30-story urban farms?

When I first heard about this idea, I thought it was dumb. With the amount of vacant land available, why bother growing food in skyscrapers? But there may be something to it.

Why build vertical farms in cities? Growing crops in a controlled environment has benefits: no animals to transfer disease through untreated waste; no massive crop failures as a result of weather-related disasters; less likelihood of genetically modified “rogue” strains entering the “natural” plant world. All food could be grown organically, without herbicides, pesticides, or fertilizers, eliminating agricultural runoff. And 80 percent of the world’s population will be living in urban areas by 2050. Cities already have the density and infrastructure needed to support vertical farms, and super-green skyscrapers could supply not just food but energy, creating a truly self-sustaining environment.

I'm particularly sympathetic to the idea of being able to isolate your crops to keep out GMOs and insect pests, having spent enough time in my life picking bugs off spinach, zucchinis and apple trees. Of course, if you ever got an infestation in the kinds of monocultures they would have in these buildings, it would be game over...

Update: Kate Petersen at Politicook sends me to City Farms, a blog about Urban Agriculture (not the skyscraper kind)