A $30 Device Turns the Cold of Outer Space Into Renewable Energy (vice.com) 62
ted_pikul writes: A team of scientists have created a device that turns the cold of space into enough electricity to power an LED light. As described in a paper published on Thursday in the journal Joule, the device is based off of a thermoelectric generator that creates electricity from the difference in temperature between a "hot side" and a "cold side." The researchers -- UCLA scientist Aaswath Raman, and Stanford scientists Wei Li and Shanhui Fan -- decided to take this idea one step further and use the ambient environment of Earth as a heat source and the cold of outer space as one gigantic cold sink.
The prototype consists of four stilts supporting two plates sandwiched between a thermoelectric generator. One plate is aimed at the ground, the other at the sky. The downward-facing plate draws heat from the air around it, while the upward-facing plate is paired with an aluminum disk painted black. The disk acts as an emitter that radiates heat into space through Earth's atmosphere, cooling the plate to below ambient temperature. This effect is known as radiative cooling, Raman said, and scientists have known about the phenomenon for years. It's the reason why a window can be frosty in the morning even when last night's temperature wasn't below freezing, and, as Raman explained in a 2018 TED Talk, it's the reason ancient Persians were able to make and store ice in the desert.
The prototype consists of four stilts supporting two plates sandwiched between a thermoelectric generator. One plate is aimed at the ground, the other at the sky. The downward-facing plate draws heat from the air around it, while the upward-facing plate is paired with an aluminum disk painted black. The disk acts as an emitter that radiates heat into space through Earth's atmosphere, cooling the plate to below ambient temperature. This effect is known as radiative cooling, Raman said, and scientists have known about the phenomenon for years. It's the reason why a window can be frosty in the morning even when last night's temperature wasn't below freezing, and, as Raman explained in a 2018 TED Talk, it's the reason ancient Persians were able to make and store ice in the desert.
Headline No Make Sense (Score:3)
Re:Headline No Make Sense (Score:5, Insightful)
You don't turn 'cold' into energy.
You are correct, and this device captures energy the same way every other one does.. Using the flow of heat and increasing entropy. So this doesn't really use "cold" or "hot" sides, but the flow of heat from the "hot" to "cold" sides of the device.
Also, thermo electric generators are not new. 30 years ago I built a radio that ran on a candle that used dissimilar wire to generate a small current to run the radio. Not to mention that the Voyager missions used the same technique to create power from a radio active decay heat source.
Re:Headline No Make Sense (Score:4, Interesting)
The interesting thing about using the Peltier effect for producing electricity (as opposed to the other way around - transferring heat using electricity) is that the limiting factor is usually on the cooling side. There has to be that heat differential, and the larger the differential, the more power it will generate. If you slap one of these on the side of, say, a wood burner, it will work briefly until both sides have been heated up to the temperature of the wood burner. Then it stops producing power. The typical way to keep them running is to use large cooling fins to try and dissipate that heat through convection. Obviously you could put a cooling fan on it to increase efficiency even more, but then you're consuming the little bit of electrical power that you're creating.
The thing that is a little unique about what they are doing is that they are using radiant transfer to cool (which always happens to some degree anyway, but it is typically far exceeded by convective cooling to the air). The point with this is that it is passive, and really doesn't even need air to work at all. However a high enough air temperature (higher than that of the ground) would be heating the cool side faster than it could radiate heat, bringing all power generation to a halt. Same with the sun during daylight hours - the radiant energy from the sun would vastly exceed the amount of energy it in turn radiates, so it would not be producing power during daylight.
Re: (Score:2)
The example of frost on top of a car only works (to the degree [see what I did there] that there's actually "frost") on non-cloudy days.
Notice that a vehicle under a carport doesn't have frost on top.
Also, there's no frost on the sides because the temperature differential between that and adjacent buildings, other cars, and whatnot is not as great as the top and outer space.
Re:Headline No Make Sense (Score:5, Informative)
The interesting thing about using the Peltier effect for producing electricity (as opposed to the other way around
Nitpick: This is actually the Seebeck effect [wikipedia.org].
It is the Peltier effect [wikipedia.org] that is the other way around.
Seebeck effect: Electric power generated from a temperature difference.
Peltier effect: Temperature difference created from an electric current.
Both effects are simple and reliable, but very inefficient.
Re: (Score:2)
"Efficient" can mean different things. Peltier devices can be very space-efficient, for instance, for certain applications.
Re: (Score:2)
IIRC the generation of electricity from a temperature difference is actually called the Seebeck Effect [wikipedia.org]. The Peltier Effect is the transfer of heat using electricity.
Re: (Score:2)
Also, thermo electric generators are not new. 30 years ago I built a radio that ran on a candle that used dissimilar wire to generate a small current to run the radio. Not to mention that the Voyager missions used the same technique to create power from a radio active decay heat source.
400 BC. Really not new.
Re:Headline No Make Sense (Score:4, Informative)
Except as the device heats up, the heat it absorbs is greater than the heat it can radiate (radiation is the only way heat can leave something in space - convection and conduction are out) away and eventually the whole thing gets hot, including the "cold" side, then electricity production stops. No laws of physics are broken. No perpetual energy device is invented. I wish them luck in their trials.
PS - space is only "cold" in the dark. In sunlight it's actually pretty damned hot and overheating is a major concern for things like the ISS, which is why it has big-ass radiators. And unfortunately vacuum is almost a perfect insulator, which is why thermoses work so well...so once you acquire heat you struggle to get rid of it.
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
Technically you're correct, but in practice a heat sink is harder to arrange than a heat source.
In any event the efficiency of Peltier/Seebeck junctions is so meagre that you'd probably be much better of with a PV or solar thermal generator anyway.
Re: (Score:2)
in practice a heat sink is harder to arrange than a heat source.
What? I can light just about anything on fire and make it a heat sink.... /s
Low efficiency [Re:Headline No Make Sense] (Score:2)
You don't turn 'cold' into energy.
Well, a heat engine works by tapping the difference between hot and a cold source. Usually we think of the hot source as being hotter than room temperature, but you can equally well put the "hot" as being room temperature, in which case it works because the cold is colder than room temperature.
I just have problems believing that this can produce significant amounts of power. A perfect blackbody can radiate up to 420 watts per square meter at 20 C, true, but at the earth's surface you're not really radiatin
Re: (Score:3)
You don't turn 'cold' into energy.
I just have problems believing that this can produce significant amounts of power. A perfect blackbody can radiate up to 420 watts per square meter at 20 C, true, but at the earth's surface you're not really radiating to empty space; you're radiating to the atmosphere.
MIT have developed a coating which reflects more than 90% of incoming solar radiation but naturally radiates in the infrared at about 10 microns wavelength. This is a wavelength/frequency where there is a window of transparency in the atmosphere and heat will pass through to space without being absorbed. This is also in the part of the spectrum used by military and police surveillance FLIR cameras.
I think this idea is stupid as a means of generating electricity but shows great potential for high efficiency
Re: (Score:2)
Ah thanks..I must have missed that detail.
Re: (Score:2)
I just have problems believing that this can produce significant amounts of power. A perfect blackbody can radiate up to 420 watts per square meter at 20 C, true, but at the earth's surface you're not really radiating to empty space; you're radiating to the atmosphere.
MIT have developed a coating which reflects more than 90% of incoming solar radiation but naturally radiates in the infrared at about 10 microns wavelength.
That's actually easy to do. Silica-- glass-- is transparent in the visible but black in the infrared. Put silver on the back of a piece of glass, and you make a device that radiates in the IR but reflects in the visible solar spectrum. This is used a lot in spacecraft thermal control, and NASA has some new very effective coatings to do this even more selectively: https://www.nasa.gov/feature/c... [nasa.gov]
This would be useful if they were trying to make a device to operate during the daytime.
This is a wavelength/frequency where there is a window of transparency in the atmosphere and heat will pass through to space without being absorbed
Turns out you can't emit
Re: Headline No Make Sense (Score:2)
You also can't turn the heat of the Sun into energy if you're already on the Sun.
A difference in temperature is how a Sterling engine works. And demonstrates the basic theory behind thermodynamics.
And The Heat Will Bounce Back... (Score:1)
Re: And The Heat Will Bounce Back... (Score:3, Insightful)
Re: (Score:1)
How is it being "moved outside the atmosphere"? A rocket? I must have missed something.
Re: (Score:2)
Never mind...it was explained above.
Re: (Score:2)
"How is it being "moved outside the atmosphere"? A rocket? I must have missed something."
Yes, you did. It's called "radiation". Crack open a middle-school level science book.
Peltier (Score:3)
So the researchers took a peltier junction device, stuck a heat sink on one side and a metal plate on the other? They must have watched this Youtube video from six years ago:
https://www.youtube.com/watch?... [youtube.com]
Unpedant (Score:3)
I never referenced the Peltier *effect* but a Peltier *device* You are correct in that it is the Seebeck effect generating electricity, but nobody calls them Seebeck devices. Some may be called Peltier-Seebeck devices I suppose, but I've never seen one.
Re:Peltier (Score:4, Interesting)
yes - except with one addition. They coated the top with their special material that converts heat into light in the proper spectrum to cut through our atmosphere to pump the energy into space. so, the "cool" side remains cool because of electromagnetic radiation cooling.
Re: (Score:2)
What? I missed that part. The LED was just a demonstration of the energy produced. I'm confused how this is associated with "Outer Space" at all.
Re: (Score:2)
That's where the heat radiated from the cold plate is going.
Re: (Score:2)
Well yeah...but ummmm...they didn't convert heat to light and beam it into space. They just...radiated...it out
Re: (Score:2)
Outer space is at 2.7 kelvins (ignoring losses through Earth's atmosphere). That's the "cold" side of the temperature differential. It's not absolute zero for two (2) reasons:
1.) The presence of the cosmic background radiation left over from the big bang and
2.) Absolute zero is a mathematical construct which cannot exist in nature because we would know a physical value for sure. That would violate Heisenberg's uncertainty principle.
Re: (Score:2)
Um....what? The cold side is just sitting near the ground pointing at the sky. WTF are you guys talking about?
Re: (Score:2)
IR... entropy
The way all energy eventually leaves the earth
Tiny power (Score:3)
Thermoelectric generators using the Peltier are very inefficient (in that they only convert a small amount of the thermal energy to electricity). When you couple this with the small amounts of thermal energy involved, this thing wouldn't produce much power for the cost and size. Solar would blow it away as far as power production goes.
FTA:
power an LED bulb through the night at about 10 percent of its possible brightness.
“The big caveat with this work that I’d like to state upfront is that the amount of power we’re generating is very small,” Raman said.
So it can only power a single LED at 10% brightness. Again, a TINY amount of current. Maybe enough to run something like a classic Casio wristwatch or a solar powered calculator. I can't think of any cases where this would be superior to solar, and it would not work in conditions where the air temperature is warmer than the ground temperature, etc.
Re: (Score:2)
It would be nifty if they could integrate this tech into solar panels or something but yeah, I don't see it as any more than a party trick for now.
And it cools the earth (Score:2)
Almost all power sources heat the Earth by some degree or another. By increasing the amount of heat radiating into space this will actually cool the planet while generating electricity. Also, it sounds like an expensive way to generate tiny amounts of power.
Re: (Score:2)
Almost all power sources heat the Earth by some degree or another. By increasing the amount of heat radiating into space this will actually cool the planet while generating electricity. Also, it sounds like an expensive way to generate tiny amounts of power.
"Generating electricity" does not come without heat losses. It's not a perpetual motion design.
thats what happened to Atlantis (Score:4, Funny)
Old news isn't even news (Score:2)
Re: (Score:3)
Because the new thing is to coat the "cold" side with a material so that it radiates EM at a frequency that is not stopped (much) by the atmosphere.
Re: (Score:2)
Oh geat! (Score:2)
HOW exactly? (Score:2)
The problem with space isn't that it's "cold".
It's that there's no way to actually dissipate heat in a vacuum.
So how is this device supposed to actually get rid of this waste heat?
Re:HOW exactly? (Score:4, Funny)
It's that there's no way to actually dissipate heat in a vacuum.
I'm sure that you're eager to collect your Nobel Prize in physics for finally disproving the myth of thermal radiation.
Re: (Score:2)
yeah if there was a way to transmit energy through a vacuum the hot Sun would be heating the earth!
Re:HOW exactly? (Score:5, Informative)
It's that there's no way to actually dissipate heat in a vacuum.
Yes there is [wikipedia.org]. The ISS carries this [wikipedia.org] to eliminate its excess heat. It radiates up to 70 kW of heat from the ISS. All larger satellites also carry radiators for the same purpose.
Radiative heat transfer [Re:HOW exactly?] (Score:2)
The problem with space isn't that it's "cold". It's that there's no way to actually dissipate heat in a vacuum.
Yes, there is: radiative heat transfer.
So how is this device supposed to actually get rid of this waste heat?
It radiates it to space in the form of thermal infrared.
https://www.engineeringtoolbox.com/radiation-heat-transfer-d_431.html
Re: (Score:2)
To everyone who took the time to clue me in.
Thank you.
This is not new... (Score:1)
This is old as dirt..
Using heat transfer from hot to cold is exactly how the Voyager probes generate power. Those things where launched more than 40 years ago and the technology they used to power them wasn't exactly new technology then. The RTG was invented in 1954 (65 years ago) but the power generating part, The thermocouple, was discovered in 1821 (198 years ago) by Thomas Seebeck. So the RTG is
Congratulations.. You discovered nothing new, but you got your headline. What's next, a Nobel prize for inv
What, now school physics is a story? (Score:2, Troll)
Has education gotten his bad?
Tower of Babel (Score:2)
Perhaps if we were able to construct a tower such that we might physically reach the heavens, we could create a more efficient model?
When I was a kid the big scam was free energy. The proposal was basically a heat pump , but they made it sound like you didn't need to put any energy in.
Looks like they figured that part out.
If there is a way to make this more efficient it might help to solve that whole "there is no solar power at night" problem. Because with a black plate on top, that seems like the only tim
Re: (Score:2)
If blindseer were here he would be able to explain why building a series 3 nuclear fission reactor would be the way to make this work best. /wink
Re: (Score:2)
Perhaps if we were able to construct a tower such that we might physically reach the heavens
Sure. All we need to do is discover Unobtainium.
Ocean Temperature (Score:2)
So if the sun shines on this, it screws the effectiveness on this, right? And it produces very little power. But I have a question - what if you put them on the ocean floor, where the depth will protect them from the sun and the water will provide some cooling on the top, pull heat out of the ocean floor, and radiate it out into space. With a large number, could that work to negate some of the unhealthy ocean temperature rise that we have? Or am I thinking about this wrong?
How is this "news"? (Score:2)
Well great... (Score:2)
This is the size of a hockey puck, now build one 10m2 and see how well it scales up and put it in a desert where the radiative cooling will be best at night!
No it's not a great amount of energy, but it's "free" except for material costs.
TED Talk (Score:2)
The TED Talk mentioned in the article is much more interesting. It shows just what this guys is actually working on.
The device he built for the LED was really just to show that for as little as $30 using off-the-shelf-parts one can demonstrate this well known phenomenon. He suggested the High School students should be doing this.
But his own actual research is fascinating, as he has managed to design a system that works during the day and in full sunlight.
https://www.ted.com/talks/aasw... [ted.com]
Why (Score:3)
Try fucken millennia.
Some asshat slaps a heat sink on a peltier cooler and then posts an article about it with a snappy headline.
Whoever decided this was worth posting should have a high school physics textbook thrown at their head.
Why do "green" thinkers ignore practicality? (Score:4, Insightful)
While I applaud their ingenuity, what they're leveraging is extremely old technology. There's a reason why this isn't employed; practically speaking, high quality solar panels under strong sunlight generate about 150-200 watts per square meter. Having "a pathway" towards 5 watts per meter square is functionally useless. Given this design uses space as a heat-sink, it has the same drawback as solar panels, i.e. *clouds*. Clouds are effective insulators that seriously degrade the ability to use space as a black body heat-sink.
What we have here is a "solution" that is at least an order of magnitude less space efficient than solar (watt per space) that is still at the whims of the weather.
We have zero carbon, reliable, compact, high output power generation capabilities right now - it's called nuclear. Only fear, poor education and political pandering prevent its use.
Re: (Score:2)
I should have read the source article more slowly. They believe 0.5 watts per square meter is possible. This is again an order of magnitude more useless than I initially characterized.
Re: (Score:2)
However, it looks like there are new meta-material thin films that can reject IR energy to space at better than 100w/m sq. This could be used for real world cooling applications; cooling tends to be among the most power hungry functions in industrialized societies.
Direct cooling would be considerably more efficient than trying to leverage the temperature differential to generate power using the Seebeck effect.
https://www.researchgate.net/p... [researchgate.net]
At least it got off the front page... (Score:2)
https://hardware.slashdot.org/... [slashdot.org]
Same people, different links. And I think this story also hit the news (and /.) several months ago.