I have written a number of posts about food security and the growing concern that as the global population increases there may not be enough food to go around. Not only does the global population continue to grow it continues to move. Earlier this decade analysts indicated that for the first time in history more people were living in urban than rural environments. Although most analysts agree that city dwellers use resources more efficiently than those living in rural areas, urbanites cannot produce all of the food they need to sustain themselves. Lack of space is one of the challenges faced by those living in urban areas. That lack of space generally convinces people that, as a concept, urban farming is non-starter. Having said that, I have written a couple of previous posts about urban farming (Urban Farmers and Precision Agriculture). In the first post, I discussed an idea raised by Dickson D. Despommier, a professor of public health at Columbia University. He recommends constructing agricultural skyscrapers that would support “vertical farming.” His ideas for high-rise farms take advantage of both hydroponic and aeroponic technologies. Despommier believes that vertical farming could be economically viable because crops grown indoors use less water, aren’t subject to weather damage, use less pesticides, and dramatically reduce transportation costs since the food is being grown nearby where it is going to be eaten.

Growing food indoors is being considered for a lot places even outside of the city [“Giant Greenhouses Mean Flavorful Tomatoes All Year,” by Chris Ladd, New York Times, 30 March 2010]. Ladd reports:

“An icy mixture of rain and sleet fell on the glass roof of Greenhouse Two at Backyard Farms here, but as its big blue door slid open and the warm, green, celery smell of tomato plants wafted out, it was summer. When it was built three years ago, the company’s first 24-acre greenhouse in Madison was already the largest building in Maine. This second connected greenhouse, completed last year, brought the total area under glass to some 42 acres, or roughly the size of 32 football fields. Even in the depths of winter, a million tomatoes ripen indoors to harvest each week, snipped from their vines by workers in T-shirts and shorts.”

Ladd notes that the Maine complex is only medium-sized when compared to “the 318-acre monster in Arizona” or the area around Leamington, Ontario, where “some 1,600 covered acres, roughly equivalent to putting Manhattan, south of Houston Street,” has been put under glass. To put the Maine complex into perspective, if you converted the office space available in the Empire State Building from square feet into acres it would amount to nearly 50 acres. According to Roberta Cook, a marketing economist, “In the U.S., it’s hard to be competitive without a 20-acre minimum block.” I’m assuming that the amount of vertical space needed in a city would be greater to help offset infrastructure costs. What also helps is the fact that customers are willing to pay a premium for out of season produce. Ladd reports that “with shoppers willing to pay a premium — even $4 to $5 a pound — for red vine-ripened ones with more flavor, greenhouse tomatoes now represent more than half of every dollar spent on fresh tomatoes in American supermarkets, according to figures from the Perishables Group, a market research firm in Chicago.” He goes on to explain how tomatoes are being grown indoors:

“The plants here at Backyard Farms number about 550,000. Each consists of two plants — the vines of new varieties, constantly tweaked for flavor, color, freshness and myriad other traits; and the roots of another, grafted together at a thickly scarred ‘V’ near the base. One half grows down into a sterile dirt-substitute made from fibers spun out of volcanic basalt, absorbing a custom hydroponic cocktail mixed by [Tim de Kok, one of the company’s head growers]. The other half stretches toward the glass ceiling, growing a foot every week along a nine-foot length of twine. When the plants reach the top, workers reel more twine from the spool, shift the entire row horizontally and band each vine to its neighbor so that by the end of a plant’s life it might grow parallel to the concrete floor for as many as 20 or 30 feet, a dozen vines tangled together like garden hoses, before each makes its own graceful turn upward. ‘It’s like a bonsai tree — you have to treat every plant exactly the same,’ Mr. de Kok said. ‘As soon as it gets uneven, that’s when it starts to get away from you.'”

With colorful vegetables hanging from suspended plants in Babylonian fashion, the operation is aesthetically pleasing as well as productive. Another benefit to growing tomatoes indoors is flavor. Ladd explains:

“As tomatoes ripen on the vine they develop more of those sugars and acids and other flavor elements. But most of the major farms growing tomatoes that are sold fresh year round are in areas where the climate is more hospitable to varieties best picked green. By creating their own climate — whether in Arizona, Maine or Canada — greenhouses allow growers to pick and ship tomatoes only when they’re ripe. That’s a major advantage. And while no one would mistake a Backyard Beauty for a tomato picked from a backyard in late summer — it is not as tender and its flavor is not as complex — it is juicier and has much more flavor than what you’d find in your deli sandwich.”

What makes greenhouse gardening (and, potentially, vertical farming) possible is advances in technology. Ladd continues:

“Some of the technical advances that have allowed for these changes don’t even seem like technology. Twenty years ago, the millions of blossoms on these vines would all have been pollinated by hand, electric vibrators shaking pollen loose from anther to pistil every 48 hours. Today, that work is done by bees, shipped in cardboard hives from Michigan that are stacked seven high at the end of the rows. Aphids, when they’re found, are kept in check by a small species of wasp, no bigger than a flying ant, that lays its eggs in the pest’s larvae. Lately, the greenhouse has been experimenting with interplanting young plants alongside older ones so that when one generation is discarded, the next is already yielding fruit. The aim is a continuous flow of production, tomatoes ripening fully on the vine year round and landing in outlets as far away as Maryland within 24 hours of harvest. … [During the winter months when daylight is shortened, Backyard Farms] employs some 20,000 high-pressure sodium lights, fueled by cheap power from Madison’s town-owned hydroelectric plant. Switched on, the lights use as much electricity in 32 minutes as the average American household does in a year. Some of its 200 employees wear sunglasses.”

That amount of electricity usage raises a number of environmental questions. Ladd indicates that it is a “touchy subject.”

“Backyard Farms’ chief executive, Roy Lubetkin, when pressed, pointed to biological controls like the wasps that allow the company to grow tomatoes without pesticides, and to the four-acre reservoir of reclaimed rain runoff that supplies, almost exclusively, their irrigation water. And because there is no dirt at Backyard Farms, fruit needn’t be washed. ‘It’s real sunlight, it’s real rainwater, these are real bees,’ he said. ‘What we’re really doing is allowing nature to do its thing.’ But which is greener, a field tomato shipped to Maine from Florida or one grown in-state in a greenhouse? ‘We’re redder,’ he said. Across from the four-acre reservoir of recycled runoff, hidden from the road, are three very large propane tanks that serve a boiler system that keeps temperatures hovering around 70 degrees year round. Two enormous tanks, filled with carbon dioxide, stand on end beside them. The gas, fed along the vines in perforated plastic bags, adds bulk to the fruit and speeds growth. The tanks suggest that greenhouse tomatoes, while delicious, aren’t particularly green. Such were the findings of a 2005 study by the British government that compared the ecological footprints of tomatoes grown locally in heated greenhouses with those grown in fields and imported from Spain. Even taking into account emissions from an additional 700 miles of shipping, the local greenhouse tomatoes were still responsible for emitting nearly four times more greenhouse gases than the imported fruit. Barring some advance in heating or lighting, or possibly even in the tomatoes themselves, such is the cost of perpetual summer.”

With the number of breakthroughs that are being announced on an almost daily basis, I’m guessing that solar and wind power will be able to dramatically reduce the carbon footprint of greenhouse or vertical farming in the future. One company that has already begun vertical farming is AeroFarms [“Aerofarms urban agriculture system – less space, less water and no pesticides,” by Sam Marginson, Gizmag, 11 June 2010]. Marginson reports:

“With increasing pressure on global food supplies requiring ever more intelligent use of technology, urbanized vertical aeroponic methods are shaping up as a promising alternative to traditional farming. Aeroponics requires less space, less water and no pesticides and the AeroFarms system takes things further by using LEDs in stacked units to maximize efficiency and use of available space. The AeroFarms system allows leafy greens and herbs in particular to be grown at room temperature indoors in urban environments. As soil is replaced by a proprietary reusable cloth growing medium, there’s no washing of produce required, resulting in an increase in shelf-life of anywhere from one to four weeks depending on what’s being grown. In addition, due to the indoor growing environment and shortened growth cycle, the lack of pests allows produce to be grown pesticide-free. Also, aeroponic methods use less than 20% of the water required by traditional agricultural methods and less than 80% of that required by hydroponic methods. Finally, transportation costs are almost negligible when compared to agricultural methods that make production in urban areas impossible. One criticism often leveled at aeroponic systems that use artificial light is that a significant amount of energy is required. Aerofarms’ seeks to minimize energy use through the use of LEDs which have nearly five times the life expectancy of High pressure sodium (HPS) lamps, can be placed closer to the plant (which assists in stacking) and can be designed to evenly distribute light to the crop. Aerofarms’ has also conducted research into what specific wavelengths of light are required by growing plants. By using LEDs that target these wavelengths, it’s thought that significant energy savings can be achieved. It should be pointed out, however, that Aerofarms’ system is not for hobby farmers. But if you’re thinking of setting up a commercial farm in an urban setting, the company claims a 20 to 33% return on investment.”

If urban farming ever becomes a serious contributor to the food supply, vertical farming will be the reason why. That doesn’t mean that industrious urbanites won’t get their hands dirty growing food the old-fashioned way. In some urban environments there is more fallow government-owned land than one might imagine. In the Salt Lake City area, people are putting some of that property to use [“Urban farms sprouting on government land,” by Jeremiah Stettler, Salt Lake Tribune, 10 August 2010]. Stettler reports:

“Standing in an open field spared from suburban sprawl, Diane Jones can’t help but wonder if she was born in the wrong century. She is a farmer at heart — just take a peek in the back of her truck at the basket of purple carrots, scarlet-red turnips and a radish that looks more like an icicle than a vegetable — who sees potential in a grassy swath of unused government land along 13800 South near 300 East. … Jones is among the first farmers to take advantage of Salt Lake County’s new urban-farming program, which leaders approved last year to put fallow public lands — set aside for future parks — to productive use until the county has money to develop them. The county reported this month that it will turn about 50 government acres into farm fields — allowing growers such as Bell Organic Gardens, Tagge’s Famous Fruit, Schmidt Family Farms and, of course, Jones’ Cottage Greens Farms to till the soil and plant seeds. It also has identified 29 acres that can be used for community gardens. In Salt Lake City, safflower already has sprouted from a once-empty plot that the capital has reserved for a future wastewater treatment plant. It now will produce hundreds of gallons of biofuel a year for the city’s fleet. … And it hasn’t cost taxpayers any extra money. … The county plans to lease the property to Jones for three years. After that, she will have the option of farming for an additional two years if officials aren’t ready to turn her land into a park.”

In closing, let me turn from fallow land to the petri dish. Perhaps the most fantastic food source I’ve read about that could be grown in an urban environment is meat from stem cells [“Jason Matheny’s Meatloaf from a Petri Dish,” by Elizabeth Lopatto, Bloomberg BusinessWeek, 27 May 2010]. Lopatto reports:

“Jason G. Matheny wants to take a single stem cell and make meatloaf. In 2004, Matheny, then 29, created a nonprofit called New Harvest to turn that idea into reality. Thanks in part to his efforts, meat made in petri dishes may arrive at supermarkets within 5 to 10 years. ‘It’s a way to satisfy the growing global demand for meat in a way that’s healthier, more energy efficient, and sustainable,’ says Matheny, who has an MBA from Duke University and is studying for a PhD in applied economics at Johns Hopkins University. Matheny’s meat starts in a lab, where scientists extract stem cells from animal muscles. The cells are placed in a nutrient bath to develop and then on plastic scaffolding that allows them to form into strips as they multiply. Mark Post, a professor of tissue engineering at Eindhoven University of Technology in the Netherlands, may be close to realizing New Harvest’s vision. Post’s lab is producing 2 mm thick strips that are almost an inch long and a quarter-inch wide. Pack enough together, and you’ve got a meal.”

The obvious question is: how does it taste? Post doesn’t know because he’s never tried eating it. “But he’s been told by those who have that it doesn’t taste like the real thing.” Although it may not sound appetizing, Matheny insists it sounds more appetizing than eating meat from animals that “are raised shoulder-to-shoulder, living in their own waste, pumped full of drugs, in a shed.” He claims that his process is like growing “hydroponic vegetables, in a way.” If vertical farming does catch on, I can see meat and vegetables growing together in high rise farms. It could even help lower the overall carbon footprint of vertical farming.

“Matheny claims that test tube meat could do more for the environment than ‘everyone trading their cars for bicycles,’ and he has a point: The meat industry generates some 18% of the world’s greenhouse gases, according to a 2006 UN report. That proportion is expected to grow as consumers in developing countries such as China and India consume more meat.”

Clearly the future of urban farming has yet to be determined. If I were the mayor of a big city with high unemployment and lots of vacant buildings, I might just start wondering whether or not there is an opportunity knocking.