Vertical farming only really works as either artistic preference for maximum visual appeal or the kind of science fiction where you assume only a small handful of technology advanced.
But that’s hardly required as solar panels to LED’s can’t reach 100% efficiency. Further, the limited lifespan of solar panels and LED’s means you need to cover their construction etc which requires resources.
Ultimately, looking at theoretical limits it’s simply a net loss.
PS: Monoculture is far from required, it’s an outgrowth of current automation rather than having any theoretical advantage.
Those blurple lights are just awful, and not only do the LEDs have far less energy efficiency being old tech, but their supposed "optimal" wavelengths are anything but. They are blasting out extremely narrow wavelengths of light and trying to make it more continuous by using a bunch of slightly different narrow range colors, but it doesn't work as well as one would hope, especially when they are coming from different point sources.
Aside from environmental effects, it’s also just a more secure logistics chain. A person needs water, food, and shelter to survive. Sometimes it feels strange to me that the trend of the past centuries has been to increase the distance between a person and those sources — to introduce more points of failure between you and the things you need in order to survive.
In the UK you can grow crops all year round outdoors [0], and the growing seasons could easily be extended with a passive greenhouse (polycarbonate is more insulating than glass). You can also use tried and tested preservation techniques like canning and fermenting to keep food for other seasons.
[0] https://www.gardenorganic.org.uk/vegetables-all-year-round
That 1200 watts is only really covering a 6 by 6 foot square worth of growth area at about 35 watts a square foot at 200 lumens per watts. It could be slightly larger but only if you want most plants to grow extremely slow or be really weak, and you can go up to 50 watts per square foot before requiring supplemental CO2 but not all plants like that amount of light.
Converting that to 1 acre worth of coverage, which is what is about what is needed to feed a single human for one year, you are looking at about 1,500,000 watts running 12-18 hours per day. That is a ridiculous amount of energy. Even assuming you can get away with 1/3 of that area by super careful and efficient growth year round that is still a half million watts in lighting costs alone. Not to mention all the other work and costs.
I don't see indoor farms being good for anything other than extreme specialty plants or extremely fragile plants until we can pull essentially limitless energy out for far cheaper than we can get even with fossil fuels.
This is for an indoor leafy green, mostly sallad, aquaponics growing facility.
Perhaps with a bigger more automated setup I could do slower growth, but there are other costs like ventilation or dehumidification or possibly heating or cooling too that don't really change a lot whether the plants are growing fast or slow, which makes faster growth possible optimal financially, even if I might be losing out a few percentage worth of light absorption.
As far as the urban agriculture crowd goes, they're concerned about the length of their logistics lines to their tables. Raspberries grown half a mile down the street in winter is better for the environment than flying them in from another hemisphere... provided you get the energy costs of the indoor farming system low enough.