THE world's largest offshore windfarm could power one million homes in Scotland and help meet the Holyrood Government's ambitious targets for green energy, the developers of the huge scheme have claimed.

Almost half of Scotland’s population could be supplied by the giant Moray Firth windfarm of between 200 and 300 turbines, which is proposed for a site 13 miles off the Caithness coast.

The two international energy companies behind the Moray Firth Development Zone yesterday gave more details of the multi-billion pound development, which they expect to be as powerful as all of Scotland’s hydro schemes combined.

The power would be collected by up to eight offshore electrical platforms, before being sent to shore via a grid connection point at Peterhead Power Station. Locally it could support between 360 and 1400 jobs during construction, between 130 and 280 jobs through operation, and between 450 and 3230 jobs through maintenance across Scotland.

Moray Offshore Renewables hopes to submit a planning application to the government agency Marine Scotland in June or July next year with a view to construction beginning in 2015.

If all goes to plan it would be the largest offshore windfarm on the planet. That title is currently held by Swedish energy giant Vattenfall’s 300MW development of 100 turbines, seven miles off Foreness Point in Thanet, Kent.

Critics of the SNP administration, including the chancellor George Osborne, have in recent weeks argued that the prospect of a referendum was putting investors off Scotland. Analysts Citigroup also warned investors that their returns may fall short if Scotland breaks away from the UK.

But Moray Offshore Renewables said it would be investing between £40 million and £50 million by the time the planning application is lodged next summer and forecasts a total investment of up to £5billion.

The company’s majority owner is EDPR UK, an arm of Portugal’s former state-owned power company which is the third largest onshore windfarm developer in the world. The other partner had been Aberdeen-based SeaEnergy but in the summer it announced it was selling its offshore wind unit to Spanish oil giant Repsol in a deal worth nearly £40m.

Managing director of EDPR UK, Dan Finch, said: “We are investing significant amounts of money – £40-£50 million – to get through the planning and development process, building up to planning consent. But if it goes ahead it will be huge. ”

Mr Finch said they were taking on staff and had offices in Edinburgh, adding: “We are doing this because we think Scotland is the place to be.

“Our partners, Repsol, have joined us in Edinburgh because they think this is the place to be as well. We made this decision consciously. We could have gone somewhere else.

“We are now recruiting senior staff to take us through to construction and beyond. We already have around 30 people in Edinburgh and we are looking to expand that with more well-paid jobs so that is an indication of our confidence in the market. Repsol have shown their confidence and we’re looking for other projects from our Edinburgh office.”

The development is located on the Smith Bank in the Moray Firth and covers an area of 320 square miles in waters up to 200ft deep. Alex Salmond has set a target of 100% of Scotland’s electricity coming from renewable sources by 2020.