Scientists have been researching this type of energy production for years, but the task of converting the energy from raindrops into electricity is much more complex than obtaining it from hydroelectric plants. These use the movement of an ascending tide or a flowing current to produce electricity, and are the evolution of the old mills that took advantage of the current of rivers to generate energy.
Therefore, the efficiency of energy conversion with this approach is quite low, and the so-called triboelectric effect (the physical phenomenon that allows energy to be produced when a drop hits a surface) that has been achieved with traditional generators has always had a very wide range. limited.
New research published in Nature , however, appears to have found a method that could generate enough power from a single raindrop to light up 100 tiny LED bulbs. This is an extraordinary leap forward in efficiency – several thousand times more than traditional devices .
Specifically, researchers from the City University of Hong Kong (CityU) say that with a drop of 100 microliters of water released from a height of 15 centimeters they can obtain a voltage of more than 140V. Thus, according to the data provided by the team, the instantaneous power density of its drip electric generator would reach up to 50.1W per square meter .
Taking advantage of the water cycle and generating electricity from rainy days could be one way to increase our use of renewable energy.
The trick lies in the use of polytetrafluoroethylene
The research was led by Wang Zuankai , from CityU’s Department of Mechanical Engineering; Zeng Xiaocheng , from the University of Nebraska-Lincoln, United States; and Wang Zhonglin , chief scientist at the Institute of Nanoenergy and Nanosystems of the Chinese Academy of Sciences in Beijing.
One of the tricks that the team of researchers resorted to to make their raindrop-based electricity generator much more efficient was the use of a polytetrafluoroethylene (PTFE) film, which is capable of accumulating a surface charge as it moves. it is continually hit by drops of water.
As the droplets hit the surface and spread, they act as a “bridge” connecting two electrodes : an aluminum electrode and an indium tin oxide electrode (with the PTFE on top).
The water droplet bridge, in turn, forms a closed-loop surface so that all the collected energy can be released: the droplets act as resistors and the surface coating acts as a capacitor.
In other words, any surface on which the drops of water hit when they fall can be susceptible to taking advantage of this finding , from an umbrella to the hull of a ship.
However, they are still in the preliminary stages of testing this Hong Kong system and there is still much work to be done in order to be considered optimal for practical use . The results are promising, but the researchers don’t expect to have a prototype ready for another five years.
