From raindrop to power source
Rain as a source of energy? What has long sounded like a dream of the future is becoming tangible. Researchers around the world are developing new processes to generate electricity from falling drops. Be it through a plug-like flow of water or through nanotechnology in solar systems. The energy revolution is thus becoming feasible even in bad weather.
In future, water that falls through pipes can do more than just flow away. It can generate electricity. Researchers at the National University of Singapore have developed a method to generate electrical energy using a so-called “plug flow”, a steady stream of drops. In initial laboratory tests, it has already been possible to power 12 LEDs for 20 seconds using only artificially generated rain. The decisive factor here is the separation of electrical charges when the droplets hit a polymer-coated pipe wall.
The efficiency of this system is remarkable. More than 10 % of the energy of falling drops is converted into electricity. A multiple compared to conventional water systems. The output can be scaled by connecting several tubes in parallel. An approach with potential for urban rain management concepts or as a backup system in solar plants.
Electricity from friction
In addition to flow technology, the triboelectric effect also opens up new ways of generating energy. Triboelectric nanogenerators (TENG) convert the kinetic energy of raindrops into electricity through the contact and separation of two materials. In solar systems, these generators can be integrated on the surface without impairing light transmission. This generates additional energy when it rains. An ideal addition for days with little sunshine.
In the laboratory, 50 to 100 watts per square metre have already been generated, which corresponds to around a third of the maximum output of modern PV modules. According to the Fraunhofer Institute, this technology will soon be ready for the market.
Prospects for architecture, energy and mobility
The applications extend far beyond solar roofs. In the future, clothing, shoes or façades with TENG coatings could also generate electricity with every movement or drop of rain. This opens up new possibilities for decentralised power supply, building technology and energy self-sufficient systems, especially in urban regions with high rainfall frequency.