📋 Project Overview
Cruachan is Scotland's "Hollow Mountain" — a pumped storage hydro station built inside Ben Cruachan above Loch Awe in Argyll. Opened in 1965, it was the first large-scale pumped storage station in Scotland. Four 110 MW reversible Francis turbines respond rapidly to grid needs. Drax Group, which now owns the station, has received consent to build Cruachan II — an additional 600 MW facility in adjacent caverns.
Site Schematic
Schematic diagram — not to scale. Illustrative layout based on project specifications.
⚡ Key Facts
One of the world's first large-scale pumped storage stations when built in 1965
Visitor centre inside the mountain — 100,000 visitors per year
The mountain's summit is visible from over 30 km away
Cruachan II (600 MW) consented — to be built alongside existing station
Drax Group acquired from E.ON in 2018 for £702 million
The dam at the top is 316 metres long and 54 metres high
🔧 Technical Specifications
| Capacity (MW) | 440 MW |
| Storage (MWh) | 7,700 MWh |
| No. of turbines/units | 4 |
| Turbine / unit model | Reversible Francis pump-turbines |
| Unit capacity | 110 MW each |
| Head (hydro) | 363 m |
| Upper reservoir | Cruachan Reservoir (9.4 million m³ at 395m elevation) |
| Lower reservoir | Loch Awe (at 37m elevation) |
| Response time | 0 to 440 MW in under 30 seconds |
| Annual output | 500 GWh/year |
| Homes powered | 120,000 homes |
🔌 Grid Connection & Infrastructure
🏢 Development & Ownership
| Developer | North of Scotland Hydro-Electric Board (NSHEB) |
| Owner / operator | Drax Group |
| Construction started | 1959 |
| Commissioned / target | 1965 |
| Location | Inside Ben Cruachan, above Loch Awe, Argyll |
| Region | Scotland |
| Coordinates | 56.41°N, 5.13°W |
📅 Project Timeline
1959
Construction begins — tunnelling through Ben Cruachan
1965
Station commissioned
2018
Drax Group acquires station from E.ON
2023
Cruachan II (600 MW expansion) receives DCO consent
🌿 Environmental & Planning
Located near Loch Awe, a Site of Special Scientific Interest. The water intake at Loch Awe has fish screens to protect migrating salmon and sea trout. The surface reservoir and dam are now considered part of the natural landscape by most visitors.