Cheap material converts heat to electricity
sciencemag.org
sciencemag.org
This is literally inventing half a solution. Shockley didn't go to the press when he'd built half a diode.
(OK, this is snarky, but I think this is another case where people need to understand the difference between "a small but valid advancement in the art" and "actual products". As a materials science paper this is valid.)
(I did research in nano thermoelectrics and published a few papers in this field)
What makes a material p or n?
Graphene can be modified by changing its topology to be p or n, but GO is n by default. Do electron and hole features have to match in these constructions?
https://simple.wikipedia.org/wiki/P-type_semiconductor (property 2)
Modern condensing gas boilers for domestic use are better than 90% efficient, the exhaust gas is very cool so I don't think that thermoelectric devices have much to offer there.
There are systems here listed at 98.5 AFUE
However in real boilers, there is no need for this - by condensing that water vapor back into liquid water you can get more energy out. That's the 'Higher heating value'.
When measuring efficiency, we always use the lower heating value, whereas we ought to use the higher heating value. Therefore a "98% efficient furnace" is actually more like 88% efficient when considering the higher heating value.
The place this would be useful is in capturing otherwise unusable energy from low grade heat waste. For example, the output water of a steam turbine might still be "hot", but there's very little you can do with it - it's in the wrong place for heating houses, it's too cold for steam turbines. Generally that energy is lost to the air.
Also, cold exhaust doesn't exhaust (since it cant rise through a density change). So, if your exhaust is too cold, it will collect in your basement (CO2 should be a bit denser than air, so absent any drafts it'll collect)
The previous owners of my house installed my high efficiency stove improperly using the old brick flue. The fumes eventually ate away at the mortar and a few bricks fell I'm clogging it.
Unless you have a fan blowing smoke into flue. Without fan, my furnace would not work, exhaust is only slightly above water temperature and furnace is designed so that condensate pools in special container, which you have to empty or connect to sewage.
That kind of efficiency would be a big breakthrough if it where affordable, imagine the applications.
Or tack them on ice engines.
Having had the evaporator fan go out in an old fridge once, I think you'll find fridge fans not as generic nor replacements as easy to find as you might hope.
Interesting, I've definitely seen a normal sized house fridge with a fan on the hot side, but I don't know what is typical.
> I think you'll find fridge fans not as generic nor replacements as easy to find as you might hope.
Current generation probably not, but there's no reason these can't be your typical $20 computer case fan, especially on the hot side where there's no worries about condensation... for peltier elements you could even stick a off the shelf CPU heat sink on top (though presumably at scale you would build the heat sink custom).
Nope, if you use this on hot side, AC will have to work more to get rid of heat, but this device will still provide less power than ac must now use. Design criterium for AC's is that hot side should be as cool as possible (so it has a big fan to cool it down), but thermoelectrics require hot side to be as hot as possible.
AFAIK compressor units are still way more efficient than this device, so no reason to bog them down with something with less efficiency.
The solid state methods can sustain a temperature differential with a given power/heat flow. If the hot side is cooler, the cold side can be cooler, or less power is required.
If you use that new device as a cooling enchancer, you will have to provide some power. If your first cooler user more efficient method, you should just make bigger unit using more efficient method, because otherwise whole apparatus will be less efficient.
It would be very nice to have an AC where you don't need to deal with that. I thought about many ways to get rid of heat without having to dump it somewhere, but thermodynamics is such a terrible thing.
This is likely a stupid question but temperature is a statistical property describing the energy of molecules right? Is there no way to tap the energy of the molecules for useful work without having a temperature difference?
I found it intreaguing and read more about it but I can't quite umderstand the proposed solutions, likely due to my lack of background in thermodynamics.
I once read in some article that CPUs have the same power consumption as equivalent output of a nuclear reactor, based on size, of course. So the 1 inch of a CPU takes as much energy as 1 inch of a nuclear fusion output from a nuclear reactor. Again, I don't know if this is true, but if it is, that's a lot of heat energy, given the number of computers in the world.
But maybe I remember wrong, this was probably 15 or 20 years ago that I read this.
In summer, the sun (rudely) gives me excess unwanted heat in my house. I need to expend even more energy to get that heat from inside to outside my house. (We call this process "Air Conditioning".)
What would be ideal is if the heat energy could be converted into some other form of energy that I could dispose of. Maybe if I could turn it into electricity I'd put a lightbulb in my window and shine the converted heat energy away.
I don't really care if that process is inefficient because that heat was completely free and unasked-for. I don't need to do anything useful with the converted heat energy, I just want it gone. If the process of converting heat to a disposable form of energy can be done for less energy than air conditioning needs, then its worth doing.
I know what I proposed would require our understanding of thermodynamics to be wrong, but this is in response to an article about a material that converts heat into electricity. I would love to hook up this material to a lightbulb in my window and save money!
That would be nice, wouldn't it. If you ever build a universe, you should definitely implement that. In this universe the laws of thermodynamics specifically forbid destroying heat, or converting it into something else.
Heat will naturally spread out evenly over time, but if we would prefer to do the opposite, moving heat where we want it (or away from where we don't want it), we need to use a heat pump which expends energy to do that, and that energy produces further waste heat which, yes, we also need to move. This is a core principle of how our universe works. Nobody is going to invent a new material that violates the laws of thermodynamics, for the same reason nobody is going to find an even integer that was hiding between 2 and 4 somehow without us noticing it.
But wait, what does a Stirling engine run on? Or a steam engine? You clearly can get some energy out of heat.
Also, objects that are hotter than absolute zero radiate infrared light — and you, in principle, could convert light, regardless of its spectrum, into electricity.
You can most certainly convert heat into something else. It's called the law of conservation of energy, not heat, which is just one form of energy.
E.g., if your machine relies on all energy in my room to spontaneously gather in my coffee mug to heat it up, while simultaneously cooling my warm room, this would be perfectly fine with conservation of energy and super useful. Unfortunately, it would also violate the 2nd law and it's thus something that doesn't happen in our universe.
Selenium is moderately available but it is toxic waste when you need to replace it (all things have finite lifespans) and then need to dispose of the discard.
[0] https://medium.com/swlh/heating-my-home-with-crypto-mining-1...
Are you telling me this sort of thing already exists today?
“It is impossible to devise a cyclically operating device, the sole effect of which is to absorb energy in the form of heat from a single thermal reservoir and to deliver an equivalent amount of work.”
For example you could convert the heat into photons (infrared radiation) and beam that out of the room without needing a pipe. You would probably need an infrared transparent patch on the window to aim at.
https://spie.org/news/5129-a-metamaterial-to-convert-heat-to...
It is a terrible analogy, a modern physicist would prefer being caught dead rather than using it, but one can think of heat as a liquid (traditionally called caloric ) stored in a vessel. Temperature is the level of the liquid. For flow you need another vessel where the level is low, that would allow flow of heat from a vessel with higher level to a lower one and one can then convert that flow into power of a form one desires. Its possible to go in the opposite direction also, that's called a heat pump. Charge and voltage would be another (incorrect) way of thinking about heat and temperature.