Take a stroll through the local grocery store and notice how much of what you're seeing comes from just a few miles away. Chances are it's less than 10 percent, with the rest coming from other states and frequently other continents. Getting this stuff-say fruit in the off season that's grown in a different hemisphere-from field to store requires a lot of energy, raising the cost of both food and oil, while polluting at each stage of the process. Meanwhile, the amount of good farmland around most cities is shrinking as a result of urban sprawl, stretching supply chains even further.
So why not solve both problems at once by building vertical farms right in the middle of cities, says Dickson Despommier, a 67-year-old microbiologist at Columbia University. Every major city, after all, has hundreds of abandoned buildings, most with water and electricity hookups. Convert them to hydroponic farms and you use no new land, while producing food that has virtually no commute. Or build new state-of-the-art skyscraper farms from scratch: A 30-story farm covering one city block would, estimates Despommier, produce enough food to feed 50,000 of its neighbors each year, with no pesticide runoff or other agricultural waste.
The technology that makes this kind of radical break with current practice possible is hydroponics (from the Greek hydros, water, and ponos, labor), a time-tested way of growing plants in liquid nutrient solutions. Soil, it turns out, is just a placeholder for the minerals and inorganic ions that plants absorb through their roots. Water does just as good a job, and for decades people have been growing certain crops hydroponically. In the state-of-the-art version proposed by Despommier, the plants will travel by automated conveyer belts past grow lights and through nutrient-rich solutions. Because such a farm would capture and reuse the water that evaporates from crop leaves, it would theoretically use just a fraction of the water that an outdoor farm of the same size uses, while producing dozens of varieties of fruits and vegetables. Further down the road, Despommier envisions genetically engineered and selectively bred plants that are perfectly suited for the environment (a nice tie-in with Monsanto et al.). Plant waste might go into an on-site biofuel distillery that produces part of the energy to run the farm.
In some climates, the rest of the energy might come from rooftop solar panels. The benefits of making each city partially self-sufficient in food are legion. A shorter supply chain means less oil use and less CO2 in the atmosphere. It means less farmland and more forest, again producing a cleaner environment. It means less water being pulled from rivers, lakes, and aquifers. And it means fresh vegetables available year-round to people who today don't eat nearly as well as they should. The vertical farm blends a whole lot of green ideas into one very attractive concept.
Vertical Farms' Growth Prospects
Is it doable at market prices? Not yet. The first few buildings would require serious subsidies, though not out of line with what is now being directed to solar power in some countries-or to current subsidies for traditional farming. In early 2008, it appeared that Despommier would have a chance to build a prototype, thanks to research grants from various sources. "Ten years from now," he predicted in a 2007 interview, "there will be vertical farms throughout the world. I guarantee it." At the moment there's nothing to invest in here, but if the concept works, it's easy to imagine a whole constellation of companies running such farms, making specialized gear and designing new plant varieties. So put vertical farming in the 2012 file.