Run-of-River Schemes

To most people the phrase ‘hydro scheme’ conjures up an image of a large concrete dam and a flooded glen. And certainly all of the very large ones are like this.  But that is not where the current growth is coming from.  The vast majority of new developments are ‘run-of-river’ hydro schemes where there is no reservoir; simply a weir across the burn to form an intake to enable a portion of the water (as agreed with SEPA) to be extracted. This is then fed down the hill in a penstock (high pressure pipe) usually buried about one metre deep, and into a small powerhouse which would typically look like a farm building.  In there the water is used to turn a turbine which drives a generator and thus produces electicity.  The water is then returned to the burn.

In low-head cases the weir may already exist; a remnant of a time gone by when they were built to extract water into a lade to power a traditional waterwheel.

In either case the weirs are likely to be only two or three metres high and include a fish-pass if there are salmon in the watercourse.