Swedish Vattenfall winner in the UK’s green power revolution.

Britain’s Prime Minister Gordon Brown will launch a £100 billion green power revolution this week as he awards a raft of development contracts to build a new generation of offshore wind farms, the Sunday Times wrote.

Among the winners are Sweden’s state-owned power group Vattenfall that together with Scottish Power are understood to have been given the rights for a 5GW parcel off the Norfolk coast.

A group including RWE AG unit Npower, Scottish & Southern Energy Plc, Norway’s Statkraft SF and Statoil ASA may have won the rights to develop the largest site in the Dogger Bank zone, located 100km off the east coast of England. That project alone would cost £35 billion, the report said.

Also Sea Energy and EDP-Energias de Portugal SA won for a site in Scotland.

By 2020 a third of the UK’s energy will be coming from wind power, the government envisages. The plan is the most ambitious in the world.

Yet big questions remain over the wisdom of betting so heavily on wind power, a largely untested power source sited in one of the harshest operating environments, the sea.

“There remain a lot of issues that are still not fully understood. Reliability has got to be the biggest.” Andy Cox, energy partner at KPMG told Sunday Times. “If a gearbox goes down in November, it [the turbine] is going to be shut down for the whole of the winter.”