Scottish Ministers have approved plans for the first first tidal energy project in Scotland's Pentland Firth.
MeyGen's project will be the largest tidal array in Europe when it is built.
It will be installed in stages, beginning with a 9MW demonstration project of up to six turbines.
A phase 1 project would then see the construction of up to 61 tidal turbines in the Inner Sound of the Pentland Firth, between the Island of Stroma and the north east coast of the Scottish mainland.
It will encompass almost 1.1sq km of fast flowing water and up to 86MW electricity generated will be exported onshore for transmission to the national grid.
The full development could eventually produce up to 398MW.
Speaking ahead of Scottish Renewables' Marine Renewables conference in Inverness today, energy minister Fergus Ewing said: "When fully operational, the 86MW array could generate enough electricity to power the equivalent of 42,000 homes – around 40% of homes in the Highlands."
MeyGen Limited is a joint venture between investment bank Morgan Stanley (45%), independent power generator GDF Suez (45%) and tidal technology supplier Atlantis Resources Corporation (10%).
Mr Ewing will also announce that Scottish wave energy firms Aquamarine Power and Pelamis Wave Power are to share a slice of a £13 million wave first array support programme – part of the Scottish Government’s Marine Renewables Commercialisation Fund.
Image: A graphic of the MeyGen tidal energy project, which will be Europe’s largest tidal energy project.