In an experiment, one tube produced 440 microwatts. When the researchers used four tubes at once, they could power 12 LEDs for 20 seconds.
We already use rain to produce lots of electricity, it’s called a hydroelectric dam. I wish people would think before they produced stuff like this.
The article is talking about an entirely different way to generate electricity from water
Normally, when we generate electricity from water, we use the movement of lots of it to drive a turbine in a river, the sea or even in drinking water pipes. But water flowing over an electrically conductive surface can generate its own electrical charge through a process called charge separation. This is driven by positively charged protons of the water molecules staying in the liquid and negatively charged electrons being donated to the surface, much as you can generate static electricity by rubbing a balloon on your hair.
Others have explained why this is inefficient and useless elsewhere in the thread, I suggest looking at those conversations.
Charge separation is a real thing. It’s the opposite of how an LED works. It’s not very efficient in that direction, but it’s real.
It works with electrons being excited by photons, though.
What that has to do with the interface of water and air, I can’t figure out.
third paragraph:
Normally, when we generate electricity from water, we use the movement of lots of it to drive a turbine in a river, the sea or even in drinking water pipes. But water flowing over an electrically conductive surface can generate its own electrical charge through a process called charge separation. This is driven by positively charged protons of the water molecules staying in the liquid and negatively charged electrons being donated to the surface, much as you can generate static electricity by rubbing a balloon on your hair.
charge separation is a lot more than just photoinduced charge separation
If that was a real thing, at least in charges strong enough to harness for work, surely we wouldn’t ground sensitive electronics to metal water pipes. And metal fuel containers would be spontaneously exploding all the time. I can’t find any evidence of this phenomenon anywhere but in this article. Can you provide a source?
https://en.wikipedia.org/wiki/Triboelectric_effect#Liquids_and_gases
Since triboelectricity requires asperities, I would guess the interiors of such containers are smoothed out. It’s also not unheard of for fuel containers to spontaneously explode when they fall, and movies that often happens when they smash against the ground.
Huh. TIL. Neat!
At least it’s better than solar roadways. I think?
What’s wrong with getting some more out of its kinetic energy?
Unless you are harnessing a box store, factory or warehouse roof you aren’t going to have the throughput to generate any really useful amount of energy. Also hydro works best where there is constant flow. So sewers would be a better place if you could solve the solids issue.
Sewer poop knifes that spin?
There are many keepers of the poop knife lore, but none so innovative as you my friend. Get this person a promotion!
Brand new sentence.
I like the way you think!
Yeah but think of how many LEDs you could light for 20 seconds once a week if you spent thousands filling your roof with these!
box store, factory or warehouse roof
But isn’t that exactly the sort of implementation we’re talking about here? Especially if you deploy this in large farms around the watershed. One problem with dams is that they have limited potential energy, since you can’t really build a hydroelectric dam in the sky. Harnessing additional kinetic energy for free on its way to the reservoir, capturing energy that otherwise would’ve just gone into the “plop” sound on the dirt, seems like a reasonably good idea; especially if it’s cheap.
Of course, there’s no way it’s ever going to rival solar or wind (or true hydroelectric). But I hope we learned our lesson long ago to not put all of our energy eggs in one basket.
EDIT: Nah, you’re right, on a large scale this is unlikely to be able to pay its own manufacturing costs. Perhaps this is more useful as a small-scale energy source.
This isn’t a terrible idea, and it could be useful as a source of emergency power in places that have high rainfall (paired with a battery system). From my background, I just don’t see it as viable for general use.
I also wonder about stacking them, particularly in places with a lot of rainfall.
Somewhere that has lots of drop, sure. But hydro relies on head pressure. Which is why most dams are a resevoir with multiple turbines.
That’s exactly what hydroelectric dams do…
Ok so this plus dams equals more efficient dams. What’s the issue
The issue is that it’s a waste of resources. A dam is harnessing energy from the rainfall over hundreds to thousands of square miles of land area. So the resources required to build it, even though large, are very efficiently used over decades of use.
A tiny system uses orders of magnitude less materials but harvests many orders of magnitude less power. A tiny system probably isn’t going to ever generate more energy than it took to manufacture.
Systems like this are at best a novelty. We need to all be wary of greenwashed scams, and this is one of them.
Tiny energy sources have a niche to fill. Think about the minuscule solar panels that power calculators, for instance; that tiny little 0.02W solar cell might be useless for broad-scale deployment, but if you’re instead looking to provide energy to something small and specific in a niche situation, it can be really useful.
I know this article is talking about deploying this on a house scale, and I even bought into that idea (or, rather, a larger one) in a previous comment; but you’re right, this is unlikely to be a good use of resources.
Instead, what about deploying this as the power source for a remote meteorological test rig deep in a rainforest? When the rain falls, it gathers energy to make its measurements, stores some in a battery, and transmits its findings.
Or perhaps deploying it for a small community in a monsoon area which doesn’t rely on much electricity but still needs it for communication in case of emergency. Having a wind, solar, and rain energy collector on it, all feeding a battery, could allow them to have access to emergency services when they otherwise wouldn’t (or when it would otherwise be difficult).
I’m just saying, energy diversification is a good thing.
Yes, but you screw up the ecosystems in rivers when you use hydro power.
Yes and the production of millions of tiny plastic tubes to stick everywhere is a wonderful alternative.
It doesn’t have to be plastic. There are plenty of sustainable alternatives to plastic.
Remarkably, I was just reading some old xkcd "What If"s during lunch, when I happened across this one (third question).
tl;dr: at 2012 energy costs (and assuming perfectly efficient turbines), capturing kinetic energy for electricity on a house’s footprint in the rainiest place in the US takes about a century to be worth the cost of manufacturing and installing it. That’s in the best-case scenario.
Edit: turns out OP’s article is about charge separation, not driving turbines.
I can’t replicate the findings of that equation even after doing the omitted conversion from ft²×m to L. That said I don’t understand what the unit of energy even means from its SI conversion lol, so obviously don’t take my word over that of a rocket scientist.
12 LED’s for 20 seconds is bad. The CO2 released just in production and even transporting them to your house will counter this.
Its a cool thought, but this is counter productive.
For 4 tubes. The interesting thing is that they are 2 mm wide, so feasibility you could add more to bring up generation. That being said, it would take a lot of work to get it to the point where you could get OK energy levels, but only when it’s raining.
So infinite energy in the UK then. /s
Maybe enough turn on the kettle once a year, it is a pretty small amount.
I can’t claim to know the manufacturing but this sounds just like the “The production of EV batteries is worse for the environment than burning fossil fuels” argument that ignores the fact that batteries are reusable
It is the same argument, but you cant even start to compare it. EV emits less than manufacturing, this wont at its current state.
Lets just look at the transportation.
These will probably be manufatured in Asia. Lets just say its not, and its only 20km from your house. How much energy would it take for you to get these with a car, or how much energy would the truck require to get them to the store.
Even if the car/truck is electric, these tubes would never in 100 years generate enough for the product to move to you.
And this is only if its manufactured nearby.
I have no problem with the work these scientists are doing establishing the basic research and proving the principal works. Basic research is the foundation that leads to future large scale projects. However, at this time we are a long LONG way from any large scale practical application of this. The amount of power generated is very VERY small, and that assumes everything goes perfectly.
In a real rain storm dirt could easily block the tubes cutting off the effect and stopping power generation, as an example. This doesn’t mean the underlying principal is flawed, but more work will have to be done to make a practical application out of this, now proven, principal.
I wonder if this could be used with existing solar arrays to kind of use the panels as rain collectors to funnel into something like this. Would have the benefit of giving some extra power when solar is weakest.
Yeah, seems like having solar, wind, and rain energy gathering devices would be useful for small-scale applications.
You cant gather more energy out of the rain than its potential energy from you roof to the ground.
Even at 100% efficiency it wont do anything.
That’s not nothing. It’s almost nothing, but not literally nothing.
No, true.
But factoring CO2 emitted from manufacturing + transportation from factory to your house, it will be net negative in emission. Even from transportation alone.
Actually, Randall Munroe did the calculations for his “What If” series. It is net positive in cost over a long enough time, which means that it will eventually be net positive in emissions, assuming it lasts long enough.
Yeah, the line for when its net positive is key. Otherwise we cant really draw conclusions.
