Urban farming only makes sense for high value, easily perishable produce. Fresh herbs, leafy greens, tomatoes, and other salad ingredients can be produced with higher quality when they are harvested and used on the same day, and when the plants don't have to be bred for shipment-and-storage durability. The real benefit is superior flavor and texture for quality-focused, price-insensitive eaters.

Note that this product site touts how much lettuce the system can grow.

More radical claims about how vertical farms will reduce CO2 emissions or feed a growing world population are aspirational to the point of delusion. Vertical farming isn't going to replace the calories that people get from potatoes and beans grown in big plots of dirt outdoors. If you ate potatoes grown in a nearby vertical farm instead of ones grown in Idaho and shipped across the country, you'd actually be increasing your carbon footprint.

It takes only a little energy to move a potato a thousand miles cross-country. It takes a lot of energy to grow a potato under artificial light. Even though renewable energy is ~20x better in life cycle emissions than fossil energy, it takes more than 20x as much energy to grow potatoes under artificial light. From a CO2 life cycle perspective you're better off eating potatoes that had ordinary diesel powered tractors, trains, and trucks involved in their production and delivery than to eat potatoes that were grown in a wind-powered vertical farm next door to you.