Tesla's Ambient Heat Engine Theory - Right or Wrong ?

[Tom Booth]

In 1900 Tesla presented a method or theory for extracting energy from Ambient Heat.

Over 100 years have gone by and to my knowledge his idea or theory has been given little attention, has not been proven or disproven, nor, as far as I know has it been tested.

His explanation makes quite a bit of sense to me, but if true, why has this not been utilized ?

Here is an excerpt (edited for length)

POSSIBILITY OF A "SELF-ACTING" ENGINE OR MACHINE, ..CAPABLE,... OF DERIVING ENERGY FROM THE MEDIUM--THE IDEAL WAY OF OBTAINING MOTIVE POWER.
...Clearly, then, the problem was to discover some new method which would make it possible both to utilize more of the heat-energy of the medium and also to draw it away from the same at a more rapid rate.

I was vainly endeavoring to form an idea of how this might be accomplished, when I read some statements from Carnot and Lord Kelvin (then Sir William Thomson) which meant virtually that it is impossible for an inanimate mechanism or self-acting machine to cool a portion of the medium below the temperature of the surrounding, and operate by the heat abstracted. These statements interested me intensely....

Conceive, for the sake of illustration, [a cylindrical] enclosure T, as illustrated in diagram b, such that energy could not be transferred across it except through a channel or path O, and that, by some means or other, in this enclosure a medium were maintained which would have little energy, and that on the outer side of the same there would be the ordinary ambient medium with much energy. Under these assumptions the energy would flow through the path O, as indicated by the arrow, and might then be converted on its passage into some other form of energy. The question was, Could such a condition be attained? Could we produce artificially such a "sink" for the energy of the ambient medium to flow in? Suppose that an extremely low temperature could be maintained by some process in a given space; the surrounding medium would then be compelled to give off heat, which could be converted into mechanical or other form of energy, and utilized. By realizing such a plan, we should be enabled to get at any point of the globe a continuous supply of energy, day and night. More than this, reasoning in the abstract, it would seem possible to cause a quick circulation of the medium, and thus draw the energy at a very rapid rate.

Here, then, was an idea which, if realizable, afforded a happy solution of the problem of getting energy from the medium. But was it realizable? I convinced myself that it was so in a number of ways, ... Heat, like water, flows from high to low level, ... Heat, like water, can perform work in flowing down,... But can we produce cold in a given portion of the space and cause the heat to flow in continually? To create such a "sink," or "cold hole," as we might say, in the medium, would be equivalent to producing in the lake a space either empty or filled with something much lighter than water. This we could do by placing in the lake a tank, and pumping all the water out of the latter. We know, then, that the water, if allowed to flow back into the tank, would, theoretically, be able to perform exactly the same amount of work which was used in pumping it out, but not a bit more. Consequently nothing could be gained in this double operation of first raising the water and then letting it fall down. This would mean that it is impossible to create such a sink in the medium. But let us reflect a moment. Heat, though following certain general laws of mechanics, like a fluid, is not such; it is energy which may be converted into other forms of energy as it passes from a high to a low level. To make our mechanical analogy complete and true, we must, therefore, assume that the water, in its passage into the tank, is converted into something else, which may be taken out of it without using any, or by using very little, power. ... If the process of heat transformation were absolutely perfect, no heat at all would arrive at the low level, since all of it would be converted into other forms of energy. ... We would thus produce, by expending initially a certain amount of work to create a sink for the heat ... to flow in, a condition enabling us to get any amount of energy without further effort. This would be an ideal way of obtaining motive power. We do not know of any such absolutely perfect process of heat-conversion, and consequently some heat will generally reach the low level, ... But evidently there will be less to pump out than flows in, or, in other words, less energy will be needed to maintain the initial condition than is developed by the fall, and this is to say that some energy will be gained from the medium. What is not converted in flowing down can just be raised up with its own energy, and what is converted is clear gain. Thus the virtue of the principle I have discovered resides wholly in the conversion of the energy on the downward flow."

The full article can be found at either of these links:

http://www.tfcbooks.com/tesla/1900-06-00.htm

http://www.pbs.org/tesla/res/res_art09.html

I would like to know, does this idea have any merit ?

What happens to the heat that powers a heat engine ? Is it, like Tesla says, CONVERTED into something else ? Another form of energy. Or does it simply pass through from heat source to heat sink ?

How might this idea be tested ?

This isn't a "New Theory" as it was proposed by Tesla over 100 years ago but I don't know where else might be more appropriate for such a theoretical discussion.

Any thoughts or insights, experiments, observations etc. would be most appreciated.

[angryScientist]

I think it does have merit. It comes with a caveat though; Every trick in the book should be used.

What most people that bring up the laws of thermodynamics don't realize is the LATENT heat does not get calculated.

LATENT from Latin; to lie hidden

The heat absorbed in the phase change from a liquid to a gas does not get computed in the PVT calculations. The heat gets a free ride. That is what makes a heat pump ~%400 efficient.

There are other changes in phase that can be exploited. When a gas dissociates there is latent heat absorbed. When it re-associates the latent heat reappears and can make a turbine engine about %60 efficient, I hear tell.

YES! Tesla was right. He may not have had the most efficient engines back then.

WRONG is what people are when they only see half of reality.

[Tom Booth]

While Tesla may have been brilliant with electrical devices, I don't think he understood thermodynamics.

Just my opinion, but I think Tesla understood thermodynamics.

For non quantum sized devices, the second law of thermodynamics would prohibit such a device working if there was no temperature gradient.

I think Tesla also was well aware of the second law of thermodynamics as he references the authorities on the subject in his article.

In what he proposes, there IS a thermal gradient.

As a practical example of what he was proposing, take a Stirling Engine "running on ice". Tesla was quite aware that a thermal or temperature gradient or differential was necessary and would need to be supplied in order to get such an engine started.

What he was saying is that once started, Assuming that your supplied heat sink is perfectly insulated from ambient heat, except insofar as that heat that might reach it in passing through the engine, the engine would convert the heat trying to reach the sink into something other than heat. i.e. motive power and/or electricity etc.

Put another way, if you started a Stirling (heat or hot air) Engine running on ice, It would actually be getting its energy source from the surrounding ambient heat.

Now if the ice were in a thermally insulated bowl, like a dewar bulb or thermos bottle but open at the top with the Stirling Engine sitting on top of that, Then no (or very little) heat could reach the ice except by passing through and powering the engine, but in so doing, the heat, or some percentage of it, would be converted into mechanical energy, or if the engine were coupled to a generator, into electricity. so the heat would be converted into some other form of energy before it reached the heat sink. and so it would never actually get to the ice to melt it.

What he is suggesting, in effect, I think is; If you had a very efficient heat engine running on ice, and there was no other way for heat to reach the ice from the environment except through powering the engine then the ice would never melt or so little heat would reach the ice that that heat could be easily removed by utilizing the power derived from the heat which was converted.

I think many people in arguing against this say that IT TAKES ENERGY TO MAKE ICE, and have the misconception that a Stirling Engine "running on ice" is actually running on energy STORED IN THE ICE by an ice maker. But this is not the case. The engine "running on ice" is really running on ambient heat. If the heat in passing into the engine is CONVERTED before it reaches the ice then the ice would never melt, or melt much more slowly than it would if exposed to the open air.

So it would take less energy to maintain the temperature gradient once established than would be derived from that gradient from the ambient heat being converted by the engine.

[Tom Booth]

I think it does have merit....
YES! Tesla was right. He may not have had the most efficient engines back then.

OK, but if so, and given modern advances in technology that were not available in Tesla's day, why has this not been exploited in 100+ years ?

I've seen dozens of LTD type Stirling Engines on YouTube "running on ice" but have never seen anyone in any of these videos bothering to INSULATE the ice from the surrounding Ambient Heat.

Also, as much as I've seen talk of coupling a heat engine with a heat pump, as appears to be the case in your illustration, as far as I'm aware, nobody has ever actually put something like that together. Or if they have, they have not reported on the results of any such experiment.

[angryScientist]

Phase change and latent heat etc is not important when considering a device with regard to the second law. A heat pump obeys the second law. It is just its cycle is reversed compared to a heat engine.

One could not connect the output of a heatpump to the input of a heat engine and have it run 'self looped'. Such a system would be creating output work with no overall temperature differential and thus break the 2nd law.

That's not entirely true. Among other things the scale is important. At the macroscopic level that will generally hold true (unless some animal walks into the scene and messes everything up. Crazy nature. How is one to account for that? Never mind, I'm just say'n.) On the microscopic scale things get weird and it becomes more and more possible that extra energy is going to appear from know where or maybe change form and disappear.

A heat pump clearly violates the second law of thermodynamics. It reverses entropy. It gathers heat and compresses it into a small space increasing the temperature there and reducing it elsewhere. That is the exact opposite of entropy.

A heat pump and an engine are not really the same. We would think that something is wrong if a heat pump were not more than %100 efficient. We expect %300 to %400 percent efficiency. An engine on the other hand can NEVER be more than %100 efficient.

A heat pump can be thought of as a heat concentrator.
An engine can be thought of as a heat converter. I takes heat and turns it into something that is not heat. You end up with less heat but that energy in now in another form, mechanical, for instance.

Looking at the math, I would say that it is possible to connect the output of a heat pump to the input of a heat engine and have it run 'self looped'. You may end up with less heat but that energy will be still be there, in another form. Perhaps a form that would be more useful.