Lochaber hydroelectric scheme | |
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Country |
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Location | Fort William, Scotland, UK |
Coordinates | 56°49′47″N5°04′13″W / 56.8296°N 5.0702°W |
Status | Operational |
Construction began | 1924 |
Commission date | 1929 (refurbished 2008-2012) |
Power generation | |
Units operational | 5 × 17.3 MW |
Make and model | Andritz Hydro Francis turbines |
Nameplate capacity |
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External links | |
Commons | Related media on Commons |
The Lochaber hydroelectric scheme is a hydroelectric power generation project constructed in the Lochaber area of the western Scottish Highlands after the First World War. Like its predecessors at Kinlochleven and Foyers, it was designed to provide electricity for aluminium production, this time at Fort William.
Water is collected from the River Spean catchment, plus the headwaters of the River Spey and some smaller watercourses. It contains two main reservoirs Loch Treig and Laggan Reservoir, and 18 miles (29 km) of tunnels excavated through the hillside.
The scheme was originally built between 1924 and 1943 by the British Aluminium Company. This company was bought by Canadian-based Alcan in 1982 which was subsequently bought by Rio Tinto in 2008. Rio Tinto Alcan then sold the scheme to GFG Alliance in November 2016. [1]
The hydroelectric scheme and aluminium smelter are still in operation.
The hydro scheme has a catchment area of 303 square miles (780 km2), [2] including the headwaters of the River Spey, the River Spean and River Treig, and the northern flanks of the Grey Corries and Ben Nevis. There are two principle reservoirs, Loch Treig and Loch Laggan (which was extended as Laggan Reservoir), both with a top water level of about 820 feet (250 m) above sea level. These reservoirs are linked by a 2¾ mile (4.4 km) long, 15 feet (4.6 m) diameter low pressure tunnel, [2] which collects water from three intermediate streams.
From Loch Treig, a main pressure tunnel 15 miles (24 km) long was driven around the Ben Nevis massif. This has a horseshoe shaped cross-section, with an equivalent diameter of 15 feet 2 inches (4.6 m), and lined with concrete to reduce friction. This tunnel also collects water from a further eleven burns along the way. It was, until 1970, the longest water-carrying tunnel in the world.[ citation needed ] Steel penstocks then convey the water down the western flank of Ben Nevis to the power house below.
Turbines in the power house generate electricity to power the adjacent aluminium smelting plant. The power house and smelter are located to the northeast of Fort William, on the eastern bank of the River Lochy, into which the tailrace discharges.
The scheme was expanded to increase output to meet demand for aluminium in World War II. [3] Floodwaters of the Spey are captured by Spey Dam and diverted via an open cut to Loch Crunachdan then through a tunnel to Loch Laggan. [3] In addition, the River Mashie (a tributary of the Spey) is diverted via an aqueduct and tunnel into the River Pattack, which flows into Loch Laggan.
The scheme was initially designed by engineer Charles Meik but after his death in 1923, the scheme’s realisation was left to William Halcrow, by then a partner in the firm founded by Meik’s father Thomas Meik.
The project was finally sanctioned by Parliament in 1921, but construction did not start until 1924. Given the scale of construction, it was undertaken in three main phases: [2] [4]
Over 3,000 men were employed during the peak of construction. [5]
A narrow-gauge railway was used in construction and subsequent maintenance of phases 1 and 2, see Lochaber Narrow Gauge Railway for details.
The first stage of construction took five years, from 1924 to 1930, and cost around £3m. [5]
The main challenge was the pressure tunnel from Loch Treig under the Ben Nevis massif, which commenced in summer 1926. The tunnel was dug by hand through the solid rock, with compressed air drills used to bore holes for the explosive charges. Initially liquid oxygen based explosives were used, but despite being safer their use was complicated, so gelignite was used instead. The final stage of construction, was to connect the tunnel to Loch Treig, having dug to a point about 20 feet (6 m) from the bottom of the loch and 100 feet (30 m) below the surface. On 3 January 1930, a charge of 1.5 tons of specially prepared gelignite was detonated to blast out the remaining section of rock. [6]
To facilitate construction, work progressed in both directions from 11 intermediate points: four vertical shafts and seven horizontal adits, giving a total of 23 working faces including the western portal above Fort William. These intermediate points were located close to watercourses, which were later captured by a series of dams and contributed around 16% of the total water for the scheme. [7]
The power station and smelter were completed by the end of 1929, initially equipped with five 6,800 kW generators, connected to Pelton turbines. The turbines sat in a deep rock excavation, as close to sea level as possible to maximise the head of the scheme. [5]
On 30 December 1929, the first aluminium was cast, [8] powered only by the waters from the side streams. [5]
A Supplementary Act of Parliament was obtained in July 1930 extending the time to complete the second stage of the scheme. Work started early the following year and the civil engineering works on the Treig and Laggan dams plus connecting tunnel were completed by 1934. [9]
Three years later, following a period of slack demand for aluminium, the power station was upgraded. Three additional pipes were installed on the hillside above the power station. These were 69 inches (1.8 m) in diameter, delivered in 30 feet (9.1 m) long sections, and welded together in-situ. Five additional Pelton turbines and generators were installed, each rated at 7,000 kW. [10]
A dam was built approximately 1/4 mile (400 m) downstream of Loch Treig, raising the top water level by 35 feet (11 m) to 819 feet (250 m) OD. This significantly increased the storage available, with 7,838 million cubic feet (221.9 million m3) available above the lowest draw-down level of 695 feet (212 m) OD. The dam also increased the head of the hydro scheme, providing more power. [11]
The dam is rock-filled with a central concrete core-wall keyed into the bedrock. The exposed part of the dam is 40 feet (12 m) high and 380 feet (120 m) wide, while the core wall has a crest length of 675 feet (206 m) and maximum depth of 122 feet (37 m). Both upstream and downstream faces have a slope of 3:1, with the spillway protected by reinforced concrete, cast in-situ. [11]
Construction of the reservoir also necessitated diverting 1.5 miles (2.4 km) of the West Highland Line along the shores of Loch Treig.
Laggan Dam was constructed at a constriction in the valley approximately 4.5 miles (7 km) downstream of Loch Laggan creating Laggan Reservoir. This is linked to Loch Laggan by a short section of the River Spean, which was dredged to make use of the storage capacity in the loch. While the downstream dam site required a larger dam than an alterative location upstream it had several advantages: [11]
The dam is a massive concrete gravity structure, 700 feet (210 m) long and 130 feet (40 m) high. [12] In plan, the dam has a slight curve with a radius of 2,000 feet (610 m), although it does not function as an arched dam. The dam has a plain spillway along its length, together with six siphons to increase the flood flow capacity. [11]
Laggan Reservoir has a usable storage of 1,480 million cubic feet (42 million m3), between a top water level of 820 feet (250 m) OD and maximum drawdown level of 804 feet (245 m). [11] The level of Loch Laggan was not raised by the dam, as this would have required significant diversion of the adjacent A86 road and would have also inundated valuable property. [12]
As with the main pressure tunnel downstream of Loch Treig, the tunnel between Laggan Reservoir was driven through rock and lined with concrete. Again, it was constructed from multiple faces with three intermediate adits, which were then used to collect water from streams. The tunnel is approximately 14 feet (4.3 m) in diameter with a flattened invert, and has a fall of 15 feet (4.6 m) over the 2.75 miles (4.4 km) length. [11]
The third and final phase of the scheme was undertaken between 1941 and 1943, and further enlarged the catchment of Loch Laggan by harnessing the headwaters of the River Spey. The work was supervised by Syril Minchin Roberts, a partner in Sir William Halcrow and Partners. It was constructed by Balfour Beatty, with assistance from the 1st Tunnelling Company of the Canadian Army. [13] [14] Many of these Canadian soldiers were ex-miners from Kirkland Lake. [4]
The Spey Dam was constructed in 1942–1943, just downstream of the confluence of the River Markie. The main structure is a concrete gravity dam, 943 feet (287 m) long and 57 feet (17 m) high. It has a spillway 93 metres (305 ft) long at a crest level of 268.2 metres (880 ft) OD, and a mass fill section to the north, approximately 2 metres (6.6 ft) higher. The dam incorporates a fish pass at the southern side. [3] [10] [15]
Water impounded by the dam flows westwards through a cut into Loch Crunachdan, against the natural flow of water. It then passes through a tunnel approximately 2 miles (3 km) long which discharges into the eastern end of Loch Laggan. The maximum abstraction from the Spey is 776 cubic feet per second (22.0 m3/s), although the average for 2020–2022 was just 14 m3/s. The tunnel was constructed in 1941, completed at the end of December. [10] [15]
A smaller dam was constructed across the River Mashie, a tributary of the Spey, just upstream of the A86 road. Water is transferred via an aqueduct and two smaller tunnels to the River Pattack, the main inflow to Loch Laggan. The maximum abstraction is 11.3 m3/s (400 cu ft/s). [15]
In 2008, Rio Tinto Alcan awarded a contract worth €30m for the upgrade of the hydroelectric turbines to Andritz Tech Hydro. [16] This was to replace the original twelve turbines, which were horizontal-axis twin-jet Pelton wheel machines driving two DC generators with a total capacity of 72 MW. [16] [17] Five new horizontal-axis Francis turbines driving AC generators were installed by 2012, [18] each rated at 17.3 MW giving a 20% increase in power output. [19]
Following the closure of Rio Tinto/Alcan's other UK smelters at Invergordon (1981), Kinlochleven (2000), Anglesey (2009) and Lynemouth (2012) the hydro-electric scheme and smelter at Fort William was operated by Rio Tinto Alcan. Under threat of closure the smelter was put up for sale in 2016. GFG Alliance, which incorporates SIMEC and the Liberty House Group, as the successful bidder, bought the Lochaber Smelter for £330 million. It announced plans to expand the factory and produce car parts such as alloy wheels. [20] This was later dropped, replaced by plans for an aluminium recycling facility announced in November 2020. [21]
On 3 April 2021, it came to light that the Jahama Highland Estates (formerly the "Alcan Estate") had been purchased in 2016 as part of the Rio Tinto Mines deal for the Lochaber aluminium plant, because the furnace requires so much power that the smelter is located near a hydroelectric plant, which drains the basin of the 114,000 acre Estate. Alcan designed all their smelters that way. The Estate includes the north face of Ben Nevis. According to reports, the Scottish Government mandated that the Estate never be split from the hydro plant and aluminium smelter, but Gupta ignored them and placed ownership of the Estate in a company that is domiciled on the Isle of Man. The 2016 deal was worth £330 million and was guaranteed by the UK Chancellor of the Exchequer. Conservative finance spokesperson Murdo Fraser was critical about the alleged breach of the Scottish Government agreement and urged the Scottish Government to "take whatever steps are necessary to protect public funds". [22]
Fort William is a town in Lochaber in the Scottish Highlands, located on the eastern shore of Loch Linnhe. At the 2011 census, Fort William had a population of 10,459, making it the second largest settlement in both the Highland council area, and the whole of the Scottish Highlands; only the city of Inverness has a larger population.
Kinlochleven is a coastal village located in Lochaber, in the Scottish Highlands and lies at the eastern end of Loch Leven. To the north lie the Mamores ridge; to the south lie the mountains flanking Glen Coe.
Loch Treig is a deep freshwater loch situated in a steep-sided glen 20km east of Fort William, in Lochaber, Highland, Scotland. While there are no roads alongside the loch, the West Highland Line follows its eastern bank.
The Falls of Foyers are two waterfalls on the River Foyers, which feeds Loch Ness, in Highland, Scotland. They are located on the lower portion of the River Foyers, and consist of the upper falls, with a drop of 46 feet (14 m) and the lower falls, which drop 98 feet (30 m).
The River Shin is a river in the Scottish North West Highlands.
Laggan Dam is a mass concrete gravity dam located on the River Spean south west of Loch Laggan in the Scottish Highlands. It forms the second reservoir for the Lochaber hydroelectric scheme.
The Lochaber Narrow Gauge Railway was a 3 ft narrow-gauge industrial railway. It was a relatively long line, built for the construction and subsequent maintenance of a 15-mile-long (24-kilometre) tunnel from Loch Treig to a factory near Fort William in Scotland. The tunnel was excavated to carry water for the Lochaber hydroelectric scheme in connection with aluminium production by British Aluminium. The railway came to be known colloquially as the 'Old Puggy Line'.
The River Conon is a river in the Highlands of Scotland. It begins at Loch Luichart, and flows in a south-easterly direction to be joined by the River Meig at Scatwell before passing through Loch Achonachie. It is joined by the Black Water at Moy Bridge, and the River Orrin at Urray, before flowing past Conon Bridge and into the Cromarty Firth.
The Tummel hydro-electric power scheme is an interconnected network of dams, power stations, aqueducts and electric power transmission in the Grampian Mountains of Scotland. Roughly bounded by Dalwhinnie in the north, Rannoch Moor in the west and Pitlochry in the east it comprises a water catchment area of around 1,800 square kilometres and primary water storage at Loch Ericht, Loch Errochty, Loch Rannoch and Loch Tummel, in Perth and Kinross. Water, depending on where it originates and the path it takes, may pass through as many as five of the schemes nine power stations as it progresses from north-west to south-east. The scheme was constructed in the 1940s and 50s incorporating some earlier sites. It is managed by SSE plc.
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 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 Renewables Obligation in 2001 caused Scottish and Southern Energy (SSE) to reconsider a number of schemes that had been mothballed in the 1960s by the North of Scotland Hydro-Electric Board, and plans for the Glendoe scheme were resurrected.
The River Garry in Inverness-shire is a Scottish river punctuated by two long Lochs, in the region of Lochaber. It flows broadly west to east through Glen Garry, starting in a wilderness to the east of Knoydart and ending at Loch Oich in the Great Glen, which forms part of the Caledonian Canal. There are a few tiny settlements within Glen Garry, but the only village of any size near to the river is Invergarry, at its mouth. Loch Quoich at the western end of the watercourse is dammed by the largest mass earth fill dam in Scotland, and supplies water to Quoich hydroelectric power station. Loch Garry is dammed by a much smaller dam in the gorge where the river begins its descent to Invergarry, and supplies water to Invergarry hydroelectric power station, close to the mouth of the river. Both hydroelectric schemes were built in the 1950s, with the aim of stimulating economic regeneration in the area. They have altered the ecology of the river, as both lochs were made considerably bigger as a result of constructing the dams.
The Loch Sloy Hydro-Electric Scheme is a hydro-electric facility situated between Loch Sloy and Inveruglas on the west bank of Loch Lomond in Scotland.
The River Moriston is a river in Inverness-shire, Scotland. It flows broadly east-north-east from the outfall of the dam at Loch Cluanie to Loch Ness. Its waters and those of its tributaries have been harnessed to generate hydro-electric power.
The Breadalbane Hydro-Electric Scheme is a hydroelectric scheme in the Breadalbane area of Perthshire, Scotland. It comprises seven power stations which generate 120MW of power from the dams around Loch Lyon, Loch Earn and Loch Tay.
Fersit Halt railway station named after the nearby hamlet of Fersit, was situated close to Tulloch railway station in Lochaber, Highland council area, Scotland. Fersit was a remote rural temporary private halt at the north end of Loch Treig where workers were housed who worked on the Lochaber hydroelectric scheme. The halt was opened in 1931 by the LNER, it was located near the site of a contractors railway ballast siding.
The Awe Hydro-Electric Scheme was the penultimate scheme developed by the North of Scotland Hydro-Electric Board. It centres around Loch Awe, in Argyll and Bute, on the southern edge of the Scottish Highlands. It consists of three power stations, two conventional hydro-electric stations, and the Cruachan power station, the first large pumped storage scheme built by the Board. It was completed in 1965.
Lussa Hydro-Electric Scheme is a small-scale hydro-electric power station, built by the North of Scotland Hydro-Electric Board and commissioned in 1956. It is located near Peninver on the Kintyre peninsula, part of Argyll and Bute in Scotland. It was originally designed to supply power to Campbeltown, but is now connected to the National Grid.
Loch Gair Hydro-Electric Scheme is a small-scale hydro-electric power station, built by the North of Scotland Hydro-Electric Board and commissioned in 1956. It is located near Lochgair, a hamlet to the north-east of Lochgilphead, Argyll and Bute in Scotland. It was originally designed to supply power to Lochgilphead and the surrounding communities, but is now connected to the National Grid.
The Kinlochleven hydroelectric scheme was built between 1905 and 1909 to supply power for an Aluminium smelter owned by British Aluminium. It was the second in Scotland after the 1896 Falls of Foyers scheme. The smelter and power house were constructed on the south bank of the River Leven in the village of Kinlochleven, in the south-west of the Scottish Highlands.