Friday, May 24, 2019

Inside The Mountain

Cruachan Hydro Electric Power Station

Why is there a spike in the demand for electric in the UK when a party political broadcast is on the TV?

Answer, as half the population go to the loo, the other half put the kettle on.

And all those 4kw kettles going on at the same time adds up, so it's very useful when a power station can go from 0 to full power in about two minutes. It takes a coal station days and a nuclear one weeks to get going fully, so with all the politics we have in this country, we have a need for these power generators that are speedy.

Due to deadlines and other such novel things, I didn't go on the visit. Walking around underground while there is an ENTIRE loch of water over my head, is not for me. So he went and reported back.

The instigation for it all was the final report of the Water Resources Committee that was set up to investigate potential sources of hydro power in Britain, contained a scheme for a 400 megawatt development at Cruachan with four 100 megawatt machines.
It's pronounced Crew A Kin!

The construction started in 1959 and took 6 years to complete. The work was dangerous as much of the internal excavations were carried out by using explosions to blow away portions of the rock. In difficult and dangerous conditions the 'Tunnel Tigers' would work 12 hour shifts and get paid almost 10 times the average weekly wage at the time for their efforts. 16 died working in the tunnels and another 15 outside around the site. As a consequence the local amenities were turned into something akin to wild west towns with a huge campsite being constructed to cope with the large number of incoming workers.

My friend tells me that one of those deaths was suspicious, so the rumour goes, and that one day he is going to write THAT novel.

The idea was simple. There would be an upper reservoir from which water would cascade down to drive the mighty turbines which generate the electricity. The upper reservoir was created by building a concrete gravity buttress dam, 316 meters long and 46 metres high, across a wind swept corrie (a basin shaped hollow in the mountainside) high on the flanks of Ben Cruachan. The dam houses two water intakes, feeding water to the power station. Each intake can be closed by means of a 3.7 m x 4.9 m control gate which is backed by a 3.8 m x 5.9 m bulkhead.

Nineteen kilometres of tunnels and piped aqueducts divert water streams from around the mountain into this reservoir increasing the catchment area from 8 sq km to 23 sq km, thus supplementing the water pumped up from Loch Awe.

Deep in the heart of the mountain, almost 400 metres below the upper reservoir, a series of chambers were cut out of the solid rock to house the underground power station. In total, the excavations extracted 220, 000 cubic metres of rock and spoil.

A gradually sloping tunnel, 1 kilometre long, was driven into the mountain to provide road access to the power station. This tunnel is about 7 metres wide and 4 metres high. At the lower end of the tunnel is the 'cross-roads' which provides access points to the machine hall, transformer halls and the visitors' gallery.

The largest chamber, the machine hall, housing the turbine and generator sets is about 90 metres long and 36 metres high, large enough to contain a seven storey building erected on a full size football pitch.

Inside the hollow mountain the temperature remains at a comfortable 23 degrees all year round now matter how cold or hot outside. Often described as a temperate forest and indeed there have been experiments in growing plants in this sun light free environment and several  plants do actually grow very well when there is no natural daylight.

Here is a very nice video by the power guys that takes you inside the dam.

Did you spot the dinosaur?

Caro Ramsay ( not inside a mountain)

1 comment:

  1. I'm still working through the dimensions. Is the dinosaur a wood burning stove?