A new hydropower prototype from the University of Michigan could end up using even slower river and ocean currents to generate energy. VIVACE, which stands for Vortex Induced Vibrations for Aquatic Clean Energy, can generate power from as little as 2 knots, making it more useful than most turbine and water mill systems out there, which need an average of 5 to 6 knots to operate efficiently.
The system works by harnessing “vortex induced vibrations,” the thrumming caused by the flow of liquid or air over rounded objects. A cylinder placed underwater is subject to the current and starts to vibrate as liquid sticks and creates eddies on the object's opposite side. It's the same scientific principle that caused the collapse of the Tacoma Narrows bridge in 1940.