Energy from rain

Here :)

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The method relies on a plastic called PVDF (for polyvinylidene difluoride), which is used in a range of products from pipes, films, and wire insulators to high-end paints for metal. PVDF has the unusual property of piezoelectricity, which means it can produce a charge when it's mechanically deformed.

Guigon and his team embedded electrodes into a thin membrane of PVDF, just 25 micrometers thick (it takes 1,000 micrometers to make one millimeter). Then they bombarded the sheet with drops of water varying in diameter from 1 to 5 mm.
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As the drops hit the material, they create vibrations, which creates a charge. The electrodes recover the charge for use as power.

Not surprisingly, the largest drops cause the biggest vibrations. The researchers found the system could scavenge 12 milliwatts from the largest drops and generate at least 1 microwatt of continuous power.
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