The Breadalbane Hydro-Electric Scheme is a

hydroelectric Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

scheme in the Breadalbane area of

Perthshire Perthshire (Scottish English, locally: ; ), officially the County of Perth, is a Shires of Scotland, historic county and registration county in central Scotland. Geographically it extends from Strathmore, Angus and Perth & Kinross, Strathmore ...

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

. It comprises seven power stations which generate 120MW of power from the dams around

Loch Lyon Loch Lyon (Scottish Gaelic, ''Loch Lìobhann'')Loch Lìobhann/Loch Lyon

Loch Earn Loch Earn (Scottish Gaelic, ''Loch Eire/Loch Éireann'') is a freshwater loch in the southern highlands of Scotland, in the districts of Perth and Kinross and Stirling. The name is thought to mean "Loch of Scotland", and it has been suggeste ...

and

Loch Tay Loch Tay () is a freshwater loch in the central Scottish Highlands, highlands of Scotland, in the Perth and Kinross and Stirling (council area), Stirling Subdivisions of Scotland#Council areas, council areas, the largest body of fresh water in ...

History

The politician Tom Johnston during his time as Secretary of State for Scotland, championed the Hydro-electric Development (Scotland) Act 1943, which created the

North of Scotland Hydro-Electric Board The North of Scotland Hydro-Electric Board (1943–1990) was founded to design, construct and manage hydroelectricity projects in the Highlands of Scotland. It is regarded as one of the major achievements of Scottish politician Thomas Johnston, ...

. Johnston's vision was for a public body that could build hydro-electric stations throughout the Highlands. Profits made by selling bulk electricity to the Scottish lowlands would be used to fund "the economic development and social improvement of the North of Scotland." Private consumers would be offered a supply of cheap electricity, and their connection to that supply would not reflect the actual cost of its provision in remote and sparsely populated areas. The chairman of the new Board was to be

Lord Airlie Earl of Airlie is a title of the peerage in Scotland created on 2 April 1639 for James Ogilvy, 1st Earl of Airlie, James Ogilvy, 7th Lord Ogilvy of Airlie, along with the title "Lord Ogilvy of Alith and Lintrathen". The title "Lord Ogilvy of A ...

, who had initially been critical of the 1943 Act because its scope was too limited. The deputy chairman and chief executive was

Edward MacColl Edward MacColl (8 July 1882 - 15 July 1951), later Sir Edward MacColl, was a Scottish engineer, whose greatest achievements were made during the time he was Vice Chairman and chief executive officer for the North of Scotland Hydro-Electric Boar ...

, an engineer with wide experience of hydro-electric projects and electrical distribution networks. It soon became clear that MacColl intended to push ahead with the aspirations of the Act at breakneck speeds. He produced a list of 102 potential sites in just three months, and in June 1944, the first constructional scheme was published, for the large Loch Sloy scheme and two much smaller projects at Nostie Bridge and

Morar Morar (; ) is a small village on the west coast of The Rough Bounds of Scotland, south of Mallaig. The name Morar is also applied to the northern part of the peninsula containing the village, though North Morar is more usual (the region to the ...

. The Breadalbane scheme and Breadalbane Amendments scheme were published as constructional schemes 25 and 25A. Construction began in autumn 1951. The first stage was the building of Lawers Dam, at the south-eastern end of Lochan na Lairige. This was a fairly small loch, but its level was raised by , enabling it to store of water. From the dam, a tunnel and pipeline feeds the water to Finlarig power station, located on the shore of

at its south-western end. Finlarig contains a single 30 MW Pelton turbine generating set, which is the largest Pelton turbine in Britain. The dam is long and tall at its highest point. It is of the massive buttress type, for which the dam at Loch Sloy was the prototype. Water descends a

vertical distance Vertical position or vertical location is a position (mathematics), position along a vertical direction (the plumb line direction) above or below a given vertical datum (a reference level surface, such as mean sea level). Vertical distance or vert ...

of from the dam to the power station, the highest drop of any hydro-electric scheme in Scotland for more than fifty years, until it was exceeded by the

Glendoe Hydro Scheme The Glendoe Hydro Scheme for the generation of hydro-electric power is located in the Monadhliath Mountains near Fort Augustus, above Loch Ness in the Highlands of Scotland. The change in financial incentives following the publication of the ...

in 2009. To increase the amount of water available, the headwaters of streams that fed into Loch Tay, the River Lyon and the River Lochay were captured by a series of tunnels and aqueducts, increasing its catchment area to . Additionally, headwaters from two tributaries of the River Lochay are fed directly into the tunnel supplying the power station. The dam has two control towers, on either side of the central spillway. One controls the release of compensation water to the Allt a Moirneas, while the other controls the flow of water into the tunnel to Finlarig power station, which was commissioned in 1955. The scheme was expanded by the addition of six further power stations, with those to the west and north west of Finlarig comprising the Killin section and those to the south-east of Finlarig comprising the St Fillans section.

Killin section

The Killin section consists of three power stations, Cashlie, Lubreoch and Lochay, with two major dams and a third smaller one. Furthest west, Lubreoch dam was constructed at the eastern end of Loch Lyon by James Miller and Partners. It was long and high from the foundations to the crest. It was of the massive buttress type and was completed in 1958. The catchment area was increased by building a network of tunnels and aqueducts to the south of the dam, picking up the headwaters of a number of tributaries of both the River Lochay and the River Dochart. Lubreoch power station is located below the dam, and was commissioned in 1958. It has a gross head of and can generate 4 MW. To the north of the power station is Loch an Daimh, which is dammed at its eastern end by Giorra dam. The structure was built by Edmund Nuttall and is long, with a maximum height of . It is also of the massive buttress type, and was completed in 1959. Its catchment has been increased by tunnels and aqueducts to the south and east, picking up tributaries of the River Lyon. A tunnel runs from the dam to Cashlie power station, which discharges into Stronuich Reservoir. It has a gross head of , can generate 11 MW, and was commissioned in 1959. Stronuich Reservoir is formed by the Stronuich dam, a long low structure that dams the River Lyon. It stores water from the tailraces of Lubreoch and Cashlie power stations. Compensation water to maintain the flow in the River Lyon passes through a generator set below the dam. An intake gatehouse tower is located at the southern end of the dam, and controls the flow of water to Lochay power station. A long tunnel from the reservoir supplies water to Lochay power station, which discharges into the River Lochay a short distance before it joins the River Dochart and enters Loch Tay. It has a gross head of , can generate 47 MW, and was commissioned in 1958.

St Fillans section

The St Fillans section consists of another three power stations, Lednock, St Fillans and Dalchonzie, with two major dams, Breaclaich and Lednock. Lochan Breaclaich dam prevents water flowing into the Loch Tay catchment. It is a rockfill dam, with a concrete panels on the upstream side and coursed rubble on the downstream side. A gatehouse controls the inlet to a tunnel and pipeline which feeds Lednock power station. A tunnel collects headwaters from streams flowing into Loch Tay to the south-west of the reservoir, while another tunnel conveys water to Lednock power station. This contains a single 4 MW turbine, which is protected by a surge tower to the north-west of the station. The water discharges into Loch Lednock. The power station has a gross head of and was commissioned in 1961. Loch Lednock is contained by a diamond-headed buttress dam at its eastern end. The dam was constructed by

Taylor Woodrow Taylor Woodrow was one of the largest housebuilding and general construction companies in Britain. It was listed on the London Stock Exchange and was a constituent of the FTSE 100 Index until its merger with rival housebuilder George Wimpey ...

, is long and high. It was completed in 1957. The catchment of Loch Lednock is supplemented by a tunnel collecting the headwaters of the River Almond. There is only one other diamond-headed buttress dam in Scotland, at Errochty. Because it is close to the

Highland Boundary Fault The Highland Boundary Fault is a major fault zone that traverses Scotland from Arran and Helensburgh on the west coast to Stonehaven in the east. It separates two different geological terranes which give rise to two distinct physiographic ter ...

, it was designed to cope with earthquakes. A dispersal valve discharges compensation water through the dam to maintain the flow in the River Lednock. There is an intake gatehouse around half way along the loch, which controls the flow of water to St Fillans power station. This was the first of the additional power stations to be commissioned when it was completed in 1957. It has a gross head of and can generate 21 MW. The power station is constructed underground, whereas all of the others have buildings on the surface. It discharges into Loch Earn, which in turn supplies the River Earn. A small weir just below the outlet from the loch diverts some of the flow into a tunnel to provide power for Dalchonzie power station. It contains a single 4 MW turbine, and discharges back into the Earn. Its gross head is and it was commissioned in 1958.

Development

The North of Scotland Hydro-Electric Board were always looking for ways to improve their processes, and there is evidence of this at Breadalbane. The rock fill dam at Breaclaich was built to reduce the amount of cement used, and this technique had previously been used at Quoich.

Fly ash Coal combustion products (CCPs), also called coal combustion wastes (CCWs) or coal combustion residuals (CCRs), are byproducts of burning coal. They are categorized in four groups, each based on physical and chemical forms derived from coal combust ...

was used to replace some of the cement used in the construction of the dams at Lednock, Lubreoch and Giorra. This causes the concrete to harden more slowly, but is less permeable once it has cured. Although several of the dams are similar, they are different in detail, as new methods were used to reduce the amount of concrete and shuttering that was required. The massive buttress dam proved to be considerably cheaper to build than a solid gravity dam, by about 30 per cent. There were advances in tunnelling techniques too. The main tunnels connected the reservoirs to the power stations, but there were also lots of tunnels used to divert water from other catchments. In total, the scheme involved some of tunnels, and the Board worked hard to train tunnellers and improve drilling techniques. The tunnel from Stronuich to Lochay is in diameter, and some long. While a world record was claimed in October 1955 when a collecting tunnel in the St Fillans section advanced by in seven days, the Lochay tunnellers hit a water-bearing fault which resulted in per hour flowing into the workings, and flooding of the tunnel. The potential disaster was dealt with relatively easily, by pumping out the tunnel and using cast-iron segments to line a diversion. All of the tunnelling on the Killin section was completed nine months ahead of schedule. Most of the scheme was completed by late 1959, with only the Lednock station held up by issues with the Breaclaich section, resulting in it not being commissioned until March 1961.

References

Bibliography

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External links

{{Energy in Scotland Hydroelectric power stations in Scotland Buildings and structures in Perth and Kinross