One of the enormous turbines being towed out to sea. 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.