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Material Breaks Record For Turning Heat Into Electricity

Soulskill posted about a year and a half ago | from the hot-shocking-news dept.

Science 102

ananyo writes "A new material has broken the record for converting heat into electricity. The material had a conversion efficiency of about 15% — double that of one of the most well-known thermoelectrics: lead telluride (abstract). For decades, physicists have toyed with ways to convert heat into electricity directly. Materials known as thermoelectrics use temperature differences to drive electrons from one end to another. The displaced electrons create a voltage that can in turn be used to power other things, much like a battery. Such materials have found niche applications: the Curiosity rover trundling about on the surface of Mars, for example, uses thermoelectrics to turn heat from its plutonium power source into electricity. That doesn't mean that the material is ready to be used on the next Mars rover, however: NASA has been looking at similar materials for future space missions, but the agency is not yet convinced that they are ready for primetime."

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102 comments

heatsinks (3, Interesting)

Anonymous Coward | about a year and a half ago | (#41393589)

What stops this and materials like it from being used as heat sinks to recover some of the energy lost?

Re:heatsinks (5, Informative)

Anonymous Coward | about a year and a half ago | (#41393663)

In a heat-sink you want to carry heat away from an object. A termoelectric is by definition a poor heat-sink because it requires a temperature gradient to work. This gradient means that the material is a poor conductor of heat. If it were a good conductor then both sides would quickly reach the same temperature and it would stop working.

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41393743)

In a heat-sink you want to carry heat away from an object.

You are converting the heat to electricity which you can pipe anywhere you can run wires.How is that not carrying the heat away??

A termoelectric is by definition a poor heat-sink because it requires a temperature gradient to work. This gradient means that the material is a poor conductor of heat.

There's a temperature gradient between the ambient air and the heat generator that you typically attach your heat sink to. It's the exact same temperature gradient that heat sinks work off of.

If it were a good conductor then both sides would quickly reach the same temperature and it would stop working.

If both sides got to the same temperature then you would stop producing electricity, and your device would be maximally* cool, which is exactly what you're looking for.

* Of course you can get cooler by dumping ice or liquid nitrogen or any cold thing on it, but it is maximally cool for the device, which is to say, ambient temperature.

Re:heatsinks (5, Informative)

Anonymous Coward | about a year and a half ago | (#41393851)

You seem to have a very poor grasp pf thermodynamics but to put it simple I will refer to the article itself.

"Building a better thermoelectric depends on finding materials that conduct electricity, but not heat"

There it is in plain language. Thermoelectrics are poor conductors of heat.

Also, nearly everything you say in your post is simply wrong. You do not convert heat into electricity. You use a heat gradient to cause an electric field. The electrons flow out one side and return to the other. You are not "piping" heat anywhere.

Thermo-electrics do not run on the heat gradient between themselves and the air. They run on the heat gradient between two sides of the material itself. I can have a block of ceramic at relatively uniform 1000C without it being 'maximally cool'.

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41394717)

You seem to have a very poor grasp pf thermodynamics... You do not convert heat into electricity.

Then pray tell where exactly does the energy for your electric field come from?
It appears that it is you who is not familiar with the 1st law of thermodynamics, or rather more specifically, the law of conservation of energy. [wikipedia.org]
The heat will magically reappear wherever the resulting current is used. So at 15% efficiency you will effectively be removing 15% of the heat so long as the current is used somewhere outside of the system.

Re:heatsinks (1)

microbox (704317) | about a year and a half ago | (#41395049)

The point is that removing 15% is extremely poor performance compared to what a heat sink gives you.

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41395093)

That is today. Down the road, it might be possible to raise it.

Now, I wonder what would happen if a heat sink was put on the other side? IOW, create a greater gradient.

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41395447)

The point is that removing 15% is extremely poor performance compared to what a heat sink gives you.

I wasn't disputing that it would make a lousy heat sink, rather nitpicking the supposed "expert" in thermodynamics. Of course I know next to nothing about the subject except for the fact that thermal energy is indeed converted to electrical energy somewhere in the process.

And of course being able to convert thermal energy at near perfect efficiency would be a data center operator's wet dream. Personally I'd love to see the process occur at room temperature, but probably not in my lifetime.

Also why can't it be combined with a traditional heat sink? Just wondering.

Re:heatsinks (1)

Anonymous Coward | about a year and a half ago | (#41395627)

Unfortunately, you are just incorrect.

Thermal energy is not being converted. The whole thermocouple system ends up with the same or more heat no matter how much electricity is extracted. The energy is coming from an excited state (hot on one side, cold on the other) tending towards a base state (uniform temperature). It is just like extracting energy from a stretched rubber band, stretched it is in an excited state, you can extract energy from it as it unstretches, but there is still the same rubber band in the end.

It takes energy to set up a temperature gradient in the first place, and that is the energy you are extracting with this, not the heat itself, but the stored energy of the temperature differential.

Re:heatsinks (-1)

Zouden (232738) | about a year and a half ago | (#41396335)

The second law of thermodynamics [wikipedia.org] states that you can't convert thermal energy into any other form. Sorry.

Re:heatsinks (1)

Anonymous Coward | about a year and a half ago | (#41396935)

Read your own second law more closely.

Clausius statement

The German scientist Rudolf Clausius laid the foundation for the second law of thermodynamics in 1850 by examining the relation between heat transfer and work.[5] His formulation of the second law, which was published in German in 1854, is known as the Clausius statement: "Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time."[6] This may be restated as[4]
âoe No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature. â

Heat cannot spontaneously flow from cold regions to hot regions without external work being performed on the system, which is evident from ordinary experience of refrigeration, for example. In a refrigerator, heat flows from cold to hot, but only when forced by an external agent, the refrigeration system.
Kelvin statement

Lord Kelvin expressed the second law as "It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects.[7] This may be restated as[4]
âoe No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work. â

Re:heatsinks (2)

serviscope_minor (664417) | about a year and a half ago | (#41397157)

The second law of thermodynamics states that you can't convert thermal energy into any other form. Sorry.

Wow, this is one of the more bizarre claims on slashdot today.

By the way, do you own a car with an internal combustion engine?

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41399797)

The second law of thermodynamics [wikipedia.org] states that you can't convert thermal energy into any other form. Sorry.

I believe I see what you're trying to say... uniform heat energy spread completely evenly throughout a medium cannot do work (without external changes) because it has already achieved a maximum state of entropy. Hence, the thermal gradient is required.

That's my limited understanding / guess anyway.

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41395609)

No. that is not how it works at all.

It is more like a hydroelectric dam. Heat wants to move from somewhere warm to somewhere cold until everything is the same temperature. Water wants to move from someplace high to someplace low due to gravity. If you want, you can put a generator in the path of the water, it slows down the flow and produces electricity as a byproduct you can use somewhere else. Likewise you can stick a thermocouple between something hot and something cold and it will produce electricity as a byproduct as the heat just goes where it wanted to go anyway.

However, the electricity isn't piping away "heat" in the second case any more than it is piping away water in the first one. Likewise, the water will keep flowing generator or no, and the temperature will equalize whether you put a thermocouple there or not, it may however change the rate at which those things happen.

Re:heatsinks (2)

deroby (568773) | about a year and a half ago | (#41397309)

This is kinda interesting... Having read all above I think most of the confusion is in semantics, especially about the term 'heat'. Wikipedia describes it as " energy transferred from one system to another by thermal interaction" and that doesn't really make it easy to talk about it. So for my own mental sanity I'll allow myself to rather abuse the term 'heat-transfer' then which makes it easier to understand although at the same time I realize that it's akin to saying something like 'a fluid liquid' which sounds wrong too if you start thinking about it.

Anyway, in order to satisfy my (very naive) curiosity : let's assume the following experiment :

1) a 'small block' of copper is squeezed in between two equally sized vessels of water, one having a temperature of 10`C, the other 90`C.
2) a 'small block' of the article-material is squeezed in between two equally sized vessels of water, one having a temperature of 10`C, the other 90`C.
3) a 'small block' of the article-material is squeezed in between two equally sized vessels of water, one having a temperature of 10`C, the other 90`C and the 'wires are attached' resulting in a small lamp being powered in the next room.

It seems fair to assume that situations 1 and 2 will both result in everything ending up at about 50`C assuming the 'small blocks' are really very small in relation to the vessels of water and hence have (virtually) no effect on the "calorimetric sum" of the entire setup. The main difference being that they probably will require a (very?) different time-span to reach equilibrium. I guess we have no issues there ?

Likewise, it seems 'logical to me' that the energy required to light the lamp must come from 'somewhere' in situation 3. Hence, the end-state of the third setup then must end up with a lower total energy because some of it was piped away in the form of electricity. This leads me to assume that in the end, the system will end up in an equilibrium of somewhere in the upper forties degrees C at what time no electricity will be 'generated' any more.

Given that in the last setup the 'cold' side ends up at a lower temperature than in the first two setup, I too 'feel' that less heat is transferred. However, from a point of view of the (initially) hot vessel in situation 3, actually MORE heat was transferred as the end situation is at a lower temperature than the other setups so more energy was drained from it.

So both sides are correct : both less AND more heat was transferred =)

Right ?

reverse heatsink (1)

DarthVain (724186) | about a year and a half ago | (#41400559)

Would this function sort of like a reverse peltier once used for cooling on CPU back in the day? So more like a reverse heatsink.

With a peltier, you actually applied current, and the current would produce heat on one side of the peltier (to be dispersed using a fan), whilst the other side would become cool, lowering the tempature of the CPU in question.

Here it would seem to work in reverse with these materials, whereby heat is applied to the material, and as a result of the poor heat conduction, an electical current is generated?

It is too bad the efficiency is so low, I can see many poissibilities for such a device simply using waste heat of various objects.

Re:heatsinks (1)

Rockoon (1252108) | about a year and a half ago | (#41393855)

If both sides got to the same temperature then you would stop producing electricity, and your device would be maximally* cool

...or maximally hot.

Re:heatsinks (1)

thejuggler (610249) | about a year and a half ago | (#41393701)

Nothing really - that would be a very creative use to recapture some lost energy dissipated as heat. But at 15% efficiency it's possible that it's not feasible to add into any device. Besides the thermoelectric material you have to have an addition circuit to capture the energy and a battery storage. If the device already has a battery then it needs to be rechargeable. Its likely that this would act more as a trickle charge than a full fledge charger. In my reading of TFA I did not notice a temperature range that these thermoelectric materials need to operate within.

Re:heatsinks (2)

Rei (128717) | about a year and a half ago | (#41395385)

One thing that this article isn't really consistent on is whether this is 15% of the Carnot efficiency for a given temperature gradient or 15% of the total difference in temperature between the two thermal reservoirs. Also, its performance under different temperature conditions can be very important for some applications, but that's not made clear.

And for anyone saying "it's not an engine, Carnot doesn't come into account".... wrong. It amazes me how many people think this. Carnot's law applies to any generation of work from heat, period. If you can break Carnot's law, no matter with what sort of device, you can create a perpetual motion machine - that is, you could have your work generated from heat run a high-COP heat pump to pump heat back up against the gradient to keep your machine running. Remember that heat pumps can have COP notably greater than 1.0 - that is, they often can move several times more energy against the gradient than goes into running them. To put it another way, a heat engine will never be able to harness more work from a given temperature gradient than the maximal-efficient heat pump for the same temperature differential.

Re:heatsinks (1)

evilviper (135110) | about a year and a half ago | (#41399827)

Carnot's law applies to any generation of work from heat, period. If you can break Carnot's law, no matter with what sort of device, you can create a perpetual motion machine

While I don't see anything technically incorrect in your post, I'd just like to point out that Carnot doesn't apply to photovoltaics.

And PVs are very relevant both because they can operate on infrared (something which the unsophisticated would just call "heat"), and also because they have been eyed for quite some time as a replacement (or supplement) for TECs in RTGs and similar applications.

Re:heatsinks (1)

marcosdumay (620877) | about a year and a half ago | (#41402081)

Yes, it does apply to photovoltaics. Altough they can operate at the infrared, they can't turn into energy the emisions of a body at the same temperature that they are. And they lose efficiency when the gradient reduces, above what Carnot's law postulate as a minimum (in iother words, they are always worse than Carnot cycle).

They'd be interesting at nuclear batteries because the origial radiation of a nuclear reaction has an extremely hight temperature. If you can deal with it without turning it into heat, you can achieve great efficiencies.

Re:heatsinks (2)

Rockoon (1252108) | about a year and a half ago | (#41393829)

It should be noted that this article is about materials that perform the job of converting temperature gradients into electricity directly. Other methods of doing so are still more efficient (see your local coal, oil, gas, or nuclear plant.)

Re:heatsinks (1)

sumdumass (711423) | about a year and a half ago | (#41394907)

Well, yes, but what if you can encase them in the lining of an industrial chimney or along the steam lines leaving the turbine generators of the coal, oil, gas, or nuclear plants.

I think what the op was getting at was recovering energy from waste heat streams. The term heat sink I think was more illustrative of a process of waste heat rather then a function of gathering energy.

Let's assume your hybrid electric car has a gas engine. What is we ran the exhaust alongside some materials like this so not only do you get a power boost when the engine kicks in to charge or add more power as needed, you get a charge from the waste stream of the process too (sort of like regenerative breaking for internal combustion engines).

Re:heatsinks (4, Informative)

dbIII (701233) | about a year and a half ago | (#41394971)

Well, yes, but what if you can encase them in the lining of an industrial chimney or along the steam lines leaving the turbine generators of the coal, oil, gas, or nuclear plants.

Interesting idea, but a similar thing has been done for a century+ with the outgoing steam being used to preheat the incoming water. There's orders of magnitude of difference in energy gained between that and thermocouples at huge scales. However at small scales a steam plant is not possilbe while a thermocouple is.

Re:heatsinks (1)

scary_jeff (538884) | about a year and a half ago | (#41398037)

Don't forget that heat in a chimney is often not wasted energy. When burning fuel, you can lose more in the reduction in burner efficiency, caused the lack of draw that results from a cool chimney, than you gain from 'recovering' energy out of the chimney.

Re:heatsinks (1)

jank1887 (815982) | about a year and a half ago | (#41398091)

"What is we ran the exhaust alongside some materials like this"

you mean like this:
http://www.gentherm.com/page/automotive-0 [gentherm.com]
http://phx.corporate-ir.net/phoenix.zhtml?c=107768&p=irol-newsArticle_print&ID=1326140&highlight= [corporate-ir.net]
http://www.greencarcongress.com/2011/08/bmwthermal-20110830.html [greencarcongress.com]

or this:
http://www.serdp.org/Program-Areas/Energy-and-Water/Energy/Conservation-and-Efficiency/EW-1651 [serdp.org]
http://www.navysbir.com/10_3/8.htm [navysbir.com]
http://adsabs.harvard.edu/abs/2012SPIE.8377E..15S [harvard.edu]

The problem is usually in actually getting that level of total conversion efficiency. By the time you take all of the efficiency chain fractions into account, you're far below the theoretical 15% (which only occurs at peak, steady conditions).

Re:heatsinks (1)

Baloroth (2370816) | about a year and a half ago | (#41394077)

IIRC some laptops do exactly this to recover energy. However, it isn't terribly effective or cost-efficient. You certainly can, though (tends to reduce the effectiveness of the sink as well, although that depends on the exact design.)

Re:heatsinks (1)

jank1887 (815982) | about a year and a half ago | (#41398109)

I would love to know which laptop models are using this or similar heat recovery technology.

Re:heatsinks (1)

Baloroth (2370816) | about a year and a half ago | (#41398757)

Hmm, now that I google it looks like my memory may have been bad. I remember there was plans to do this on some laptops (ultrabooks specifically, I think), but looks like they never followed through. Or I just can't find them.

Re:heatsinks (2)

macraig (621737) | about a year and a half ago | (#41394233)

No. You would be attaching a heat sink to one side of this material if, as is most likely, you were going to use it to cool something by driving current through it. That works in reverse when you "flip it over". The most likely first commercial uses of it would be to replace current "Peltier" thermoelectric devices in computer component "coolers" and the portable electric "ice chests" that are actually capable of heating or cooling contents. If this is a more efficient conversion without being much more expensive, then it realizes a power savings for those devices.

The application TFS is describing for the material is analogous to turning a motor into a generator: instead of current being the input and a temperature gradient across the device being the output, temperature differential becomes the input and a generated current the output.

Re:heatsinks (4, Informative)

Requiem18th (742389) | about a year and a half ago | (#41394531)

Poor AC getting so mean comments.

Actually you ARE right, but only from a certain point of view. Firstly, you are right that thermoelectric materials take heat away, and thus cool down whatever they are attached to.

The critical point here is that merely cooling down is not enough for a heat sink. The heat sink has to be cooled down FAST. Faster than it's heat source is heating it. Thermoelectrics just can't turn heat into electricity fast enough to let a heat sink do it's job.

So it's not really a matter of thermoelectrics heating up heat sinks, they don't heat them up, they in fact cool them down, what is heating up the heat sink is the heat source (say a CPU or a power engine).

The problem is that no thermoelectric so far can transform heat intro electricity faster than a CPU turns electricity into heat.

Re:heatsinks (1)

jhol13 (1087781) | about a year and a half ago | (#41395145)

But it might me usable in cars. AFAIK there are already systems which generate electricity from exhaust heat.

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41396457)

The problem is that no thermoelectric so far can transform heat intro electricity faster than a CPU turns electricity into heat.

Ah, but grasshopper, you started out with electricity, why then change it into heat in the first place if you cannot change it back ?

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41396953)

That's not thinking about the possibility of putting several heat receivers along a heat sink system.

Spread the load. It may not be cost-feasible for say a home PC, but for systems that require ultimate efficiency at ultimate cost?

Re:heatsinks (5, Interesting)

Thammuz (970395) | about a year and a half ago | (#41397103)

Long time lurker, commenting because I know something about this one (doing my PhD in thermoelectrics).

First of all, you _can_ use thermoelectrics to cool things like CPUs or fridges, but don't expect to generate any energy from them when you do it because you need to be putting electricity into the system, essentially carrying the thermal energy with it. You will cool one end and heat the other end. If you've ever heard of a Peltier cooler then you know what I am talking about.

A good background can be found here: http://thermal.ferrotec.com/technology/thermal/thermoelectric-reference-guide/ [ferrotec.com]

Second, this is something people have been messing around with the nanostructure of tellurium alloys for ~20 years or so, with the sole purpose of reducing thermal conductivity. The figure of merit for thermoelectrics is ZT = thermopower^2 x electrical conductivity x temperature / thermal conductivity. You can't increase electrical conductivity without reducing thermopower and increasing thermal conductivity (as there is a lattice and an electrical contribution). Thermopower is more or less a function of the number of carriers (lower is better) and their effective mass, so this is difficult to increase without durastic changes in the crystal structure or killing electrical conductivity. This leaves thermal conductivity. If you increase disorder in the material you make it harder for thermal energy to travel through it, which as lead to lots of research on how you manage this without messing up your carrier conduction. These are known as PGEC (phonon glass electron crystal) materials.

Third, there are lots of applications of these (in heating/cooling and power conversion) if they can be made efficient and cheap. Anywhere you have a heat source pretty much. To use the classic car analogy, BMW, Ford, GE (amongst others) are looking at using a thermoelectric module to generate power for the car from the waste heat in the exhaust gases from the engine. This would increase the power of your engine by removing the alternator and also make the car lighter.

The problem is the efficient and cheap part. These kinds of thermoelectrics are based on tellurium, an element about as abundant in the earth's crust as platinum, but to my knowledge isn't specifically mined for. Most other elements involved are toxic heavy metals (Pb, Sb, Bi, etc.)... so these aren't exactly nice things to have around or to make.

This is where oxides come in. Made of lighter, more abundant, less toxic elements they are much cheaper to make (not just sourcing the materials, heath and safety too etc.), and are stable at much higher temperatures. As you know from Carnot, the higher the temperature a heat engine works at the more efficient it becomes; rather than 900 K (600C) you're looking at more like 1300 k (1000C) and upwards. Current high ZT oxides are things like NaxCoO2 and Ca3Co2O6, which have layered structures; one part is great at absorbing thermal energy (due to Na disorder for example) and the other is good at conducting electricity (like the CoO2 portion of NaxCoO2)

TL;DR
The way I see this paper: great proof of concept, PGECs are doing what they say on the tin and this will be great for low T applications. But for high power generation we need something more like the oxides which are cheaper, easier to produce, and work at higher temperatures.

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41399907)

Thanks for the expertise!

Re:heatsinks (0)

Anonymous Coward | about a year and a half ago | (#41408807)

Most other elements involved are toxic heavy metals (Pb, Sb, Bi, etc.)

Bismuth is entirely non-toxic, which is surprising given it's neighbors in the periodic table. Anitmony isn't that toxic, either, though we do not use it to treat gastric ulcers.

Re:heatsinks (1)

strikethree (811449) | about a year and a half ago | (#41400147)

I suspect what they were getting at is using waste heat from the CPU (and GPU). So instead of calling this material a heat sink, you have it draw heat away from the heat sink. It would only be one source of heat draw so the heat sink will still be efficient at what it does... but, you recover some energy in the process.

You could use the energy for cool lighting effects in the case or to help power a cooling solution (fan?), or just feed it back in to the power supply to reduce the draw at the wall outlet. *shrug* I dunno. Just running with it.
 

Re:heatsinks (1)

chilenexus (2660641) | about a year and a half ago | (#41402217)

These devices need a difference in temperature, so in use they actually have heat sinks of their own on the cool end of them - they sit between a heat source and the heat sink, but I don't know that they'd conduct enough heat to the heat sink to be used on something like a processor. The use of thermoelectrics isn't new - much of the equipment the astronauts used on the moon were powered by RTGs, and the CIA lost some spy equipment in India that was spying on the Chinese back in '64 ( http://www.damninteresting.com/spies-on-the-roof-of-the-world/ [damninteresting.com] ).

Space missions?! (0)

Anonymous Coward | about a year and a half ago | (#41393605)

Just think of the applications in things like hybrid cars! All that heat from the engine and braking can be used for charging the batteries.

And of course the tech is being developed for the Space Program.

*Space Program* - people - NOT a waste!

Timer ticking down ..... Don't make me imitate Neil deGrasse Tyson! Actually, I can't. He's smarter and MUCH better spoken than I am.

Very cool (1)

multiben (1916126) | about a year and a half ago | (#41393609)

But what I can't tell FTA is whether or not the process of dis-ordering the material to prevent heat transfer also degrades the electrical conductivity. Obviously there is an over-all benefit, but I can't imagine that it is not affected at all.

Re:Very cool (1)

mspohr (589790) | about a year and a half ago | (#41394125)

The article states that dis-ordering the material reduces heat transfer but not electrical conductivity. (They added some sodium to improve electrical conductivity.)

What's the rationale of using it in Curiosity? (0)

Anonymous Coward | about a year and a half ago | (#41393661)

From what I understand, 15% efficiency is quite low by today's standards and Mars rover seem to be this kind of scenario where you would save every bit of energy available.

Re:What's the rationale of using it in Curiosity? (1)

Githaron (2462596) | about a year and a half ago | (#41393831)

I am guessing they were trying to lower system dependencies. The more parts you have (especially moving parts) the more chances for failure.

Re:What's the rationale of using it in Curiosity? (1)

hrvatska (790627) | about a year and a half ago | (#41393965)

My guess would be that while the efficiency is low the reliability is extremely high, due to a lack of moving parts.

Re:What's the rationale of using it in Curiosity? (1)

Formalin (1945560) | about a year and a half ago | (#41394287)

They're talking about the thermocouples inside the RTG power source, I presume... 15% is shitty, but it's still 'free' power. Beats the alternatives of batteries, unwieldy solar panels, etc.

MMRTG [wikipedia.org]

Re:What's the rationale of using it in Curiosity? (1)

jadrie (1928444) | about a year and a half ago | (#41394399)

Not to mention that waste heat that doesn't get turned to electricity still gets used - by pumping it along the rovers extremities to help keep the temperature more tolerable for the equipment.

Plutonium Power Source?! Sweet (0)

LifesABeach (234436) | about a year and a half ago | (#41393711)

...uses thermoelectrics to turn heat from its plutonium power source into electricity...

I've love to drop a Plutonium power source into a Rover Discovery. There would be no place on Mars I couldn't drive to. As long as Chevron/BP/Shell never got wind of it.

Re:Plutonium Power Source?! Sweet (3, Informative)

sphealey (2855) | about a year and a half ago | (#41393973)

Discovery in fact uses a radioisotope thermal generator (RTG) with plutonium as the power source. It used a substantial fraction of the Pu-238 available for space missions.

sPh

Re:Plutonium Power Source?! Sweet (1)

FunkDup (995643) | about a year and a half ago | (#41394905)

Did you mean

Curiosity in fact uses a radioisotope thermal generator...

Re:Plutonium Power Source?! Sweet (0)

Anonymous Coward | about a year and a half ago | (#41396987)

I'm curious why 238 would be difficult to procure for space missions? It's a byproduct.

figure this out for the robots, did we? (0)

gsgriffin (1195771) | about a year and a half ago | (#41393713)

Once again, another article that shows how we are figuring it all out for the robots now. Scorching the skies to try to cut off their power source from the sun won't do much good as we will now make getting electricity from the heat produced by humans all the easier.

Re:figure this out for the robots, did we? (0)

Anonymous Coward | about a year and a half ago | (#41394595)

I recommend you take the blue pill.

Hooray for global warming! (0)

Anonymous Coward | about a year and a half ago | (#41393721)

First, we burn all the hydrocarbons to maximize the CO2 and heat retention capabilities of the atmosphere. Then, we use all the blessed heat to create electricity. It's the gift that keeps on giving!

Re:Hooray for global warming! (1)

Githaron (2462596) | about a year and a half ago | (#41393847)

If maximizing heat trumps everything else, why not just push the planet into the Sun?

Temperature != Heat (1)

mosb1000 (710161) | about a year and a half ago | (#41394315)

Heat is the transfer of energy [wikipedia.org] . It is not the the energy itself.

Re:Temperature != Heat (0)

Anonymous Coward | about a year and a half ago | (#41395479)

Heat is the transfer of energy [wikipedia.org]. It is not the the energy itself.

From your link [wikipedia.org] (emphasis mine):

Heat is energy transferred from one system to another by thermal interaction

Re:Temperature != Heat (1)

mosb1000 (710161) | about a year and a half ago | (#41395659)

In physics, "heat" is by definition a transfer of energy and is always associated with a process of some kind.

Temperature (0)

Anonymous Coward | about a year and a half ago | (#41395503)

is a measurement of heat, aka thermal energy.

Re:Temperature (1)

mosb1000 (710161) | about a year and a half ago | (#41395679)

No, it isn't. Heat is a transfer of energy. Read the Wikipedia article if you don't believe me.

Re:Temperature (0)

Anonymous Coward | about a year and a half ago | (#41400135)

No, as a physicist... that is wrong. And from the looks of Wikipedia's talk page, many agree with me, and there is a stubborn editor that keeps trying to change it back to transfer.

Some half-assed quick ways to differentiate: heat is measured in joules, units of energy, while heat transfer (... the necessity of the word transfer should suggest heat alone is not a transfer) would be measured in watts, units of change in energy with time.

Re:Temperature (1)

mosb1000 (710161) | about a year and a half ago | (#41405231)

No, a energy transfer can be measured in joules. Take heat of combustion [wikipedia.org] for example. It is usually measured in J/mol or J/kg. You couldn't possibly measure it in watts because you have no idea how long combustion takes to occur. Nevertheless it is a transfer of energy:

The heat of combustion is the energy released as heat when a compound undergoes complete combustion with oxygen under standard conditions.

In reality, this argument is not really about whatever common definitions physicists use. It is a philosophical one. There is little reason to consider how much energy may exist in a system unless such energy is available to use. That being true, any meaningful use of the term "heat" will refer to it in the context of transferring it from one body to another, so there is little reason to define heat in any other context.

As a chemical engineer, I find your claim that most physicists use your definition appalling, given the amount of training in thermodynamics you must have had. In any case, all the authoritative sources I've consulted have agreed with my definition.

Obvious application (0)

dkleinsc (563838) | about a year and a half ago | (#41393739)

One potential use of these sorts of materials is to power Washington D.C. on the hot air generated by politicians. Hey, we might as well have them do something useful for a change!

Sounds Pretty Good Actually.. (0)

tetrahedrassface (675645) | about a year and a half ago | (#41393773)

I'll take some 15% more efficient LED bulb, and a 15% more efficient Central Heat and Air unit.. What about a 15% more efficient datacenter and laptop too while we are at it. The key to financial gain is either low cost energy or higher efficiency and the former isn't going to happen ever in my life, so yeah.. this is a good thing even back on Terra Firma. Of course real world applications may only have 8 or 6% gains, but still that's a big recovery if you suddenly added it to every gadget in the United States...

Sent from my Pantech that hasn't been the same since it fell in the pool.

Re:Sounds Pretty Good Actually.. (1)

rroman (2627559) | about a year and a half ago | (#41393823)

Well, I wouldn't agree that this material could be used in so many places to retrieve the used energy back. For example you might need to wrap it around the light bulb to get the energy back, but the material might not be transparent.

Re:Sounds Pretty Bad Actually.. (0)

Anonymous Coward | about a year and a half ago | (#41394049)

lots of countries it doesnt matter wasted energy in lights turn to heat and it in return reduces the need to heat the housings... (country where i live might be hitting 10-11 months a year electric lightning isnt wasted at all) esp becouse the sunshines 24/7 during midsummer :D

despite this fact that when we actually need lights indoors the waste energy is converted to heating is in deed used fully almost like 95% of time in year, and they go huge hulabaloo of energy saving lamps etc pretty funny how retarded people are.

also one must apply Production costs&salaries if were talking about net savings of system overall, often stuff is expensive because manufacturing consumes heaps of energy and then there the western engineers get paid well and travel all around world to spend their moneys(this is also nearly impossibility for green party hippies to understand)
 

Re:Sounds Pretty Good Actually.. (0)

Anonymous Coward | about a year and a half ago | (#41393891)

How about using 15% of the excess heat from a power plant.

The material (0)

Anonymous Coward | about a year and a half ago | (#41393803)

The useless summary didn't say, but I read TFA and it says the material is a mix of Na-doped PbTe and SrTe.

Great (0)

Anonymous Coward | about a year and a half ago | (#41393913)

Can we line the Congress with this and solve the energy problem?

Efficiency in sensible units (4, Informative)

johndoe42 (179131) | about a year and a half ago | (#41393923)

TFA does a good job of using units that are incomprehensible to anyone who isn't an expert in thermoelectrics. But we can convert them...

Considering a thermoelectric device with a cold-side temperature of 350K and a hot-side temperature of 950K, respective waste-heat conversion efficiencies of ~16.5% and ~20% are predicted.

For a hot-side temperature of 950 K and a cold-side temperature of 350 K, the Carnot efficiency [wikipedia.org] (i.e. the maximum possible efficiency of any device) is ~63%. So this is somewhere between 1/4 and 1/3 as efficient as it could possibly be. Large generators, such as combined cycle gas turbines [wikipedia.org] are considerably more efficient, but these devices are small and silent. In other words: not bad.

Re:Efficiency in sensible units (0)

Anonymous Coward | about a year and a half ago | (#41395209)

the Carnot efficiency (i.e. the maximum possible efficiency of any device)

That's not entirely true. Heat pumps, for example, aren't limited by Carnot efficiency.

Re:Efficiency in sensible units (0)

Anonymous Coward | about a year and a half ago | (#41397557)

The Carnot efficiency is the maximum possible efficiency for a heat engine using a gas as a working fluid. This does not apply to thermoelectrics.

Niche applications (1)

sphealey (2855) | about a year and a half ago | (#41394005)

- - - - Such materials have found niche applications: - - - -

Niche applications: other than about 387 billion thermocouples measuring the temperature of everything around the globe.

sPh

Re:Niche applications (1)

FunkDup (995643) | about a year and a half ago | (#41394967)

other than about 387 billion thermocouples

You can't realistically generate electricity with a thermocouple. With this thing you can.

Re:Niche applications (1)

blueg3 (192743) | about a year and a half ago | (#41395277)

Thermocouples are generally made out of non-novel materials because they don't need to be efficient. (In fact, any pair of dissimilar metals joined correctly will form a thermocouple, but some are better suited than others.)

Pathetic Summary. (0)

Anonymous Coward | about a year and a half ago | (#41394175)

Doesn't even say what the stuff is called.

Solar Cells (1)

mosb1000 (710161) | about a year and a half ago | (#41394345)

If the cost is low enough, you could use this to replace conventional solar cells. Just place a thermocouple between two pieces of metal (paint the top one black). The top one will get hot and the bottom one would be shaded and air cooled. Instant solar cell. You wouldn't need to worry about keeping it clean or directing it toward the sun or anything like that.

Re:Solar Cells (1)

Shavano (2541114) | about a year and a half ago | (#41394729)

Hard to get the hot side hot enough and to keep the cool side cool enough.

Re:Solar Cells (1)

Anonymous Coward | about a year and a half ago | (#41395007)

Hard to get the hot side hot enough and to keep the cool side cool enough.

Duh, you just set up a heater to heat the hot side and an air conditioner to cool the cold side.

Re:Solar Cells (0)

Anonymous Coward | about a year and a half ago | (#41395457)

You mean other than using a heat pump to pull the heat into the building? Or putting a heat sink on the back to radiate the heat outward?

Re:Solar Cells (1)

Shavano (2541114) | about a year and a half ago | (#41406949)

It takes a large temperature difference and a high heat flow to generate much electricity this way.

Re:Solar Cells (1)

Belial6 (794905) | about a year and a half ago | (#41395475)

Put the cool side on the North facing side of the roof, and the hot side inside the attic. Even in a properly ventilated attic, it is almost always noticeably hotter in the attic than outside. The only question would be whether it was cost effective.

Re:Solar Cells (1)

rrohbeck (944847) | about a year and a half ago | (#41395489)

The efficiency is way lower than PV right now.
But you can stick one on the back side of a solar panel with a heat sink. Those solar cells get quite hot in full sun.
If it would be cost effective is another question of course.

Photovoltaic and thermoelectric combined (1)

advid.net (595837) | about a year and a half ago | (#41396805)

There's an on going thesis [google.fr] on this : Association of thermoelectric and photoelectric effects to improve the performance of photovoltaic

Better Options? (1)

Dereck1701 (1922824) | about a year and a half ago | (#41394899)

I think even the simplest Stirling engines beat this thing out for efficiency, I think 30% is easily attainable and better engineered systems I believe can top 45%. The only issue with them is there is some maintenance (though NASA is working on eliminating that). I think the next generation of Radioisotope thermoelectric generators are supposed to use Stirling generators.

Re:Better Options? (0)

Anonymous Coward | about a year and a half ago | (#41395249)

The advantage of thermoelectric is that they do not wear out. OTOH, sterling engines DO. In addition, a sterling engine requires a much high gradient to be efficient. The question is, how to dissipate the heat efficiently and long can a sterling last?
Note that if a thermoelectric was increased by 300% (which this was), then the real question becomes, is it possible to increase it again by 300%? If so, that would bring it up to 45%.

I am still in hopes that JTEC will come to fruition [wikipedia.org]

Windbourne

Hot air (1)

SnarfQuest (469614) | about a year and a half ago | (#41396455)

Think of how much energy would be produced by attaching one of these to Obama! You could provide half of the US electricity just from the hot air being produced.

Bob Lazar already talked about better materials (0)

Anonymous Coward | about a year and a half ago | (#41396607)

They should use Bob Lazar's thermo-electric generators instead.

Terraforming (1)

jimshatt (1002452) | about a year and a half ago | (#41396809)

Let's start terraforming the sahara desert! We just need some of that water of the melting ice caps and we can get going. We'll use the energy of these heat-to-electricy-thingies to pump melted arctic water to the desert. And while we're melting the polar caps we might as well do some terraforming over there (south pole and greenland). It's gonna be great guys!

Didn't break any records (1)

EmagGeek (574360) | about a year and a half ago | (#41397271)

Diesel-electric generators are far more efficient than 15% at converting heat into electricity.

comment (-1)

Anonymous Coward | about a year and a half ago | (#41397387)

Dhdh dhdhd dhdud dhdhd hdhdDish network the sender immediately after work and the intended rush and you duet with you

America's Lament (1)

ThatsNotPudding (1045640) | about a year and a half ago | (#41397405)

They had this in the McDLT*, and they threw it away! The fools!

* - "It keeps the hot side hot and the cold side cold!"

Submarines as a big niche app (0)

Anonymous Coward | about a year and a half ago | (#41397751)

A few years back, a US Navy Admiral let it slip during a speech [sorry, no link] that the thermoelectric effect was being considered for the main propulsion and power sources on future US nuclear submarines.

Efficiency be damned. It would be a homogeneous reactor with embedded thermoelectric transducers. The system would have no moving parts other than the electric motors, and propeller shaft. It could be loaded with enough fuel to last 30 years, and welded completely shut, with no hatches or access ports needed. I presume they would need some penetrations for wires..

At the end of its lifetime, the containment forms its own waste disposal container. Therefore it never needs to be opened.

I suppose if they could make it work with magnetohydrodynamic propulsion, then even the motor and shaft could be eliminated and there would be zero internal moving parts..

If that idea is really being developed, then new thermoelectric materials should be very interesting to them.

I'm a bit fuzzy on the details. Maybe they could put the thermoelectric and propulsion parts outside the reactor containment. Then the reactor could be truly homogenous, and permanently sealed with no penetrations. Any heat generated in the internal volume must eventually find its way to the external boundaries even without circulation. There's no place else for the heat to go.

 

Sterling engines are a far better choice (1)

evilviper (135110) | about a year and a half ago | (#41399531)

NASA hasn't been pursuing better RTG materials, instead they've been developing Sterling engines to replace the Peltiers.

The future of RTGs is in Advanced Stirling Radioisotope Generators (ASRGs):

https://en.wikipedia.org/wiki/Advanced_Stirling_Radioisotope_Generator [wikipedia.org]

See the "Proposals" section for a number of missions which planned (or currently do plan) to include them. With better luck, we could well have had them in current space-craft. Instead, it's one of those "any day now..." things. But once they are proven, I'd expect ASRGs to become the standard. The efficiency is just so much better, requiring less than a quarter as much radio-isotope fuel, and significantly reducing size and cost as a result.

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