Plans have been submitted to build one of the world's biggest wind farms, which could generate enough electricity to supply a quarter of London homes.
The £1.5bn London Array wind farm could see 270 turbines over 152 sq miles (245 sq km) in the Greater Thames Estuary.
Concerns have been raised about the impact on wildlife, the environment and shipping hazards.
But Friends of the Earth's Tony Juniper said it is the type of development needed to tackle climate change.
London Array Limited won the right to lease an offshore site between the Essex and Kent coasts in December 2003 but has just applied to the government and local planning authorities for permission to develop the area.
The off-shore wind farm, which could produce up to 1,000 megawatts of renewable electricity, would be built 12 miles (20km) off shore by 2011.
The consortium says it would not be an eyesore, because it is so far out, and says it will would mean 1.9m tonnes less carbon dioxide each year.
Jason Scagell, of E.ON UK Renewables - part of the London Array Consortium along with Shell WindEnergy and CORE Limited - said they wanted to reduce carbon emissions.
He said: "It's only through building more powerful wind farm sites such as this that we'll be able to reach the government's tough targets for renewable generation."
The wind farm's current layout is opposed by the Port of London Authority because of potential naval hazards.
And some green groups are concerned about the impact on local wildlife and the environment.
But Friends of the Earth director Mr Juniper said climate change was the biggest threat to the planet and London Array was "exactly the sort of development that is urgently required to tackle the problem".