Turbine Hall, Ben Cruachan Hydro Electric Scheme, Oban North and Lorn, Argyll and Bute

Description

James Williamson and Partners; George Rennie (resident engineer for North of Scotland hydro Electric Board technical panel); J B Armstrong (architect); 1959-65. Monumental underground barrel vaulted chamber forming turbine hall hollowed out from solid bedrock with long sloping vaulted access tunnel; additional chambers housing transformers and tunnels, one forming access roadway to machine hall. Large turbine hall 36 metres high, 90 metres long with viewing gallery to NE corner at upper level and concrete lined vaulted roof. Regularly spaced columns to N supporting track for overhead gantry cranes. Tiled floor. Control panels to S wall with large inlaid timber mural by Elizabeth Faulkner above to SE. Alternating timber panels and acoustic baffling panels of concrete consisting of regular geometric shapes to remainder of S wall. Offices to S including control room at upper level with projecting faceted timber and plate glass window overlooking turbine hall floor; transformer room and surge shaft to far S. Large overhead lighting panels with lights contained by panelled timber wings cantilevered from large central beam. Matt grey square ceramic tiles to entrance and replacement tiles to turbine hall.

ACCESS TUNNEL: vaulted vehicular access tunnel running for 1 kilometre from tunnel entrance. Terminating in round arched entrance to turbine hall lined with rectangular slate tiles. Pedestrian entrance to offices directly adjacent to left (E) with split slate tiles forming apron around doorway.

Statement of Interest

Ben Cruachan Turbine hall forms and A-group with Ben Cruachan Dam (see separate listing). Ben Cruachan turbine hall is a monumental engineering achievement and an integral part of one Britain's most innovative hydro electric power schemes and the first example of the use of reversible turbine pumped storage technology. The 3240 cubic metre turbine hall was hollowed out entirely from solid bedrock and is set deep within the side of the Ben Cruachan ridge. The turbine hall is accessed by a 1 kilometre long vehicular access tunnel. The lower end of the tunnel terminates in 'the crossroads' where secondary tunnels give access to visitors viewing gallery, transformer hall and surge shaft. The housing of a power station of this scale wholly underground in addition to secondary features such as transformers and pressure tunnels was pioneering and allowed for the development of a power station large enough to play a nationally significant role in energy supply in an area renowned for scenic beauty with very limited visual impact. The station exhibits a number of period design features dating from the 1960s including the timber artwork panel by Elizabeth Faulkner and careful attention to detail in lighting and acoustic design, all with imaginative uses of timber and concrete.

Cruachan was groundbreaking in its use of pumped storage when it was opened by the Queen in 1965, and still provides vital peak load capacity today. During periods of cheap electricity the turbines are run in reverse to pump water from Loch Awe back up into the reservoir, a process which provides 90% of the water used for generation by the station. Prior to the design of Cruachan pumped storage facilities had required separate pumps and a separate pipe network to pump water back into reservoirs, making them much more expensive to build than conventional hydro systems. The use of reversible turbines at Cruachan was highly innovative and removed the costly requirement for separate pumping infrastructure. The reversible technology was first developed in the 1930s, but Cruachan was one of the first large-scale applications in Europe. The Lünerseewerk station of 1958 in Austria pre-dates Cruachan, but has a smaller capacity of 232 MW. The technology became more widely used, in Britain and worldwide, from the later 1960s onwards with further schemes in Wales at Ffestiniog in 1963 with a 360MW station

The turbine hall houses four turbines capable of a combined capacity of 440MW with 2 sets generating at 120 MW and the original 2 at 100MW. Each set uses approximately 110MW of power to pump water back up to the dam (see separate listing). The station can move from standstill to full generating output in under 2 minutes, compared to a time of several hours for a thermal power station. The station fulfils a key strategic requirement for the UK with the capability to produce enough power to re-start essential services nationwide (a so called 'Black Start').

Cruachan was the penultimate of the major post-war hydro electric developments by the North of Scotland Hydro electric Board (NoSHEB). The scheme played a key role in the realisation of the social agenda of NoSHEB by generating electricity which could be easily exported to the grid (via a connection at Windyhill on the fringe of Glasgow) and sold to Scotland's central belt. Revenue from the sale of the power subsidised the provision of electricity to remote north Highland communities on loss making schemes and stimulated economic regeneration. Under the leadership of eminent chairman Sir Tom Johnston the board undertook developments throughout Highland Scotland. This commitment saw the development of schemes in locations such as Loch Dubh near Ullapool and Storr Lochs on Skye. Johnstone's social aspirations ensured these schemes remained a key part of the NoSHEB development plan.

The design is typical of Williamson and Partners approach. James Williamson had completed a large number of innovative designs on behalf of NoSHEB, including developing the buttress dam which he first used at Loch Sloy (see separate listing) before his death in 1953. The scale and degree of innovation behind the plans for Cruachan is characteristic of the skill of the firm and their long experience with hydro power and commitment to developing Scotland's resources. Williamson had specialised in the design of dams following his work on the Galloway Hydro Electric scheme (see separate listings) in the 1930s. He acted as one of the chief engineering advisors to NoSHEB and was the lead engineer for a number of schemes before his death in 1953. After this date the company of James Williamson and Partners continued to be closely involved in the work of NoSHEB and were the lead team of engineers on a number of schemes, including Cruachan.

(Listed 2011 as part of Hydro Electric Power Thematic Survey)

External Links

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