The Anonymous Widower

Repurposing The Affric/Beauly Hydro-Electric Scheme

The Affric/Beauly hydro-electric scheme was built in the 1950s and early 1960s, by the North of Scotland Hydroelectric Board.

  • The scheme is now owned by SSE Renewables and has a page on their web site.
  • There are six individual power stations; Mullardoch, Fasnakyle, Deanie, Culligran, Aigas and Kilmorack.
  • There are seven dams; Mullardoch, Benevean, Monar, Loichel, Beannacharan, Aigas and Kilmorack.

This map from the SSE Renewables web site shows the layout of the dams and power stations.

This description of the scheme is from Wikipedia.

The Affric / Beauly hydro-electric power scheme for the generation of hydro-electric power is located in the western Highlands of Scotland. It is based around Glen Strathfarrar, Glen Cannich and Glen Affric, and Strathglass further downstream.

The scheme was developed by the North of Scotland Hydro-Electric Board, with plans being approved in 1947.

The largest dam of the scheme is at Loch Mullardoch, at the head of Glen Cannich. From there, a tunnel takes water to Loch Beinn a’ Mheadhoinn (Loch Benevean) in Glen Affric, via a small underground power station near Mullardoch dam. Loch Benevean is also dammed, with a tunnel taking water to the main power station of Fasnakyle, near Cannich.

To the north in Glen Strathfarrar, Loch Monar is dammed, and a 9 km tunnel carries water to an underground power station at Deanie. Further down the glen, the River Farrar is dammed just below Loch Beannacharan, with a tunnel to take water to Culligran power station (also underground).

The River Farrar joins with the River Glass near Struy to form the River Beauly. Downstream on the River Beauly, dams and power stations have been built in gorges at Aigas and Kilmorack.

As the rivers in this scheme are important for Atlantic salmon, flow in the rivers is kept above agreed levels. The dams at Kilmorack, Aigas and Beannacharn contain Borland fish lifts to allow salmon to pass.


  1. Culligran, Deanie and Mullardoch power stations are underground.
  2. Loch Beannacharan is the English name for Loch Beinn a’ Mheadhoin.
  3. The salmon impose a constraint on water levels.

The sizes of the power stations in the scheme are as follows.

  • Mullardoch – 2.4 MW
  • Fasnakyle – 69 MW
  • Deanie – 38 MW
  • Culligran – 19 MW
  • Aigas – 20 MW
  • Kilmorack – 20 MW

This gives a total power of 168.4 MW.

This Google Map shows the Western area of the SSE Renewables Map.


  1. The three lochs; Monar, Mullardoch and Beinn a’ Mheadhoin can be picked out on both maps.
  2. Fasnakyle, where the largest of the hydro-electric power stations in the Affric/Beauly scheme, is at the Eastern edge of the map about half-way up.
  3. The area doesn’t seem to have a large population.

This Google Map shows the location of Fasnakyle power station in more detail.


  1. Fasnakyle power station is in the South-West corner of the map. marked by a grey flag.
  2. It appears that all of the water that goes through the power station flows into the River Glass, Strathglass, which meanders its way towards Inverness on the bottom of what appears to be a broad valley.

This Google Map shows the next section of the river.

The River Glass, Strathglass joins the River Farrar near the top of the map an becomes the River Beauly.

This Google Map the River Beauly to Kilmorack.

Wikipedia says this about this section of the River Beauly.

The river is part of the Affric-Beauly hydro-electric power scheme, with dams and power stations at Aigas and Kilmorack. Both have 20MW generators and include fish ladders to allow salmon to pass, the Aigas fish ladder is open to visitors in the summer.

This last Google Map shows the Beauly Firth.


  1. Kilmorack is in the South-West corner of the map.
  2. The River Beauly flows into the Beauly Firth and ultimately out to see in the Moray Firth.
  3. The water flows past Inverness to the North.

It does strike me, that a lot of the water collected in the dams to the West of Fasnakyle, flows out to sea.

Strathclyde University And Pumped Storage Power For Scotland

This page on the Strathclyde University gives a list of the pumped storage potential for Scottish hydrogen-electric dams and power stations.

A figure is given for only one dam or power station in the Affric/Beauly scheme.

  • Fasnakyle – 78 GWh

That would be a lot of pumped storage.

Water Flows In The Affric/Beauly Scheme

Looking at the SSE Renewables map of the Conon scheme, water flows appear to be as follows.

  • Loch Monar to Loch Beannacharan via Deanie power station
  • Loch Beannacharan to River Beauly via Culligran power station
  • Lochs Mullardoch and Beinn a’ Mheadhoin both supply water to the Fasnakyle power station
  • Fasnakyle power station to River Beauly via the River Glass, Strathglass.
  • River Beauly to Beauly Firth via Aigas and Kilmorack power stations.


  1. Water from Loch Moray goes via Deanie , Culligran, Aigas and Kilmorack power stations on its journey to the sea.
  2. Water from Loch Mullardoch goes via Mullardoch , Fasnakyle, Aigas and Kilmorack power stations on its journey to the sea.
  3. Water from Loch Beinn a’ Mheadhoin goes via Fasnakyle, Aigas and Kilmorack power stations on its journey to the sea.

Fasnakyle, Aigas and Kilmorack power stations must work very hard.

Refurbishing And Repurposing The Affric/Beauly Scheme

Perhaps as the power stations are now over fifty years old, one simple way to increase the generating capacity of the Affric/Beauly scheme  might be to selectively replace the turbines, with modern turbines, that can generate electricity more efficiently.

I suspect that SSE Renewables have an ongoing program of improvements and replacements for all of their hydro-electric stations in Scotland. Some turbines at Sloy power station have already been replaced with larger ones.

I also suspect that the whole scheme has a very sophisticated control system.


  • There is a need to control water levels to agreed minimum levels for the Atlantic salmon.
  • Hydro-electric power stations have the ability to get to full power quickly, to cover sudden demands for more electricity.
  • Electricity only needs to be generated if it can be used.
  • Water might be held in Lochs Mullardoch and Beinn a’ Mheadhoin, as a reserve, as it goes through three or four power stations when it is released.

Over the years, SSE Renewables will have developed very sophisticated control philosophies.

Adding Pumped Storage To The Affric/Beauly Scheme

To do this a source of fresh-water must be pumped into Loch Mullardoch or Beinn a’ Mheadhoin, when there is a surplus of electricity.

It looks from Google Maps, that the river system between Fasnakyle and Aigas power stations has been effectively turned into a canal.

  • I wonder, if it is deep enough to contain enough water to act as the lower level reservoir of a pumped-storage system.
  • The higher level reservoir would be Loch Mullardoch.
  • There would be a height difference of 200 metres.
  • Calculations show around 1850 cubic metres of water would need to be pumped into Loch Mullardoch to store one MWh.

So long as enough water is left for the salmon, I suspect that if a way of pumping water from the River Glass to Loch Mullardoch, that an amount of pumped-storage can be added.


There would appear to be only one scheme, but if it was built it could add over 50 GWh of pumped storage.


February 20, 2022 - Posted by | Energy, Energy Storage | , , , , , ,


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