lancelot21

If I understand it well, the cold spot of the Kender engine is a heat sink since it will be heated up by the (warmer) air outside - and the definition of a heat sink (according to http://en.wikipedia.org/wiki/Heat_sink ) is "an environment or object that absorbs and dissipates heat from another object using thermal contact".

Following your own formulas I get rather: [math]COP . \eta = (T_h-T_c)^2/T_h[/math] In other words (if I understand your formulas well): if the system has no losses and is ideal, there is a net gain of energy as long as the temperature differential is big enough.

I think there is a difference between running a heat engine from a heat pump and running a wind farm from a fan: The heat pump generates heat with a coefficient of performance of 3-4 (according to http://en.wikipedia.org/wiki/Heat_pump), which means if I understand correctly that one joule of electrical energy can cause a heat pump to move 3 or 4 joules of heat from a cooler place to a warmer place. But, according to http://en.wikipedia.org/wiki/Heat_engine, a heat engine (specifically a steam-cooled combined cycle gas turbine, whatever that is), has a 60% efficiency. This means if I understand correctly that one joule of heat can cause such a heat engine to produce 0.6 joules of electricity. The whole cycle becomes 1 joule of electricity producing 3 to 4 joules of heat producing back 0.6x3 (=1.8) to 0.6x4 (=2.4) joules of electricity. I believe this is exactly what Kender is trying to achieve.

As far as I know, a heat pump produces heat with little electricity, much less than it normally takes to heat a house. Let's assume we heat one room of a hypothetical house with a heat pump. We then get different heats between the room thus heated and another unheated room of the house, with much less electricity than by heating the room without a heat pump. If we then use the heat difference to run a Stirling engine like the one in the first (German) video posted by NuclearError, a heat pump could produce electricity (after having consumed some first): the normal (unheated) room stands respectively for the room and then the ice cube of the video on one end and the warm room stands respectively for the hot cup and then the room of the other end (of the heat differential) in the video. I fail to see where it breaks any thermodynamic law or conservation of energy law. It only comes down to whether the electricity consumed by the heat pump is smaller than the electricity produced by the Stirling engine. And maybe under high pressure and with high temperature differential and the right volumes it is the case. And maybe Kender does this and found the right combination, or maybe another company will, but if such a possibility exists, I would think it is worth investigating.

From what I understand of the Kender process, the initial pressure of the gas (be it Helium or whatever, not really a concern for me as long as the gas is reasonably inert) rushes it from a section of the engine (let's call it section A) to another section (say section B) through a sort of turbine (generating electricity); the temperature of the gas inside this closed section B drops because the pressure of the gas drops (I'm not sure of what happens to the volume of the gas, maybe section B is also larger than section A?). This could be the refrigeration cycle you talk about. I agree with CaptainPanic that the turbine must probably get locked at this stage. Then the gas is pushed (by another turbine? Anyway this step is consuming electricity) to a section C (the "solar panel", which looks to me more like a heat exchanger). I guess this goes on until section B is empty or empty enough (whatever that is). Then the second turbine must also get locked. The gas in section C is still at a very low temperature at first, but is gradually heating up due to heat exchanges with the atmosphere. As it is heating up, the pressure of the gas is also increasing. If section C is the same as section A, I guess the cycle is completed when the gas is somewhat back to its initial pressure and temperature and the first turbine is about to be unlocked. Or maybe there are more sections somewhere. Does the process I just described really break the law of conservation of energy or of thermodynamics? I still don't see why - my concerns about such an engine would be: - Does the second turbine consume more electricity than the first one produces ? Otherways there would be no electricity generated (but could it still be a cheap way to cool air outside of the engine?) - How fast does the gas in section C heat back up (and how fast does its pressure go back up) ? I agree with Mr Skeptic 0.22 seconds is fast, the more time the cycle takes the less electricity is generated if any.

My understanding is that the stored energy present in the atmosphere is huge, as it would take a huge amount of energy to heat the same quantity of air as contained in Earth atmosphere from 0K up to the average air temperature (293K?). Thus, a device that could hypothetically extract heat from the Earth atmosphere and produce electricity from it would not need to bypass the law of conservation of energy to be able to produce massive amounts of electricity before running out of "fuel", ie when outside air temperature would be so low (below -70C according to Kender home page) that it wouldn't work properly any longer.

Like sunshine, I feel it a bit unfair to judge whether Kender Solar works based on the limited info available on their web site, as I don't think they should make available all their secrets anyway. Moreover, I'm more concerned here about whether a company could in theory succeed in doing a similar engine, rather than knowing whether this particular company (Kender) will. My understanding is that what they are trying to achieve can also be compared to heat pumps as far as thermodynamics are concerned: In heat pumps, the cold air from outside the house becomes colder while the warm air inside the house becomes warmer. A small amount of electricity is used, but doesn't consume as much as a normal heater or else nobody would bother installing heat pumps in their house. Another way to see this is that some energy was taken from stored solar heat outside the house and converted into heat. The (small?) new step taken by Kender is to take some energy from stored solar heat outside the house and convert it into electricity instead of heat. This is not to say that they will achieve the efficiency they claim or even that they will produce electricity at all (as electricity is needed to run heat pumps in the first place), just that I don't see why their claim should be impossible according to the laws of thermodynamics.