What is a Hydrodynamic Screw?
This recently adapted technology harnesses energy from the fall of water from a higher to lower level (this difference is commonly called the 'head'). Whereas a conventional turbine, wheel or propeller type comes into contact with the water at only one point along the water's drop, the screw captures this energy (the weight of the water working with gravity) along its entire length.
This energy (from the fall of the water) is transferred into rotational movement of the Hydro Screw, driving a generator at the top which creates electricity.
The screw is highly efficient for low head sites, harnessing up to 87% of the energy captured from the turning motion. These sites range from a one metre up to ten metre heads, and can handle flow rate 
between 0.1m3/s up to 15m3/s per screw. In this range the Hydro Screw has been proven to be the most efficient source of hydropower.
In March 2010, the Environment Agency released a document “Opportunity and environmental sensitivity mapping for hydropower” which identifies the hotspot areas for hydropower development within the UK. This document takes into account fish migration and identifies Hydro Screws as their preferred turbine.
The lifetime of the screw is very long due to the simplicity of its components and its low rotational speeds. With expected life spans of 40 years and relatively low maintenance makes the screw a viable and attractive option to anyone considering hassle free or unmanned hydro systems.
History:
Archimedes invented the screw pump that bears his name around 260BC but it wasn’t until 1997 that the flow of water was reversed to power a generator. Until 1997 hydropower was only available for high head sites however, with the introduction of the Hydro Screw, it is now possible to capture energy from low heads as well as from rivers and streams with much lower flow rates.
This has meant that hydropower, which was originally the preserve of large corporations, is now available on a much smaller scale for domestic and private micro generation schemes.
Since the introduction of the Hydro Screw into the UK in 2004, twenty six thousand potential sites with low heads of water have been identified across the country.
The first ever Hydro Screw was installed in Hranice, Czech Republic in 1997. It wasn’t until 2004 that the technology began to take off and by 2007 there were 12 throughout Europe. Currently there are less than 200 Hydro Screws throughout Europe.