Silver Commonwealth wrote:Could urban farming be realistically implemented on such a scale, that it could sustain cities with food? (Of course, with all the setbacks, and obstacles during the program.)
No.
Plants need light. Sunlight is a function of surface area (any additional sunlight falling on the sides of a tower come at the expense of whatever is in its shadow, the surface area available for agriculture places the upper limit on the amount of sunlight available for photosynthesis). The energy costs of replacing the sun in agriculture are astronomical and there is no economic case for such a thing.
Stacking people and businesses is in contrast much more practical.