Vertical farms are going to be huge. They're almost fully isolated from the outside environment save for taking in local air and removing carbon from it. They require magnitudes less water than traditional agriculture and no fertilizers. You can build them in the middle of a downtown core if you need to. And you could optimize power consumption so that the majority of your energy comes from renewable sources. See Aer…
Please note that vertical farming is mostly about producing leafy greens and other low-footprint, high-value goods. Purely from the energy standpoint there is no sense in using vertical farming for the bulk of calorie consumption. Compare traditional farming: sunshine -> green parts of the plant -> seeds -> food -> people with vertical farming: sunshine -> [... -> electricity -> LED light] -> green parts of the plant…
I was reading an interesting article about the farmer's market in my country, production is actually not the largest cost, it's less than half of the actual sale price.
See for example:
http://capreform.eu/farmers-share-of-food-chain-value-added/
(spanish) the article I was reading: http://www.cnfr.org.uy/uploads/files/Manual_de_comercializac...