Lochaber hydroelectric scheme

Lochaber hydroelectric scheme
Country	United Kingdom
Location	Fort William, Scotland, UK
Coordinates	56°49′47″N 5°04′13″W / 56.8296°N 5.0702°W / 56.8296; -5.0702
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	88 MW
External links
Commons	Related media on Commons
[edit on Wikidata]

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 whcih 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.

Scheme Layout

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). 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.

Construction

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]

1. The works to the west of Loch Treig, including the pressure tunnel, intake, powerhouse, and smelter.
2. The Treig and Laggan dams, plus connecting tunnel and intakes.
3. The Spey dam, Crunachdan cut and tunnel, plus the River Mashie diversion and Strathmashie tunnel.

A narrow-gauge railway was used in construction and subsequent maintenance of phases 1 and 2, see Lochaber Narrow Gauge Railway for details.

On 30 December 1929, the first aluminium was cast.^[5] It took about 95% of the 82,000 kW of power generated. It eventually became part of British Aluminium.

The third phase of construction, the Spey Dam and tunnel plus the River Mashie diversion and tunnel, was supervised by Syril Minchin Roberts a partner in Sir William Halcrow and Partners. It was constructed by Balfour Beatty in 1942/43 with assistance from the Canadian Army.^[6][3] Many of these Canadian soldiers were ex-miners from Kirkland Lake.^[4]

Turbine upgrade

In 2008, Rio Tinto Alcan awarded a contract worth €30m for the upgrade of the hydroelectric turbines to Andritz Tech Hydro.^[7] 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.^[7][8] Five new horizontal-axis Francis turbines driving AC generators were installed by 2012,^[9] each rated at 17.3 MW giving a 20% increase in power output.^[10]

Present operation

Fort William Smelter

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.^[11] This was later dropped, replaced by plans for a aluminium recycling facility announced in November 2020.^[12]

The Alcan Estate

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".^[13]

See also

• Lochaber Narrow Gauge Railway for the construction and maintenance of the water-carrying tunnel
• Problem of water in vertical shafts, see item 5 at http://www.spanglefish.com/ooooppss/index.asp?pageid=608087

References

• Miller, James (2007). The Dam Builders: Power from the Glens. Edinburgh: Birlinn Limited. ISBN 978-1-84158-225-2.
• Wood, Emma (2002). The Hydro Boys. Edinburgh: Luath Press. ISBN 978-1-84282-047-6.

Wikimedia Commons has media related to Lochaber hydro-electric scheme.

This page was last edited on 13 April 2024, at 15:44