The Anonymous Widower

The Development Of The Foyers Pumped Storage Scheme

This leaflet from SSE Renewables probably gives as good a record as any others about the development of the Foyers Pumped Storage Scheme.

This is the introduction.

The Foyers Scheme is a 300 Megawatt (MW) combined conventional hydro and pumped storage scheme. 1896 saw the British Aluminium Company commission Foyers for the smelting of aluminium. The plant was in continuous operation for 70 years until it’s closure in 1967. The scheme was promoted by NOSHEB in February 1968 and after receiving statutory approval in April 1969 work started that autumn and was commissioned in 1975 . The high level reservoir is Loch Mhor which was formed under the original development by enlarging and joining Loch Garth and Loch Farraline.

The full catchment area of Loch Mhòr today is now 207 sq km.

Note that NOSHEB stands for North of Scotland Hydro Electric Board.

This Google Map shows Loch Mhòr.


  1. Loch Ness is in the North West corner of the map.
  2. Loch Mhòr is the loch running diagonally across the map.
  3. Loch Mhòr was originally two separate lochs; Loch Garth in the South-West and Loch Farraline in the North-East.
  4. The power station is on the shores of Loch Ness.

I have found a document on the Internet, that says that the current storage capacity of Loch Mhòr is 10 GWh. That figure, if it is correct, would make the Foyers pumped storage scheme a small amount bigger than Electric Mountain.

The Original Scheme

The original scheme appears to have been a straight hydro-electric scheme with the water running from Loch Mhòr into Loch Ness through turbines. I don’t know how big it was and if anybody does, the figure needs to be inserted in this post. So if you know it, please tell me!

This gazetteer gives the figure at 3750 kW and also this history.

The British Aluminum Company development at Foyers was the first large-scale use of hydropower in Scotland. The scheme was highly influential, proving not only the viability of the technology to produce electricity with water driven turbines, but also that the power could be successfully applied to industrial processes. The British Aluminum Company went on to develop two large smelters in Scotland at Kinlochleven and Lochaber.

The original scheme generated electricity for seventy years.

The Current Scheme

There are effectively two parts of the current scheme, which was created in the early 1970s.

  • The original 3.7 MW turbines have been replaced by a 5 MW turbine in the old power station.
  • A new separate pumped storage power station has been built with two 150 MW pump/turbines.

This paragraph from the leaflet from SSE Renewables, gives brief details of the engineering.

When the station is generating, water flows from Loch Mhor through 2 miles of tunnels and shafts to the power station. When pumping, energy is drawn from the main transmission system at times of low load to drive the two 150 megawatt machines in the reverse direction and pump water from Loch Ness up to Loch Mhor. The existing gravity dam at the outlet of Loch Mhor (231.7m long and 9.14m high) was retained by NOSHEB . Remedial work was carried out on subsidiary earth embankment dams. The waters of the River Fechlin are diverted into Loch Mhor by a tunnel and the channel of the river.

From the complete description in the leaflet, it looks to be sound engineering.

Did Modern Project Management Enable This Scheme?

As someone, who was involved in writing project management software from about 1972, I do wonder if the arrival of ,odern project management around the mid-1960s was one of factors that prompted NOSHEB to carry out this scheme.

Other factors would have been.

  • The original turbines were on their last legs after seventy years of generating electricity.
  • There was a need for more pumped storage.
  • This scheme was feasible.

I would very much like to meet one of the engineers and talk the scheme through.


This power station and its rebuilding as a pumped storage scheme has been carried out to an excellent standard and I wonder if similar techniques can be used to create new pumped storage systems around the world.

February 15, 2022 - Posted by | Energy, Energy Storage | , , , ,


  1. Regarding your question about the original
    hydroelectric power plant, Foyers was set up by the British Aluminium Company in 1896 and originally contained 5 Swiss-built Girard vertical shaft turbines and Oerlikon DC generators, with two additional auxiliary sets. By the early 1900s the plant was reported as producing approximately 5% of the world’s aluminium.
    The sources of information are questionable but it is said it was capable of producing about 3.7MW of hydroelectric power from its turbines, while the six aluminium smelters were said to be fed with 65 volts at 8000 amps implying that just over 3.1MW were consumed in the production of aluminium.
    Many of the articles refer to Girard’s device as being a pelton wheel, an impulse turbine, however this is incorrect.
    While Girard spent much of his life developing impulse devices, the Girard Turbine is an axial flow device and is described in the following link.

    Comment by fammorris | February 16, 2022 | Reply

  2. Thanks for that!

    3.7 MW, which was replaced by the current 5 MW turbine by NOSHEB, would be sensible, as it would mean that during construction, there was no loss of power in the area.

    It probably says that the engineers at Foyers did a excellent job in converting a seventy-year-old 3.7 MW hydro-electric station into a 300 MW/10 GWh pumped-storage system.

    I have just had a think in the bath and we have to remember the dates. The project must have been planned in the mid-1960s and it was about that time that modern project management was starting. From what has been done at Foyers, I feel that they used critical path analysis and planned everything properly. At Sizewell A, it was all done manually on a giant whiteboard running the length of the Control Room. Perhaps a similar system was used at Foyers.

    I would also suspect that given the age of the turbines, they had been up for replacement for some time.

    I wouldn’t be surprised to find that the application of good project management allowed the project to be built.

    Comment by AnonW | February 16, 2022 | Reply

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