A generator that harvests the pitter-patter of raindrops can produce enough electricity to power LED lights, though it is unclear how practical it might be.
Yonghui Zhang and colleagues at Dalian University of Technology in China created a device that they call a superhydrophobic magnetoelectric generator (MSMEG), which is essentially a canister the size of a tin of soup with a water-repelling film lid that is stuck to a coil of wire. When a raindrop hits the film, it deforms it momentarily, moving the coil relative to a magnet inside the canister and creating a tiny electrical charge.
In tests with simulated raindrops from a height of 50 centimetres, the MSMEG created a maximum current of around 13 milliamperes and was able to charge a small capacitor in 200 seconds that subsequently powered LEDs and fans. Its hydrophobic surface ensures that raindrops shed off the device quickly, allowing it to keep working even under constant rain.
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at the University of Sheffield, UK, says that the device is interesting but impractical. 鈥淲e do [already] have rain power,鈥� he says. 鈥淚t鈥檚 a well-established method of extracting energy from rain; it鈥檚 called putting it in a dam and then using hydroelectric.鈥� As rain falls into rivers and is collected together, you benefit from the advantage of scale, he says.
For smaller-scale energy generation, solar and wind power offer much simpler solutions, says Stone. 鈥淚t does seem a little bit strange to be trying to sort of extract energy from raindrops.鈥�
ACS Applied Materials & Interfaces
