New Material Breaks World Record Turning Heat into Electricity • Hacker News Board

Re: New Material Breaks World Record Turning Heat into Electricity

#131

Post by hinkley » Tue, Dec 31, 2019, 7:22 PM UTC

forgotmypwd123 wrote: post #59

Dylan16807 wrote: post #29

Earlier quoted context omitted.

The thing is, a chip generally cools just fine with heat pipes and fins up to 200 or more watts. And the built-in heat spreader gets rid of hot spots very effectively. At that power level a peltier tends to be worse than useless, even if you're putting enormous amounts of power through it. Even if you double the efficiency it's still a bad option.

Overclocked threadrippers can hit 500W[1]. I can see peltiers and 'vapochill' style phase-change cooling making a comeback... 1. https://www.anandtech.com/show/13124/the-amd-threadripper-29...

I think I accept the argument that in a desktop with a giant cooler attached to the CPU, this may not improve things or make them worse.

But there are an awful lot of mobile processors with passive cooling or complex heat pipes, and it would take more convincing that such a scheme would also fail there.

I'm also wondering if it might be useful for 'race to idle' situations by extending the time until thermal throttling kicks in.

Re: New Material Breaks World Record Turning Heat into Electricity

#132

Post by Matumio » Tue, Dec 31, 2019, 7:36 PM UTC

pharke wrote: post #119

bagacrap wrote: post #104

Earlier quoted context omitted.

What would they use all that energy for, and how would they use it in a way that wouldn't radiate heat or light on par with the amount captured?

A good use might be computing power whether its for storing the minds of everyone in the civilization or powering one big mind or simulating universes or maybe it's all dedicated to finding a way to reverse entropy. If we're assuming a highly advanced civilization aiming for maximal efficiency I would hope that they have figured out how to make all of their electrical systems out of high temperature superconductors.

Is there really a way to "use" energy for computation that doesn't just convert all of it to heat?

Re: New Material Breaks World Record Turning Heat into Electricity

#133

Post by Misdicorl » Tue, Dec 31, 2019, 7:41 PM UTC

ailideex wrote: post #126

Misdicorl wrote: post #117

Earlier quoted context omitted.

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...

Except when discussing technologically hyper advanced civilizations, the 2nd law of thermodynamics is a (vaguely) reasonable place to expect our laws to break.

The 2nd law is an observed fact with very shaky theoretical underpinnings (I am not talking about the behavior which has very strong underpinnings). It appears to be an emergent behavior rather than a fundamental one. It is a surprising fact given what else we know about the universe. It breaks the time symmetry of the other laws of physics. This is akin to learning that even though the laws of physics dont break position and rotational symmetries, there is a preferred direction and spin. In fact there is a preferred spin- all neutrinos are left handed. There are huge research efforts to understand why or if there are corresponding right handed particles. Broken symmetries mean big things because as far as we can tell the universe is ruled by what symmetries exist and in what ways they are broken.

Re: New Material Breaks World Record Turning Heat into Electricity

#134

Post by abdullahkhalids » Tue, Dec 31, 2019, 7:59 PM UTC

amluto wrote: post #46

icegreentea2 wrote: post #20

Earlier quoted context omitted.

From mucking about with the device efficiency formula from wiki ( https://en.wikipedia.org/wiki/Thermoelectric_materials#Therm... ), and a change of zT from 2.5 to 5, we see a maximal possible efficiency increase of 38% (when T_c == T_h). Wiki also tells me that the best TEG modules currently lock in around 8%, so we're looking at like 10-11% at best with the new material. So from a bulk scale electricity standpoint.…

You have some kind of error here: with T_c = T_h, not only does Wikipedia’s formula give 0% efficiency, but it must : any power at all generated with no temperature difference would make a perpetual motion machine.

For T_c=293 and T_h=303, you get efficiency = 1.4% for zT=5 and efficiency = 1.0% for zT=2.5. So about a 40% relative increase as OP calculated and negligible absolute change.

Re: New Material Breaks World Record Turning Heat into Electricity

#135

Post by peter_d_sherman » Tue, Dec 31, 2019, 8:14 PM UTC

adw wrote: post #37

jcims wrote: post #7

Every time some phenomenon arises from a recipe of fairly typical materials I wonder what other surprises nature has in store for us. The idea that the crystalline structure plays a large role in the bulk thermal conductivity of the material is kind of mind-blowing at first and then retrospectively obvious.

I am twenty years removed from it, but I used to be well-informed on this kind of thing; I have a PhD in mineral physics. Let's see how well I can explain this (haven't read the article, yet, sorry! Waiting for a plane...) So you're no doubt familiar with the physics of a vibrating string; it resonates at wavelengths (length of string, 2 * length of string, 3 * length of string... n as n->inf). So you can express any…

Great information!

Also, (and I may be totally wrong about this!), the concept of Annealing from metallurgy -- seems related to that of Quartz Inversion:

https://en.wikipedia.org/wiki/Annealing_(metallurgy)

Re: New Material Breaks World Record Turning Heat into Electricity

#136

Post by asdfman123 » Tue, Dec 31, 2019, 8:19 PM UTC

grecy wrote: post #124

asdfman123 wrote: post #108

Earlier quoted context omitted.

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.

That's interesting. I'm curious about your living situation, though. Do you live out there most of the year (are you there right now?), or is it kind of a vacation home?

Sounds cool... I'm always interested in off-the-grid living arrangements.

Re: New Material Breaks World Record Turning Heat into Electricity

#137

Post by grecy » Tue, Dec 31, 2019, 8:20 PM UTC

ip26 wrote: post #128

grecy wrote: post #64

I'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.

Don't get me wrong, I'll still have a good deal of solar. I just want to supplement it in the winter, especially the ~20 hours a day when the sun is below the horizon!

Re: New Material Breaks World Record Turning Heat into Electricity

#138

Post by logfromblammo » Tue, Dec 31, 2019, 8:22 PM UTC

hinkley wrote: post #129

logfromblammo wrote: post #90

Earlier quoted context omitted.

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.

Couldn't you get around that with a really long USB-A-to-whatever charger cable?

Slapping a Stirling engine on a rocket stove just seems like a really good idea to me. My major concern would be the in-backpack weight and volume.

Re: New Material Breaks World Record Turning Heat into Electricity

#139

Post by Baeocystin » Tue, Dec 31, 2019, 8:48 PM UTC

serf wrote: post #48

Baeocystin wrote: post #22

Earlier quoted context omitted.

My camp cooler is powered by a 60W peltier. Plugs in to any automotive cigarette lighter. It will keep things refrigerator cold for as long as you want, and it's almost completely silent in operation. There's tons of different models on the market. FWIW.

>It will keep things refrigerator cold for as long as you want, and it's almost completely silent in operation. that's more a function of the insulation , rather than the cooling ability. The wattage needed for 'thermal maintenance' is far lower than needed for actually removing heat from the system. Peltiers' are kind of on the same scale of efficiency as using your car (on purpose) to cook food in the engine bay.

...and yet that is still useful enough to be the right answer for some products. For the camp cooler example, it means I don't have to waste precious space on ice packs, nor worry about water as ice melts. If I put in room temperature sodas, they will be cold within 24 hours, which is good enough to be useful. On cold days I can run it in reverse and have a hot drink at break time. And the cooler/heater itself barely adds any weight to the cooler itself.

As a side note, look up the book 'manifold destiny'. It's all about cooking with one's engine bay. An amusing read!

Re: New Material Breaks World Record Turning Heat into Electricity

#140

Post by Baeocystin » Tue, Dec 31, 2019, 8:50 PM UTC

londons_explore wrote: post #23

Baeocystin wrote: post #22

Earlier quoted context omitted.

My camp cooler is powered by a 60W peltier. Plugs in to any automotive cigarette lighter. It will keep things refrigerator cold for as long as you want, and it's almost completely silent in operation. There's tons of different models on the market. FWIW.

You realise how inefficient they are when you load it full of warm beer and run it for a few days and the beer isn't even cool yet. From that 60 watts of input power, you only get ~4 watts of cooling, and with some leaking through the walls of the box, the time to cool down something of substantial mass can be weeks. That's why you have to use a real fridge to do the work before starting the journey. And at that poin…

Obviously, using pre-cooled drinks is better, but if I put in a 12 pack of some beverage, it will be fridge-cold within 24 hours. In practice, it's never been an issue.