Pitter-patter of raindrops could power devices

24 January 2008
Paul Marks
Magazine issue 2640
Here's something residents of cloudy northern Europe should appreciate: a way of using rain to generate power.

Jean-Jacques Chaillout and colleagues at the Atomic Energy Commission (CEA) in Grenoble, France, have shown that piezoelectric materials, which generate voltage in response to mechanical force, can be made to produce useful amounts of electrical power when hit by falling rain. "We thought of raindrops because they are one of the still- unexploited energy sources in nature," Chaillout says.

His team started by looking up data on different types of rainfall. Drizzle, they found, produces droplets of about 1 millimetre in diameter which have an impact energy of around 2 microjoules, while droplets from a downpour were typically 5 millimetres across and gave 1 millijoule of impact energy.