On a visit to Caithness yesterday, Mr Salmond also made it clear that any move to have the Firth, considered to be one of the best tidal energy hotspots on earth, designated under environmental regulations would not stand in the way of the energy revolution.

The First Minister spoke as the Crown Estate confirmed it is opening up the firth seabed for applications for commercial-scale marine energy development. It is estimated that more than 700MW of energy could be generated by 2020, but Mr Salmond said there is potential for 20-30 times that amount.

In addition to the environmental benefits, he said marine renewables could kick-start economic regeneration in the area to counter the rundown of the Dounreay nuclear plant.

The Crown Estate's announcement means the first marine energy devices could be in the water by 2010 or 2011.

Rob Hastings, the director of the marine estate at the Crown Estate, said: "Unlocking the potential of the Pentland Firth is crucial to meeting Scottish Government renewable targets, stimulating the north of Scotland economy and boosting the fledgling renewables industry."

ScottishPower also confirmed it expects to lodge planning applications next summer for large-tidal stream projects in the Pentland Firth, Islay and off the North Antrim coast.

Between five and 20 tidal turbines will be installed in each site, with each turbine having an installed capacity of 1MW. This could lead to a total output of 60MW, enough for more than 40,000 homes.

A new energy company, based in Scotland, has been set up with a view to building the tidal machines.

Giving the keynote address to the Caithness Regeneration Conference, Mr Salmond said the announcements are a significant step in Scotland's journey to become a world leader in renewable energy: "We have talked about the potential of marine power for many years and it's now here and now; it's not in the hereafter any more.

"The tides in the Pentland Firth potentially have enough energy to be the powerhouse of Europe in terms of future electricity supplies."

He said existing onshore transmission lines can cope with some expansion, but for the "extraordinary" amounts of energy which could be produced in future new seabed inter-connectors would be needed.

"The sort of power that potentially could come from this area is not some hundreds of megawatts, its not just like one conventional power station, its 20 gigawatts and more than that, that's like 20 conventional power stations.

"The economics of transporting power underwater is advancing by leaps and bounds and we have to get in a position where we have a supergrid from Scotland, not just to England but across to Europe to sell that energy to people who need it."

On the possibility of a seabird reserve being established in the Pentland Firth, the First Minister was unequivocal: "The agencies have their statutory responsibilities to carry out but nothing is going to be allowed to stop the potential that Scotland has to harness these vast natural resources. The resources of the seas are the key to much of Scotland's future."

John Thurso, the Caithness and Sutherland MP, said: "We are now a long way down the road to turning what was seen as a dream five years ago into a reality.

"That reality is about high quality jobs in this community and a future post-Dounreay."

Meanwhile, Scrabster Harbour Trust is seeking £50 million investment to develop to serve the marine renewables and oil and gas sectors. It said this could create 130 jobs and generate and extra £5.8 million to the Caithness economy.