Scotland to launch world’s largest tidal farm

Sensemaking / Scotland to launch world’s largest tidal farm

Ten underwater turbines will generate 30GWh a year from the seafloor in the Sound of Islay, following government approval.

21 Jul 2011

Ten underwater turbines will generate 30GWh a year from the seafloor in the Sound of Islay, following government approval.

A £40 million tidal array harnessing electricity from one of the UK’s most reliable and strongest tidal streams has been granted approval by the Scottish Government.

The 10MW tidal turbine project in the Sound of Islay, between the islands of Islay and Jura, will be the largest scheme of its kind in the world and will generate approximately 30GWh per year, enough to power all the homes on Islay and Jura – and, crucially, their whisky distilleries.

Scotland has been described as the Saudi Arabia of offshore renewables by First Minister Alex Salmond. The Scottish Government offers higher subsidies for wave and tidal energy through Renewables Obligation Certificates (ROCs) than the rest of the UK. (That’s five ROCs for wave and three for tidal in Scotland, compared to two ROCs for both in the UK.)

The ten turbines will sit 50m deep on the seabed in a 1km-wide underwater canyon where the peak tidal flow is a (more than sufficient) 3m per second. Each turbine will have an installed effect in excess of 1MW, and the first will be in place in 2013, with the full project running from 2015.

Unlike their wind-powered cousins, tidal turbines can’t be accused of any visible or audible pollution. Vessels will be able to operate on the surface without restrictions, and marine life will not be at risk from the turbines’ slow-turning arms. The tripod design also means the turbines will have a minimal ‘footprint’ on the ocean floor.

For Andrew Macdonald, Tidal Energy Project Manager of the Islay Energy Trust, the “real significance of this site” will be the lessons learnt for future, even larger, developments – including a 400MW installation proposed for the Pentland Firth. “It gives us a chance to show the systematic interaction between the turbines before hundreds are placed in the Pentland Firth.” Maintenance of multiple turbines in such a high-pressure and hard to reach environment will also be thoroughly tested.

The project is being built by ScottishPower Renewables using ten HS1000 turbines developed by Hammerfest Strom AS, and local contractors, ornithologists and divers. The Islay Energy Trust will get a (yet to be decided) cut of the profits to fund community projects in Islay, Jura and Colonsay, which all share the same grid.

Other significant tidal projects in the pipeline include South Korea’s Incheon Bay power station which, with a capacity of 1,320MW, will be the largest in the world when it opens in 2017.

– Laura Dixon 

Image credit: Hammerfest Strom AS

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