The world’s biggest offshore wind farm has opened off the coast of Kent

Energy Secretary Chris Huhne told Sky News: "We are determined to create more of our own energy within the United Kingdom. This will make us safe from the shocks we have seen in the past in the oil markets and gas markets. That is good news for consumers and businesses."

Construction work at the £780m wind farm, which lies seven miles (12km) off Foreness Point in Thanet, began two years ago. The 380ft (115m) tall wind turbines are spread over an area of more than 22 square miles (35 sq km) and are visible from the shore on a clear day.

The wind farm will boost the country’s capacity to generate wind power by 30%, a big step towards reaching the tough EU targets. There are now around 250 wind farms operating in the UK, 13 of them offshore, with just under 3,000 wind turbines in all.

But overall Britain is still lagging behind European neighbours in wind energy – the reason why the Thanet wind farm has had to use Danish-built wind turbines (Vestas) and is run by a Swedish firm.

Vattenfall also owns the 30-turbine Kentish Flats wind farm, off Herne Bay, which was one of the UK’s first such projects when it opened five years ago. Environmental campaigners have urged the Government to invest more in renewable energy.

Craig Bennett, the campaigns and policy director for Friends of the Earth, said the Thanet wind farm was an "important stride forward" but added the UK’s record on renewable energy was "dismal".

It will be improved considerably, however, with the completion of an even bigger wind farm nearby. When finished the London Array site in the outer Thames estuary will have 341 wind turbines with the potential to power 750,000 homes.