Scientists shocked by water’s hidden electrical power

Researchers have discovered that water generates an electrical charge up to 10 times greater than previously understood when moving across surfaces, according to findings published on Tuesday by RMIT University and the University of Melbourne.

The research team observed that when water droplets become stuck on tiny bumps or rough spots, force builds up until the droplet “jumps or slips” past the obstacle, creating an irreversible charge not previously reported in scientific literature.

“Most people would observe that rainwater drips down a window or a car windscreen in a haphazard way, but would be unaware that it generates a tiny bit of electrical charge,” said Dr Peter Sherrell from RMIT’s School of Science, whose research specialises in capturing ambient energy from the environment.

The team measured electrical charge and contact areas created by water droplets spreading and contracting on a flat plate of Teflon, using a specialised camera to capture individual frames of droplets sticking and slipping.

PhD student Shuaijia Chen, the study’s first author, noted that the first time water touched the surface created the biggest change in charge, from 0 to 4.1 nanocoulombs. The charge then oscillated between 3.2 and 4.1 nanocoulombs as the water-surface interaction alternated between wet and dry phases.

Dr Joe Berry from the University of Melbourne emphasised the safety implications of this discovery, particularly for fuel containers with flammable liquids where electric shocks could be dangerous.

“Understanding how and why electric charge is generated during the flow of liquids over surfaces is important as we start to adopt the new renewable flammable fuels required for a transition to net zero,” Berry said.

The team, led by Dr Joe Berry, Dr Peter Sherrell and Professor Amanda Ellis, observed when a water droplet became stuck on a tiny bump or rough spot, the force built up until it “jumped or slipped” past an obstacle, creating an irreversible charge that had not been reported before.

The researchers plan to investigate the phenomenon with other liquids and surfaces, with potential applications ranging from improving safety in fuel-holding systems to boosting energy storage and charging rates.

The study was published in Physical Review Letters.

Picture: credit Peter Clarke, RMIT University