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What attempts are there been at converting on Earth's surface, night/day temperature differences, so that the dilation of a large bimetal is converted into mechanical work ?

At small scale it would look like a bimetal strip that drives a linear gear with the adequate reduction ratio (overdrive in this case) to match the dynamo or generator requirements.

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It may not even need to be a bimetal, it could only involve a single material with high dialtion ratio that converts this linear dialtion into rotary motion.

The idea would be to size a piece of metal so that its thermal inertia matches (on average) the day/night cycle, and combine this with an efficient overdriving gear train.

How unscalable or inefficient would this contraption be and why?

user721108
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  • You need a certain specific power (the power per pound of machine) in order to pay for the machine over it's lifetime, and this wouldn't do it. It doesn't collect heat efficiently. If you had a mirror that concentrated heat every 2 minutes and then shaded the device, you would get about 500times as much power, and you still wouldn't pay for the machine. Solar reflector steam plants driving a sterling cycle engine are a better option and are basically doing the same thing. – Phil Sweet Sep 04 '22 at 11:09
  • @PhilSweet thanks for your comment, I don't get the "power per pound of machine" concept, mostly if the heavy part is cheap, think about a concrete dam that is in some way part of the whole machinery – user721108 Sep 04 '22 at 11:23
  • also is the lake behind the dam part of the whole thing and does it count in power per pound of machine calculation (still in this analogy with hydroelectric pwr generation) – user721108 Sep 04 '22 at 11:49
  • How much does metal move with temperature change? Start by quantifying that. – Solar Mike Sep 04 '22 at 12:34
  • @SolarMike thanks I get your point, thats why I rather think about the amount of force required to prevent a 20m steel beam to shrink 1mm when it is cooled down. this is a large force for a short movement, still this is a large force. – user721108 Sep 04 '22 at 13:59
  • So, you are thinking like the 1" punch of Bruce Lee... then think about the losses. – Solar Mike Sep 04 '22 at 15:07
  • @SolarMike in this case the punch lasts for 12 hours, plenty of time to gather the energy from it, even if it is a small displacement – user721108 Sep 04 '22 at 15:19
  • Hope you're aware that this basic mech is what ran all house thermostats prior to the introduction of digital processor-based units. The energy storage per kg or per cc is pretty tiny. – Carl Witthoft Sep 06 '22 at 12:59

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