@ 3D farming:
for those that are unfamiliar with the concept, my understanding is this: It's a sky-scraper with a farm inside.
The bulk of the light the plants get comes from sun-lamps.
At present there are certain hurdles yet to be overcome; most notably, for reasons as yet to be determined, many plants simply refuse to grow well in-doors. There's also the issues of a lack of corporate interest, the further centralizing of food production away from small farms, the energy requirements for the lighting and irrigation and their associated costs, etc.
It's not a bad idea, per se, but there's quite a bit of work to be done before it becomes a viable option.
Disclaimer: this is my understanding of the concept, but I'm not 100% sure that it's entirely accurate. Independent research is advised.