Drax, owner of the famous “Hollow Mountain” at Loch Awe, plans to excavate one million tonnes of rock, creating a second cavern next to the existing one.

If it goes ahead, this will be the largest energy infrastructure project in Scotland for decades.

And it would more than double the station’s capacity for generating electricity.

Work could get underway as early as 2024 with the six-year construction period supporting around 900 jobs.

The existing station employs 30 people. Drax said that until design work is finalised, it is difficult to say how many new permanent jobs will be created.

The final round of public consultation events is taking place this week.

‘It all looks very ambitious’

An exhibition was held at Dalmally Community Centre and a similar event was hosted at Taynuilt Village Hall.

Loch Awe resident Tony Graham was at Dalmally.

He said: “It all looks very ambitious. There is concern about how much disruption there will be during the construction period.

Loch Awe resident Tony Graham.

“Will all of these workers be located locally and does that put pressure on housing and accommodation?

“While it could be great for some local businesses it could bring disruption for the rest of us.

“In general, the principle behind it is welcomed. But there are concerns about the length of time it could take.”

Development manager Steve Marshall said that of the construction workers, around 75 would stay locally and that Drax is in talks with landowners about building housing for them.

Mr Marshall said: “People welcome the project.

“The majority, 95-96% of people, are very supportive because of the benefits to the community in terms of jobs.

“Cruachan has a special place in their hearts.  Some folk who were involved in the construction of the first project 50 years ago have come along.  They are happy to see this is being developed again.”

How will it work?

Ben Cruachan is the highest mountain in Argyll. It is already home to an underground pumped storage hydropower station.

The new 600MW power station will also be located inside the mountain – and increase the site’s total capacity to 1.04GW.

It would be built within a new, hollowed-out cavern which would be large enough to fit Big Ben on its side, to the east of Drax’s existing 440MW pumped storage hydro station.

Like the current site, the new station will be able to provide lifeline stability services to the power system alongside acting like a giant water battery.

By using reversible turbines to pump water from Loch Awe to the upper reservoir on the mountainside, the station can store power from wind farms when supply outstrips demand.

The stored water would then be released back through the turbines to generate power quickly and reliably when demand increases.

This will help to cut energy costs by reducing the need for wind farms to be paid to turn off when they are generating excess power.

The new station would have the capacity to generate enough power for around a million homes.

What happens next?

Drax will now seek permission from the Scottish Government. A decision is expected in 2023.

The project requires a new financial stability support mechanism from the UK government to secure private investment in long-duration storage sites such as Cruachan.

If this is developed and the planning application is approved, then work to build the new station could get underway in 2024, with the facility operational in 2030.

Last summer, the mountain and its iconic dam became a filmset and were used as the backdrop for the latest Star Wars TV series Andor.