Small farms (below 350,000 / yr gross income) account for 25% of production value and 90% of total number of farms [0] and if you look at the crops being produced by large farms they're often not for direct human consumption.

Urban farm development is high density farming which doesn't require the same available area and often produces crops with higher nutrient density. It seems technically feasible for medium density urban areas to produce a large percentage of edible food locally in the near future; though that doesn't guarantee a viable business model will exist.

[0]https://www.ers.usda.gov/data-products/ag-and-food-statistic...

> It seems technically feasible for medium density urban areas to produce a large percentage of edible food locally in the near future

I absolutely agree with this - but I don't understand what the selling point is. You can't use greenhouses in an urban setting - if you've ever seen a modern hydroponic greenhouse light up the night sky you know why - and the efficiency loss from entirely replacing sunlight is staggering.

I guess I don't get it.. what's the selling point that I'm missing?

The initial selling points will be for high end markets. This style farm would give more control over the humidity and temp to the farmer who could then make significant changes to the flavor profiles that would be easily repeatable. Additionally, all out of season crops will taste in season and there will be no issue with shipping time leading to degradation.

This could be enough of a selling point for certain high end restaurants.

The loss of sunlight does seem staggering to overcome, but plants can only use a few narrow spectrum bands of light which can be efficiently replaced with led.

> This style farm would give more control over the humidity and temp to the farmer

I'm not following; any modern greenhouse has automated humidity and temperature control (and, more important than humidity, artificially increased and controlled CO2 levels).

What sets the temperature and humidity control apart from a modern hydroponic greenhouse ag operation like Houwelings? http://www.houwelings.com/files-2/why-greenhouse.php

> plants can only use a few narrow spectrum bands of light which can be efficiently replaced with led.

Yes on the light spectrum - but I'm not sure what you mean by "efficiently replaced"; my understanding is that the energy required to replace sunlight with best-in-class LEDs remains substantially more kWh/lb of produce than shipping as far as across the entire country.

The Cornell lecture I linked to elsewhere talks about this: https://youtu.be/VrpyUA1pQqE?t=1842

Temp controllers aren't a new idea, but using them in a large greenhouse limits you because the sunlight is heating the greenhouse in the summer and the glass is cooling it in the winter. You can't insulate this area, so you need increasingly larger heater or AC to effectively maintain a temp as the ambient temp deviates seasonally. I know high CO2 helps plants cope with higher temps and increases metabolic rate, but I'm not sure what its effects on secondary metabolites that produce the flavors are.

By only using 460 nm and 640 nm light you reduce unnecessary spectra for a chlorophyll b containing plant. Compared to other lighting sources which emit a broad specta of light, LED is much more efficient in terms of usable photons / kwH though it is likely still cheaper to ship from a freely lit greenhouse in a high light density area.

The selling point is the value addition of having a high degree of temperature and lighting control; and hinges on that leading to the additional production of certain flavors and nutrients that wouldn't be possible with less control.

Thanks for the video btw, it comes to the opposite conclusions about heat retention in closed vs open systems.

Here's a good reference on spectra induced morphological differences in plants to explain effects of lighting control better: https://www.youtube.com/watch?v=8L7uODfuKLY&list=PLHPXm2Es8a...