ScottishPower, the operator of the 440 megawatt (MW) Cruachan Pumped Storage hydro plant near Oban, has completed a two-year feasibility study to determine whether it is possible to expand the station.

The findings show that it would be possible to develop between 400-600 MW additional capacity, with investment of between £300 million to £400 million.

The study shows that a new cavern would need to be excavated within Ben Cruachan, and the possibility that new dams could be constructed to increase the capacity of the upper reservoir. ScottishPower is now considering all the options, but any project to expand Cruachan would include:

• 8-10 year build programme for extension
• 2-3 years to secure Section 36 planning consent and other necessary consents
• 6-7 years for construction and commissioning
• New cavern requires to be constructed and potential for new dam
• Will require up to c800 workers for the main civil construction works at peak

Cruachan can produce electricity for the grid in two minutes - or 30 seconds if its turbines are already primed.‎ This flexibility means that National Grid often calls on Cruachan to support peak demand from homes and businesses, typically at breakfast and tea time.

At full operation Cruachan can meet the power demands of more than 200,000 homes. ‎However, unlike other power stations, Cruachan can also act as a ‘battery’. When the turbines are reversed they use excess electricity from the national grid to pump water back in to the upper reservoir, ultimately storing this energy.

Given the increasing importance of renewable energy in Scotland, and the increasing need for energy storage, ScottishPower believes that Cruachan is well placed to help support the grid.

Hugh Finlay, Generation Director at ScottishPower, said: “A new generation of pumped storage hydro would be a major asset for electricity systems worldwide as more renewable electricity continues to come on line. As well as being able to further support peak demand, expanded pumped storage would also be able to effectively store greater levels of electricity at times when renewable energy output is high but demand is low.

“Pumped storage hydro is the most cost effective and well-developed large-scale electricity storage technology in existence. We will now take forward our Cruachan findings with government and regulators.”

ScottishPower will now consider the next steps for the project, including discussions with government on potential support mechanisms.

Cruachan celebrated its 50th anniversary in October 2015. Her Majesty the Queen presided over the official opening ceremony on 15th October 1965, six years after construction had started.

Widely regarded as an engineering masterpiece, and often referred to as The Hollow Mountain, Cruachan was devised by Sir Edward MacColl and was built by a workforce of 4000. Over 220,000 cubic metres of rock was blasted and drilled by explosives experts know as Tunnel Tigers, to create a cavern 1km inside the mountain to house the turbines and a network of pipes and tunnels.

ScottishPower Press Office - 0141 614 4660