CityU new droplet-based electricity generator: A drop of water lights up 100 small LED bulbs:
A research team led by scientists from City University of Hong Kong (CityU) has recently developed a new form of droplet-based electricity generator (DEG).
[...] The research was led by Professor Wang Zuankai from CityU's Department of Mechanical Engineering; Professor Zeng Xiaocheng from the University of Nebraska-Lincoln, US; and Professor Wang Zhonglin, Founding Director and Chief Scientist at the Beijing Institute of Nanoenergy and Nanosystems of Chinese Academy of Sciences.
[...] Professor Wang pointed out that there are two crucial factors for the invention. First, the team found that the continuous droplets impinging on PTFE[*], an electret material with a quasi-permanent electric charge, provides a new route for the accumulation and storage of high-density surface charges. They found that when water droplets continuously hit the surface of PTFE, the surface charge generated will accumulate and gradually reach saturation. This new discovery has helped to overcome the bottleneck of the low-charge density encountered in previous work.
[...] The device consists of an aluminium electrode and an indium tin oxide (ITO) electrode with a film of PTFE deposited on it. The PTFE/ITO electrode is responsible for the charge generation, storage, and induction. When a falling water droplet hits and spreads on the PTFE/ITO surface, it naturally "bridges" the aluminium electrode and the PTFE/ITO electrode, translating the original system into a closed-loop electric circuit.
With this special design, a high density of surface charge can be accumulated on the PTFE through continuous droplet impinging. Meanwhile, when the spreading water connects the two electrodes, all the stored charges on the PTFE can be fully released for the generation of electric current. As a result, both the instantaneous power density and energy conversion efficiency are much higher.
"Our research shows that a drop of 100 microlitres [1 microlitre = one-millionth litre] of water released from a height of 15 cm can generate a voltage of over 140V, and the power generated can light up 100 small LED lights," said Professor Wang.
[*] PTFE - Polytetrafluoroethylene, also known as Teflon®
The report contains a link to a small video showing the device at work.
Journal Reference:
Wanghuai Xu, et al. A droplet-based electricity generator with high instantaneous power density. Nature, 2020; (DOI: 10.1038/s41586-020-1985-6)
(Score: 2) by Barenflimski on Monday February 10 2020, @05:47PM
I enjoy watching the micro-electricity world blossom. It seems there is power just waiting to be generated from everything we use. Anti-solar. Micro-litre drops.
Makes me wonder what one could capture in a rain storm or from a device that captures electricity from water flowing through a pipe.
Cool stuff.
(Score: 2, Touché) by Anonymous Coward on Monday February 10 2020, @05:50PM (1 child)
"a device that captures electricity from water flowing through a pipe"
like a water wheel?
(Score: 2, Informative) by shanec on Monday February 10 2020, @06:10PM
Portland’s New Pipes Harvest Power From Drinking Water
https://www.fastcompany.com/3041300/portlands-new-pipes-harvest-power-from-drinking-water [fastcompany.com]
(Score: 2, Informative) by Anonymous Coward on Monday February 10 2020, @06:43PM (6 children)
To measure how long the power lasts. Those LEDs may flash for a microsecond and your eye will still register it.
If it pans out, someday this could replace mechanical hydroelectric generators
(Score: 2) by ikanreed on Monday February 10 2020, @07:44PM (2 children)
Having recently done a hobbyist project using exactly 100 LEDs, I can safely say it's in the neighborhood of 30 watts.
(Score: 2) by c0lo on Monday February 10 2020, @11:27PM (1 child)
Try about half of that with SMD LEDs 1.8V @ 1mA [mouser.com] - $0.15/pcs or thereabout in retail prices for quantities of 100.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by ikanreed on Tuesday February 11 2020, @01:45PM
that makes sense, in retrospect. My project was individually addressable variable LEDs(and it just occured to me, 3 ACTUAL leds per "LED")
(Score: 4, Informative) by c0lo on Monday February 10 2020, @11:17PM (2 children)
100 μL = 1e-4 kg of water.
A 15cm ... umm... drop of the droplet (ignoring drag loses) will get a total energy of 147μJ (m*g*Δh = 1e-4*9.8*0.15)
Using LEDs with 1.8V voltage drop @1mA current (=1.8mW - pretty dam' good ones), 100 of them will eat 0.18W. Which leads to a lighting time of 0.8ms (0.8e-3s). With loses and whatnot, at 60% efficiency, let's say about 0.5ms of light duration/droplet.
To keep those 100 LEDs working all the time, you need about 2000 of such drops every second, which is about 0.2 liters water/sec or 30liters/min. Which is about the flow rate of my garden irrigation faucet. Make the height 6 times higher (i.e. about 1m) and may only need 5 liters/min (I do have the feeling that the effect doesn't scale linearly with the mechanical energy on impact, somewhere there'll be a saturation)
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Wednesday February 12 2020, @03:49AM (1 child)
Self illuminating night fountains utilizing the splashing of the streams to power the leds making it glow. Sounds like a perfect use of it. Please make sure this post is used as a publishing of the idea so it doesn't get patented in the future :)
(Score: 2) by c0lo on Wednesday February 12 2020, @03:58AM
Heh. Long way from idea to prototype.
E.g. what works for water droplets may (likely) not work for streams (for example, leaking that 140v-causing separation of charge to the incoming stream instead of the other electrode).
Besides, there's also this problem of what to do with the water after the impact/separation of charge. See, 140V is likely to electrolyze the water if lingering too long between the two electrodes - getting it out fast enough will likely require some energy.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Funny) by SomeGuy on Monday February 10 2020, @08:45PM (1 child)
Please at least tell me these aren't #$^$%&#$&^ blue LEDs!
(Score: 2) by c0lo on Monday February 10 2020, @11:19PM
No, they're IR LEDs, this system won't work with anything else. Pleased now? (grin)
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Monday February 10 2020, @08:56PM
You can rig up a daisy chain of them and they'll light up near a microwave or any other RF noise. I think there is a high freq diode in the circuit somewhere to get the electrons flowing even though the LEDs are diodes.
(Score: 2) by c0lo on Monday February 10 2020, @11:37PM (4 children)
Ummm... birdeye view, looks like China rents research facilities in US (grin)
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by sonamchauhan on Tuesday February 11 2020, @01:27AM (3 children)
Could also be the other way around. The Chinese dude is the third author.
(Score: 0) by Anonymous Coward on Tuesday February 11 2020, @01:45AM (1 child)
Yes, because Hong Kong is the capital city of some American state.
(Score: 2) by sonamchauhan on Tuesday February 11 2020, @03:13AM
Aha.
(Score: 2) by sonamchauhan on Tuesday February 11 2020, @03:11AM
And by "dude", I meant "citizen" :-)
(Score: 3, Insightful) by progo on Tuesday February 11 2020, @01:20AM (1 child)
So, we've got liters, meters, and volts in the original summary, and oh look, a new unit of measurement: small LED lights! Power generation/usage rate can be measured in "small LED lights" now.
Why can't writers put actual values with real units in their stories?
(Score: 2) by progo on Tuesday February 11 2020, @01:25AM
Wait, I don't even know wtf they're claiming. Are they claiming one drop can generate so many joules or watthours, measured in small LED lights?
The original story doesn't make a coherent claim.