A FARM ON THE TOP FLOOR
At six o'clock every morning, chef Daniel Tan takes the lift from his restaurant kitchen up to the roof of the same building in Singapore. He goes there to pick the herbs and salad leaves he needs for that day's menu. Tan cuts the leaves himself. Then he types the amounts into a tablet on the wall, to let the farm's staff know what to plant next and to record how much of each plant is left. By seven, the greens are on his kitchen table.(lines 1–5)
The farm on the roof uses no soil at all. The roots of the plants hang in trays of water mixed with minerals, and the trays are piled in towers up to the ceiling, which is why such places are called "vertical farms." The water is cleaned and used again and again. Purple LED lamps give the plants only the colors of light they need. Because the room is completely sealed, insects cannot get in, so the plants never have to be sprayed with chemicals.(lines 6–10)
For Singapore, farms like this are more than an interesting idea. The country is a small island, and only about one percent of its land is used for agriculture. For years, nearly all of its fresh vegetables arrived by ship or truck from nearby countries, and any delay meant empty shelves. Today the government rents the roofs of public buildings to farmers at low prices. Meanwhile, Dubai, a desert city with a similar problem, is turning empty warehouses into indoor farms.(lines 11–15)
Not everyone is so enthusiastic. "The lamps are on for up to eighteen hours a day, and the air inside has to be cooled all the time," says Dr. Leah Morgan, who studies the way cities get their food. "All that electricity is expensive, so a lettuce from a vertical farm can cost twice as much as one from a field. Many families simply can't pay that much. Unless these farms find cheaper energy, their vegetables will remain a luxury."(lines 16–20)
The farm in Tan's building has tried to answer this criticism. Last year it covered the rest of the roof with solar panels, which now produce about a third of its electricity. It also sends the warm air from its lamps down to the restaurant, where it helps to heat the water for washing dishes. "Every dollar we save on energy comes off the price," says the farm's manager, Priya Nair. "Our lettuce is still not cheap, but it costs less than it did two years ago."(lines 21–25)
Morgan believes that vertical farms will never replace ordinary ones. "Herbs and salad leaves grow quickly and need little space, so it makes sense to grow them indoors," she says. "But wheat, rice and potatoes take months to grow and need huge areas, and growing them under lamps would cost a fortune. That is why we will always need fields. Still, for a crowded city that wants fresh greens close to home, a farm on the roof may be a very good answer."(lines 26–30)