The project, which would have a capacity up to 600MW, would be built to the north-west of Loch Lochy in the Great Glen. It would be the first new pumped storage scheme to be developed in Great Britain since work began on the Dinorwig scheme in Wales in 1974. With a cost currently estimated at £800m it would also be one of the largest construction projects in Scotland.

The scheme would require the construction of a new dam and upper reservoir at Loch a’ Choire Ghlais. At an estimated height above ground level of up to 92m, this would be one of the largest dams in the UK. A powerhouse complex would be constructed underground, together with a series of tunnels. An outlet area comprising an administration building and jetty, tunnel portals and a tailrace structure would also be constructed on the shores of Loch Lochy.

Once completed the scheme would have minimal visual impact in the Great Glen, the company said. The project would take around five years to build, employing an average workforce of around 150 throughout this time.

If the project receives consent, a final investment decision is unlikely to be taken before 2014 at the earliest, and progress of this scheme (and other similar developments) will be dependent upon a satisfactory public policy and regulatory framework, including a change in transmission charging regime.