Original URL: http://www.theregister.co.uk/2013/07/23/reg_man_delves_deep_to_find_the_power/

Boffins, Tunnel Tigers and Scotland's world-first power mountain

The hollowing heroes who reversed nature

By Bill Ray

Posted in Geek's Guide, 23rd July 2013 08:03 GMT

Geek's Guide to Britain In the middle of a Scottish mountain is a man-made cavern 90 metres high and 36 metres long - tall enough to stuff an entire Cathedral in its belly - which is only accessible through a kilometre-long rock tunnel. This is the home of the Cruachan Power Station.

In 1921 - with one world war down and one to go - the British government surveyed its mountains with a view to generating hydro-electric power. That survey established that Cruachan, near Oban on the west coast of Scotland, would make an ideal site for storing power - if only the technology existed to make it practical.

One world war later, the technology had arrived. Within a decade, nuclear power was generating an overnight excess in need of storage, so in 1959 they broke ground to build the world's first reversible-turbine power station, which essentially uses large amounts of water to store excess energy.

A boffin

Only boffins of this calibre could realise the dream.
Still from Cruachan, The Hollow Mountain, National Library of Scotland.

That power station now comprises an artificial loch, dammed with 200,000 tonnes of concrete and storing 7 gigawatt-hours' worth of water - 22 hours supply with a 12-hour reserve. That water drops down a sloping 305 metres into four turbines housed in the middle of the mountain, where we're allowed to visit them.

The idea is simple to explain, rather harder to realise: water falls from the loch above through turbines to generate electricity, 440MW of it at peak, but at night the same turbines are turned (using excess power) to push the water back to the top loch again, making the whole thing a huge storage battery designed to buffer between the constant generation and variable consumption of electricity.

Pylons

The outwards sign of something significant within

Not that you'd know it driving past Cruachan. The only signs that give away what lies beneath are the suspicious number of pylons - and a large sign pointing visitors towards the centre. Once you've got there, you can buy tea and cake, buy postcards and novelties, press buttons in the exhibition and board the minibus which takes visitors to the heart of the mountain.

A tunnel

Descending into the bowels of the earth, The Channel Tunnel should look like this

Cruachan's biggest problem in becoming a hydro plant was the lack of upper loch from which water could flow. The mountains had a nice valley but it drained neatly into Loch Awe, so the first order of business was to build an enormous dam. That took two years, thanks to the remote location and inclement weather, and below the dam shafts were dug at a 55° incline to ensure a smooth flow of water to the four generators below in their huge machine room. It is that scale of construction which most impresses.

Three contractors took on the project: one for the aqueducts, one for the tunnelling and one for the fitting out. Each brought in gangs of workers from around the UK, totally 1,300 men at its peak, accommodated in temporary camps which promptly became rife with drinking and gambling as the self-styled "Tunnel Tigers" relaxed in the way unique to young men whose employment involves considerable risk to limb and life.

Men placing explosives

Real men packing real explosives into the wall.
Still from Cruachan, The Hollow Mountain, National Library of Scotland

Thirty-six men died in all, 15 underground digging out the cavern and the rest in the construction of the tunnels and network of aqueducts feeding the upper loch.

There are four-and-a-half kilometres of aqueduct and more than 14km of tunnels catching rainwater from the surrounding hills. That rainwater took nine months to fill the reservoir and still contributes about 10 per cent of the power generated.

Having driven the kilometre into the mountain, visitors leave the bus and climb a short flight of steps to a sloping path past the fire system - where 20,000 gallons of water sit just in case they're ever needed. Our guide, the slightly over-enthused Ian, tells us that the system is tested twice a week, but has never been used.

From there we're led past tropical plants, carefully placed to emphasise the heat - that far underground it remains a steady 18°C - and some of the tools used to dig out the caverns.

At last... the final cavern

Which brings us to the final cavern, the thing we're here to see. Viewed from above it's a little difficult to fathom the scale of the space, and a good deal of it is held empty against the necessary removal of the turbines for servicing (something which happens every three years, with a complete refit every 15).

The machine hall

The yellow cylinders are the starter, or "pony" motors. The turbines are underneath.

The 15 men who died underground are commemorated in a carved tribute affixed to the side of the machine hall. Visitors aren't allowed in the machine hall itself, we just look down from a viewing gallery high in one end, and photographs are forbidden for fear terrorists could make use of them, so you'll have to take our word for it that it's bloody big in there.

A good deal of the time the turbines sit idle, but when power is demanded they can be spun up in less than two minutes, under a minute if the pony (starter) motor is already spinning.

As we return Ian tells us of the 'Tigers and the life they led, and that one of the deaths wasn't the accident it appeared to be: the chap who kept the gambling book managed to get himself crushed under a truck in suspicious circumstances.

Certainly they were hard men, and the lack of health and safety shortened the life of many more than the 36 it killed as the (now) traditional Irish ditty Crooked Jack reminds us.

But at least they got paid, unlike the prisoners of war who worked on the Loch Sloy (non-reversible) hydro electric scheme a decade earlier.

One tends to think of hydroelectric power as a modern conceit, when in fact Cruachan will soon be up for its Golden Jubilee - Ian is even trying to get some of the Tunnel Tigers back on site this October to record their thoughts ahead of the 2015 anniversary.

Boffins smoking pipes

When men where real men, and boffins smoked pipes even when underground.
Still from Cruachan, The Hollow Mountain, National Library of Scotland

Back in the visitors' centre there are buttons to push and panels to read, courtesy of Scottish Power. Visitors, or their children, can turn a clock to see when power is used and read all about how Scottish Power will supply it - they even have one of their Smart Meters on display.

Having said that, the exhibition, and accompanying video, won't entertain for very long, and while the trip into the mountain is impressively brought alive by Ian's commentary, it lasts only half an hour.

A hike up to the dam isn't difficult, though you cannot set out from the visitors' centre (a short drive is needed) and the climb requires stout shoes and a tolerance for bogs. Walk Highlands has an excellent guide.

The Reservoir

We didn't manage the walk, but James Hearton did and put his photograph under the Creative Commons Licence.

But for the lazy, or offspring-encumbered, the Cruachan power station is more of a marvellous place to stop for a long lunch than a destination in itself. Makes for a very interesting lunch though, and the food isn't bad either.

GPS

56.395284,-5.11591

Post code

PA33 1AN

Getting there

By car: Cruachan Visitor Centre is on the north bank of Loch Awe, 19 miles east of Oban on the A85. By train: to Falls of Cruachan station 200 metres away, with services between Glasgow and Oban.

Entrance

Adults: £6.50, senior citizens/students: £5.50, children: six - 16 years £2.50, under six years are free.
Opening hours:
April - October: 9:30am – 4.45pm, 7 days per week.
November, December, February and March: 10am – 3.45pm, Monday to Friday only.
Closed in January.
Bookings for tours strongly advised; the train station - charmingly named Falls of Cruachan - might be occasionally closed for engineering or maintenance, so if you're travelling by rail, call ahead.

Other resources

Visitcruachan.co.uk