Suffolk’s growing reputation as the “green coast” has received a major shot in the arm after officials approved a 140 turbine offshore wind farm.

The 504MW Galloper project - 27km from Sizewell - is expected to be worth £20million to the local economy and create 850 jobs.

It would generate enough electricity to power half a million homes.

Permission for the development was granted yesterday by the Secretary of State for Energy and Climate Change.

The scheme - set for completion in 2017 - is a joint venture between RWE npower renewables and SSE.

It is an extension of their existing Greater Gabbard wind farm, which was brought on-line last year and effectively doubles its capacity to 1GW.

With Scottish Power Renewables and Vattenfall Wind Power also consulting on plans for their 7,200MW East Anglia One wind farm a little further up the coast, yesterday’s decision was hailed as a boost to businesses hoping to cash in on “green” technology.

John Dugmore, chief executive of Suffolk Chamber of Commerce, said: “We understand that over 800 jobs will be created for the construction phase alone, which of course will make a real difference locally.

“Firms across the county are working harder than ever. This decision is a big vote of confidence for the energy coast and is further evidence that big business does want to invest in Suffolk.”

Suffolk Coastal MP Therese Coffey, echoed his comments, saying: “With Sizewell, Greater Gabbard and now Galloper our part of Suffolk really is becoming the green coast. The jobs and investment this will bring will be a major boost for the local economy.”

Nick Medic, director of RenewableUK, also praised the decision, saying it came at a time when major international companies were deciding on where to build the factories that will supply a number of offshore wind projects.

But Simon Gray, chief executive of East of England Energy Group, added a note of caution, warning businesses would not get on board until the Government guaranteed a suitable price for the electricity they generate - known as a “strike price”.

“We may have the development permission, but no one will invest until we know what the Government will pay for energy,” he said. “So it is very difficult for companies within offshore wind to justify whether or not they are going to get a return on their investment.

“But it is encouraging for the local economy, as long as the Government makes a decision soon.”

A new substation will also be built as part of the Galloper development, to connect the electricity generated to the national grid via existing transmission towers.

Project director Bart Oberink said: “The consent means a valuable boost to the UK economy and is expected to support up to 850 jobs during the construction phase alone.

“In response to earlier consultation we significantly enhanced the project and undertook in-depth studies which confirmed that the scheme was very unlikely to have an adverse impact.

“Galloper wind farm will make a substantial contribution to the UK’s clean energy supply.”

A Department of Energy and Climate Change spokesperson added: “Galloper wind farm will provide large amounts of clean energy, support jobs and generate major investment in Suffolk.

“Offshore wind has an important role to play as part of a balanced energy mix. This development will enhance our energy security and help to reduce greenhouse gas emissions.”