Construction has started on three small hydro projects with a combined capacity of 3.5MW in the Scottish Highlands, Gilkes Energy announced.

The three projects are all located on the Attadale Estate near Loch Carron: Strathan Hydro is a 0.5MW, high-head, low-flow project incorporating a three intakes, a high pressure pipeline and a Gilkes twin-jet Pelton turbine; Loch an Laoigh Hydro is a 1MW, low-head, high-flow project incorporating a single intake with a small amount of storage, large bore pipeline and a Gilkes Francis turbine; and Uisge Dubh Hydro is a 2MW, low-head, high-flow project incorporating twin intakes, large bore pipeline and twin Gilkes Francis turbines.

The three projects are all very different, Gilkes said. Strathan for example drops a vertical distance of 177m and uses a new Gilkes ‘Streamline’ twin-jet Pelton turbine which is optimized for applications such as this, and uses a relatively small amount of water (360 l/s). Uisge Dubh on the other hand drops a vertical distance of just 85m and uses a much larger Francis turbine, and much more water than Strathan, nearly 10 times as much at 3,020l/s. Both projects have very different engineering specifications, technical challenges and capital costs, the company said.

These three projects bring the total capital deployed in Gilkes Energy projects to more than £70 million.