The concept of vertical farm "skyscrapers" was first imagined a little over a decade ago by Columbia University professor Dickson Despommier.
Growing up — not out — Despommier contends, is one solution to the impending global food crisis and reducing energy consumption.
By 2050, the World Health Organization estimates that seven out of 10 people will live in a city, while global population is expected to hit 9 billion.
The United Nations projects that to feed all those extra mouths would require farmers to produce 70 percent more food globally by 2050, compared to 2009 levels.
Unfortunately, fields don't magically expand as the population gets bigger, and most of the world's available arable land is already being used.
Climate change, contributing to floods and droughts, is likely to reduce the amount of cultivatable land even further in the future.
Vertical farms, a space-saving technique that allows plants to be grown in stacked layers, one on top of the other, has been presented as a sustainable answer to the world's run on land and water resources.
At least that's how Jolanta Hardej, the CEO of the nation's largest indoor vertical farm, FarmedHere, sees it.
Vertical farms typically rely on hydroponics, the method of growing plants in nutrient-rich water instead of soil. FarmedHere, which celebrated its grand opening this week, uses something called aquaponics, which combines hydroponics with raising fish, or what's known as aquaculture.
The seeds of basil, arugula, and other leafy greens are placed in small baskets made of coconut shavings, called coconut cores. The seeds germinate under artificial (compact-fluorescent) light. Once the plants are about two to three inches tall, they are transferred to a vertical grow system, made up of five to six stacked beds. Each basket is placed in a foam float so that the roots of the plants are submerged in the water.
FarmedHereThe water comes from four 800-gallon tanks containing around 800 tilapia. The water, rich with fish waste, is filtered and clarified before it's fed to the plants. The water then goes back to the fish tanks in a closed-loop system. This enables the facility to conserve 97 percent of fresh water per farm acre compared to regular agriculture, according to Hardej. (Once the fish are full-grown they are also sold at market).
Because the lights are never turned off, the growing process continues through the night. As a result, FarmedHere's produce has a much shorter growing cycle than traditional agriculture.
Leafy greens grow in 14 to 16 days, whereas traditionally farmed arugula takes 50 days, Hardej claims. Similarly, basil's growing cycle is 20 to 22 days compared to the 48- to 60-day growing cycle at a traditional farm.
"We have a 99 percent crop success, whereas traditional farming typically has 75 percent success," Hardej said. Per equivalent unit of land, "yields are 20 times bigger than yields of traditional agriculture."
A greater output per acre of land is not the only obvious benefit of growing vegetables, fruits, and grains inside of tall buildings. A climate-controlled environment means farmers don't have to worry about weather hazards, like deep freezes or drought. Crops don't have be doused in herbicides and pesticides because insects aren't problem. And, because urban farms are inherently set up to reduce the distance between where food is grown and the consumers that buy and eat it, transportation costs and carbon footprint are markedly lower.
Hardej, for example, tries not to sell her produce in supermarkets that are farther than 20 to 25 miles from the facility.
The former mortgage broker expects to produce 300,000 pounds of leafy greens by the end of 2013 and 1 million pounds of leafy greens by the following year. All of this is being conducted in a 90,000 square-foot converted Chicago warehouse (which converts to 140,000 feet of farming space). The facility is only at 20 percent capacity right now, with around 25 full-time farmers, but it won't stay that way for long.
Eventually, Hardej expects to plant roots in urban areas throughout the country, from Los Angeles to New York City.
Still, vertical farming is long-off from replacing regular farming. Stan Cox, the author of "Any Way You Slice It: The Past, Present, and Future of Rationing," points out that vegetables (not counting potatoes since they can't grow in water) make up only 1.6 percent of our total cultivated land.
If we were to convert all horizontal farming to vertical at equivalent yield per acre, we would need the floorspace of 105,000 Empire State Buildings. "And that would still leave more than 98 percent of our crop production still out in the fields," he notes.