The world's first floating wind farm is being built off the coast of Scotland

Hywind Scotland ready to be towed Roar Lindefjeld / Woldcam via Statoil

This summer five wind turbines are being towed out into the North Sea, where they will be the first ever floating offshore wind farm.

The turbines, built in Norway this year, have been dragged across the ocean to Scotland, where they will start working just off the coast.

The project — known as Hywind Scotland — cost a total of NOK 2 billion (£193 million, or $253 million).

It is expected to generate enough power for 20,000 households when it starts producing energy later this year, according to Statoil, the Norwegian state energy company behind the project.

Take a look at the slides below to see how the turbines work, and why an idea once dismissed as "crazy" is coming to life.

Here are the experimental turbines that will form the floating wind farm.

Ørjan Richardsen / Woldcam

They are designed to sit on the surface, with about 180 metres above water and 80 metres submerged.

Statoil/YouTube

The turbines can drift in all three dimensions on the water's surface, and will be held in place by anchors on the sea bed. Long cables will carry electricity back to shore.