Engineers Devise a Way to Harvest Wind Energy from Trees

Harvesting electrical power from vibrations or other mechanical stress is pretty easy. Turns out all it really takes is a bit of crystal or ceramic material and a couple of wires and, there you go, piezoelectricity. As stress is applied to the material, charge accumulates, which can then be shuttled away to do useful work. The classic example is an electric lighter, in which a spring-loaded hammer smacks a crystal, producing a spark.