It will be the world's largest offshore wind-farm development - 300 turbines erected out at sea, 13 miles from the Caithness coast. and, when they are completed, at a cost of ?4.5 billion, they will generate enough electricity to power a million homes.  Remarkably, environmental campaigners welcomed the project, despite Prince Philip's dismissive comment this week that wind power was a "useless" form of energy. Friends of the Earth described it as a "significant" contribution to a low-carbon economy, and the SNP government said that it was an important contribution to its aim of making Scotland self-sufficient in renewable energy by 2020.  although the development is seen as a boost to local jobs, the actual construction will be undertaken by a joint Spanish and Portuguese company, and its profits are unlikely to stay in Scotland.  Moray Offshore Renewables Ltd - a partnership between EDP Renewables and Repsol - won the rights to develop the offshore facility, capable of generating 1,500MW of power, from the Crown Estate. Dan Finch, managing director of EDPR UK, said the consortium was keen to work with the UK Government and business to create jobs and economic growth. Up to 1,400 jobs could be supported during construction, and 130-280 during operation.  The Scottish government said the scheme was proof that companies were still keen to invest in Scotland despite George Osborne's claims that the debate over independence was deterring business.  Stan Blackley, chief executive of Friends of the Earth Scotland, said the scheme had the potential to play "a significant part in both the transition to a low-carbon economy and in reducing carbon emissions".  He added: "This development, and other offshore renewables developments like it, could form a welcome addition to the proposed Europe-wide supergrid, connecting a diverse range of renewable energy sources from around Europe and securing the supply of clean, green electricity for British consumers.  "Our only concern is that the wind farm is being proposed and developed by Spanish and Portuguese interests and not domestic ones, which will ultimately see the income produced leave the UK. It's a r