Farm capable of feeding 50,000 people could fit 'within a city block'
Rice on the seventh floor. Wheat on the twelfth. And enough food within an 18-story tower to feed a small city of 50,000.
Vertical farms, where staple crops could be grown in environmentally friendly skyscrapers, exist today only in futuristic designs and on optimistic Web sites. Despite concerns over sky-high costs, however, an environmental health expert in New York is convinced the world has the know-how to make the concept a reality — and the imperative to do so quickly.
With a raft of studies suggesting farmers will be hard-pressed to feed the extra 3 billion people swelling the world’s ranks by the year 2050, Columbia University professor Dickson Despommier believes a new model of agriculture is vital to avoid an impending catastrophe.
“The reason why we need vertical farming is that horizontal farming is failing,” he said. If current practices don’t change by mid-century, he points outs, an area bigger than Brazil would need to become farmland just to keep pace with the demand.
Working the soil has always been an uncertain venture, and Despommier argues that the price of crop failure is growing ever steeper as the global population mushrooms. “The world,” he said, “is running out of resources faster than what it can replace.”
Critics like Bruce Bugbee, a professor of crop physiology at Utah State University in Logan, see improvements in how future farmlands are managed as more practical and cost-effective. To Despommier, though, the world already has the need and the technology to dramatically improve yields and reliability by adjusting its point of view: from out to up.
The Columbia researcher said his interest in vertical farming is an extension of his long-standing work on disease transmission among humans. Among the laundry list of benefits he cites, Despommier believes vertical farming could help break the transmission cycle of diseases in traditional agricultural settings. But it’s the potential to help solve impending food shortages that really excites him.
A recent exercise conducted by students in his medical ecology class found that a self-sustaining vertical farm able to feed 50,000 people could “fit comfortably within a city block,” rising perhaps 18 stories. With adequate funding, a smaller prototype could be up and running in seven to 10 years, he predicts. Eventually, full-scale versions could be a new feature of city skylines, climbing as high as 30 stories and filled with automated feeders, monitoring devices and harvesting equipment. And, of course, they would feature crops such as wheat, rice, sugar beets and leafy greens grown in mineral nutrient solutions or without any solid substrates at all.
These hydroponic and aeroponic growing techniques, respectively, have benefited from NASA’s strong interest because any long-term venture to the moon or beyond would require the use of self-contained and resource-limited growth chambers. Despommier concedes that current practices must be improved and systems put in place to quickly identify and quarantine plants stricken with pests or disease. “No pun intended, but the bugs need to be worked out of this thing,” he said.
He insists, though, that money is the last major obstacle. To his critics, that hurdle has tripped up past entrepreneurs and may yet be insurmountable. “I can’t be very optimistic about this study,” said Utah State’s Bugbee. “None of this is very new. But it doesn’t mean the whole concept is without merit. It just means the claims are greatly exaggerated.”
Bugbee’s chief objection is the exorbitant power requirement for such a vertical structure. Plants on the lower floors would require artificial light year-round or expensive mechanical systems to get more light to them. And during a typical winter in northern U.S. cities, he said, average sunlight is only 5 percent to 10 percent of peak summer levels due to sapped intensity and shorter days.
“November, December, January and February are really dark,” Bugbee said. “Plants aren’t limited by the temperature, they’re limited by the light.” High-pressure sodium lights may be a reasonable stand-in for sunlight to maintain plant growth, he said, but the electric bill is enormous. “Boy have a lot of people gone bankrupt trying hydroponic greenhouses for that reason.”
Nevertheless, greenhouses such as Arizona’s 265-acre Eurofresh Farms are thriving with their hydroponic tomatoes and seedless cucumbers. Gene Giacomelli, Director of the Controlled Environment Agriculture Program at the University of Arizona in Tucson, said questions of safety, quality and sustainability are pushing agriculture in a host of other directions, including Despommier’s vertical farming idea. “He’s one extreme – a very good one,” Giacomelli said.
Several years ago, Giacomelli and collaborators in Arizona explored another extreme when they won a contract to design and build a growth chamber within a new building at Antarctica’s Amundsen-Scott Research Station. The chamber can be tweaked remotely by scientists back in Arizona but is now largely managed by volunteers at the station.
Besides supplying some much-needed color and light for the research station’s residents during Antarctica’s bleak and bitterly cold winter months, the indoor chamber has yielded a range of crunchy greens, tomatoes, cucumbers, hot and sweet peppers and even cantaloupe. Next year, a student will try to grow watermelon in what is arguably the worlds’ most inhospitable place for a garden. Remarkably, the plot has produced about two-thirds of what top greenhouses in North America can deliver.
“I like to say that we can grow any plant anywhere and any time, but for a price,” Giacomelli said. The catch in Antarctica is that electricity for the lights and pumps has inflated the cost to about $50 per pound of fresh vegetables . “Now, the local person at the supermarket would say you’re crazy for spending that much money on vegetables,” he said. “But you give that number to NASA and they’d say, ‘Wow, that’s a good number.’”
Back on Earth, Despommier said urban farms could defray some of their own expense by significantly cutting transportation costs. And as the local food movement gains in popularity with environmentally conscious consumers, he said, what could be more local than vertical farming? Despite a lack of major technological advances, the effort also stands to benefit from small but steady improvements in hydroponics and automated systems to control temperature, humidity and nutrient delivery, according to Giacomelli.
To curb the excessive reliance on electricity, Giacomelli’s own group is planning to experiment with fiber-optic tubes called solar pipes that can capture sunlight from the Antarctic growth chamber’s roof. Meanwhile, Utah State University researchers have developed a clear piece of curved polyethylene that can retain heat in the ground and extend the growing season by up to four months for summer squash and tomatoes.
As for keeping up with global food demand by growing crops such as rice and wheat, “we’re going to have to get better at farming marginal lands,” Bugbee said, “but it’s still going to be done outside because the sunlight is so cheap — well, free — and the sunlight levels are so high in the summer.”
He agrees that some farming will move toward more controlled environments, especially for high-value crops like fresh herbs that otherwise would be difficult to supply year-round. “Chefs will pay a lot for fresh basil,” Bugbee said, “but we’re not going to feed the world with that.”