clipped from: www.abc.net.au   
Tracy Staedter

Energy is everywhere. In the sun, wind and now rain.

raindrop

Researchers have developed a technique that harvests energy from rain showers and converts it into electricity.

The technology could work in industrial air conditioning systems, where water condenses and drops like rain.

It could also be used with solar power to scavenge as much energy from the environment as possible, or to power tiny, wireless sensors designed to monitor environmental conditions.

"Our calculations show that even in the most unfavourable conditions, the mechanical energy of the raindrops ... is high enough to power low-consumption devices,
The method relies on a plastic called PVDF (polyvinylidene difluoride)
PVDF has the unusual property of piezoelectricity; it can produce a charge when it's mechanically deformed
As the drops hit the material, they create vibrations, which creates a charge.
Not surprisingly, the largest drops cause the biggest vibrations