The first turbine on the biggest windfarm off the East Anglian coast has started turning and generating green electricity for the first time.
Eventually more than a hundred wind turbines will produce enough renewable energy to power 630,000 homes - enough for 85% of the households in Norfolk and Suffolk.
The £2.5 billion windfarm called East Anglia ONE is 27 miles off the coast of Lowestoft.
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So far 25 turbines have been built and the final total of 102 are due to be completed by 2020.
The turbines consist of three 75-metre (nearly 250 ft) blades and they are being pre-assembled at Great Yarmouth's outer harbour before being transported out to sea.
When constructed the turbines stand 90 metres (300 ft tall) - the height of more than 20 double-decker buses.
The East Anglia ONE offshore windfarm is a joint venture between ScottishPower Renewables and Green Investment Group.
It is the first of four offshore windfarms ScottishPower Renewables is developing in the region.
The power generated from the turbines is transferred via underground cables under the seabed from the windfarm to an onshore substation at Burstall, near Bramford in Suffolk.