SeaGen became the world's first commercial tidal-stream power station in 2008.
Installed in Strangford Lough, Northern Ireland, SeaGen used underwater rotors driven by tidal currents. Its two turbines were mounted on a crossbeam attached to a central tower, and the system was designed so the rotors could operate as tides flowed in both directions.
SeaGen was developed by Marine Current Turbines and began generating in 2008. It demonstrated that predictable tidal currents could be converted into grid electricity at commercial scale. The project was later decommissioned, but its engineering lessons influenced subsequent tidal-energy development.
SeaGen is often confused with France's La Rance facility. La Rance opened in 1966 and is a tidal barrage power station, using a dam across an estuary. SeaGen instead used tidal-stream turbines placed in moving water, without barraging the estuary.