Agricultural researchers believe that building indoor farms in the middle of cities could help solve the world's hunger problem. Experts say that vertical farming could feed up to 10 billion people and make agriculture independent of the weather and the need for land. There's only one snag: The urban farms need huge amounts of energy.

One day, Choi Kyu Hong might find himself in a vegetable garden on the 65th floor of a skyscraper. But, so far, his dream of picking fresh vegetables some 200 meters (655 feet) up has only been realized in hundreds of architectural designs.

In real life, the agricultural scientist remains far below such dizzying heights, conducting his work in a nondescript three-story building in the South Korean city of Suwon. The only thing that makes the squat structure stand out is the solar panels on its roof, which provide power for the prototype of a farm Choi is working on. If he and his colleagues succeed, their efforts may change the future of urban farming -- and how the world gets its food.

From the outside, the so-called vertical farm has nothing in common with the luxury high-rises surrounding it. Inside the building, heads of lettuce covering 450 square meters (4,800 square feet) are being painstakingly cultivated. Light and temperature levels are precisely regulated. Meanwhile, in the surrounding city, some 20 million people are hustling among the high-rises and apartment complexes, going about their daily lives.

Every person who steps foot in the Suwon vertical farm must first pass through an "air shower" to keep outside germs and bacteria from influencing the scientific experiment. Other than this oddity, though, the indoor agricultural center closely resembles a traditional rural farm. There are a few more technological bells and whistles (not to mention bright pink lighting) which remind visitors this is no normal farm. But the damp air, with its scent of fresh flowers, recalls that of a greenhouse.

Heads of lettuce are lined up in stacked layers. At the very bottom, small seedlings are thriving while, further up, there are riper plants almost ready to be picked. Unlike in conventional greenhouses, the one in Suwon uses no pesticides between the sowing and harvest periods, and all water is recycled. This makes the facility completely organic. It is also far more productive than a conventional greenhouse.