Scientists from the National University of Singapore are working on a new method of generating electricity from rainwater. Their study has been published in the American Chemical Society’s journal ACS Central Science, Newatlas.com reports.
Typically, power generation from water is achieved by moving large volumes of water to rotate turbines at hydroelectric power plants or via tidal waves. However, water flowing over an electrically conductive surface can also generate energy through a process called charge separation.
“Water that falls through a vertical tube generates a substantial amount of electricity by using a specific pattern of water flow: plug flow,” says Siowling Soh, the author of the new study. “This plug flow pattern could allow rain energy to be harvested for generating clean and renewable electricity.”
The researchers created a rain-based generator prototype: a tower topped with a metallic needle that allowed rain-sized drops of water to drip down. Beneath it, they placed a 32-cm-tall tube with a diameter of 2 mm made of an electrically conductive polymer. Raindrop-like drops collide in the top of this tube and trap air bubbles, creating a so-called plug flow as they fall. This helps separate the electrical charges of the water molecules as they move down the tube. Electrodes at the ends of the tube harvest the generated electricity.
As a result, they managed to convert some 10% of the energy from falling water into electricity. Later tests showed that the use of two tubes doubled the power output, which was enough to continuously power 12 LED lamps for 20 seconds.
The experimental rain-based generator is not very powerful yet. “That’s no Hoover Dam,” Newatlas.com reporters joke, referring to one of the largest HPPs in the United States with a capacity of 2,078.8 MW, which was built back in 1936.
However, the Singaporean researchers believe that after some tweaking their system could become popular as a local energy source: it could, for instance, be installed on roofs to provide urban buildings with environmentally-friendly energy. They also note that the drops passing through their prototype are much less efficient than real natural precipitation since raindrops fall from a height of several kilometers, which means that the system should work even better in outdoor conditions.
