The thing that always baffles me with vertical farming is sunlight. Assuming most crops are pretty good at turning full spectrum sunlight into useful stuff, why shrink your solar energy per crop?

And assuming you get around this via grow lights, surely the energy and material cost goes up too much for high-volume crops to make economical sense.

I think it's hard to generalize whether vertical farms are good or bad; efficient or inefficient. It seems that whether it works or not relies very heavily on the locality.

In my part of Ohio, we have lots of farmland -- and plenty of water that just falls out of the sky. We've got reasonably-long, generally-hot days during our growing season and we get some serious crop production done here while it lasts.

The rest of the year? The days are short. It's dark and cold outside; frozen, even. We can't grow crops outside here in the winter.

But vertical farms (eg, fancy greenhouses) can just keep going. With artificial light and/or supplemental heat, they're still producing even in the depths of winter.

Thus, I can go to the grocery store near my house and buy a locally-grown tomato in February. It's expensive to get this done, but the alternatives include paying someone to drive it up here from thousands of miles away or just going without a tomato until after things have warmed up again and stayed that way for awhile.

This only makes sense in certain circumstances I think. For example, shipping tomatoes from 5000km away when it's winter in Canada.

I recently did some research, and there are multiple local greenhouses around many large Canadian cities for just this reason. They are competitive in the winter, and sell to local supermarkets. The cost of the greenhouses vs shipping + loss.

And there is a loss in nutrition, when you harvest green and it takes weeks to hit the table, vs something picked yesterday and picked when actually ripe.

Of course, these are large warehouses, not typical greenouses.

So I guess the answer is, it can make sense in certain circumstances. A warmer place where you can grow fruit outside year round, not so much.