Skyscrapers dedicated to agriculture may not be up for permit approvals anywhere yet, but there are some ideas that come close.
"Such a high-rise farm has not yet been built. But in Devon, England, the Paignton Zoo has maintained a hydroponic, controlled-irrigation garden for several months. The yield from its 11,000-odd leafy vegetable plants-lettuce, spinach, herbs-is fed to the animals. The garden takes up 1,000 square feet in a greenhouse, about one-twentieth of what it would require in a field. Kevin Frediani, the zoo's curator of plants, says its key technology, a system of mobile nine-foot-high racks that help ensure the plants are properly fed and exposed to light and air, could be scaled up."