Hurricane Sandy--aka The Frankenstorm--has left millions of people in the dark. Here are three ways to make sure you'll never have to live without power--even when the lights go out.

Hydroelectric power has always been a pretty "green" way to generate electricty, simply interrupting the natural hydrological cycle to borrow some of its potential energy to convert to electrical power. Green, that is apart from the thousands of square miles of land that get flooded to manufacture artificial lakes behind hydroelectric power-station dams. But that's where the nation's first commercial hydrokinetic power station earns its eco-points: It's simply submerged in a river without needing a dam.