Second wind: could floating turbines reshape offshore renewables?

From the surface, the spinning blades of the wind turbine sitting off the coast of Norway look much like those of any other offshore device.

But it is underneath the waves where the difference becomes clear.

That is because unlike conventional offshore wind turbines, the Hywind device is not fixed to the seabed by foundations, but is instead attached to a cylindrical structure that floats in the water. Tethers anchored to the ocean floor prevent it from drifting out to sea.

Now the company behind the floating turbine, Statoil, is planning to build five 6MW devices off the coast of Scotland.

The 30MW pilot wind farm, which is due to be completed in 2017 near Buchan Deep, around 25km off the coast of Peterhead in Aberdeenshire, will be the first array of its kind. It is expected to generate around 135GWh of energy per year, or enough electricity to power 20,000 homes.

Unlike fixed offshore wind turbines, floating devices can be placed in deeper waters of up to 150m. This allows them to tap into the vast energy resources available further offshore, where wind speeds tend to be higher and steadier. Turbulence is also lower further offshore, which should ensure the turbines have a longer operating life.