Until now, the electricity from a storm came only from lightning. A Chinese team has just added another protagonist: a device that converts raindrops into usable energy.
The invention comes from the Frontier Science Institute of the Nanjing University of Aeronautics and Astronautics (NUAA) and will open a new avenue for renewable energies. Its technical name is Water-integrated Droplet Electricity Generator, or simply W-DEG.
The discovery. What differentiates this generator from the rest is not its power, but its logic. According to the published article in National Science Reviewthe device floats on water and uses that same water as part of the electrical circuit.
It requires no metals or heavy structures, and yet each drop of rain can release spikes of up to 250 volts. Light, cheap and efficient: a small hydrovoltaic revolution.
Rain as a source of clean energy. The physical principle behind W-DEG combines two known phenomena: contact electrification and electrostatic induction. When a droplet impacts a floating dielectric film, electrical charges are instantly redistributed between the surface of the material and the water, generating an electrical pulse. Water acts at the same time as a lower electrode and structural support, thanks to its high surface tension and incompressibility: it is firm enough to withstand the impact of drops, but fluid enough to stabilize the system.
To prevent pooled water from blocking new discharges, the researchers added micro-drainage holes that allow liquid to flow downward, but not upward. This design keeps the surface clean even during heavy rain and prevents loss of efficiency.
A small prototype. The Nanjing team built a 0.3 square meter prototype. Floating on water, the device was able to illuminate 50 LED diodes simultaneously and charge capacitors in a matter of minutes. Its modular design allows it to be easily expanded to power environmental sensors, water quality monitoring systems or small electrical equipment in rainy areas.
Furthermore, the W-DEG is a “soilless” system: it does not occupy agricultural or urban land and can be installed on bodies of water without heavy infrastructure. This makes it an ideal candidate for regions where rain is abundant and space is scarce, or where other renewable sources – such as solar or wind – are less constant.
The rise of floating energies. The new Chinese generator arrives at a time when floating energy is experiencing a global boom. Floating solar panels are being installed on ponds and reservoirs around the world, from India until the swiss alpsto produce electricity and reduce water evaporation.
However, a study from Cornell University revealed an unexpected effect: in small ponds, these installations can increase methane and carbon dioxide emissions by up to 27%, by altering the balance of aquatic ecosystems. Faced with this challenge, the W-DEG emerges as a more environmentally friendly alternative. By not covering the entire surface of the water or blocking sunlight, it allows energy to be generated without altering aquatic life or natural gas exchange.
Will storms generate light? The technology is still in the experimental phase. The NUAA team itself recognizes that it will have to optimize the device’s response to droplets of different sizes and speeds, something essential for real conditions. But the potential is undeniable: a lightweight, economical and durable generator, capable of obtaining energy directly from the natural water cycle, without occupying land or generating waste.
Researchers imagine swarms of these devices floating in lakes or reservoirs, charging environmental sensors or powering local microgrids during rain. If every storm could turn on a light or power a system, gray days would no longer be synonymous with a blackout. With inventions like this, the border between water and energy blurs, and nature begins—literally—to generate its own electricity.
Image | Unsplash
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