I never considered the solder's composition making such a difference. The way you broke it down made it obvious. Thanks for breaking down the difference between the TECs and TEGs. I always just assumed (and you know what THAT word entails) that it was just marketing to target the same device to different needs. Thanks Rob Cheers :)
There used to be a company in Iceland that made thermoelectric generators specifically designed to be use with geothermal hot water or steam......i found out about them after i saw some being used in New Zealand to make power from geothermal steam for a private hunting cabin between Taupo and Rotorua
Not so important in this instance but there is a fail-safe incorporated into most stove top fans. If you look at the base of the stand it has a grove cut in it and a bi-metallic strip screwed in on end. If the base gets too hot the strip bends and tilts the fan so only one edge is in contact! The kickback against planned obsolescence is real! ;o)
Neat. I like it. I was just trying to think of a way to self-regulate the heat transfer, then you point out its alreadyl implemented... It occurs to me that if radiator fins were incorporated in the stem, then the fan would self regulated the heat being transfered, the more heat gets past the fins the faster the fan turns and therefore cools the stem. Foolproof?
@@bikerfirefarter7280 Good idea! But it would mean losing more heat from the hot end of things making the device produce less power. That is why you see a single bladed stand and a multi bladed top.
@@totherarf Thats exactly my point why it would avoid burning out the thermo-electric module. Apart from the idea of this/any 'fan' on top of a stove makes the stove MUCH more efficient (the difference is trivial) its much more efficient to make the flue/stove itself part of a better heat transfer/capture system, or even a total re-design of the stove. These 'fans' are a fad/gimmick, but the operating principles herein are instructive to us nerds. chill. ;-)
I've a simple heat fan that ran 60 dollars on my wood stove. Went down to the Amish stove dealer in Shipshewana & a slightly bigger one was $179. I didn't buy it...Thanks for explaining the difference.
I think it would be interesting if you combined this tech with a solar setup. You explained in an earlier video how solar panels are more efficient at lower temperatures. I wonder if you could use TEGs to simultaneously cool the panels while providing extra power.
They are very inefficient so the gains would be negligible at best and most likely consume more of the extra power that the cooled solar panel will produce...I like your thinking though!
Thanks ! I made my own stove fan a few years ago using two TEC modules and some heatsinks. It didn't last very long, now I know why. Will rebuild it with some TEG's instead. Thanks for your info.
Thank you Sir Robert. ❣ This poses another opportunity for backup, especially under harsh conditions like existed in earlier world conflicts where transportation of bulky fuel engine generation was impossible.
Thank you so much for explaining this to me, these will be used in the future of mechanical engineering. say goodbye to loss of mechanical energy from friction and heat transfer.
I always wanted to try these. Turns out I ordered the wrong ones. Had I watched this video I would have known the difference. :) Ive always wondered if there was enough potential in my outdoor portion of my stovepipe to make something work. Good info, thankyou.
If you could manage to utilise the cold as well as the hot, you'd get more power. Maybe mount the TEG on the chimney indoors, with a chunk of metal leading outdoors to take the heat away much better. If you wanted to buy a few, you could maybe set up a water cooling loop using the outside cold, and put the TEGs somewhere as hot as they can stand. Or else try thermocouples as I mentioned in another post. People cooling big PC setups do all sorts of elaborate plumbing. TECs have falled out of fashion a bit but used to be a hot thing in overclocking Celeron 300s to 400MHz. Back in the day that saved a LOT of money and became a sort-of sport. So there's knowledge available on advanced TEC cooling, that you might learn useful ideas from to cool a TEG.
I have been aware of these for over 40 years but never took time to really learn about them as I have never needed to use either the TEG or TEC thanks for explaining it Robert
Great information to know both for the DIY crowd and those of us who buy ready made products. I always look forward to watching your videos simply because I'm an information junkie.
I did stumble across a place that had put teg's in graphene, claimed it did a similar thing to your gasket idea at the end, gonna have to try that gasket idea for myself. thanks for the chat good sir.
We've had great success with the fan varieties which clamp to the stove pipe and help utilize that exiting heat. Now I'm looking forward to it's demise so I can rebuild it with a TEG. :)
Hi, thanks for covering these! I've been thinking about them a lot since I first heard about them a few weeks ago, really hope to see more optimization like we've seen with solar in the last few years, I believe they have considerable potential for low maintenance green power and I want to see about building a few arrays of them for myself when I get to installing solar panels on our homestead; your other video about vertical east-west aligned (bifacial) solar panels was invaluable to me, in fact you are invaluable to the world. Keep being weird!
I did not know that you could reverse the current flow of a TEG to make the hot side cold and cold side hot. Is that process equally safe and efficient?
That surprises me, as the voltage drop across a PN junction is typically asymmetric, I would have expected a large thermal efficiency difference due to this: but then I suppose the forward current and reverse leakage current are very different and compensates. Or am I missing something?
@@ThinkingandTinkering Thanks very much for that breakdown (no pun intended). I've seen thermocouples made between the ends of dissimilar wires. They are very tolerant of high temperatures, i.e. flame-failure devices in heating/cooking, but I've not seen much in the way of edge-to-edge contact thermocouples or, for that matter, face-to-face contacts. Would these produce high currents? And could these be manufactured by ''spot welding' and/or then rolled/made cylindrical and inserted into flues? I haven't tried the experiment, as I have to rebuild my DIY spot-welder since I accidentally Oopsed it trying to make an induction heater out of its bits.
@@bikerfirefarter7280dissimilar metal thermocouples are usually welded or twisted together and brazed (sometimes using sil-phos brazing wire or silver solder).
These are great i have a number of them but i made my own using large diameter copper pipe to make a biplane as the cold side heat sink & copper pipe as the stand it's great & is very different.
Thank you so much for this video!!! It's the topic i mentioned a few weeks ago in a few comments. Its awesome you covered this topic! Thank you so much for improving my knowledge on this topic! Spectacular! ❤
Thanks for this video! That TEG (er... TEC) Fan for the Stove is really cool! One way to engineer this so that it is economically feasible is to use a solar photovoltaic cell that works well using a "concentrator" design, for example, it has a small footprint, and a Fresnel lens concentrates the light onto the cell. The TEC (or TEG) would be placed on the back end of the Solar cell (with a good thermal compound) , where it would take the waste heat and convert it to even more electricity. A large heat sink would be needed... it might help if the heat sink was in the water. You might be able to avoid this design by having some sort of TEC that could cover an entire large panel, and just use the white paint heat sink, but, I am not aware of any large TEC formats that are very low cost.
I've been trying to build this design myself. The problem is the heat in Florida makes it too hot. This design would only work well in winter. It's just too hard to dissipate the heat into 100 degree air.
@@NandR If you just want to see if the TEG helps at all, you could put a cube of ice on the heat sink part which would give you the delta T... if nothing improves then something is wrong. The other consideration is how it is all wired. You don't want the wiring of the solar panel to "power" the TEG...
Robert.... A one mil copper & iron sandwich combo (two mil actually) will produce on average 30 milivolts. Stacked 1 inch high an estimated 15 volts can be produced. Considering one micro amp per .001 inch square, a one inch square would produce one amp. So..... a one" high by 1 square inch would (should) produce 15 watts of power. Then a 20" tall by 1 square. Inch would produce 300 watts or 300 volts DC @ 1 amp. Lastly, 50 such stacks would produce 15 KW. Granted stacking these 2 mil sandwiches would require patience and approximately 700 degree temperature, but once meeting that threshold ....that thermo pile could theoretically be boarding on perpetual motion ( in supply it's own heat source using heating elements in a controlled insulated environment) and supply electrical power some 20+ years. Right?
Back round about the 1950s, the Soviets made thermally-powered radios, for people living in the country with no mains electricity. It was a collar you'd put around the neck of an oil lamp. That provided the heat, then fins spreading out provided cooling. It could generate the 90v or so, and the 6v or so, that an old valve radio needed. Those are approximate voltages, educated guess. It didn't use these sort of TEGs, since semiconductors hadn't really been invented properly. It just used old-fashioned thermocouples. You get two kinds of metal, say copper and iron, and you twist the ends together. You make lots of these twisted wire pairs. Then you connect each one at the opposite end, also twisting, copper to iron, til they're all in series. Or parallel, or however you like. A long sequence of wires all twisted together at opposite ends. Then you get all the ends on one side, and expose it to heat, and the ends on the other to cold. That's it! Of course make sure none of the wires short out touching against each other. They probably used asbestos or something but I'm sure there's a modern electrical insulator that can stand a bit of heat. The metals you choose depend on a certain table of which are more negative and which more positive. Choose metals with the greatest difference for the highest voltage. You can look this up online. Being metal, they're not likely to melt with anything you can present them with. They're also much cheaper than TEGs. A bit of time spent twisting, and tinkering, and you can save a ton of money if you wanted an emergency power source or something off-grid. It's gonna be much more robust, and easy to repair. You don't solder anything, just twist. Small thermocouples like this are used in industrial thermometers, since they don't melt easily. Shove one into a furnace, measure the voltage, and your handy meter can convert that into a temperature for you. You could try something like this to take camping. If you get a decent voltage, and current, out of it, perhaps get yourself a voltage regulator (even a good old 7805) and a USB lead and try charging things!
Fun fact. The Russians also built hundreds, or possibly thousands of nuclear TEG units to power radio relay stations and lighthouses. Most were decommissioned in the 1990's with US help. I did say most, some were unaccounted for, some dismantled by scrappers, and some still remained in use out of necessity, and some were left in place because buildings were constructed around them and no safe dismantling was possible last I heard about them. I do also remember about reading that there were a few orphan radioactive source deaths from some hunters coming across a TEG that fell off a tower and noticing the snow was melted near a block. They ended up putting the amazing warm block in their tent, and quickly becoming ill. I think that there may have been others but it was years ago. I believe it was strontium 90 that made up the radiation source. The Soviets also made plutonium smoke detectors if memory serves.
Very good. It might be possible to compare mechanical vs electronic energy recovery using just the stove fans: there's much older stirling engine driven designs of similar size. Pre-test, my guess would be that the stirling fans would be more heat tolerant and last longer, but might reach a point where the heat difference can't be maintained without active cooling. I've also wondered if one could use liquified thermo-plastics as a transfer mechanism.
- the whole thing re the operation of heat engines is to keep the hot and cold sides as "different as possible" - just that the Sterling engine will actually cease functioning altogether when the cold side gets heat soaked - cooling may not be "necessary" - for a while, but the performance will certainly be improved (drip some water over the cold side every so often - evaporation works wonders)..
I wonder if you could use that technology on windows in cold or warm climates as the inside of the house is is much warmer when its winter or much cooler when its summer. Or maybe its not enough of a difference in temps.
Very interesting. What if you had like a thermos inside a themos, one side hot and the other side cold and the only way heat could be transfered was through a peltier cell. I wonder how effective that would be to generate electricity?
I have wondered if black metal plates were put on houses (or wiring up an asphalt road) to harness solar heat and have the heat siphoned to a thermal battery, and used to power either a TeG or a thermal engine that produces needed electricity would be a better choice than solar panels, inverter, and battery route, since the thermal equipment would last longer than solar panel equipment and batteries. What is your opinion?
I believe this is the type of method used in the Mars Rovers' generators, but the heat is from a Nuclear pellet of some sort and the cold is from the Martian Atmosphere. I think I said something about this in response to another video of yours. But this is some great specific information for someone trying to DIY some sort of little generator. I might do it some day!
People do forget that chip based objects are manufactured for purpose, and just like using a toy air piston in a steam toy, its not up to the demands on average. One thing II have been thinking about is such a thing as TEG setups in furnaces, so that more of their electric power is from their waste heat, especially if said furnace is part of your hot water system.
I noticed you didnt mention that using a temperature difference of say -40 to +40 gives a difference of 80. May be much safer and more reliable. I often thought that its easier to create cold than heat..
Thank you for sharing this❤ I am fascinated with these things and how they work. I seen a video of someone using bismuth with another metal to create the effect but there were no details about it
You say "the more you spend on your TEG, the more performance you'll get" (paraphrase) Does that apply even when they're specced with the same part number? I'm thinking of sourcing a couple of thousand TEGs from China for my offgrid project, but they all look the same with the same part number, from the different vendors with different prices.
Actually, really interesting. I know what they are and own some raw components for projects I never completed (or started). And I knew they were different to each other but I did not know the details of what was different and why.
Hi Robert. Thanks for this, As Used To, Relevant Video 🙂👌👍 What about making a Graph to Show the Rate Cost of Energy Density of the Different Models that You have Talked About, so that we could see if for some, EVEN PAYING MORE, would be still Cheaper in term of €/W? 😍 Best Regards, Didier
I love all your videos I love the information you share so thank you sincerely and I was hoping you could help me I live in an RV and I have a wood stove and my solar panels don't charge my batteries fully because I live in a cloudy place and I was wondering if in one of your episodes if you could make an RV thermoelectric generator to charge batteries encounter run through what I need to do so that I can build the same thing here I would so much appreciate it and again thank you for your time😊
Very interesting, do you think it can be used with an MPPT solar regulator to get a good battery charger out of it? Given the fact that you are within the correct voltage range of course..
Nah, MPPT is a particular solar panel thing. It varies the effective load on the panels to get the best combination of volts and amps out of it. The best load to do this varies with the amount of light, so it needs a smart tracker. But TEGs don't have the operating characteristics of a solar cell. Doesn't mean you can't use it to power a battery charger circuit though. If it's producing a reliable voltage, you could do it. That just means keep the temperature on each end the same and you'd be good. Likely the voltage and current output are pretty low. But you can always buy more TEGs of course, in principle there'd be no problem. There was once a competition on Hackaday, where a guy got a load of TEG modules and some big metal plates, and ended up powering his laptop from a gas barbecue! The efficiency was terrible, but it worked!
@@greenaum Thanks for your comment, using gas via TEGs for electricity is cool but a waste for sure, but what if that guy was flippin' burgers at the same time, then his laptop would run more or less for free right? Anyways, I live off grid, up north, in the forrest and have an endless supply of wood. Most of the year my solar cells will provide more then enough power to keep my battery bank charged, but in the winter when the sun hardly rise above the tree tops they will not. Since it's freaking freezing here in winter time, I burn a lot of wood to keep my house and barn warm. So, since i'm constantly producing 5-15kw of heat, pulling out a few hunderds watts would be great, and would probably not be noticable at all. I bought some 22 watts (@ TD 300c) TEG's and was thinking to hook them up with a regulator for charging. Just like solar cells, TEG's output will vary, but an MPPT is supposed to look for that perfectly matched output right? Using an MPPT would make it all so easy. I have several Victrons lying around from previous projects, but I'm kind of scared to hook them up. Wouldn't enjoy destroying €1500 worth of TEG's you know. Any idea of how that Hackaday dude regulated his voltage output or did he just crank up the gas until his Laptop started charging? Thanks
I first came across the Peltier effect many years ago during GCE physics, but that was using dissimilar metals rather than semiconductors. I imagine they were more robust - but I assume they had some disadvantages or we would still be using them?
They are still used in 'thermocouple' flame-failure-devices in gas stove/hobs and other 'combustion' related heating systems. They are point-source contacts, and therefore limited power output They cope with direct contact with the flame for months/years. But I have wondered if they could be made tubular and fitted into flues/exhaust systems to produce high power outputs.
@@bikerfirefarter7280 Ah, no, these were not single point contacts. They were, if you like, lots of them - so metal A connected to Metal B, which at the other end of metal B connected to another metal A etc., set so that all the wires were parallel to each other. Hard to describe, but imagine you have a short piece of iron wire, connected at one end to copper wire, and laid down so that they are next to each other, rather than end-to-end. Now another piece of iron wire is connected to the distal end of the copper wire, and laid so that it, too, is parallel to the others. It forms a sort of zig-zag shape.
@@steveknight878 'Parallel' has nothing to do with it, the two junctions at different temperature is the main thing. I'm a kiln technician, we use the thermocouple effect to measure temperature (among other methods). When I said 'single point' I didn't mean it akin to 'cats whisker' device/effect, I just meant relatively small area. Sorry, my bad wording.
@@bikerfirefarter7280Yes, I realise that the parallel isn't in itself, important to the thermocouple function, but it is important to getting all the iron/copper joints on one side, and all the copper/iron joints on the other side, so you can preferentially heat one side (set of joints) and cool the other. Imagine tens or hundreds of thermocouples all joined up together in series. Your description of a thermocouple is perfectly good, and I think that a thermocouple is doing exactly the same sort of thing at that joint, but this device takes it further, and has the same effect as in this video.
I was wondering if you could make/test DIY Thermoelectric generator using conductive inks with the N and P elements mixing with sodium silicate (which can whitstand a lot of heat) and making the heat source like a blast furnace. It would be quite a project and kinda dangerous, but it would definitelly produce way more power.
It doesn't produce more power because the efficiency of such semiconductors is inversely proportional to the heat conductivity, The more efficient it is to conduct heat the less efficiently and converts that heat into electric. So far bismuth telluride is the best discovered that's commercially viable.
@petevenuti7355 I'm assume he is thinking of large areas of pn, to generate large currents, this should help to offset the temperature/voltage/efficiency drop. Correct me if i'm wrong.
@@bikerfirefarter7280 that's how I remember the comment discussion go. Thing is, with the cumulative resistance over a large area of such thin film junctions, enough energy gets wasted as resistance heat to offset the benefit of just volume of area. Of course you could build up arrays like what they do with solar panels to help solve that same problem, use silver conducters and more. It would be interesting to see someone actually test the limits! It would take testing to find out the maximum size of the most efficient possible cell, and cost effectiveness of resistance mitigation. If you believe in it, test it!
@@petevenuti7355 I would have expected larger area to have LESS resistance. I don't understand what you mean by 'volume of area'. At the mo I'm too busy with other stuff to get anywhere near 'test it'.
One thing i want to try with them is to connect one to the ground with heat pipes and connect the other to a heatsink above ground. When the air is hot, power will flow one way, and when the air is cold it will flow the other. That doesnt matter, though, if you connect it to a full bridge rectifier. I just dont know how well it will work.
@@bikerfirefarter7280 they can if there is something in it to draw the moisture to the top. Computer heat pipes use a copper powder that turns into tiny capillaries when heated enough to make there's work. I'm not sure what else will work, though. I might try sand and make some myself.
@@ancapftw9113 'heat pipes' are very polarised to vertical orientation, making them rather like a heat-diode. They use giant ones in China to keep the ground under high roads frozen, its a completely passive/self-regulating system. Huge pipes are inserted almost vertically into the ground, with a good length above ground, they are charged with a load of liquid Ammonia, during the night the Ammonia boils in the bottom of the pipes and recondenses at the colder top end then it runs back to the lower end, this 'freezes' the surrounding ground. During the day the top end of the pipe is warmer and the conensation stops, thus halting the heat transfer until the next night. The heat pipes used in computers etc are configured very differently and are backed up with forced ventilation. Your idea will work to draw power/heat from the ground, but not the other way around, unless you use forced circulation to return heat 'downwards'. I'm not saying it can't be done, but just 'heat-pipes' and 'heat-sink' wont cut it to 'recharge' the system.
I wonder how it would work if during the day electricity from solar panel would be used to make the sides hot and cold and when the sun goes down, reverse the thing and use the build up temperature difference to give electricity. Not very efficient, but no moving parts I guess.
maybe if you could put that in a sand battery and line the inner chamber with it, and then this leaks energy into reticulated carbon foam to insulated it. So that the energy is not lost, but you capitalise on the outer edges of the reservoir also, within the insulation? i wonder i that could work to scavenge an additional bit of energy maybe just to even run the battery's own GUI LCD screen...
There must be many sources of waste heat that just dissipates to atmosphere, a bit of legislation here and there would go some way to capturing and converting these loses
We can only convert about 10% of that heat at best. Combined with the construction of the devices we would be consuming more energy than we collect. We need more efficient ways to covert thermal energy to electrical.
They work on temperature difference, the difference between inside and outside your house isn't nearly enough to be worthwhile. You might be able to power a clock or something. Second problem is, they work from heat travelling through them. You want the most possible. So heat is going to escape through it at a rate of knots, you're going to have to turn your central heating up, for an overall efficiency of almost nothing from start to end. What you'd pay for heating would dwarf what you'd make in free electricity.
@@greenaum Is the 60 degree difference here in Maine not enough for some reason? When it is 1F outside, I have the inside at 60 minimum, preferably 70. Your other point is the part I said if we could figure it out.
@@NdxtremePro Nah 60F isn't much, and TEGs have really poor efficiency. They have terrible efficiency in the other direction, when used as coolers, too. The other part fair enough but AFAIK it can't be helped. Heat has to flow through the thing to work. It's, in a way, the opposite of insulation.
You'd be surprised how important that lapping is! Glad to see you mentioned it!
I never considered the solder's composition making such a difference. The way you broke it down made it obvious. Thanks for breaking down the difference between the TECs and TEGs. I always just assumed (and you know what THAT word entails) that it was just marketing to target the same device to different needs. Thanks Rob Cheers :)
There used to be a company in Iceland that made thermoelectric generators specifically designed to be use with geothermal hot water or steam......i found out about them after i saw some being used in New Zealand to make power from geothermal steam for a private hunting cabin between Taupo and Rotorua
Not so important in this instance but there is a fail-safe incorporated into most stove top fans.
If you look at the base of the stand it has a grove cut in it and a bi-metallic strip screwed in on end. If the base gets too hot the strip bends and tilts the fan so only one edge is in contact!
The kickback against planned obsolescence is real! ;o)
Neat. I like it. I was just trying to think of a way to self-regulate the heat transfer, then you point out its alreadyl implemented...
It occurs to me that if radiator fins were incorporated in the stem, then the fan would self regulated the heat being transfered, the more heat gets past the fins the faster the fan turns and therefore cools the stem. Foolproof?
@@bikerfirefarter7280 Good idea! But it would mean losing more heat from the hot end of things making the device produce less power. That is why you see a single bladed stand and a multi bladed top.
@@totherarf Thats exactly my point why it would avoid burning out the thermo-electric module. Apart from the idea of this/any 'fan' on top of a stove makes the stove MUCH more efficient (the difference is trivial) its much more efficient to make the flue/stove itself part of a better heat transfer/capture system, or even a total re-design of the stove. These 'fans' are a fad/gimmick, but the operating principles herein are instructive to us nerds. chill. ;-)
@@bikerfirefarter7280 Coolio!
Glad to hear your honest comment😅
I've a simple heat fan that ran 60 dollars on my wood stove. Went down to the Amish stove dealer in Shipshewana & a slightly bigger one was $179. I didn't buy it...Thanks for explaining the difference.
I think it would be interesting if you combined this tech with a solar setup. You explained in an earlier video how solar panels are more efficient at lower temperatures. I wonder if you could use TEGs to simultaneously cool the panels while providing extra power.
They are very inefficient so the gains would be negligible at best and most likely consume more of the extra power that the cooled solar panel will produce...I like your thinking though!
Thanks ! I made my own stove fan a few years ago using two TEC modules and some heatsinks. It didn't last very long, now I know why. Will rebuild it with some TEG's instead. Thanks for your info.
Thank you Sir Robert. ❣
This poses another opportunity for backup, especially under harsh conditions like existed in earlier world conflicts where transportation of bulky fuel engine generation was impossible.
Thank you so much for explaining this to me, these will be used in the future of mechanical engineering. say goodbye to loss of mechanical energy from friction and heat transfer.
I always wanted to try these. Turns out I ordered the wrong ones. Had I watched this video I would have known the difference. :) Ive always wondered if there was enough potential in my outdoor portion of my stovepipe to make something work. Good info, thankyou.
If you could manage to utilise the cold as well as the hot, you'd get more power. Maybe mount the TEG on the chimney indoors, with a chunk of metal leading outdoors to take the heat away much better. If you wanted to buy a few, you could maybe set up a water cooling loop using the outside cold, and put the TEGs somewhere as hot as they can stand. Or else try thermocouples as I mentioned in another post.
People cooling big PC setups do all sorts of elaborate plumbing. TECs have falled out of fashion a bit but used to be a hot thing in overclocking Celeron 300s to 400MHz. Back in the day that saved a LOT of money and became a sort-of sport. So there's knowledge available on advanced TEC cooling, that you might learn useful ideas from to cool a TEG.
I have been aware of these for over 40 years but never took time to really learn about them as I have never needed to use either the TEG or TEC thanks for explaining it Robert
Great information to know both for the DIY crowd and those of us who buy ready made products. I always look forward to watching your videos simply because I'm an information junkie.
I did stumble across a place that had put teg's in graphene, claimed it did a similar thing to your gasket idea at the end, gonna have to try that gasket idea for myself. thanks for the chat good sir.
We've had great success with the fan varieties which clamp to the stove pipe and help utilize that exiting heat. Now I'm looking forward to it's demise so I can rebuild it with a TEG. :)
lol - let me know how you get on with it!
Will be great maybe use in the parking lots, like integrate this inside the beton or asfalt. In the sunny day its can reach temps 50C+
With a good system of distributing that heat to lower layers of earth, it would work very well, but be quite expensive.
Hi, thanks for covering these! I've been thinking about them a lot since I first heard about them a few weeks ago, really hope to see more optimization like we've seen with solar in the last few years, I believe they have considerable potential for low maintenance green power and I want to see about building a few arrays of them for myself when I get to installing solar panels on our homestead; your other video about vertical east-west aligned (bifacial) solar panels was invaluable to me, in fact you are invaluable to the world. Keep being weird!
I did not know that you could reverse the current flow of a TEG to make the hot side cold and cold side hot. Is that process equally safe and efficient?
yes it really doesn't matter that much tbh
That surprises me, as the voltage drop across a PN junction is typically asymmetric, I would have expected a large thermal efficiency difference due to this: but then I suppose the forward current and reverse leakage current are very different and compensates. Or am I missing something?
@@ThinkingandTinkering Thanks very much for that breakdown (no pun intended).
I've seen thermocouples made between the ends of dissimilar wires. They are very tolerant of high temperatures, i.e. flame-failure devices in heating/cooking, but I've not seen much in the way of edge-to-edge contact thermocouples or, for that matter, face-to-face contacts. Would these produce high currents? And could these be manufactured by ''spot welding' and/or then rolled/made cylindrical and inserted into flues?
I haven't tried the experiment, as I have to rebuild my DIY spot-welder since I accidentally Oopsed it trying to make an induction heater out of its bits.
It is very safe but terribly inefficient.
@@bikerfirefarter7280dissimilar metal thermocouples are usually welded or twisted together and brazed (sometimes using sil-phos brazing wire or silver solder).
These are great i have a number of them but i made my own using large diameter copper pipe to make a biplane as the cold side heat sink & copper pipe as the stand it's great & is very different.
Thanks for that, burnt a few out and was hoping for a better explanation. Cheers
Years ago, I made a rotisserie for a camp fire with this principle.
Thank you so much for this video!!! It's the topic i mentioned a few weeks ago in a few comments. Its awesome you covered this topic! Thank you so much for improving my knowledge on this topic! Spectacular! ❤
Does the sebeck effect lowers the heat of the hot side substantially when generating electricity?
Thanks for this video! That TEG (er... TEC) Fan for the Stove is really cool!
One way to engineer this so that it is economically feasible is to use a solar photovoltaic cell that works well using a "concentrator" design, for example, it has a small footprint, and a Fresnel lens concentrates the light onto the cell. The TEC (or TEG) would be placed on the back end of the Solar cell (with a good thermal compound) , where it would take the waste heat and convert it to even more electricity. A large heat sink would be needed... it might help if the heat sink was in the water. You might be able to avoid this design by having some sort of TEC that could cover an entire large panel, and just use the white paint heat sink, but, I am not aware of any large TEC formats that are very low cost.
I've been trying to build this design myself. The problem is the heat in Florida makes it too hot. This design would only work well in winter. It's just too hard to dissipate the heat into 100 degree air.
@@NandR So, what size solar cell are you using, or are you saying just in theory?
@@marcfruchtman9473 I only tried it on a 10W panel with 3 TEGs. If there was some steady wind it would help.
@@NandR If you just want to see if the TEG helps at all, you could put a cube of ice on the heat sink part which would give you the delta T... if nothing improves then something is wrong. The other consideration is how it is all wired. You don't want the wiring of the solar panel to "power" the TEG...
@@marcfruchtman9473 it works but not very much. I need to try it in winter cold air on a sunny day.
Robert.... A one mil copper & iron sandwich combo (two mil actually) will produce on average 30 milivolts. Stacked 1 inch high an estimated 15 volts can be produced. Considering one micro amp per .001 inch square, a one inch square would produce one amp. So..... a one" high by 1 square inch would (should) produce 15 watts of power. Then a 20" tall by 1 square. Inch would produce 300 watts or 300 volts DC @ 1 amp. Lastly, 50 such stacks would produce 15 KW.
Granted stacking these 2 mil sandwiches would require patience and approximately 700 degree temperature, but once meeting that threshold ....that thermo pile could theoretically be boarding on perpetual motion ( in supply it's own heat source using heating elements in a controlled insulated environment) and supply electrical power some 20+ years. Right?
Back round about the 1950s, the Soviets made thermally-powered radios, for people living in the country with no mains electricity. It was a collar you'd put around the neck of an oil lamp. That provided the heat, then fins spreading out provided cooling. It could generate the 90v or so, and the 6v or so, that an old valve radio needed. Those are approximate voltages, educated guess.
It didn't use these sort of TEGs, since semiconductors hadn't really been invented properly. It just used old-fashioned thermocouples. You get two kinds of metal, say copper and iron, and you twist the ends together. You make lots of these twisted wire pairs. Then you connect each one at the opposite end, also twisting, copper to iron, til they're all in series. Or parallel, or however you like. A long sequence of wires all twisted together at opposite ends.
Then you get all the ends on one side, and expose it to heat, and the ends on the other to cold. That's it! Of course make sure none of the wires short out touching against each other. They probably used asbestos or something but I'm sure there's a modern electrical insulator that can stand a bit of heat.
The metals you choose depend on a certain table of which are more negative and which more positive. Choose metals with the greatest difference for the highest voltage. You can look this up online. Being metal, they're not likely to melt with anything you can present them with. They're also much cheaper than TEGs. A bit of time spent twisting, and tinkering, and you can save a ton of money if you wanted an emergency power source or something off-grid. It's gonna be much more robust, and easy to repair. You don't solder anything, just twist.
Small thermocouples like this are used in industrial thermometers, since they don't melt easily. Shove one into a furnace, measure the voltage, and your handy meter can convert that into a temperature for you.
You could try something like this to take camping. If you get a decent voltage, and current, out of it, perhaps get yourself a voltage regulator (even a good old 7805) and a USB lead and try charging things!
Fun fact. The Russians also built hundreds, or possibly thousands of nuclear TEG units to power radio relay stations and lighthouses. Most were decommissioned in the 1990's with US help. I did say most, some were unaccounted for, some dismantled by scrappers, and some still remained in use out of necessity, and some were left in place because buildings were constructed around them and no safe dismantling was possible last I heard about them. I do also remember about reading that there were a few orphan radioactive source deaths from some hunters coming across a TEG that fell off a tower and noticing the snow was melted near a block. They ended up putting the amazing warm block in their tent, and quickly becoming ill. I think that there may have been others but it was years ago. I believe it was strontium 90 that made up the radiation source. The Soviets also made plutonium smoke detectors if memory serves.
Very good. It might be possible to compare mechanical vs electronic energy recovery using just the stove fans: there's much older stirling engine driven designs of similar size. Pre-test, my guess would be that the stirling fans would be more heat tolerant and last longer, but might reach a point where the heat difference can't be maintained without active cooling.
I've also wondered if one could use liquified thermo-plastics as a transfer mechanism.
- the whole thing re the operation of heat engines is to keep the hot and cold sides as "different as possible" - just that the Sterling engine will actually cease functioning altogether when the cold side gets heat soaked - cooling may not be "necessary" - for a while, but the performance will certainly be improved (drip some water over the cold side every so often - evaporation works wonders)..
i wondering, if you have all the walls from a warm house, how many electric watt would you get?
this is the best university I've ever been too.
I wonder if you could use that technology on windows in cold or warm climates as the inside of the house is is much warmer when its winter or much cooler when its summer. Or maybe its not enough of a difference in temps.
Does that also mean using a TEG in reverse as a cooler would be more effective, because of the increased number of N&P pairs?
Very interesting. What if you had like a thermos inside a themos, one side hot and the other side cold and the only way heat could be transfered was through a peltier cell. I wonder how effective that would be to generate electricity?
I have wondered if black metal plates were put on houses (or wiring up an asphalt road) to harness solar heat and have the heat siphoned to a thermal battery, and used to power either a TeG or a thermal engine that produces needed electricity would be a better choice than solar panels, inverter, and battery route, since the thermal equipment would last longer than solar panel equipment and batteries. What is your opinion?
As the interiors are semi conductors could you decap one side and use it in a nuclear battery?
I believe this is the type of method used in the Mars Rovers' generators, but the heat is from a Nuclear pellet of some sort and the cold is from the Martian Atmosphere. I think I said something about this in response to another video of yours. But this is some great specific information for someone trying to DIY some sort of little generator. I might do it some day!
I picked up one of those exact fans last year when I got my "emergency" paraffin heater; both stored away for 'just in case'.
Prepare a little extra, it's about to get wild..
People do forget that chip based objects are manufactured for purpose, and just like using a toy air piston in a steam toy, its not up to the demands on average. One thing II have been thinking about is such a thing as TEG setups in furnaces, so that more of their electric power is from their waste heat, especially if said furnace is part of your hot water system.
I noticed you didnt mention that using a temperature difference of say -40 to +40 gives a difference of 80. May be much safer and more reliable. I often thought that its easier to create cold than heat..
Thank you for sharing this❤ I am fascinated with these things and how they work. I seen a video of someone using bismuth with another metal to create the effect but there were no details about it
i will try to find the video mate
You say "the more you spend on your TEG, the more performance you'll get" (paraphrase) Does that apply even when they're specced with the same part number? I'm thinking of sourcing a couple of thousand TEGs from China for my offgrid project, but they all look the same with the same part number, from the different vendors with different prices.
This is very interesting and well explained, thank you Robert 😌
Im not sure if this is a silly question but could these devices be used to power a small fan that could then power a generator? Like a domino effect.
yes - but thre would be losses along the way as you convert one form to another
I remember when an LED laser diode was $400! Now, I buy them at the dollar store, but the button cells to power it are $2 each...
how do we connect teg in parallel to increase current?
Actually, really interesting. I know what they are and own some raw components for projects I never completed (or started). And I knew they were different to each other but I did not know the details of what was different and why.
Hi Robert. Thanks for this, As Used To, Relevant Video 🙂👌👍
What about making a Graph to Show the Rate Cost of Energy Density of the Different Models that You have Talked About, so that we could see if for some, EVEN PAYING MORE, would be still Cheaper in term of €/W? 😍
Best Regards,
Didier
I love all your videos I love the information you share so thank you sincerely and I was hoping you could help me I live in an RV and I have a wood stove and my solar panels don't charge my batteries fully because I live in a cloudy place and I was wondering if in one of your episodes if you could make an RV thermoelectric generator to charge batteries encounter run through what I need to do so that I can build the same thing here I would so much appreciate it and again thank you for your time😊
Very interesting, do you think it can be used with an MPPT solar regulator to get a good battery charger out of it? Given the fact that you are within the correct voltage range of course..
No.
Nah, MPPT is a particular solar panel thing. It varies the effective load on the panels to get the best combination of volts and amps out of it. The best load to do this varies with the amount of light, so it needs a smart tracker.
But TEGs don't have the operating characteristics of a solar cell. Doesn't mean you can't use it to power a battery charger circuit though. If it's producing a reliable voltage, you could do it. That just means keep the temperature on each end the same and you'd be good.
Likely the voltage and current output are pretty low. But you can always buy more TEGs of course, in principle there'd be no problem. There was once a competition on Hackaday, where a guy got a load of TEG modules and some big metal plates, and ended up powering his laptop from a gas barbecue! The efficiency was terrible, but it worked!
@@greenaum Thanks for your comment, using gas via TEGs for electricity is cool but a waste for sure, but what if that guy was flippin' burgers at the same time, then his laptop would run more or less for free right?
Anyways, I live off grid, up north, in the forrest and have an endless supply of wood. Most of the year my solar cells will provide more then enough power to keep my battery bank charged, but in the winter when the sun hardly rise above the tree tops they will not. Since it's freaking freezing here in winter time, I burn a lot of wood to keep my house and barn warm.
So, since i'm constantly producing 5-15kw of heat, pulling out a few hunderds watts would be great, and would probably not be noticable at all. I bought some 22 watts (@ TD 300c) TEG's and was thinking to hook them up with a regulator for charging. Just like solar cells, TEG's output will vary, but an MPPT is supposed to look for that perfectly matched output right?
Using an MPPT would make it all so easy. I have several Victrons lying around from previous projects, but I'm kind of scared to hook them up. Wouldn't enjoy destroying €1500 worth of TEG's you know. Any idea of how that Hackaday dude regulated his voltage output or did he just crank up the gas until his Laptop started charging?
Thanks
I first came across the Peltier effect many years ago during GCE physics, but that was using dissimilar metals rather than semiconductors. I imagine they were more robust - but I assume they had some disadvantages or we would still be using them?
They are still used in 'thermocouple' flame-failure-devices in gas stove/hobs and other 'combustion' related heating systems. They are point-source contacts, and therefore limited power output They cope with direct contact with the flame for months/years.
But I have wondered if they could be made tubular and fitted into flues/exhaust systems to produce high power outputs.
@@bikerfirefarter7280 Ah, no, these were not single point contacts. They were, if you like, lots of them - so metal A connected to Metal B, which at the other end of metal B connected to another metal A etc., set so that all the wires were parallel to each other. Hard to describe, but imagine you have a short piece of iron wire, connected at one end to copper wire, and laid down so that they are next to each other, rather than end-to-end. Now another piece of iron wire is connected to the distal end of the copper wire, and laid so that it, too, is parallel to the others. It forms a sort of zig-zag shape.
@@steveknight878 'Parallel' has nothing to do with it, the two junctions at different temperature is the main thing. I'm a kiln technician, we use the thermocouple effect to measure temperature (among other methods). When I said 'single point' I didn't mean it akin to 'cats whisker' device/effect, I just meant relatively small area. Sorry, my bad wording.
@@bikerfirefarter7280Yes, I realise that the parallel isn't in itself, important to the thermocouple function, but it is important to getting all the iron/copper joints on one side, and all the copper/iron joints on the other side, so you can preferentially heat one side (set of joints) and cool the other. Imagine tens or hundreds of thermocouples all joined up together in series.
Your description of a thermocouple is perfectly good, and I think that a thermocouple is doing exactly the same sort of thing at that joint, but this device takes it further, and has the same effect as in this video.
Brilliant video. Thank you Robert
I was wondering if you could make/test DIY Thermoelectric generator using conductive inks with the N and P elements mixing with sodium silicate (which can whitstand a lot of heat) and making the heat source like a blast furnace.
It would be quite a project and kinda dangerous, but it would definitelly produce way more power.
i have done it already - but i will have to dig out the video mate
It doesn't produce more power because the efficiency of such semiconductors is inversely proportional to the heat conductivity,
The more efficient it is to conduct heat the less efficiently and converts that heat into electric.
So far bismuth telluride is the best discovered that's commercially viable.
@petevenuti7355 I'm assume he is thinking of large areas of pn, to generate large currents, this should help to offset the temperature/voltage/efficiency drop.
Correct me if i'm wrong.
@@bikerfirefarter7280 that's how I remember the comment discussion go. Thing is, with the cumulative resistance over a large area of such thin film junctions, enough energy gets wasted as resistance heat to offset the benefit of just volume of area.
Of course you could build up arrays like what they do with solar panels to help solve that same problem, use silver conducters and more. It would be interesting to see someone actually test the limits!
It would take testing to find out the maximum size of the most efficient possible cell, and cost effectiveness of resistance mitigation.
If you believe in it, test it!
@@petevenuti7355 I would have expected larger area to have LESS resistance.
I don't understand what you mean by 'volume of area'.
At the mo I'm too busy with other stuff to get anywhere near 'test it'.
Very interesting, thank you Robert.
TY!
cheers mate
Hopefully you will do some projects with these !
One thing i want to try with them is to connect one to the ground with heat pipes and connect the other to a heatsink above ground. When the air is hot, power will flow one way, and when the air is cold it will flow the other. That doesnt matter, though, if you connect it to a full bridge rectifier.
I just dont know how well it will work.
It wont work. heat pipes don't work 'downward', so no cooling that way.
@@bikerfirefarter7280 they can if there is something in it to draw the moisture to the top. Computer heat pipes use a copper powder that turns into tiny capillaries when heated enough to make there's work. I'm not sure what else will work, though. I might try sand and make some myself.
@@ancapftw9113 'heat pipes' are very polarised to vertical orientation, making them rather like a heat-diode. They use giant ones in China to keep the ground under high roads frozen, its a completely passive/self-regulating system. Huge pipes are inserted almost vertically into the ground, with a good length above ground, they are charged with a load of liquid Ammonia, during the night the Ammonia boils in the bottom of the pipes and recondenses at the colder top end then it runs back to the lower end, this 'freezes' the surrounding ground. During the day the top end of the pipe is warmer and the conensation stops, thus halting the heat transfer until the next night.
The heat pipes used in computers etc are configured very differently and are backed up with forced ventilation. Your idea will work to draw power/heat from the ground, but not the other way around, unless you use forced circulation to return heat 'downwards'.
I'm not saying it can't be done, but just 'heat-pipes' and 'heat-sink' wont cut it to 'recharge' the system.
Thank you , was very educational and entertaining :)
Graphite foil as a heat conductive gasket ...note to self
haha just realized one could use them also as ac or signal generators given a method to alternate the heat
It seems thermal electrics would be alot more efficient by now.
Thank you.
I wonder how it would work if during the day electricity from solar panel would be used to make the sides hot and cold and when the sun goes down, reverse the thing and use the build up temperature difference to give electricity. Not very efficient, but no moving parts I guess.
maybe if you could put that in a sand battery and line the inner chamber with it, and then this leaks energy into reticulated carbon foam to insulated it. So that the energy is not lost, but you capitalise on the outer edges of the reservoir also, within the insulation? i wonder i that could work to scavenge an additional bit of energy maybe just to
even run the battery's own GUI LCD screen...
Thanks.
There must be many sources of waste heat that just dissipates to atmosphere, a bit of legislation here and there would go some way to capturing and converting these loses
We can only convert about 10% of that heat at best. Combined with the construction of the devices we would be consuming more energy than we collect. We need more efficient ways to covert thermal energy to electrical.
oh loads mate
Super!
You know, if we could figure out how to put these in the outside wall of houses, we could produce quite a bit of electricity I bet.
They work on temperature difference, the difference between inside and outside your house isn't nearly enough to be worthwhile. You might be able to power a clock or something.
Second problem is, they work from heat travelling through them. You want the most possible. So heat is going to escape through it at a rate of knots, you're going to have to turn your central heating up, for an overall efficiency of almost nothing from start to end. What you'd pay for heating would dwarf what you'd make in free electricity.
@@greenaum Is the 60 degree difference here in Maine not enough for some reason? When it is 1F outside, I have the inside at 60 minimum, preferably 70.
Your other point is the part I said if we could figure it out.
@@NdxtremePro Nah 60F isn't much, and TEGs have really poor efficiency. They have terrible efficiency in the other direction, when used as coolers, too.
The other part fair enough but AFAIK it can't be helped. Heat has to flow through the thing to work. It's, in a way, the opposite of insulation.
Use a fresnel lense to generate high amounts of heat.
No, they don't 'generate' heat energy. Study basic physics.
@@bikerfirefarter7280 did I spell a word wrong you nerd?
Hi Robert, how about this, if somebody will shoulder the cost o your prototype project that produce 110 watts would you do it pls?
no mate - i wouldn't take the money - i am thinking about doing that anyway
Very Very Nice !!!!!
Steam I say😂
lol
🤔.
Merci !