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Power

New Thermocell Could Turn 'Waste Heat' Into Electricity 181

Posted by Soulskill
from the my-laptop-is-now-a-free-energy-device dept.
dryriver sends this quote from Phys.org: "Harvesting waste heat from power stations and even vehicle exhaust pipes could soon provide a valuable supply of electricity. A small team of Monash University researchers ... has developed an ionic liquid-based thermocell (abstract). Thermocell technology is based on harnessing the thermal energy from the difference in temperature between two surfaces and converting that energy into electricity. The new thermocell could be used to generate electricity from low grade steam in coal fired power stations at temperatures around 130C. This would be implemented by having the steam pass over the outer surface of the hot electrode to keep it hot while the other electrode is air or water cooled."
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New Thermocell Could Turn 'Waste Heat' Into Electricity

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  • by stevew (4845) on Tuesday July 16, 2013 @04:17PM (#44302463) Journal

    How do you keep the other side of the item cool? The waste heat goes somewhere?

    • From TFA:

      This would be implemented by having the steam pass over the outer surface of the hot electrode to keep it hot while the other electrode is air or water cooled.

    • by gl4ss (559668)

      earth cooling.. outside window, have a stream, have winter outside.. whatever.
      though at 130c you could run a steam turbine too, no? and afaik that's more efficient than usual tec's(peltiers).

      these new tec materials seem to pop up every few years. about 10 years ago there was some talk about something that could be put on the exhaust tubes of the car and have enough juice from that(being 10cm10cm slab) to run the AC in the car. haven't heard since nor seen it.. dunno if that one had some construction impract

      • i believe the idea is that the exhaust from a steam turbine is still hot enough to collect additional electricity by using this.

        • Re: (Score:3, Informative)

          by Anonymous Coward

          Exhaust from a steam turbines are on the order of 40-50 C. This works because the condenser actually operates in a vacuum (created from the thousand-fold volume decrease from steam to liquid water). And this makes more sense than wasting steam (since you would want to condense it anyways to save water).

          Really, there is no magic technology with thermoelectrics. And with any heat engine, what matters is the delta-T and entropy. Unless you waste water, you are bound by the Carnot cycle. And anybody who has wor

        • by jkflying (2190798)

          Then it would be more efficient to run another closed-cycle turbine based on ammonia or something. Peltier-style stuff is *really* inefficient.

      • by icebike (68054)

        I don't recall anything significant 10 years ago, but CalTech had improvements in Peltiers reported just last year:
        http://phys.org/news/2011-05-high-performance-bulk-thermoelectrics.html [phys.org]

    • by luckytroll (68214)

      I could totally use a version of this - I would wrap it around the exhaust riser on the diesel, and then cool the other side with incoming cooling seawater before it entered the cooling heat exchanger. The difference would be 400C inside vs 22C outside, and might be able to generate some more energy from the waste heat.

      I also considered running ammonia through this hot spot and making it an adsorption refrigerator, but that can generate some interesting (chinese) pressures, which can be a hazard.

      Of course,

    • What do you think those snow covered volcanoes are for? Fill up some reservoirs and cut down on the lahars danger all while getting our juice... of course we could end up with some pissed off Yeti...
  • by Anonymous Coward on Tuesday July 16, 2013 @04:17PM (#44302475)

    Greatest source of hot air in the country. Expected to solve the energy crisis.

    • by MightyYar (622222)

      But then the whole town would become USEFUL, and that would create a paradox that would tear space time apart.

  • We already suffer a glut of energy [oregonlive.com], but I suppose this might serve as a nice little accessory for your backyard distillery...

    • Re:Little known fact (Score:5, Informative)

      by ShanghaiBill (739463) on Tuesday July 16, 2013 @04:51PM (#44302931)

      We already suffer a glut of energy [oregonlive.com]

      A temporary and localized surplus is not what "glut" usually refers to. Hydro-power surpluses from spring rain have been around as long hydro-power. That is not proof that we have too much capacity.

      • Capacity we have plenty of, just like food and water and everything else. Distribution and who's in control are the outstanding issues that need to be dealt with.

      • by MightyYar (622222)

        Not only that, with energy you need a "glut" all the time so that you can handle unexpected shutdowns, demand spikes - or for hydro - droughts. Just like our food supply, we certainly don't want shortages.

    • by Rob Bos (3399)

      Odd that they wouldn't use the excess electricity to pump water up into a storage reservoir for future generation. That's what BC Hydro does.

      • by matfud (464184)

        They can't as during Spring there is to much water behind the damns due to snow melt and rain. They are full. Also many of them are not designed for this mode of operation (such as having large resevoirs of water to "pump up"

    • by turp182 (1020263)

      That story was for 2012 (posted in April of 2012), there's no mention of 2013 conditions. Just FYI.

      I don't know the current conditions (a great pun actually, hydro power).

  • by rossdee (243626) on Tuesday July 16, 2013 @04:25PM (#44302589)

    Did Congress repeal the Laws of Thermodynamics?

    • Re:Hmmmm (Score:5, Funny)

      by AliasMarlowe (1042386) on Tuesday July 16, 2013 @04:35PM (#44302723) Journal

      Did Congress repeal the Laws of Thermodynamics?

      Yes. And because that makes us all criminals now, it means the NSA snooping is quite legitimate...

    • Re: (Score:2, Interesting)

      by Farmer Tim (530755)

      No. If you have a machine that's 50% efficient, where does the other 50% of the energy go? That's right, heat. If you can recover 10% of that heat as electricity, your machine is now 60% efficient. Even if you could recover the theoretical 100% of the waste heat the total energy efficiency is still only 100%, so it doesn't violate the laws of thermodynamics.

      • by mattack2 (1165421)

        Wait, if you're recovering 10% of the heat, you're recovering 10% of the 50% 'wasted'. So you're really only 55% efficient in total.

    • by Greyfox (87712)
      Thermodynamics is OK with it as long as you don't get more energy out of it than you put into it. Anywhere you have a thermocline you can derive work from the differential... until the two two sides equalize in temperature. If you pump a lot of energy into one side, it gets hotter and you can get more work out of it. The other side will get hotter as a result. Eventually it will stop working again. You'll also get decreasing amounts of power out of it as the two sides equalize.

      If you're considering trying

  • I would love to see how this would work on a nuclear power plant. Since they seem to put out alot of steam this should provide a sizeable increase in power output. And the best, cleanest source of energy we have, would get even better.
  • Wrong problem (Score:3, Insightful)

    by jklovanc (1603149) on Tuesday July 16, 2013 @04:29PM (#44302635)

    The electricity issue is not a generation issue. We have enough technology to produce more electricity that we need. The problems we have are transmission , storage, and reliability. While we can produce much more energy than we need the challenge is to store it for when we need it, transmit it to where we need it and to be sure that it will not fail. For example, solar farms in the Sahara desert could power all of Europe. The issue is transmitting that power to Northern Europe and storing enough power to last the night. While Some HVDC line are being installed it is not enough to get that power to Germany and north.

    • by glenebob (414078)

      Yeah sure we can generate plenty of electricity. Just toss up another coal fired plant. Yay.

      I'm thinking solar. If this technology, coupled with tracking solar concentrators, can be done more cost and radiation efficiently than current solar technologies, then it may be a huge win.

      • yep. you're on a better track than the author of TFA who felt a need to mention coal.
      • Re:Wrong problem (Score:5, Insightful)

        by jklovanc (1603149) on Tuesday July 16, 2013 @05:25PM (#44303325)

        Solar does not work well during nigh or storms or at high latitudes. That is what I mean by the storage/transmission issue. Sure the Sahara can generate more solar electricity than we need. Getting to where and when we need it is a different story.

        • by b4upoo (166390)

          Really we do need to use less energy world wide despite the growth of population and industry. Our cities are heat islands already and global warming is serious business. No matter how clean the generation process the user ultimately converts all power received into heat. The answer is not in figuring out how to keep creating and storing more and more energy.
          It falls back to over population. When we look down at

          • by jklovanc (1603149)

            If we had a total of 60 million Americans instead of 350 million Americans our energy issues, our pollution issues, and most of our social issues would vanish quickly.

            The US does have 350 million people, and increasing every day, so we have to deal with that fact. Are you willing to volunteer yourself and you family to die to bring about your 60 million population cap? I doubt it. Technology allows these population and we will find technologies to continue to support it.

      • by jklovanc (1603149)

        I'm thinking solar. If this technology, coupled with tracking solar concentrators,

        How do you keep the cold side cool? The thermocell works on temperature differential. Keep anything in the sun and it will become evenly hot. I think cooling the back side will take more energy than the cell will produce.

  • Thermoelectric Power (Score:2, Informative)

    by Anonymous Coward

    Thermoelectric power has been around for a long time. There is, literally, nothing new about this. The efficiency is still not high enough to make it worthwhile for any sense of scale. They are better off using waste heat the way they currently do, to heat up the incoming cold fluids that get turned to steam through heat exchangers.

    On cars, you do not get enough power out of the current materials to make it worthwhile.

  • The press release: ""The device offers the possibility of a cheap and flexible design suitable for harvesting waste heat in the 100- to 200-degrees Celsius range."

    The abstract: "Power densities reached >0.5 W*m-2 in unoptimized devices, operating with a 130 C hot side."

    For half a watt per square meter had better be incredibly cheap and flexible considering wind and solar [azimuthproject.org]are about 4 and 10 times more dense, respectively, on a real-world basis. Nevermind that gains in optimization must be offset by losses

    • by khallow (566160)
      I imagine the idea is that you have a profitable process that generates waste heat. If this becomes cheap enough, it'd be a way to make a few more nickles on what you already have.
  • How different is this from existing Peltiers? Peltiers were all the rage back in the Celeron 300A days, but the amperage output is minimal at best.

  • How about placing ionic liquid-based thermocells on a home roof? Then wire the output to the "Electricity Grid?"

    I just wish I could write a Grant for this. It sounds like a "cool" project.
  • Oh please. With such lop sided support for the notion we might already have enough carbon in the air,why not apply this to low-grade heat differentials in
    * oceans
    * buildings in sunny places like the parched SW US states
    * my freakin' roof [and that is in upstate NY]


    but first, please headline the INSTALLED $/Watt. we can take it from there...or not.

    or did some coal company pay for this finding?
  • If only it could be used to cool off a CPU and generate a bit of excess energy to power misc. devices.
    • desktop cpu's typically dissipate ~50w at a moderate load (see http://en.wikipedia.org/wiki/List_of_CPU_power_dissipation [wikipedia.org] for the maximum disapation of your favourite number cruncher)

      the base of a heatsink is about 5cmx5cm (the actual die is quite a bit smaller than this), that's 50w/25cm2 or about 20 000w/m2.
      at a temperature difference of around 100c, this generates .5w/m2.

      Also, it's Seebeck coefficient of 1.5–2.2 mV K1 is 10x better than bismuth telluride (which has a Se of around 0.2 mV/K), (http:/

  • by bobbied (2522392) on Tuesday July 16, 2013 @05:56PM (#44303697)

    Without going too deep into a lesson on thermodynamics, there is not going to be much chance that this works in a modern power station.

    Let me put it this way. Current power stations are already engineered to be as efficient as possible. This generally means they are keeping the phase translations of the working liquid using the minimum temperature differentials possible to avoid entropy loss over the ideal Carnot cycle. Any thermally driven power producing device put in series with the heat exchangers is not likely to capture any more power than will be lost by the increased temperature differential required by the device. If this wasn't true, why don't we just attach a boat load of sterling heat engines (http://en.wikipedia.org/wiki/Stirling_engine) to do the same thing? Reason: It wreaks the efficiency of the power plant by making the temperature differentials higher.. Chances are this new idea has the same problem.

    Now, on your car, or other internal combustion engines, there *might* be some application, but I don't think there will be enough power output to make up for the weight increase. There is a HUGE amount of waste heat from your car engine but the question is how efficiently can we capture that and make useful energy out of it? Answer: Not very... Worth looking at because of the amount of heat being just dumped and the high differential temperatures but not likely to be much gain overall.

    • Mod parent up (Score:5, Informative)

      by Animats (122034) on Tuesday July 16, 2013 @07:02PM (#44304205) Homepage

      Right. What we have here is another crap materials science article. Somebody did something vaguely interesting at lab scale, and then issued a bullshit press release.

      Trying to get the last remnants of recoverable energy out of a heat engine is an old game, going back to the reciprocating engine era. Basic steam engines had one cylinder running off boiler pressure. Double-expansion steam engines had a second cylinder running off the output of the first. The second cylinder is bigger and runs at lower pressure. Triple expansion steam engines had a third, even bigger cylinder. Some quadruple expansion engines were built, but this is a diminishing-returns thing, and triple expansion is about as far as it's worth going economically. Marine engines were often triple-expansion.

      Large steam turbines do the same thing, with a succession of rotors of increasing size. Three to twelve stages have been used. Again, this is a diminishing returns thing. At some point the steam condenses to water, which you don't want to happen inside the turbine. Existing turbines get close to that limit. Some turbine plants have a partial vacuum going into the condenser to keep the steam as a gas below 100C. 90C exit temperatures are not uncommon. Almost all of the usable energy has been extracted with an exit temperature like that.

      If this new thermoelectric thing is a better way to convert heat to electricity than a steam turbine, it should replace steam turbines, not just be used on the cold end of the system. An efficient solid-state way of converting heat to electrical energy would be valuable. All the existing thermoelectric devices have low efficiency compared to heat engines. Back around 2011, there were several startups [bloomberg.com] getting Federal grants for R&D into "heat harvesting". Commercial products were supposed to appear in 2012. Didn't happen.

      • Let's supposed your "final" exit temperature is 90C. Also let's assume the cooling reservoir is around 10C. Let's also assume that the final stage takes steam from 200C down to 90C. That give it a theoretical Carnot limit of 110/363 ~ 30%.

        From the article, "The device offers the possibility of a cheap and flexible design suitable for harvesting waste heat in the 100- to 200-degrees Celsius range.". Assume it really work all the way to 10C, that could theoretically be 190/283 ~ 67%. If their efficiency is
    • by dbIII (701233)
      "As efficient as possible" hits problems in exactly the point the summary refers to - outgoing hot water that really isn't much hotter than the incoming water so it's hard to do much pre-heating with it. You can transfer some of the heat but it gets expensive due to volume to get a lot of it
  • by Solandri (704621) on Tuesday July 16, 2013 @07:00PM (#44304177)
    Extracting usable work energy from waste heat has always been possible [wikipedia.org]. The problem isn't making the heat do work. The problem is doing so cost-effectively. For most applications, these heat capture devices have such low power densities that it's counterproductive to add them (e.g. adding a stirling engine to your ICE car's exhaust system would burn more fuel due to the extra weight than the fuel savings you'd get from putting the heat energy to work). At that point, it's not worth implementing compared to just dumping the heat straight into a heat sink.

    The abstract says they're getting power densities of 0.5 Watts/m^2 in an unoptimized device. That's pretty deep in "not worth it" territory. This device would have to have an area of 1,5000 square meters exposed to the car's exhaust gases just to generate 1 extra hp. I suspect the additional back-pressure alone from all that piping (never mind the weight) would cost the engine a lot more than 1 hp of generation capacity.
  • Operating at 130 deg on the hot side it produces 0.5 W/m^2. If we wreap a 3 feet by 3 feet section of it around the exhaust pipe, it would give us 0.5 Watts. I am not sure, even the old thermocouples might generate this kind of power.
  • I would love it if this comes to fruition; but I am sick of the breathless articles showing us the future without actually showing us anything. CANCER CURED! headlines that later are shown to only be in one mouse which later exploded. ITER would be a great example. The other day I read a headline about a Fusion Breakthrough; basically they had laid a brick or two at the ITER project (literally this was the headline and real story). I am still interested in the above story but I wish they would moderate the
    • by iggymanz (596061)

      engineering and manufacturing and marketing reality are very harsh to small experiments that can only work in a lab. Most ideas don't pan out, most start-ups fail.

      This article's idea already has science and engineering going against it. we already have devices that convert differences in mass' temperature into electricity, and such things work best when the difference is great.

      Civilization needs more energy, not ways to recover a couple percent more energy.

  • by Bugler412 (2610815) on Tuesday July 16, 2013 @10:53PM (#44305395)
    Commercial fossil power stations already drive their stack gas temperature about as low as practical via various heat capture methods, reheat systems, etc. The limiting factor generally is not recovering more energy from stack gasses but the desire to never drive the stack gas temperature below the dew point in that exhaust gas, doing so causes all sorts of negative chemical consequences for the stack itself, pollution control equipment, etc., increasing maintenance cost and reducing equipment life due to aggressive corrosion of stack components and structure. Plants I operated were strictly kept from dropping below dewpoint on the exhaust for this reason, not to mention temperature input constraints for effective operation of some pollution control equipment, you CAN recover more energy from stack gasses, but doing so hits a cost negative and reliability wall. Always remember that waste heat/energy for a utility station equates to large $$$, if there's a practical way to extract more energy from a given amount of fuel, they are likely there as quickly as they can implement it. But the carnot cycle and other less heat cycle related limitation put up a pretty tough barrier to going further, Perhaps this is useful for more "pure" exhaust gas or waste heat streams, but I don't see it happening for commercial fossil power stations
  • I remember a 70s (probably popular science) article about using low grade waste heat to increase efficiency. In principle it works. bit the efficiency (Carnot limit) is very low, and the power density is low. In most places where waste heat is usable it is already in use (large power plants for example). It is often better to just use the heat for non power-generation applications (like heating buildings).

    In a sense the 1800s idea of the "triple expansion" steam engine was to use the waste heat from the fi

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