Archimedes' screw

The Archimedes' screw, also known as the Archimedean screw, hydrodynamic screw, water screw or Egyptian screw,^[1] is one of the earliest hydraulic machines named after Greek mathematician Archimedes who first described it around 234 BC, although the device had been used in Ancient Egypt.^[2] It is a reversible hydraulic machine, and there are several examples of Archimedes screw installations where the screw can operate at different times as either pump or generator, depending on needs for power and watercourse flow.

As a machine used for lifting water from a low-lying body of water into irrigation ditches, water is lifted by turning a screw-shaped surface inside a pipe. In the modern world, Archimedes screw pumps are widely used in wastewater treatment plants and for dewatering low-lying regions. Run in reverse, Archimedes screw turbines act as a new form of small hydroelectric powerplant that can be applied even in low head sites. Such generators operate in a wide range of flows (0.01 ${\displaystyle m^{3}/s}$ to 14.5 ${\displaystyle m^{3}/s}$) and heads (0.1 m to 10 m), including low heads and moderate flow rates that is not ideal for traditional turbines and not occupied by high performance technologies.