Brahan Archimedean Screw turbine

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The Brahan estate Archimedes Screw hydropower project, an ultra low head scheme operating on only 1.5m head and producing 100kW from twin screws was commissioned near Inverness ahead of schedule and is now delivering power to the local farm with excess being sold back to the National Grid. The river level upstream varies throughout the day by up to 700mm because of sudden water releases from a large hydropower station upstream, requiring a unique design with each screw set at a different height to optimise generation.