Renewable energy companies have been invited to bid for permission to build offshore wind farms which could quadruple the UK's wind power capacity.
The Crown Estate, which owns the sea bed, has offered nine areas around the UK as designated development zones.
Up to 25 gigawatts (GW) of new wind power could be developed by 2020, taking the UK's total capacity to 33GW.
Construction is to start in 2014 to help the UK achieve its share of the EU target of generating 20 per cent of energy from renewables by 2020.
Business secretary John Hutton said: "The launch of The Crown Estate bidding competition is a huge opportunity for investors and developers to play a part in the renewables revolution sweeping the UK. Offshore wind could dramatically increase the amount of electricity generated in this country from clean, green sources."
This will be the third phase of offshore wind farm leasing.
Under the first phase, E.ON set up the Scroby Sands project, now in its third year.
