6 world-changing innovations by teenage geniuses

Turning ocean currents into electricity, for cheap

One of the coolest things about kids' inventions is that they tend to be pretty budget-friendly. Since lunch money limits the materials available to most young inventors, they must rely on ingenuity to get the job done. That was true for Hannah Herbst, the 15-year-old who won this year's Discover Education 3M Young Scientist Award. She created a prototype of a propeller-driven machine that draws electricity from ocean currents, and it cost just $12 to make.

The device could help power desalination machines in developing countries, where access to both reliable electricity and clean drinking water are scarce. Herbst was inspired by accounts from her Ethiopian penpal, and she set out to find a practical solution to a big problem. Her efforts scored her a $25,000 cash prize.