These turbines could power most of Britain's households during strong winds.
The Crown Estate will announce the names of the consortia that will develop the nine zones in the North Sea. The biggest zone is at Dogger Bank, about 100km off the north east coast, where wind farms with a capacity of 10gw are planned at an estimated cost of £30bn.
The UK's big six energy suppliers are known to have bid for the project. The construction may begin only after 2014.