If you venture to Scottish Highlands you will find a remarkable piece of engineeging between Loch Etive and Loch Awe near Dalmally. Called Cruachan Power Station or the Hollow Mountain power station facility effectively serves as a giant battery for British electricity supply system.
The principle on which this facility is designed is very simple: if we have two reservoirs at a different level above sea and we plant a turbine between them, we can capture energy of water falling from the upper reservoir and transform it into electrical power.
But this is only the half of the story, since this principle describes work of every Hydroelectric plant. The unique function of Hollow Mountain and other Pumped Storage Plants is in its ability to pump water back into the upper reservoir. Counterproductive as it sounds, this particular function is crucial to the smooth performance of British (and not only British) electric grid.
Initial need for such energy storage facilities arose from large fluctuations in energy consumption. Think of the morning when we all wake up, turn up the heating, lights, put kettles on, cook breakfast.. After night’s quiet it creates a positive surge in demand for electricity, which PSH Plants can satisfy at less than a minute notice. Then in quieter times, it would consume a surplus energy from the grid to pump water back into upper reservoir and prepare for next rush in energy demand.
More recently role of such facilities extended to storage of energy from renewable sources. While traditional power stations are fairly reliably producing its megawatts for the grid, renewable sources are dependent on weather: sun, wind, rainfall, or, with newer developments, tides or oceanic currents. This constitutes the main problem of renewable sources of energy – it’s unreliability. And here is where Power Stations like Cruachan come to play, because despite all of humanity’s technological advances of the last century, we still didn’t invent better and cleaner large scale energy storage than Pumped Storage Hydroelectric Plants.
The Cruachan Power station was designed by Sir Edward MacColl as largely underground facility and constructed in 1959 – 1964 at cost of 35 workers lives. The 220 000 cubic meters of rock and soil is estimated to be excavated to make space for the turbine hall said to be tall enough to fit the Tower of London and wide enough to fit Big Ben on its side, and some 20 kilometres of tunnels and caverns.
Today Cruachan can provide energy for up to 200 000 homes for up to 22 hours before needing to “recharge”.
The power station is open to visitors and along with other 3 Pumped Storage Power Stations is pioneering green energy supply in the country for at least half a century.
A remark needs to be added that current owner of Cruachan, drax, plans construction of the sister station – Cruachan 2.0.
