A Japanese company called Ibasei has developed a compact underwater turbine generator that could be a silver lining during natural disasters that cause intense flooding. The Cappa looks like a small jet engine from a plane, but it's actually designed to harness rushing water and turn it into free energy.
Unlike a hydroelectric dam which has to be installed at the head of a river, the Cappa can be placed anywhere there's sufficient current to spin its vanes. In a river flowing at just four and a half miles per hour, five of these units working together can produce a kilowatt of power which can be used to power emergency equipment, or even charge an electric vehicle. And since a river doesn't stop flowing when the sun goes down, the Cappa can serve as a non-stop source of power.
Its creators are hoping the Cappa will be ready for consumer use come early 2013, and they're currently refining the design of the vanes so that they're as efficient as possible no matter how fast a river runneth. Also, why doesn't the drain in your bathtub have a tiny generator to turn draining water into free energy for your home? [DigInfo TV]