Raindrops Power New Renewable Energy Breakthrough
Haley Zaremba

Raindrops could hold the key to next generation renewable energy. Scientists in Singapore recently managed to generate electricity from rain-like water droplets with a surprisingly promising amount of efficiency. If this scientific breakthrough proves to be scalable and, eventually, commercially viable, this could have major implications for the global decarbonization movement, and could provide a new form of residential clean energy production.

In a revolutionary first, a team of researchers from the National University of Singapore generated enough energy from water droplets to power 12 LEDs for 20 seconds. The way that the process works is through harnessing the shifting charges of two different materials passing each other. When water flows over a surface, both the water and that material can change charge. This experiment successfully harnessed that change in charge to generate clean energy.

“Charge separation occurs spontaneously at the solid–liquid interface, forming an electric double layer,” the scientists wrote in a recently published scientific paper. In this case, the water droplets were passed through a narrow tube with an electrically conductive inner surface, and the scientific team was able to “separate electrical charges and harvest energy with surprising efficiency” according to Sci Tech Daily. 

“Water that falls through a vertical tube generates a substantial amount of electricity by using a specific pattern of water flow: plug flow,” said study author Siowling Soh. “This plug flow pattern could allow rain energy to be harvested for generating clean and renewable electricity.” Plug flow occurs when columns of water are shot through with pockets of air, creating optimal conditions for charge separation for energy production. 

This ‘plug flow’ system successfully converted more than 10 percent of the input water’s energy into electricity, marking an astonishingly high level of efficiency compared to other experiments with low-flow hydroelectricity production. “And compared to water flowing in a continuous stream, plug flow produced 5 orders of magnitude more electricity,” reports Sci Tech Daily. Each individual tube produced 440 microwatts of electricity, while four tubes altogether were used to power the 12 LEDs. While these amounts are small, the experiment’s efficiency is stunning and holds massive potential.

Even more promising, the flows of water tested in the study were significantly slower than droplet speeds in natural rain showers. This means that rainfall could yield significant amounts of electricity using such a plug flow system. 

“Rain falls on Earth every day. All the energy is wasted due to the lack of a system to harvest rain energy,” Soh was recently quoted by New Scientist. “Rain falls from a few kilometres up in the sky to earth, so there is a lot of room in three-dimensional space to harvest rain energy,” he continued.

Indeed, the findings published this month in ACS Central Science show enormous promise for this potentially disruptive form of carbon-free energy production. The paper demonstrates that “plug flow via harvesting energy from nature is a source of renewable power with many advantages for achieving sustainable societies.” Like solar panels, rainwater catchment and plug flow systems could be installed on rooftops so that houses can be producers as well as consumers of clean energy. 

In the biz, these producer-consumers are known as ‘prosumers’ and they are becoming an increasingly essential part of scaling decarbonization solutions. Clean energy solutions can be deployed at increasing scales and in rural, hard-to-connect grids through prosumer production. What is ore, energy systems can become more independent and resilient through this process of decentralization. 

Harvesting energy from rainfall on rooftops could be a critical complement to residential solar. While solar panels can generate power on sunny days, rainfed energy production could fill in the gaps on cloudy and stormy days, potentially providing a key solution for energy security as our global grids increasingly rely on variable forms of energy production. 

By Haley Zaremba for Oilprice.com

Haley Zaremba is a writer and journalist based in Mexico City. She has extensive experience writing and editing environmental features, travel pieces, local news in the Bay Area, and music/culture reviews.

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