Buoys Become Self-Powered Using The Least Likely Part To Generate Power

Scientific American has a short note about a patent granted for power-generating buoys:

Patent no. 8,274,167 describes a buoy that generates its own power. The floating section of the buoy is connected to a long cable anchored to the ocean floor or a weight. The cable has a core made of piezoelectric lead zirconate titanate, a chemical compound first synthesized at the Tokyo Institute of Technology. As currents flow around the cable, microeddies move it like the “strumming of a guitar string,” Hughes says. The power generated depends on the cable's length and tension, but it theoretically could be enough to power a sonar array. 

A very nice example of thinking outside the box and putting the most important piece of technology (the power generating component) into the part that's most likely an afterthought: the cable keeping the buoy in place.