D - Glasgow, B - Aberfeldy (rafting), C - Cruachan Power Station

On the 17th April 2010 I went on a trip to Cruachan Hydroelectric Power Station that was organised by final year students at Glasgow university. I heard about it through IMechE. Before we visited the power station we went White Water Rafting in Aberfeldy. It was a long day, we covered about 215 miles, but it was a very good day out.

The water in the river Tay mostly consisted of melt water from the mountains. It was freezing cold. Four of the people on the raft were from our party and the rest (excluding the guide) were on a stag party. Nice guys but they were canyoning later so they didn’t want to get wet yet. The other rafts managed to dunk their occupants at least once. Only once from capasizing and that was only because they were doing a “wheely”! People ended up in the drink from the silly games played like chasing each other round the perimeter of the raft.

Cruachan Power Station is a fascinating place. To avoid ruining the scenery with a huge power station it is situated inside the mountain. To enter, you drive down a long road 60ft into the mountain. It would make the ideal location for a Bond Villain’s lair. The tunnel was not bored by a machine – it was blasted out with dynamite! At the end of the tunnel you get to the parking spot. A sign informs drivers to reverse into their parking space. The reason for this is so that a quick escape can be made in the event of an emergency. It is operated like a mine with a tally system. There is a large board with worker’s tallys hooked on when they are down the mine so they know how many people are down there. The 8 or some members in our group were phoned in.

You walk through a door and immediately you enter a large chamber. There are four cylinders rising through the floor that contain the turbine, generator and pony motors. We didn’t go to the level below.

After talking through the basics our guide took us to the control room where we spent most of our time. The controls were explained to us and very kindly they did the first part of the sequence to pump water back into the upper reservoir. I would be quite happy in life just to have control of a machine that when you pressed a button the ground would shake! It was a very satisfying rumble.

Finally we went to the chamber with the transformers in it. These things are big and slightly ominous. The power station wasn’t active during our visit (it was scheduled to come on 2am the following morning) and I wouldn’t want to be in that room when they were on. Even while we were there, there was a humming and buzzing.

The drive out into sunlight ended our tour nicely. If I got the opportunity to visit again I certainly would!

At university we learn the theory of power stations and large machines but it is something else seeing a real one. They are awesome and it would take a long time to get bored being around one.

The most interesting thing I learned was that this particular hydroelectric power station is NOT a renewable source of energy. It basically acts like a giant battery (in the sense that it stores energy).  The price of electricity fluctuates throughout  the day. It tends to be cheapest at night. When there is a surplus of energy the power station will pump water from the lower reservoir to the upper one. This is not particularly efficient (though it’s not bad) but it is better than just letting the energy go to waste. When demand is high, water flows down from the upper reservoir through a turbine and powers a generator.

It is not a renewable source because only 10% of the water in the upper reservoir comes through its catchment area. The rest is pumped from the lower reservoir. The electricity used to pump the water will not be purely from renewable energy sources.

The start up time to generate electricity is less than two minutes which compared to a nuclear power station  (half an hour to a few days) is excellent. It is able to black start (no power from the National Grid) using a diesel generator.