Vertical farming, the best solution to support an ever growing population or just a scam?
IMHO it has a lot of potential but not being able to grow grains really is something that should be tackled sooner rather than later. But I could see this being used by self sustaining communities to provide lots of food while using very little space. And it's technically more environmentally friendly than just using vast stretches of land to produce the same amount of food.
depends extremely heavily on the efficiency of the panels.
You would need to exceed 84% solar to electricity conversion efficiency to make that conversion pay off.
As chlorophyll has an approximate 90% maximum interception of 400nm to 740nm light and your panels would be getting the extra energy from frequencies outside of that range. The energy of a photon is determined by hc/λ, with the result that the energy of a blue photon (400 nm) is 75% greater than that of a red photon (700 nm).
Anything less than that would be a net loss unless there is a significant increase of ultraviolet light in the near future.
Within the 400 to 740nm range chlorophyll has a huge gap: https://cdn.kastatic.org/ka-perseus-images/27c5e928745dbde12550494315ec70253091eee5.png whereas sunlight is strong across all of it. Grow lights usually only provide blue and red wavelengths that are better absorbed. Also, most plants' growth are not limited by sunlight but usually either by water/nutrients or CO2, so most of them can receive a bit less light than the sun typically provides.
The calculation we had done a few years ago, that gave us the result that a square meter of PV could light up almost 2 square meter of crops, only took these spectra into account.
Since then, I have read really counter intuitive things that may even raise the efficiency higher (and the weirdness of grow boxes even more). People started using LASER LEDs to grow plants. Low power of course, but it turns out that concentrating the light on where the plants and leaves actually are does indeed maximize the number of photons that get absorbed.
Here again, I am not sure this is something desirable or the future that I want, but this is a possibility that is out there.
and how did the experimental test of the calculated results turn out?
I would be quite interested to learn more.
This was just a theoretical discussion, like I said, I am not sure this would be a good idea per se even if possible.