Rainfall Becomes an Effective Renewable Energy

People have tried many times to use rainwater to generate electricity, but this may be one of the more effective solutions to date. A research team led by scientists from the City University of Hong Kong (CityU) recently developed a new type of water droplet-based generator (DEG). It is characterized by a field-effect transistor (FET), which can achieve high-efficiency energy conversion, and its instantaneous power density is increased by thousands of times compared to a transistor without a field-effect. It uses a transistor-type field-effect concept, and the water droplets instantly generate a surprisingly high voltage. Water droplets can generate 140 volts of energy, which is enough to briefly light up 100 small LED bulbs. This breakthrough result will help advance scientific research on hydropower and solve the energy crisis.

The research was conducted by Professor Wang Zukai. Their findings were published in the latest issue of the well-known scientific magazine "Nature", entitled "Droplet Generator with High Instantaneous Power Density".The new design arranges the aluminum electrode and the indium tin oxide electrode in a layer of quasi-permanently charged polytetrafluoroethylene (PTFE). When a drop falls on the surface of Teflon /Tin, it connects the two electrodes to form a closed-loop circuit. This helps to completely release any stored charge. This technology can also handle continuous rainfall. If there is a continuous drop, the charge accumulates and eventually reaches the saturation point.

Source: (W. Xu, H. Zheng et. al A droplet-based electricity generator with high instantaneous power density[J]. Nature 2020, 578: 392-396.)

There is still much work to be done to convert it into an actual product. Nonetheless, the potential uses are obvious for example you can apply such a generator to any place where it may rain (or other water splashes). Building a roof can at least offset part of the electricity consumption from the people below, and electric boats can extend their range. It can even be used to power devices that are often wet, such as umbrellas. Rainwater is usually the most terrible nightmare for solar cells, but a team of Chinese scientists has developed a solar cell with an atomic thickness of graphene layer that can collect energy from raindrops, even on the darkest days. Water actually attaches to graphene, forming a natural capacitor-the huge difference in energy between the electrons of graphene and water ions generates electrical energy.