This thread is intended to provide a space for 'crazy' ideas. Ideas that spontaneously come to mind (and feel great), ideas you long wanted to tell but never found the place and time for and also for ideas you think should be obvious and simple - but nobody ever mentions them.
Rules for this thread:
- Each crazy idea goes into its own top level comment and may be commented there.
- Voting should be based primarily on how original the idea is.
- Meta discussion of the thread should go to the top level comment intended for that purpose.
I've heard of cars powered by liquid nitrogen, since it boils at ambient temperature (even if the weather is below freezing), you can use it to expand a piston. The energy comes from the ambient environment.
Thermal equilibrium with outer space is about 4 Kelvin (due to background radiation). That's really cold. If we could make a large radiator exposed to open sky at night could we use it to produce liquid nitrogen? Not exactly, because the air itself can emit radiation. This is the greenhouse effect.
But would it be possible to coat the radiator with quantum dots that preferentially emit thermal radiation at a frequency not absorbed by the atmosphere?
If it works, this would be a completely passive system capable of producing fuel, and might also make cryonics and systems using superconductors more economical, such as long distance power transfer and grid scale energy storage in magnetic fields.
In case you missed it and for future readers:
It does indeed look like something like this is possible. At least two companies in the space: SkyCool and Radi-Cool. Here is an article covering mainly the former.
I believes this qualifies the idea as No Longer Crazy™.