How an offshore windfarm is built - in pictures

Technicians sit in the transition piece (the 'join' between foundation and turbine tower) waiting for the first tower section to be delivered. The Ormonde windfarm has been built in the Irish Sea, 10km off Barrow-in-Furness. It comprises 30 5MW wind turbines with the capacity of 150 megawatts. It is expected to produce around 500 gigawatt hours of electricity every year, enough to supply the equivalent of approximately 100,000 homes per year with clean power Photograph: Ben Barden/ Vattenfall

The second tower section is lifted. The rotor is at bottom of the picture. The windfarm took four months to finish and was completed three weeks ahead of schedule. It will begin generating electricity for the first time later this summer Photograph: Ben Barden/ Vattenfall

The second tower section is lowered into place onto the first tower section. The turbines are being built by Swedish energy firm Vattenfall Photograph: Ben Barden/ Vattenfall

The generator unit - the nacelle - is lifted. The final generator was installed at 3am Photograph: Ben Barden/ Vattenfall

The nacelle is lowered onto the tower, which has, by now been fixed into place with dumbbell-sized bolts Photograph: Ben Barden/ Vattenfall

The very tricky rotor lift Photograph: Ben Barden/ Vattenfall

The rotor is slotted into place on the nacelle Photograph: Ben Barden/ Vattenfall

The completed wind turbine Photograph: Ben Barden/ Vattenfall