Professors at the University of Michigan are working on a method of harnessing power from slow-moving currents such as those in rivers:
VIVACE is the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2 miles per hour.) Most of the Earth’s currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently.
VIVACE stands for Vortex Induced Vibrations for Aquatic Clean Energy. It doesn’t depend on waves, tides, turbines or dams. It’s a unique hydrokinetic energy system that relies on “vortex induced vibrations.”
Vortex-Induced Vibrations were the cause of the infamous Tacoma Narrows bridge, or should I say, Gallopin’ Gertie, collapse. I guess that stands as proof-of-concept that there’s available energy!