Four new hydro projects totalling 5.5MW have now been commissioned and started generating in Scotland, Gilkes Energy has announced.

The projects – Strathan, Loch an Laoigh, Uisge Dubh and Pattack – are some of the largest to date developed by Gilkes Energy.

The Strathan, Loch an Laoigh and Uisge Dubh hydro projects are located on the Attadale Estate near the village of Strathcarron, Wester Ross in the Western Scottish Highlands. The three projects combined are 3.5MW capacity, use a combination of Pelton and Francis turbines and are connected to the grid via a common private wire.

The Pattack project is located on the Ardverikie Estate near Loch Laggan in the central Highlands of Scotland. It is a 2MW medium-head, high-flow design incorporating a dam and single intake, high-pressure pipeline and a high-efficiency Francis turbine in a purpose built powerhouse. Pattack has a 6.5km long pipeline, but drops a relatively short vertical distance of 150m, meaning that the flow rate is high for its power output and large-diameter high-flow pipes (up to 1.7m in diameter) are required. Much of the cost of the project is in the dam and the pipeline so a significant 'value-engineering' exercise had to take place in order to make the project economics sufficiently robust. One of the main challenges of this project was to ensure that approximately 500 large-diameter, glass reinforced plastic 'GRP' pipes are placed with almost millimetre precision over a distance of 6.5km over a mix of different ground conditions.

Commenting on the projects, Carl Crompton of Gilkes Energy said: "Thanks to everyone who has worked on bringing these ambitious projects to fruition. It's unusual for four such large projects to come to fruition at the same time. The four projects supported approximately 80 full-time jobs at a very local level, for the duration of the construction period, along with 8-10 highly skilled engineering and project management jobs, all based in Scotland. “

Once operational the projects will employ a number of permanent part-time local 'caretakers' and maintenance and routine servicing will be provided to the projects by the Gilkes Service Centres in Invergordon and Fort William.