In 2007, Michael Bernitsas, a professor at the University of Michigan, found a way to harness the kinetic energy of a flowing river by looking at how fish move through water. He created a device he calls VIVACE, which is short for Vortex Induced Vibration for Aquatic Clean Energy [sources: Vortex Energy, Lafay].
As any trout fisherman can tell you, when a school of fish moves through water, the fish curve their bodies and create tiny swirling vortices. The fish push their bodies off the vortices to propel themselves forward. VIVACE works the same way. Engineers place a series of cylinders on the river or ocean bottom. The passing current flows over the cylinders creating vortices, which move the cylinders up and down. Inside each cylinder is a magnet that moves over a metal coil, generating an electrical DC current. VIVACE then takes the DC current and converts it into AC. Unlike other hydrokinetic technologies, Bernitsas' invention can harness energy from slow-moving rivers [sources: Vortex Energy, Lafay].