Do hydroelectric turbines harm fish?
ASmall scale hydroelectricity projects have been springing up all over Britain in the past decade as a means of harnessing clean energy from local rivers. Eight years ago, the weir next to the ruined water mill at Howsham on my local river, the Yorkshire Derwent, became the first site in the country to house an Archimedean screw turbine. The screw lies in a trough half in, half out of the water and rotates rather slowly as gravity pulls the water down the drop. The technology is exceptionally fish-friendly – far from helter-skeltering around the screw as some visitors imagine, the fish (and other waterborne objects) drop gently through the thread as it turns above them and emerge at the bottom, unscathed and arguably safer than they would be running the weir itself. The same can’t be said for devices with fastspinning blades, which require mesh screens to prevent fish from being drawn in, adding to set-up and maintenance costs as the screens constantly clog with debris.