With an installed capacity of around 100 MW, Glendoe will be Scotland’s first conventional large-scale hydro-electric power station for 50 years.

The Prime Minister detonated an explosion beginning development of the tunnels which will allow water from a new reservoir, which will be built over 600m above Loch Ness, to reach an underground power station near the south east corner of the loch before being discharged into the loch itself.

Commercial operations are due to commence from the winter of 2008-2009.

Ian Marchant, chief executive of SSE, said: “Glendoe complements SSE’s investment in refurbishing our existing hydro stations, in onshore wind energy and in biomass.”