Turbine to produce electricity from river or tidal streams

The device, from Cambridge-based Green-Tide Turbines (G-TT), works by causing the flow of water to rotate before capturing the rotational kinetic energy with a reaction turbine.

This differs from current technologies that use bladed fans or oscillating hydrofoils to convert kinetic energy in a flowing current of water into rotary motion driving a generator.

With the G-TT device, the water first flows through a duct, where it meets a series of stator blades that cause the water to rotate and form a vortex. The water then flows through a series of channels that are angled in a way that makes the fluid travel in the shape of a helix. The channels dogleg, causing the water to change direction and lose momentum.

The changing direction creates equal and opposite forces that act tangentially to the axis of the turbine rotor. This creates the torque needed to power a generator. 

Michael Evans, the inventor and chief executive of G-TT, said that his company’s design puts less strain on the turbine and reduces failures that would be a result of fatigue. He pointed out that this greatly reduces operation and maintenance costs.