ENERGY FROM RAIN

WAM - 18 Aprol, 2025 - Researchers from Singapore have developed an innovative method to generate electricity from raindrops, producing enough energy to power 12 LED lights for 20 seconds using a small vertical tube and precisely timed droplets.

The study demonstrated how a phenomenon known as plug flow - in which all particles in a given cross-section have identical velocity and direction of motion - can dramatically boost electricity generation from falling water.

According to Siowling Soh, PhD, an associate professor at the National University of Singapore and the study's corresponding author, when two materials come into contact, the charged entities on their surfaces get a slight nudge, similar to the static electricity that builds up when you rub a balloon against your skin.

"Water that falls through a vertical tube generates a substantial amount of electricity by using a specific pattern of water flow: plug flow," Soh explained. "This plug flow pattern could allow rain energy to be harvested for generating clean and renewable electricity."

The chemical engineering expert explained that while running water can generate electricity by turning a turbine, hydroelectric power is limited to areas with abundant water sources, such as rivers.

The device relies on the motion of rain-sized droplets falling into a slim vertical tube. When the droplets hit the top, they form short slugs of water separated by pockets of air, a pattern that enhances charge separation as the water moves downward.

This segmented flow allows electrical charges to build along the conductive inner surface of the tube. The water is then collected in a cup at the bottom, where wires at both ends capture the electricity generated during its descent.

The system converted over 10 percent of the falling water's energy into electricity—outperforming the output from a continuous water stream by five orders of magnitude.

Although the experiment used slower droplet speeds than natural rainfall, the researchers believe the system would be even more effective under real-world conditions. Further testing showed that routing water through two tubes simultaneously or in sequence doubled the energy output. Expanding to four tubes, the system successfully powered 12 LED lights for 20 seconds.

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