Solar panels don’t generate electricity when it is raining. But that doesn’t mean you have to give up on renewable electricity. Researchers have now found a way to generate clean power from rain drops.
The new device, reported in the journal ACS Central Science, generates electricity by harnessing the energy of rain water as it moves through tiny tubes. The method could power up 12 LED lights in tests. One day, by converting it into a rooftop device, it could lead to a way to keep your lights on in a rainstorm.
Humans have been generating power from the flow of water for ages, of course. Hydroelectricity relies on large dams and powerful flows of water to turn utility-scale turbines. Newer wave power generation devices also mostly rely on using the movement of water to drive a generator.
Siowling Soh of the National University of Singapore and colleagues devised a technique that relies on charge separation. The phenomenon, which underlies static electricity, involves oppositely charged particles becoming separated, creating a voltage between them.
Researchers have recently made devices based on this concept to make fake plants and even solar panels that harness the energy in rainwater.
Soh and team chose a slightly different route. Their method relies on the flow of water over an electrically conductive surface. This water flow can create charge separation, but the separation is typically too small to harness for electricity. The Singapore team found a clever way to boost that power.
They used gravity to move rain-sized drops of water through a 32 centimeters-tall, 2 millimeters-wide tube made of an electrically conductive polymer. But the key is to move the water through the tube in a specific way called “plug flow.” Instead of having the water flow through it continuously, plug flow involves water moving in small columns separated by air gaps. This results in 100,000 times more charge separation.
The researchers placed a steel cup under the tubes to collect the charged droplets. Wires connected to the top of the tube and the bottom of the cup harvested the electricity created by the dripping water. Four of the tubes produced enough electricity to continuously power 12 LED lightbulbs, although just for 20 seconds.
Scaling up the system for installation on roofs could be a way to produce clean electricity especially in rainy places.
Source: Chi Kit Ao et al. Plug Flow: Generating Renewable Electricity with Water from Nature by Breaking the Limit of Debye Length. ACS Cent. Sci. 2025.
Image: Photo by Javier Haro on Unsplash
