Rain-powered electricity for flood prevention

December 27, 2025

Rainfall does more than overwhelm city streets—it can now generate electricity to help prevent flooding.

Scientists at South Korea’s Ulsan National Institute of Science and Technology (UNIST) have developed an innovative technology that converts raindrops hitting rooftops into electrical energy. This breakthrough allows stormwater drainage systems and flood warning mechanisms to operate using power produced entirely by rainfall.

The newly developed system transforms the kinetic energy of falling raindrops into electrical signals strong enough to activate flood control equipment—without the need for batteries or external power supplies.

The research team, led by Professor Young-Bin Park from UNIST’s Department of Mechanical Engineering, engineered a droplet-based electricity generator (DEG) using carbon fiber-reinforced polymer (CFRP), a material known for its durability and lightweight strength.

Durable rain-powered electricity generation

The device, officially named the Superhydrophobic Fiber-Reinforced Polymer Droplet-Based Electricity Generator (S-FRP-DEG), produces power instantly when rain makes contact with its surface.

Unlike many experimental rain-harvesting devices that rely on fragile metals or laboratory-grade materials, this system was designed for real-world conditions. CFRP composites are already widely used in aerospace, construction, and transportation due to their resistance to corrosion, low weight, and long lifespan—making them ideal for outdoor urban infrastructure.

This allows the generator to be installed on rooftops, drainage systems, and other exposed structures where long-term reliability is essential.

How the rain-powered generator works

The electricity generation process is similar to static electricity. As raindrops fall through the atmosphere, they accumulate a positive charge.

When these droplets strike the generator’s negatively charged, superhydrophobic surface, a rapid charge exchange occurs. The droplets immediately detach and roll off, triggering an electrical current that flows through carbon fibers embedded within the composite structure.

To boost efficiency, the researchers applied surface micro-texturing and a lotus-leaf-inspired coating. This design improves water repellency while preventing the buildup of dirt, soot, and other pollutants that often degrade performance in urban environments.

Traditional metal-based droplet generators frequently suffer from corrosion caused by moisture and air pollution. In contrast, the CFRP-based system maintains consistent performance even after repeated exposure to rain and harsh weather conditions.

Impressive performance and scalability

Laboratory testing showed that a single raindrop with a volume of approximately 92 microliters could generate up to 60 volts and several microamps of current.

When four generator units were connected in series, the system successfully powered 144 LED lights for a short period—demonstrating that the technology can be scaled for practical applications.

Smart flood control and real-world testing

Beyond lab experiments, the research team installed the generators on building rooftops and drainage pipes to evaluate real-world performance.

As rainfall intensity increased, the electrical signals became stronger and more frequent. This enabled the system to distinguish between light, moderate, and heavy rainfall events and activate drainage pumps only when necessary.

Such intelligent responsiveness could significantly reduce energy consumption while enhancing real-time flood prevention in densely populated urban areas.

“This technology allows urban infrastructure to monitor rainfall and respond to flood risks using only the energy provided by rain,” Professor Park explained. “In the future, it could also be integrated into transportation systems such as vehicles or aircraft, where carbon fiber composites are already widely used.”

The study was authored by Dr. Seong-Hwan Lee and Dr. Jae-Jin Kim and supported by South Korea’s Ministry of Science and ICT along with the National Research Foundation. The research findings were published online in Advanced Functional Materials.