The hollow mountain

one of the most formidable engineering projects ever undertaken in Scotland that continues to awe and inspire.

Providing for the energy needs for homes across the United Kingdom, the stores of power at Cruachan can power some of the nation’s largest cities, such as Birmingham or Glasgow. It seems hardly believable that inside the Cruachan mountain lies a huge industrial power generation factory that barely even troubles the beautiful landscape. In the centre of Ben Cruachan there is a massive cavern, high enough to house the Tower of London. Here enormous turbines convert the power of water into electricity. The power is then used to power the national grid at peak times of use – in order that the national supply never diminishes. Cruachan power station was constructed between 1959 and 1965. The innovative project was designed by Sir Edward McColl of Dumbarton who had come up with the concept some 30 years before. The scheme was ‘forced’ through parliament in 1947 by Tom Johnston the Secretary of State for Scotland, in order that the post-war demand for electricity was met. The construction phase lasted six years and at the height of the workforce employed more than 1,300 men. The first plant items to be installed in the cavern were the turbine casings, which were mounted at the lower levels within the cavern. A 275,000 volt transmission line was constructed to carry the power from the top of the cable shaft just in front of the dam, to Dalmally substation, five miles east of Cruachan, and then on to Windyhill, north of Glasgow. This line passes through rough terrain, and at its highest reaches 549 metres. When built, Cruachan was the highest head reversible pump/turbine power station on this scale in the world. A lot of time was spent at the design stage, optimising all aspects of construction and operation. Many working models of the turbines were built and work tests were carried out on complete alternators before shipping to site. Because of the limitations of local roads and the size of the access tunnel, all the equipment had to be broken down into manageable loads for transportation. Cruachan today generates more than 440mega watts of electricity. A second stage of development is now in the design stage and could see the output of the hollow mountain double. At 1,126 metres, Ben Cruachan is classed as one of the finest Munros in the southern Highlands and is popular with hill walkers and climbers alike. Its pointed peak towers above its rocky satellites, offer spectacular views. A ridge walk to Stob Diamh provides a circular route around the Cruachan reservoir.