Just to clarify why these aren't used everywhere: heat-to-power devices act as insulation (compared to just letting the heat escape). If you have something that you're trying to keep cool, like a CPU, a system that shunts heat straight to the surroundings will always give better cooling than a system that puts layers in between. Contrariwise, if you have a need for electricity, mechanical heat engines will almost always be more efficient. Solid-state heat-to-power only makes sense in a narrow set of cases which aren't suitable for direct cooling or heat engines.
New Material Breaks World Record Turning Heat into Electricity
121–130 of 163 posts
Re: New Material Breaks World Record Turning Heat into Electricity
#122Earlier quoted context omitted.
> Would they be able to capture enough energy so their star would be indistinguishable from the ambient temperature of space? You would still see infrared: https://en.wikipedia.org/wiki/Fermi_paradox#Conjectures_abou... > Such a feat of astroengineering would drastically alter the observed spectrum of the star involved, changing it at least partly from the normal emission lines of a natural stellar atmosphere to thos…
Only if the 2nd law of thermodynamics holds. When speculating about advanced civilizations building Dyson spheres, why not speculate about the bedrock of science as well? There are (probably) other paths to avoiding this conundrum as well. Spitballing here, but perhaps the 'satellites' in this case can be pairs of orbiting black holes which emit the waste heat in a band we don't detect (gravitational waves).
I always forget about the concept of gravitational engineering, probably because it's just a bit scary to think about the unknowns involved. If you could mass produce small black holes and position them you could pretty easily construct giant lenses capable of redirecting the output of a star to anywhere you please. That's more than a little terrifying.
Re: New Material Breaks World Record Turning Heat into Electricity
#123Earlier quoted context omitted.
> Won't this reduce the thermal output of your stove quite significantly I'm going to chime in and say that I think it will be insignificant. I don't know for sure, but I really doubt you could do much to cool the stove. When it's cold in the Yukon, I'm literally stuffing in ~8-10 big logs every ~12 hours. It's not at all uncommon for the base of the chimney to be glowing red. Obviously not ideal, but it happens. Whe…
Thermoelectrics have terrible efficiency, that's why they're hardly used despite the fact that waste heat is literally everywhere. Your computer, your phone, your car engine, everywhere there is energy to be recovered. In theory, any heat-based powerplant could use them, but instead they all boil water and drive steam through turbines, which is much more efficient.
> Thermoelectrics have terrible efficiency
I agree with what you're saying, but the point is that the woodstove is running 24x7 in the winter, and the solar is very pool. Whatever energy I can get from the TECs is an order of magnitude more than I'll be making without them - i.e. zero.
Re: New Material Breaks World Record Turning Heat into Electricity
#124Earlier quoted context omitted.
Hello fellow Canadian :) Wouldn't a home made Sterling Engine be easier and cheaper? Then use the motion to power a small generator. But like others commented you may just end up cooling your stove. The Yukon can get pretty cool. Maybe an old washer motor, a prop to generate power from wind? Or solar in the summer when light is ample.
Yeah, I've seen people who use small wind turbines to generate electricity far north. Seems like the best way to do it.
They're very noisy, and you have to get them above the trees, which is quite high. Also where I live is not very windy.
Re: New Material Breaks World Record Turning Heat into Electricity
#125Earlier quoted context omitted.
> Won't this reduce the thermal output of your stove quite significantly I'm going to chime in and say that I think it will be insignificant. I don't know for sure, but I really doubt you could do much to cool the stove. When it's cold in the Yukon, I'm literally stuffing in ~8-10 big logs every ~12 hours. It's not at all uncommon for the base of the chimney to be glowing red. Obviously not ideal, but it happens. Whe…
Thermoelectrics have terrible efficiency, that's why they're hardly used despite the fact that waste heat is literally everywhere. Your computer, your phone, your car engine, everywhere there is energy to be recovered. In theory, any heat-based powerplant could use them, but instead they all boil water and drive steam through turbines, which is much more efficient.
Thermoelectrics you can order from a catalog have real world efficiency ~6%, which is on the order of what a well engineered practical Sterling engine will do for converting heat to electricity without any moving parts to wear out, exotic working fluids/seals, or ... complete lack of supply chain for any of the above. If this new material pans out it could be on the order of 24% efficient, which would be preposterously better than any heat engine you can fit in an Alaska cabin.
I hate the computer programmer weeb meme of suggesting a Sterling engine for every damn thing. None of you jokers suggesting this has ever built a real world heat engine, let alone attempted to engineer an efficient one from scratch, which is what you'd be doing in the case of log cabin Sterling engines. There are excellent reasons they're not commonly used, and less thermodynamically efficient external combustion engines (like steam) are used. The problems with making them work efficiently are immense.
Re: New Material Breaks World Record Turning Heat into Electricity
#126Earlier quoted context omitted.
> Would they be able to capture enough energy so their star would be indistinguishable from the ambient temperature of space? You would still see infrared: https://en.wikipedia.org/wiki/Fermi_paradox#Conjectures_abou... > Such a feat of astroengineering would drastically alter the observed spectrum of the star involved, changing it at least partly from the normal emission lines of a natural stellar atmosphere to thos…
Only if the 2nd law of thermodynamics holds. When speculating about advanced civilizations building Dyson spheres, why not speculate about the bedrock of science as well? There are (probably) other paths to avoiding this conundrum as well. Spitballing here, but perhaps the 'satellites' in this case can be pairs of orbiting black holes which emit the waste heat in a band we don't detect (gravitational waves).
> Only if the 2nd law of thermodynamics holds. When speculating about advanced civilizations building Dyson spheres, why not speculate about the bedrock of science as well?
If the person I replied to qualified their comment with "lets assume laws of physicis is not relevant" then sure...
Re: New Material Breaks World Record Turning Heat into Electricity
#127Earlier quoted context omitted.
The plan is to have a tank of glycol coolant sitting outside (at around -20C to -40C ambient) and mount a radiator outside. I'll use a fish tank pump or similar to circulate the coolant. Put water cooling blocks onto the TECs so the wood stove heats one side to around 100C to 200C, and the cold coolant coming in brings it back down, to hopefully get a temperature difference in the range of 100C (ish). It's all just a…
You could use the waste heat that goes up the chimney to warm the fluid with something like an automotive intercooler and set the system up backwards, maybe?
Ohhh, I hadn't thought of that idea. Interesting. I will be sure to experiment with that!
Re: New Material Breaks World Record Turning Heat into Electricity
#128I've always wanted to build a little hobby project where I put TECs on top of my wood stove and have a radiator outside with coolant to get a nice big heat difference (maybe 100C to 200C) across them and make power in winter when solar isn't so great in the Yukon. I know it won't be a massive amount of power, but given it will be 24/7 for about 6 months of winter when the wood stove runs, I think it will be a useful…
Solar & lithium batteries are so cheap from scale, it's worth comparing the cost, even though production is very low in winter.
Re: New Material Breaks World Record Turning Heat into Electricity
#129I've always wanted to build a little hobby project where I put TECs on top of my wood stove and have a radiator outside with coolant to get a nice big heat difference (maybe 100C to 200C) across them and make power in winter when solar isn't so great in the Yukon. I know it won't be a massive amount of power, but given it will be 24/7 for about 6 months of winter when the wood stove runs, I think it will be a useful…
Co-generate with a Stirling engine or steam turbine. Your application is the wrong scope for TECs. It will be a hundred times more expensive, and a tenth of the efficiency.
Last time I was looking at efficient camp stoves I ran into this guy:
https://www.bioliteenergy.com/products/campstove-2
The idea of putting my phone, or any lithium battery really, that close to fire... this plan is not for me.
Re: New Material Breaks World Record Turning Heat into Electricity
#130Just to clarify why these aren't used everywhere: heat-to-power devices act as insulation (compared to just letting the heat escape). If you have something that you're trying to keep cool, like a CPU, a system that shunts heat straight to the surroundings will always give better cooling than a system that puts layers in between. Contrariwise, if you have a need for electricity, mechanical heat engines will almost alw…
But there are some pretty cool applications. Apparently the heat difference between a buried water-pipe and the surrounding earth is already enough to power a wireless sensor, which can transmit data to localize leaks, for example.