alt Hacker NewsMechanical power generation using Earth's ambient radiation
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If anyone is interested in passive sub-ambient cooling (not for power generation, just for "free" cooling) I strongly recommend https://www.youtube.com/@Nighthawkinlight -- he has been doing a lot of experiments in this space and releasing recipes as he goes. Stuff you can do in your kitchen.
Vid of the engine in action, from the team that made the paper
https://www.youtube.com/watch?v=5VSmBl8Rv_o
This one shows that it is not as unbelievable as it sounds :)
DIY radiative cooling paint from YouTuber NightHawkInLight - https://www.youtube.com/watch?v=N3bJnKmeNJY&list=PL1a2HkcVbm...
It has pretty impressive performance.
Tech Ingredients did one or two vids as well - https://www.youtube.com/watch?v=dNs_kNilSjk
Was thinking of whipping up a batch for my rv.
Somewhat different, but this reminds me of an approach that uses temperature gradients in the ocean to power a heat engine.
https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversio...
> 400 milliwatts per square meter
About two orders of magnitude weaker than solar panels, even over 24 hours.
E = (T2-T1) / T2
In one of the later Foundation series books, Isaac Asimov had a whole world run on this.
Cost to build, maintain this machine? $/watt?
Since we're talking about stirling engines, I've always wondered how using geothermal heat for a larger stirling engine would work.
https://youtu.be/duuk_r--lqU?t=99
Even though the video uses the sun to heat the oil, I would think it would be feasible to use geothermal heat instead.
400 milliwatts per square meter? That's interesting that they can do it at all, but that level is completely impractical for real use.
Great! Now I desperately need this Stirling engine for my morning coffee: https://a.co/d/6Ja2LeF
Video of how it works: https://www.youtube.com/watch?v=Q5QEBqjkNjo
Not an engine, but some friends of mine got a mylar sheet that's black on one side and reflective on the other. We tried it out in the desert tied onto trees/vehicles. You put the shiny side down, so the hot IR radiation of the earth is reflected away, and the black side sees the extremely cold (in IR) desert sky. If you put a little hole in the middle and put a bucket under it, you get a fair bit of water, because the mylar sheet gets about 20 degrees C below ambient and a lot of water condenses on it. (even in the desert)