The use of renewable energy is constantly being promoted and soon, we may be able to generate a significant amount of electricity from raindrops to use in our everyday lives. Already, researchers at the City University of Hong Kong (CityU) have developed a droplet-based electricity generator (DEG). The latter uses a single rain droplet to generate enough power to light up 100 small LED bulbs, according to Science Alert report on February 16, 2020.

The Race to Generate Electrical Power Using Rain Water

Scientists have often sought ways to generate electricity in a cheaper and environmentally friendly way. One potential source of energy is water, and specifically, raindrops. However, getting water droplets to generate electricity has proved to be a difficult feat.

Systems that can generate power from rainwater are also being researched. And several energy harvesting techniques have been devised to convert mechanical energy from raindrops into electrical energy to power electronic devices and sensors.

Scientists Make Major Leap in Research

Accordingly, scientists at CityU have made a major leap in their research. Reportedly, they have developed a droplet-based electricity generator (DEG) that uses droplets of rainwater to generate energy to light up 100 small LED bulbs.

Wang Zuankai, biomedical engineer Wang Zuankai also explained the physics behind the system. According to Zuankai, the research revealed that 100 microlitres of raindrop released from a height of 15 centimeters can produce a voltage of over 140V. This voltage can supply enough power to light up these bulbs.

Devices Stores Charges Created by Water Droplets On a Surface

The DEG, in question, stores charges that are created when droplets of rainwater hit a surface. In this case, the DEG takes advantage of a polytetrafluoroethylene or PTFE film that helps in the accumulation of a surface charge as water droplets fall on it. At some point, it reaches saturation.

Furthermore, the researchers discovered that each time droplets of water hit the surface and spreads, the drop serves as a bridge between the electrodes. These electrodes are the aluminum electrode and an indium tin oxide (ITO) electrode. In line with that, the droplet bridge helps to create a closed-loop surface that enables the accumulated energy to be released.

Xiao Cheng Zeng, a chemist Xiao Cheng Zeng from the University of Nebraska-Lincoln said:

"The significance of this technology is the much enhanced electric power per falling rain droplet, which makes the device much more efficient to convert energy from a falling droplet to electricity."

DEG is Still Impractical for Everyday Use

On the other hand, the team behind the device noted that it is not practical enough to be put into everyday use. In their opinion, the system is unable to supply a continuous supply of power. It is, however, a promising step towards a new form of renewable electricity. And the goal is to turn the new technology into a system that can power people's homes.

That aside, scientists are constantly looking into ways of producing electrical power using water. There have been experiments to harvest energy from a rising tide or flowing stream. Nonetheless, the use of raindrops as a power source can also be very promising.

The latter can be tied to the fact that there are times where solar energy is difficult to exploit. For instance, rainy days often have 90% less sunlight. Hence, in outdoor environments with lots of water or where it rains more frequently, these systems would serve as a good alternative to power systems. It could be useful to generate electricity from both the sun and rain.

15-Year-Old Also Designs Energy Generating Device

Another reported case of the use of rainwater to generate electricity is a device created by Reyhan Jamalova. In 2018, Jamalova who was 15-years-old at the time, developed the Rainergy to harvest energy from rainwater.

According to Jamalova, the aim of the project is to combat energy deficiency in rainy and low-income countries. Interestingly, Rainergy could also store power in a battery to ensure the user still has electrical power when there is no rain.