Archimedean Screws have been used for thousands of years but until recently their purpose has always been to raise water. Recent developments in turbine technology have enabled hydro power schemes to be developed at “low-head” locations (where the drop in water level from above the scheme to below it is relatively low). By “reverse-engineering” Archimedean screws it is possible to utilise the energy generated by river flow and head (drop). Water passes from upstream of the installation into the screw channel. It then passes through the screw and the force from the flow turns the screw. The turning of the screw is used to generate clean electricity which can then be used or sold on.
The application of this technology is not new with many working schemes currently operating in the UK. The only nuance is that the weir is tidal for 8 of the 24 hours each day. The only impact this has is that the head (or drop) is variable for these hours and so production of electricity may be reduced during this time. This is a financial consideration and has been built in to the financial forecasts.
Archimedean screws have been shown to be the most ecologically safe hydro power technology and are the preferred technology of the UK Environment Agency.