Popular Science had an article on something similar. It does seem a very good idea. instead of just having the farming be out in the open and spread out, why not in a building and have it be vertical. It would take up less space since some of the farm would be on a number of floors, as well as they could control the internal environment and could grow food closer to some cities so less distance it would need to be transported. & the technology is there to start doing something like this I would assume.