Foyers is a very small community on the south side of Loch Ness. Loch Ness has very steep sides and there is an amazing waterfall at Foyers. The energy from it was harnessed for hydroelectricity for the first aluminium smelter in the UK. It was so long ago that Lord Kelvin was involved.
These are the old smelter buildings. Production ceased in the 1960s. In 1974 some of the plant was reopened as a hydroelectric power station.
The water flows in from the river above the village. It is a long way up the hill from the lochside factory.
It is said to be a small station at 5MW but Glenridding hydro in Cumbria is only 1/10th the size at 500kW. Also compare it with 200MW at the old Chapel Cross nuclear power station that I can see from my house. It seems quite big. But a lot of wind farms are much bigger. Foyers has a 108m drop from top to bottom. Let's say that the generator runs on the loss of gravitational potential energy mgh. Power = energy changed/time taken. Thus power = dm/dt x gh. Mass flow rate dm/dt thus calculates out at about 4.5 tonnes per second. That's about 25 baths of water every second. Not inconceivable. It may be higher because if the 5MW is the electrical output there will be losses in the generator mechanism.
