A number of schemes are centred around Loch Ness, where critics say the projects will damage the local environment. 

Brian Shaw, river director of the Ness District Salmon Fishery Board, said: “In places such as Loch Ness, this scale of pump storage hydro will overrun natural ecological processes, destroy the loch and surrounding ecosystems’ biodiversity, and devalue one of Scotland’s premier tourism destinations, all in the quest for not-so-cheap electricity.”

One of the largest is Earba, near Dalwhinnie, on the Ardverikie Estate, whose stately home was used for filming TV series including The Crown and Monarch of the Glen. 

Davie Black, of Mountaineering Scotland, which represents climbers and hikers, said such projects were “incursions into the wild qualities of our hill country”.

He said: “These are the only ‘wild’ places left where people can escape the pressures of modern urban living. We risk demeaning one of Scotland’s, and Britain’s, most precious and fragile assets – its open wild landscapes.”

However, Mr Miliband has made clear that low-carbon energy generation will almost always take precedence over landscape protection, having already approved a number of giant solar farms and pylon schemes across prime English farmland.