Lunar panels

A couple of years back, I remember vividly once telling my daughter about what solar panels are. She quickly grasped their crucial limitation and then announced that, "we should have lunar panels too". Well, I said, it would great if you could invent one of those when you go to university. 


Well, maybe she could build an effective lunar panel, as researchers at UCLA and Stanford have built in their lab a precursor, which they call a Radiative Cooler.

It's an aluminium disk that's exposed to the night sky, and exploits a phenomenon called Radiative Sky Cooling to coax small amounts of electricity from the temperature difference between the surface looking up at the night sky and the air immediately surrounding it. So, I suppose you could say that the device is powered by the total absence of the sun, rather than the presence of moonlight.

The effect means that if you were to sit on your roof at night - and I'm not recommending that you do! - you'd find that the tiles, regardless of material, were colder than the air. More practically, you can witness frost forming on outdoor surfaces when the temperature is above zero celsius.

When I say small amounts of electricity, I really mean tiny amounts presently, as their lab version today generates 25 mW (milliwatts) per m2 of cooler surface, enough to power 25 hearing aids (or in the case of their prototype: a 3mm white LED lamp. But they believe that they already have a pathway to boosting that to half a watt per m2.

And so you can understand that with some more development, it might be feasible to power small household items from a rooftop collector the size of a solar panel, and certainly low-draw items like sensors in the near future.

So, maybe my daughter's generation will have a roof covered in lunar panels, or combined lunar/solar - luso? - panels. Maybe even ones that she will one day commercialise.

If you want to read more, see Raman, A., Li, W. and Fan, S. (2019). Generating Light from Darkness. Joule

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