Fish-friendly hydropower at Sowton Weir
Sowton Mill stands on the River Teign in Devon and has been using hydro power for over 400 years, initially to mill corn and then, from the 1950s, to generate electricity. In the 1980s a 16kW crossflow turbine was installed which was the U.K.s smallest electricity contributor to the National Grid. To improve the power generation and aid fish migration a decision was made to install the fish-friendly Archimedean Screw hydro turbine. Sowton hydropower scheme was developed by a private client to provide a renewable source of electricity to the property on site with all excess power sold to the National Grid.
Mann Power Consulting Ltd.,designed the Open Compact Archimedean Screw for this particular site which was manufactured by Landustrie in Holland. An Open Compact is a self-supporting U-shaped steel construction minimising necessary civil work on site. The generator unit is an integral part of the construction, easily accessible via a weatherproof, hinged generator cover. The length and diameter of an Archimedean Screw will be dictated by the parameters of the particular site and are finished in the colour of your choice. All Archimedean Screws are manufactured as bespoke installations. Rated at 95kW it is expected to save in excess of 165 tonnes of Carbon Dioxide (C02) annually. The predicted annual output is 368,000kWh per year.
Improvements were also made to the fish pass at the nearby Weir. These measures will make it easier for fish to move upstream and will add to the understanding of their migration patterns. The Archimedes hydropower installation has improved the fisheries ecology of the river Teign by allowing more juvenile salmon and sea trout reach the sea. The improved fish pass at the weir means more salmon and sea trout can reach spawning grounds on the upper Teign. An automatic fish counter was also installed to count the fish numbers and species using the pass. This provides invaluable information for the Environment Agency and the Teign fishing association.
Once again we see the Ancient power of Archimedes being used for hydropower generation because if it’s fish-friendly credentials. The Archimedean Screw turbine provides a fish-friendly alternative to conventional turbines, ideally suited to low-head (1m-10m) sites, and sites with fish protection issues. Extensive fish passage tests have conclusively demonstrated that the large water chambers and slow rotation of the Archimedean Screw allow fish of all sizes, and debris, safe passage through the turbine. As a result, the Environment Agency has agreed that no screening is required.
