Ocean Current / River / Tidal > Vortex Hydro Energy - VIVACE (Vortex Induced Vibrations Aquatic Clean Energy) extracts energy from ocean, river, tidal and other water currents over a wide range of current speeds. It is non-obtrusive, environmentally friendly, and has an extremely high energy density (50x less acreage required than wave power). A working prototype has met expectations, leading to a multi-kilowatt field demonstration.