 degrees allowing them to operate in both flow directions – on ebb and flood tides. The power units of each system are mounted on arm-like extensions either side of a tubular steel monopile some 3 metres (9.8 ft) in diameter and the arms with the power units can be raised above the surface for safe and easy maintenance access. The SeaGen was built at Belfast's Harland and Wolff's shipyards.^[9]

Environmental impact

SeaGen has been licensed to operate over a period of 5 years, during which there will be a comprehensive environmental monitoring programme to determine the precise impact on the marine environment.