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From the November 2009 Scientific American Magazine | 32 comments

Growing Skyscrapers: The Rise of Vertical Farms

Growing crops in city skyscrapers would use less water and fossil fuel than outdoor farming, eliminate agricultural runoff, and provide fresh food

By Dickson Despommier   

 


Kenn Brown Mondolithic Studios

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Key Concepts

  • Farming is ruining the environment, and not enough arable land remains to feed a projected 9.5 billion people by 2050.
  • Growing food in glass high-rises could drastically reduce fossil-fuel emissions and recycle city wastewater that now pollutes waterways.
  • A one-square-block farm 30 stories high could yield as much food as 2,400 outdoor acres, with less subsequent spoilage.
  • Existing hydroponic greenhouses provide a basis for prototype vertical farms now being considered by urban planners in cities worldwide.

More from the Magazine

Together the world’s 6.8 billion people use land equal in size to South America to grow food and raise livestock—an astounding agricultural footprint. And demographers predict the planet will host 9.5 billion people by 2050. Because each of us requires a minimum of 1,500 calories a day, civilization will have to cultivate another Brazil’s worth of land—2.1 billion acres—if farming continues to be practiced as it is today. That much new, arable earth simply does not exist. To quote the great American humorist Mark Twain: “Buy land. They’re not making it any more.”

Agriculture also uses 70 percent of the world’s available freshwater for irrigation, rendering it unusable for drinking as a result of contamination with fertilizers, pesticides, herbicides and silt. If current trends continue, safe drinking water will be impossible to come by in certain densely populated regions. Farming involves huge quantities of fossil fuels, too—20 percent of all the gasoline and diesel fuel consumed in the U.S. The resulting greenhouse gas emissions are of course a major concern, but so is the price of food as it becomes linked to the price of fuel, a mechanism that roughly doubled the cost of eating in most places worldwide between 2005 and 2008.

Some agronomists believe that the solution lies in even more intensive industrial farming, carried out by an ever decreasing number of highly mechanized farming consortia that grow crops having higher yields—a result of genetic modification and more powerful agrochemicals. Even if this solution were to be implemented, it is a short-term remedy at best, because the rapid shift in climate continues to rearrange the agricultural landscape, foiling even the most sophisticated strategies. Shortly after the Obama administration took office, Secretary of Energy Steven Chu warned the public that climate change could wipe out farming in California by the end of the century.

What is more, if we continue wholesale deforestation just to generate new farmland, global warming will accelerate at an even more catastrophic rate. And far greater volumes of agricultural runoff could well create enough aquatic “dead zones” to turn most estuaries and even parts of the oceans into barren wastelands.

As if all that were not enough to worry about, foodborne illnesses account for a significant number of deaths worldwide—salmonella, cholera, Escherichia coli and shigella, to name just a few. Even more of a problem are life-threatening parasitic infections, such as malaria and schistosomiasis. Furthermore, the common practice of using human feces as a fertilizer in most of Southeast Asia, many parts of Africa, and Central and South America (commercial fertilizers are too expensive) facilitates the spread of parasitic worm infections that afflict 2.5 billion people.

Clearly, radical change is needed. One strategic shift would do away with almost every ill just noted: grow crops indoors, under rigorously controlled conditions, in vertical farms. Plants grown in high-rise buildings erected on now vacant city lots and in large, multistory rooftop greenhouses could produce food year-round using significantly less water, producing little waste, with less risk of infectious diseases, and no need for fossil-fueled machinery or trans­port from distant rural farms. Vertical farming could revolutionize how we feed ourselves and the rising population to come. Our meals would taste better, too; “locally grown” would become the norm.

The working description I am about to explain might sound outrageous at first. But engineers, urban planners and agronomists who have scrutinized the necessary technologies are convinced that vertical farming is not only feasible but should be tried.

Do No Harm
Growing our food on land that used to be intact forests and prairies is killing the planet, setting up the processes of our own extinction. The minimum requirement should be a variation of the physician’s credo: “Do no harm.” In this case, do no further harm to the earth. Humans have risen to conquer impossible odds before. From Charles Darwin’s time in the mid-1800s and forward, with each Malthusian prediction of the end of the world because of a growing population came a series of technological breakthroughs that bailed us out. Farming machines of all kinds, improved fertilizers and pesticides, plants artificially bred for greater productivity and disease resistance, plus vaccines and drugs for common animal diseases all resulted in more food than the rising population needed to stay alive.



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