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Author Topic: Parametric Charging  (Read 42404 times)
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Hi Partzman,

I've always found this line of thinking very intriguing. I think it was in about 1991 that I tried to get extra energy out of varactors but I just didn't know enough electronics to do it. (Don't know much more now!)

I can see that this version doesn't suffer from the capacitive coupling and offset issues that plagued your earlier tests.

Here's me being dumb-- what's the purpose of C1? Wouldn't the presence of fixed capacitance just lower the overall change in C and reduce the parametric amplification?

And for that matter, although the mosfets have obvious advantages over varactors, the varactors can have C ratios > 15, inherently giving more bang for the buck, I think.

It's good to be back!

Fred

Hi Fred,

Welcome back!

C1 serves as the storage load device for the parametric capacitors in the mosfets.

Yes, varactors would be interesting to examine.

Regards,
Pm
   
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Hi Partzman,

Yes, I realized that C1 was the load after I wrote that. You had said as much in your description.

Fred
   
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Hi partzman,

I'm surprised there hasn't been any comments about your research. I know from reading the thread about your previous tests that there were several errors that arose, but your present design takes those issues into account, and it's difficult to see how the results can be error. Of course it's always possible! But until an error is found, there's room for some excitement here!

Maybe it's not as glamorous and esoteric as some other projects, but that begs the question, are we looking for something that works, or something that's complicated and fraught with perplexities?

I searched long and hard and haven't ever found any detailed description of conservation of energy as applied to parametric processes. As far as it goes is the analogy to a parallel plate capacitor and the work needed to move the plates. But the diffusion layer in a semiconductor is a very different animal.

Fred

   
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Hello partzman,

with MOSFETs instead of diodes please consider the following:

you increase new unknown parameters,  that is 3 different capacitances and their dependence of the current, voltage,  temperature and their mutual interactions which makes this setup more complex.

You like it that way eh  ;) ?

https://www.rohm.com/electronics-basics/transistors/understanding-mosfet-characteristics

Miller-Capacitance here:

https://electronics.stackexchange.com/questions/83712/gate-capacitance-and-miller-capacitance-on-the-mosfet#83730

I am sure you know this but that is not the main point I wish to make, its the MOSFET-Driver which is my concern.

The MOSFET-Driver has been developed in order to accelerate the shutdown-time by removing the gate-charge as fast as possible. This charge is part of you power-in measurement and lost at the end of each single pulse.

What if we could recuperate this charge ? ...or we use another puls-methode which does not remove the gate-charge so at least this parameter and its interaction with the Miller capacitance is stable ?

And what would then be the value of your Input-Power ?

Mike



   
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Hi Mike,

That's a very good point! I'd thought of this when fiddling with varactors, but never connected it here.
These gate charge recovery circuits do exist. A few minutes looking turned this up:

https://ieeexplore.ieee.org/document/885437

which is behind a paywall, but I'm pretty sure I have some circuits for charge recovery in my files somewhere.. looking now...

Fred

   
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Hi Partzman,


This patent might be of interest. It's a Mosfet Parametric Amplifier with a charge pump type topology using two batteries, two switches and two mosfets. It doesn't include charge recovery.

https://patents.google.com/patent/US20050275026?oq=tsividis+mosfet+parametric#citedBy

Fred



   
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Hello partzman,

with MOSFETs instead of diodes please consider the following:

you increase new unknown parameters,  that is 3 different capacitances and their dependence of the current, voltage,  temperature and their mutual interactions which makes this setup more complex.

You like it that way eh  ;) ?

Hi Mike.  Sorry for the late reply but we had business to take care of this weekend so I apologize.  I totally agree that mosfet capacitances are complex so in this device I attempted to reduce that complexity to the basic drain capacitance with the gate and source shorted.  There is however another reverse capacitance and that is bulk or substrate diode which varies with the particular mosfet geometry.  Anyway, in themselves, these capacitances normally are all conservative with charge/discharge cycles that yield ~95% efficiency.

Quote
https://www.rohm.com/electronics-basics/transistors/understanding-mosfet-characteristics

Miller-Capacitance here:

https://electronics.stackexchange.com/questions/83712/gate-capacitance-and-miller-capacitance-on-the-mosfet#83730

I am sure you know this but that is not the main point I wish to make, its the MOSFET-Driver which is my concern.

The MOSFET-Driver has been developed in order to accelerate the shutdown-time by removing the gate-charge as fast as possible. This charge is part of you power-in measurement and lost at the end of each single pulse.

What if we could recuperate this charge ? ...or we use another puls-methode which does not remove the gate-charge so at least this parameter and its interaction with the Miller capacitance is stable ?

And what would then be the value of your Input-Power ?

Actually with the circuit as shown, L1 presents an inductive reactance of ~1600 ohms at 687kHz.  The result is a series resonant circuit with the "C" being provided by the parametric drain capacitance.  The operating frequency is higher than the normal resonance frequency resulting in a lagging current to voltage on the input.  This is critical for the circuit to be able to produce OU and as I have found, the measurement of the slow sweeps require the highest sampling frequency available on the scope in order to be accurate and consistent.

You have offered some possible suggestions which would be interesting to test.

Regards,
Pm

Quote
Mike
   
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Hi Partzman,


This patent might be of interest. It's a Mosfet Parametric Amplifier with a charge pump type topology using two batteries, two switches and two mosfets. It doesn't include charge recovery.

https://patents.google.com/patent/US20050275026?oq=tsividis+mosfet+parametric#citedBy

Fred

Hi Fred,

Thanks for posting the patent links and this one by Tsividis is most interesting.  I attempted to replicate his circuitry in the past with no success and then I realized that the mosfet devices he used had a separate connection for the bulk or substrate diode and was not connected to the source.  If you look at the ambiguity of the connections in Fig 6 and also the connections in Fig 8, it will become apparent then looking at all the Figs that the substrate diode is connected separately from the source.  This is a critical requirement for his device to work but unfortunately, most all mosfets today have the substrate connected to the source and they will not work. 

In fact at the time, I couldn't locate any such devices but they must exist.

Regards,
Pm
   
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Hi Partzman,

I didn't see your response to Mike above, but if I understand you correctly, your present circuit already has a sort of gate charge recovery?

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Hi Partzman,

Check these datasheets out, one of these may work for a Tsvidis rep:

http://www.aldinc.com/pdf/ALD1115.pdf

http://www.aldinc.com/pdf/ALD1105.pdf

The above devices should work.

Quote
http://www.aldinc.com/pdf/ALD1121E.pdf

http://ww1.microchip.com/downloads/en/DeviceDoc/mic94050.pdf

also ..30  ..31 .. 51 in this family.

These appear to have the substrate connected to the source.

Quote
https://datasheet.octopart.com/MC14007UBCPG-ON-Semiconductor-datasheet-531527.pdf

This part appears to have the substrate connected to source.

Quote
https://www.nxp.com.cn/docs/en/data-sheet/BSS83_N.pdf

This part should work.

[/quote]
Fred
[/quote]

LtSpice appears to have seven different types of monolithic or 4-terminal mosfets.  This may provide an easy way to test the concept if the models are accurate.  We'll see!

Regards,
Pm
   
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Hi Partzman,

I didn't see your response to Mike above, but if I understand you correctly, your present circuit already has a sort of gate charge recovery?

Fred

Hi Fred,

Actually, the present circuit is not a gate charge/recovery type.  If this were the case, there would be no gain as can be shown by experiment and simulation as it would be conservative even though the elements are parametric.

This device works via off-resonance (above resonance) with the input current lagging the input voltage that produces a resultant lower input energy than output energy.  IOW, it is best described as reactive to reactive converter where the output reactive energy is greater than the input reactive energy.

The following is a modification of the original and performs at a more consistent level.  The schematic is shown first and it can be seen that effectively we have C1 being charged on the positive input pulse by the bulk or substrate diodes in M1-M4. 

The parametric capacitance provides the resonant "C" with L1 and at the proper frequency, this resonant circuit produces the parametric increase in the voltage across C1.  Without the parametric capacitance change in the mosfet drain to gate/source capacitance or the correct frequency, the voltage across C1 would simply reach a level equal to the supply voltage minus two diode drops and remain there.  It is obvious the voltage increases in C1 above the supply voltage during the scan.

The 1st scope pix is the Pin scan which shows 8.117mw consumed over 64.76ms resulting in an input energy level of 8.117e-3*64.67e-3 = 525uJ .

The 2nd scope pix shows the start and finish voltage change in C1 which results in an output energy level of (36.01^2-26.42^2)*3.94e-6/2 = 1179uJ for an apparent COP = 1179/525 = 2.25 .

The 3rd scope pix is an expanded view of the Pin scan and shows the basic cyclic waveforms.

I would like to point out that this scan was biased as seen in the schematic and therefore represents a fairly accurate result one could expect from a continuously operating device.  Also, the vertical resolution of these measurements  is 16 bits and the horizontal sweep rate is 100 mega samples/second.

I will also add that when running continuously at the proper frequency wherein C1 reaches a stabilized voltage level, the Pin will be negative due to the reactive voltage/current phasing. 

The drawback to this device at present is the overall low power.

Regards,
Pm 
   
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Quote
The parametric capacitance provides the resonant "C" with L1 and at the proper frequency, this resonant circuit produces the parametric increase in the voltage across C1.  Without the parametric capacitance change in the mosfet drain to gate/source capacitance or the correct frequency, the voltage across C1 would simply reach a level equal to the supply voltage minus two diode drops and remain there.  It is obvious the voltage increases in C1 above the supply voltage during the scan.

Interesting circuit, I see a series capacitor-inductor and mosfet switching on either side of the cap but I can't see a clear mechanism for gain.

However I can follow your line of reasoning that we could add/subtract series capacitance to vary a parameter ergo a parametric function. The reasoning behind the series parameter eludes me because the capacitance is in effect a storage mechanism relative to the action of the inductance. I can see the benefits of a charge pump configuration switching between series/parallel capacitance to modify the inductor I-V curve however what would the supposed change in a parameter act on?, it cannot act on itself in a series configuration.

This may help, the process in most of these FE devices relates more to energy or an energy state than a simple parametric function. If A happens we can expect B to follow as cause and effect plays out. However if we can hide B or part of it from A the normal flow of energy becomes interrupted. At this point "something" must intervene to conserve the energy in the system as energy must always be conserved in every case locally. Yes we could diverge on some tangent that energy is always conserved universally however that is not our concern.

In some sense it's like a game of hide and go seek, if action A happens then so must reaction B however if we could hide or transform part of B then energy cannot be conserved within the system and something internal/external must act to balance the equation.

My greatest insights came not from my R&D in electromagnetics or electrodynamics but more so critical thinking, reasoning, philosophy. The understanding that no matter how hard or fast I kick a dead horse it ain't going anywhere thus I should probably move on and try something different, something unique unlike what others do.

You will know it when you see it because it will be very much unlike anything you have done or thought in the past... something new.

Regards
AC









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Interesting circuit, I see a series capacitor-inductor and mosfet switching on either side of the cap but I can't see a clear mechanism for gain.

Your description of the circuit is too simplistic as the mosfets do not switch but rather provide the series parametric resonance capacitance change.  In order to help visualize the gain mechanism, ask yourself what causes the increase in voltage across C1 above the peak pulse voltage when the substrate diodes in M1-M4 are no longer forward conducting?

Quote
However I can follow your line of reasoning that we could add/subtract series capacitance to vary a parameter ergo a parametric function. The reasoning behind the series parameter eludes me because the capacitance is in effect a storage mechanism relative to the action of the inductance. I can see the benefits of a charge pump configuration switching between series/parallel capacitance to modify the inductor I-V curve however what would the supposed change in a parameter act on?, it cannot act on itself in a series configuration.

The parametric capacitance change may not even be needed as I'm reasoning at this point.  This conclusion came from the observation that as the voltage across C1 increases, the drain to gate/source parametric capacitance decreases and causes a higher off-resonance frequency.  When this state occurs, the input energy increases greatly and the gain drops to COP<1.

I would describe this circuit as a high frequency reactive to low frequency reactive converter requiring a driving frequency that is higher than the high frequency resonance during operation.  If this is true, then a fixed series capacitance would work with a higher efficiency than the parametric capacitance.  Testing will confirm this to be correct or not.  If this is correct, then scaling is no problem.   

Quote
This may help, the process in most of these FE devices relates more to energy or an energy state than a simple parametric function. If A happens we can expect B to follow as cause and effect plays out. However if we can hide B or part of it from A the normal flow of energy becomes interrupted. At this point "something" must intervene to conserve the energy in the system as energy must always be conserved in every case locally. Yes we could diverge on some tangent that energy is always conserved universally however that is not our concern.

In some sense it's like a game of hide and go seek, if action A happens then so must reaction B however if we could hide or transform part of B then energy cannot be conserved within the system and something internal/external must act to balance the equation.

My greatest insights came not from my R&D in electromagnetics or electrodynamics but more so critical thinking, reasoning, philosophy. The understanding that no matter how hard or fast I kick a dead horse it ain't going anywhere thus I should probably move on and try something different, something unique unlike what others do.

You will know it when you see it because it will be very much unlike anything you have done or thought in the past... something new.

Regards
AC

For those interested, here is a sim that shows the parametric drain capacitance change over time with a 20ma bias current up to the maximum 55v rating for the device.  This is not the same device as used on the bench circuit which is the 14N05L or logic version which I'm sure is graded from the 1405 die.  The error log displays the drain capacitance in nfd at the different time intervals.

Regards,
Pm
   
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Hi Allcanadian,

I see Partzman has answered you far better than I can, but since I already wrote this I'll send it for what it's worth.

The gain is from parametric amplification.

https://en.wikipedia.org/wiki/Parametric_oscillator#Parametric_amplifiers

The Mosfets are not being used as switches but as a form of variable capacitor. Parametric amplification doesn't happen by switching reactive elements-- the C or L of the element has to change while holding a charge or flux.* Using a Mosfet as a parametric amplifier is completely conventional in itself, there are fiber optic amplifiers that do this now. The hypothesis is that the increase in stored energy can be more than the energy used to change the parameter. In the wiki article above, the typical example of a parallel plate capacitor is used, but the energy balance in mosfets and varactor diodes is much murkier, so there seems to be a possibility of excess energy there.

It looks like Partzman is not adhering to the idea of a parametric gain, but I don't yet understand where else any gain could be coming from... gotta read more...

*There does seem to be a possible counter example to that. A long time ago I posted a paper by W.L. Barrow where he used a mechanically switched capacitor to generate oscillations. It's near the start of the Mandelshtam and Papaleksi thread in this forum.

Fred
   
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Hi Allcanadian,

I see Partzman has answered you far better than I can, but since I already wrote this I'll send it for what it's worth.

The gain is from parametric amplification.

https://en.wikipedia.org/wiki/Parametric_oscillator#Parametric_amplifiers

The Mosfets are not being used as switches but as a form of variable capacitor. Parametric amplification doesn't happen by switching reactive elements-- the C or L of the element has to change while holding a charge or flux.* Using a Mosfet as a parametric amplifier is completely conventional in itself, there are fiber optic amplifiers that do this now. The hypothesis is that the increase in stored energy can be more than the energy used to change the parameter. In the wiki article above, the typical example of a parallel plate capacitor is used, but the energy balance in mosfets and varactor diodes is much murkier, so there seems to be a possibility of excess energy there.

It looks like Partzman is not adhering to the idea of a parametric gain, but I don't yet understand where else any gain could be coming from... gotta read more...

*There does seem to be a possible counter example to that. A long time ago I posted a paper by W.L. Barrow where he used a mechanically switched capacitor to generate oscillations. It's near the start of the Mandelshtam and Papaleksi thread in this forum.

Fred

Hi Fred,

My conclusion that I stated in my last post which I repeat here,

The parametric capacitance change may not even be needed as I'm reasoning at this point.  This conclusion came from the observation that as the voltage across C1 increases, the drain to gate/source parametric capacitance decreases and causes a higher off-resonance frequency.  When this state occurs, the input energy increases greatly and the gain drops to COP<1.

is totally incorrect!!!

Bench tests prove that I was wrong in that there is no increase in the voltage across C1 with a fixed capacitor of 3.3nf in parallel with an STPS 2150 Schottky diode.

However, logic did dictate that perhaps two parametric sources on either side of C1 was redundant and in fact that proved to be true.  So, the right side of C1 is now connected to the CSR and single ended measurements can now be taken which simplifies things.  So the circuit is now reduced to a pulse source, one parametric mosfet network, and C1.

I will be doing more testing on this arrangement.

Regards,
Pm

   
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I would like to state that I have been having measurements of the various PC circuits that vary throughout the course of any given day.  This problem reared it's ugly head in the earlier posts of this thread and I have to admit that I do not understand the problem. 

There are times during the day that COPs are consistently in the 2 range and then after a period of time will change  to .8 or so.  This may be due to the long sweep times that push the limits of my Tek MDO scope therefore producing measurement errors.  The waveforms when expanded look accurate but perhaps beat waveforms are being produced between the switching frequency and the sweep rates which confuse the measurement calculations.   At the high sweep rate of 100 Msamples/sec, it takes about 15-20 seconds for the math calculations to complete and this is where and when I suspect the errors occur.

I have considered diurnal effects as well but the variations seem too broad over a short period of time IMO.

At any rate, if the devices worked at their best, the power levels are in the tens of milliwatts range which is not very useful unless large value parametric caps were found.

So, unless answers become apparent on the problem, I'll be leaving this research at the present time.

Regards,
Pm

 
   
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...
So, unless answers become apparent on the problem, I'll be leaving this research at the present time.
...
Hi partzman,

After several experiments on parametric systems, I came to the conclusion that changing a parameter has a price, and that you can't get back more than that price.
However the way is not to be abandoned if we can make this price paid by a free natural phenomenon, for example the ambient heat. But I haven't got the right idea for that yet...


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Hi F6FLT,

Yes, I tend to agree, although I still wonder about the hyperabrupt varactors....

In terms of ambient changes in light, heat, etc. Partzman and I tried some things along this line with the variable capacitance of solar panels. We actively varied the load to vary the C of the cells while in operation, to extract parametric power on top of the DC power. This didn't turn out to be very successful.

There are a lot of advantages to using solar panels as they are already installed everywhere.

Another way to use solar panels would be to switch them to parametric operation when the panel output goes below the controller's minimum voltage. Then, you simply charge the panels as a capacitor at irradiance peaks  and discharge it when light intensity drops. Since the C rises with solar voltage, the charge/discharge cycle could be controlled by a solar cell. Since the output power is determined as much by the charging voltage as the parametric cycling, this might be a pretty good way to get considerably more power out of the panels from dusk to dawn.

Another thought I had along these lines would to use oscillations of the E field of the earth to bias a bank of varactors or mosfets and once again charge and discharge them to gather power.

There are also variable inductors designed so that a very small variation in gap causes a large change in L. These could draw power from ambient vibrations.

There have been numerous patents along these lines since the 50s, when ambient parametric generators were considered to power ocean monitoring buoys and other remote sensors.

Fred

   
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Hi Fred,

Everything you said is very much in line with the kind of ideas I am exploring as well. I didn't know that there was a capacitive effect in solar panels, it is indeed an interesting track.
I came up with the idea of modifying a capacitance by heat, following some experiments with old capacitors from the 70s. When I used them in a high frequency oscillator, they were heating up, and the oscillation frequency was changing, which means that the capacitance was changing with the temperature. Unfortunately, the capacitance would have to decrease with temperature for the stored energy to increase, and the opposite was happening. I tested all kinds of capacitors, but either the capacitance remains stable or it varies in the wrong direction. Even if we had the right type, there would still be the problem that the thermal effects are slow, which makes effective practical applications difficult, as with the variable inductors you mentioned.
Using the oscillations of the electric field of the earth is also theoretically possible, but although the fields are high, the impedances under which they occur are also very high so that the recoverable powers are very low. The variations of the earth's magnetic field can also be used theoretically, but since they are very weak and slow, there again no practical application is possible.

The hyperabrupt varactors you mentioned seem to me to be the most interesting way, as well as all systems where very sharp nonlinearities appear. Systems out of their equilibrium state and in phases of rapid change seem to me to have been little studied in physics. Perhaps we could find new phenomena and solutions for our goal.

François


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Hi F6FLT,

Two books from 1965 have complete analyses of a "ferroelectric converter" using BaTi and PZT capacitors doped in various ways to get a better time constant. These are "Direct Energy Conversion" by Angrist, and "Direct Generation Of Electricity" by Spring, both packed with interesting approaches to energy conversion. In order for the device to operate the cycling temperatures need to be from the Curie point, around 120 C, to above it. At high voltages the efficiency can approach Carnot but electrical breakdown occurs before that point. In most cases the efficiency seems to hover around 3 percent. And with the required rapid cycling of heat, I could only see them being used in, for instance, a device that rotates in sunlight.

Another concept for below the Curie point would be to pair the heat-exposed caps with an inductor and then work with an L drop rather than a C rise.

I thought of using the E field because these very abrupt varactors have a very high reverse bia impedance. And so do the FETs used for instance in atmospheric electrometers. I haven't explored the idea thoroughly.   

A bit off topic, I did a patent evaluation of several thousand patents in the direct energy conversion field. Global, and as far back as I could get, which was usually around 1920 in most countries. Back to the beginning of the patent system in the US. This was how I noticed the C effect in solar cells, among hundreds of other interesting possibilities. The place where I could see the most likely possibility of vast improvements in efficiency and utility were in Seebeck generators. Before the development of ceramic materials, many clever inventors discovered and rediscovered the possibility of dramatically reducing heat transfer through the active portion of the thermocouple. They used point contacts, capacitive induction, arcs, and sparks to more or less completely decouple heat flow from current, and get around the Weidemann-Franz law that links heat and electrical conduction, and greatly limits the efficiency of these devices. The more sophisticated versions of this approach got efficiencies around 40%, which makes them competitive with other heat engines. I have a vast file on these various approaches but not being a hands on researcher but more of a paper pusher, I've failed to get anyone to seriously approach the subject.

Fred   
   
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@Orthofield

Efficiencies around 40% are not bad. I have also followed a lot of the improvements that have taken place in the last few years, especially with 2D materials or with the transverse thermoelectric effect. One has the impression that progress is important in the experimental field, but one does not see really interesting practical applications coming out of it.
So I'm going back to work...   :)

François


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Hi F6FLT,

Yes, given the current max efficiency of about 8%, 40% is way better than "not bad"! Like in photovoltaics, where there is stuff in the lab that can get maybe 30% (optical rectennas, metamaterials, etc.) these experiments will not be low cost alternatives in the next decade or so. If it isn't cheaper than other sources of power, it makes little difference that a lab has made it work.

The TEG tech I'm referring to doesn't require new materials.  The problem is it requires AC or quasi-AC operation, which thermoelectric engineers can't seem to wrap their heads around...

Fred

   
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Hi Orthofield

...
Yes, given the current max efficiency of about 8%, 40% is way better than "not bad"!
of course. It's just an ironic way of talking, like saying "that girl isn't ugly" when she's a charming model.   :)

Quote
Like in photovoltaics, where there is stuff in the lab that can get maybe 30% (optical rectennas, metamaterials, etc.) these experiments will not be low cost alternatives in the next decade or so. If it isn't cheaper than other sources of power, it makes little difference that a lab has made it work.

It is rather reassuring to know that it is a problem of cost rather than technique, as there is often subsequent research into cheaper alternative materials using the newly discovered principle.

Quote
The TEG tech I'm referring to doesn't require new materials.  The problem is it requires AC or quasi-AC operation, which thermoelectric engineers can't seem to wrap their heads around...

Fred

I have confidence in the engineers. They are no different from experimenters as us. They are very pragmatic and are always looking for ways to get around difficulties. I just think the issue is complex.


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