The company behind plans to carve out a mountain cavern large enough to house Big Ben has appointed an Italian engineering consultancy to head up the Scottish hydro power project.

Drax, owner of the “Hollow Mountain” power station located within Ben Cruachan on the shores of Loch Awe, has named Studio Pietrangeli as “owner’s engineer” on the project to create an even larger underground plant adjacent to its existing facility in Argyll. Located in Rome, Studio Pietrangeli has provided dam and hydropower engineering services in more than 30 countries.

The expansion plans require consent from the Scottish Government, with a decision expected by the end of this year. Drax is also awaiting publication of an updated policy and market support mechanism for pumped storage hydro from the UK Government.

READ MORE: Drax to top profit predictions on strong demand for renewables

A consultation on the latter is due to launch in the coming months and a new framework is expected to be implemented next year, after which Drax will make a final decision on whether to go ahead with the £500 million project.

The market support mechanism will set a minimum amount on the revenues which the plant will receive in its first 10 to 15 years of operation. Investors usually require such guarantees before underwriting long-term, large-scale undertakings such as the proposed project at Cruachan, which is expected to be under construction for six years.

Such frameworks are in place for other types of power generation projects, but there have been no pumped storage hydro plants built in the UK since 1984. That pre-dates the privatisation of the power market, meaning that all four of the UK’s existing pumped storage facilities were built by the government, negating any need for an accompanying market support mechanism.

HeraldScotland: A UK icon, London’s Big Ben stands at 316 feetA UK icon, London’s Big Ben stands at 316 feet (Image: PA)

Once completed, Cruachan 2 will have the capacity to generate 600 megawatts of electricity. The existing plant can reach full generation in less than 30 seconds and has capacity for 440 megawatts – enough to power more than 90,000 homes.

“This is a significant moment in Drax’s planned expansion of Cruachan,” said Ian Kinnaird, director of Scottish assets at Drax.

“The scale of the proposed development matches Drax’s ambitions when it comes to tackling the climate crisis. More than two million tonnes of rock will be excavated to create a new cavern inside the mountain which will be big enough to house Big Ben on its side.”

READ MORE: Drax keeps the profits flowing as decision on Cruachan looms

Noting that there are nearby quarries, the company said it is currently exploring options for the disposal of the excavated rock. It could be used for creating pathways through windfarms, or in the construction and maintenance of harbours.

Drax says increasing the UK’s pumped storage hydro capacity is critical to enabling more wind and solar power to come online.

“Pumped storage hydro is vital to strengthening the UK’s energy security by enabling more homegrown renewable electricity to come online, cutting the need to import power or fossil fuels from abroad,” Mr Kinnaird said.

HeraldScotland: The turbine hall at Cruachan power stationThe turbine hall at Cruachan power station (Image: Drax)

“This will be a major infrastructure project which will support hundreds of jobs and provide a real boost to Scotland’s economy.”

As owner’s engineer, Studio Pietrangeli will support key activities including optimisation of the detailed design and layout of the new plant. The Italian consultancy will also provide expertise around the major civil engineering components of the project.

Separately, a Drax spokesman said the company is in continuing discussions with workers at its Scottish hydro operations who have voted in favour of industrial action in a dispute over pay. This includes about 50 staff at power stations in Cruachan, Lanark and Castle Douglas.

Union representatives at Unite confirmed the result of the vote as last month as Drax – most widely known for its eponymous power station in North Yorkshire – posted an 84 per cent surge in profits for 2022. The group, which provides 7% of Britain’s electricity, posted an annual adjusted core profit of £731m, up from £398m the previous year.

A meeting between Drax and union representatives is scheduled for tomorrow.