World's first tidal stream generating system

1.2 MW plant installed off the coast of Northern Ireland

A new type of renewable energy has been connected to the European grid: tidal energy turbines. The SeaGen Tidal System has been installed in the Strangford Narrows, about 400 metres off the coast of Northern Ireland, by Marine Current Turbines Ltd (MCT). The installation was completed last April and the generators were successfully connected to the grid on 17th July. It produces 1.2 MW of power, operating 18 to 20 hours a day. The total manufacturing and installation cost was nearly £10 million.

Like a wind turbine, but more predictable

The Seagen Tidal System consists of a fixed structure bearing two 16m diameter axial flow rotors, each connected to a generator via a gearbox. In contrast with other existing tidal power plants — such as the one on the Rance in France — this system does not require a barrage closing in an estuary. It is sited offshore on a large piling.

The technology is similar in many respects to a wind turbine. However, its principle advantage compared to most other renewable sources is that tidal energy is entirely predictable. In addition, its visual impact is much smaller since it is almost entirely submerged. The slow rotation speed (10 to 15 revolutions per minute) is unlikely to pose a threat to either fish or marine mammals.

Potential sites identified

The manufacturer MCT aims at developing a 10.5 MW tidal energy farm of the same type off the coast of the Welsh Island of Anglesey within the next three years. The main barrier to a large-scale development of this technology is likely to be the limited number of suitable sites.

Nevertheless, other potential sites have already been identified in the UK, as well as in Australia, Canada, Chile, France, Indonesia, New-Zealand, Turkey, and the US. 'With the right funding and regulatory framework, we believe we can realistically achieve up to 500 MW of tidal capacity by 2015 based on this new SeaGen technology,' says Martin Wright, Managing Director of MCT.

References

• Article 'Largest Tidal Stream System Installed' on the Energy Blog
• Article 'Tidal Power now online feeding Irish grid' on Mendo Coast Current
• Website Marine Current Turbines Ltd