Skyfarmers –  Soon farms may have a new look. Urban, 1000 feet high, right in the middle of downtown. Not what your typical getaway to grandma’s. Some scientist think that the farms of the future may be located as mentioned: on the roofs of skyscrapers. The idea is similar to that of a green roof, but with food production involved. Food would be grown using soil-free hydroponic (water) farming, which would cut the demand for energy. This method would utilize already existing space (city buildings) for a continual necessity (food). Added bonus: the food would be grown close to demand, eliminating costly transportation fees.
http://www.verticalfarm.com/