ScottishPower could expand by 400MW–600MW the 440MW Cruachan pumped storage hydro plant near Oban.
The company has completed a feasibility study that concludes that investment of between £300m to £400m would be needed for the expansion.
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 said it is now considering all the options and will consider possible next steps, including discussions with government on potential support mechanisms.
It added that any project to expand Cruachan would include: an eight to 10 year build programme for the extension; two to three years to secure Section 36 planning consent and other consents; and six to seven years for construction and commissioning.
Image: the Cruachan pumped storage hydro plant (ScottishPower)
The company said up to 800 workers would be needed for the main civil construction works at peak times.
ScottishPower generation director Hugh Finlay 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.
