The system developed by researchers at the National University of Singapore (NUS) exploits a phenomenon known as “plug flow”. Concretely, raindrops penetrating vertical tubes just two millimeters in diameter (thinner than a USB cable) where they alternate with air pockets. Inside, the drops slide across a conductive surface made of a special polymer and stainless steel. This contact causes a separation of the electrical charges naturally carried by each drop, charges then recovered by electrodes placed at the base of the device.

The results are remarkable, the system converts more than 10% of the kinetic energy of the drops into electricity, i.e. a power density of approximately 100 W/m². This efficiency is 5 times higher than that of a conventional continuous flow of water. In laboratory tests, two tubes are enough to power 12 LED bulbs for 20 consecutive seconds. Installation on building roofs would constitute the most immediate application, particularly in tropical cities exposed at regular intervals. The researchers point out that the system performs even better when the drops flow slowly, suggesting even greater potential in real-world conditions.

This advance, although in the experimental phase, draws the outlines of a future where each shower could contribute to the power supply of cities.